diff --git a/.cspell.config.yaml b/.cspell.config.yaml
index 4e91dee24f..293e39f0c7 100644
--- a/.cspell.config.yaml
+++ b/.cspell.config.yaml
@@ -374,7 +374,6 @@ words:
   - venv
   - vfalco
   - vinnie
-  - vkeylet
   - wasmi
   - wasmparser
   - Werror
@@ -398,3 +397,4 @@ words:
   - xxhasher
   - zstdio
   - CGNAT
+  - ungated
diff --git a/.github/actions/release-info/action.yml b/.github/actions/release-info/action.yml
index ab69a35f68..e03170b2c8 100644
--- a/.github/actions/release-info/action.yml
+++ b/.github/actions/release-info/action.yml
@@ -7,10 +7,10 @@ outputs:
     value: ${{ steps.version.outputs.version }}
   channel:
     description: "The release channel this build belongs to."
-    value: ${{ steps.channel.outputs.channel }}
+    value: ${{ steps.release_info.outputs.channel }}
   pkg_release:
-    description: "The package release number: 1 for a tag, the run number otherwise."
-    value: ${{ steps.pkg_release.outputs.pkg_release }}
+    description: "The package release number: 1 for a tag, <run number>.<commit date>git<short commit hash> otherwise."
+    value: ${{ steps.release_info.outputs.pkg_release }}
 
 runs:
   using: composite
@@ -39,52 +39,6 @@ runs:
 
         echo "version=${version}" | tee -a "${GITHUB_OUTPUT}"
 
-    # Only a tag says how mature a build is: a push is a develop build whatever
-    # its version, and a non-public codebase keeps its packages to itself.
-    - name: Determine release channel
-      id: channel
-      shell: bash
-      env:
-        IS_TAG: ${{ startsWith(github.ref, 'refs/tags/') }}
-        REF_NAME: ${{ github.ref_name }}
-        VISIBILITY: ${{ github.event.repository.visibility }}
-      run: |
-        pre_release=""
-        if [[ "${REF_NAME}" == *-* ]]; then
-            pre_release="${REF_NAME#*-}"
-        fi
-
-        if [[ "${VISIBILITY}" != "public" ]]; then
-            channel=private
-        elif [[ "${IS_TAG}" != "true" ]]; then
-            channel=develop
-        elif [[ -z "${pre_release}" ]]; then
-            channel=stable
-        elif [[ "${pre_release}" =~ ^rc[0-9]+(\+.*)?$ ]]; then
-            channel=rc
-        elif [[ "${pre_release}" =~ ^b(0|[1-9][0-9]*)(\+.*)?$ ]]; then
-            channel=beta
-        else
-            echo "Unsupported pre-release in tag '${REF_NAME}'. Use bN or rcN." >&2
-            exit 1
-        fi
-
-        echo "channel=${channel}" | tee -a "${GITHUB_OUTPUT}"
-
-    # A tag is packaged once, so its release number is fixed at 1. Develop builds
-    # repeat the same version, so the run number is what makes each push an
-    # upgrade rather than a reinstall.
-    - name: Determine package release
-      id: pkg_release
-      shell: bash
-      env:
-        IS_TAG: ${{ startsWith(github.ref, 'refs/tags/') }}
-        RUN_NUMBER: ${{ github.run_number }}
-      run: |
-        if [[ "${IS_TAG}" == "true" ]]; then
-            pkg_release=1
-        else
-            pkg_release="${RUN_NUMBER}"
-        fi
-
-        echo "pkg_release=${pkg_release}" | tee -a "${GITHUB_OUTPUT}"
+    - name: Determine release channel and package release
+      id: release_info
+      uses: XRPLF/actions/release-info@7cc0e4a8d9d0b838f92c48d312856b190341bbba
diff --git a/.github/actions/setup-nix-env/action.yml b/.github/actions/setup-nix-env/action.yml
index a95053e536..38b8365649 100644
--- a/.github/actions/setup-nix-env/action.yml
+++ b/.github/actions/setup-nix-env/action.yml
@@ -40,10 +40,11 @@ runs:
         # Unlike the Linux nix images, macOS needs no SSL_CERT_FILE: it has its
         # own trust store, and pinning would break TLS to hosts relying on it.
 
-        # Workspace-local, so `cleanup-workspace` clears it, but not the
-        # `.conan2` prepare-runner hands the system toolchain: that Conan is a
-        # different version, and the two would migrate each other's cache.
-        echo "CONAN_HOME=${{ github.workspace }}/.conan2-nix" >>"${GITHUB_ENV}"
+        # In RUNNER_TEMP, which the runner empties per job, like the `.conan2`
+        # prepare-runner hands the system toolchain - but under its own name:
+        # that Conan is a different version, and the two would migrate each
+        # other's cache.
+        echo "CONAN_HOME=${RUNNER_TEMP}/.conan2-nix" >>"${GITHUB_ENV}"
 
     # Config, profiles and remote, exactly as the dev shell sets them up on
     # entry; the `setup-conan` action is skipped for this toolchain.
diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
index 95d75c04b4..e0d511c467 100644
--- a/.github/pull_request_template.md
+++ b/.github/pull_request_template.md
@@ -18,7 +18,7 @@ If too broad, please consider splitting into multiple PRs.
 If there is a relevant task or issue, please link it here.
 -->
 
-### Context of Change
+## Context of Change
 
 <!--
 Please include the context of a change.
@@ -29,7 +29,7 @@ If a refactor, how is this better than the previous implementation?
 If there is a spec or design document for this feature, please link it here.
 -->
 
-### API Impact
+## API Impact
 
 <!--
 Please check [x] relevant options, delete irrelevant ones.
diff --git a/.github/scripts/strategy-matrix/linux.json b/.github/scripts/strategy-matrix/linux.json
index 731536a748..2229332e41 100644
--- a/.github/scripts/strategy-matrix/linux.json
+++ b/.github/scripts/strategy-matrix/linux.json
@@ -1,5 +1,5 @@
 {
-  "image_tag": "sha-473fe44",
+  "image_tag": "sha-060957e",
   "configs": {
     "ubuntu": [
       {
@@ -74,7 +74,7 @@
         "extra_cmake_args": "-Dvalidator_keys=ON",
         "package": {
           "type": "deb",
-          "image": "ghcr.io/xrplf/xrpld/packaging-debian:sha-45e4b88"
+          "image": "ghcr.io/xrplf/xrpld/packaging-debian:sha-49cdc10"
         }
       }
     ],
@@ -88,7 +88,7 @@
         "extra_cmake_args": "-Dvalidator_keys=ON",
         "package": {
           "type": "rpm",
-          "image": "ghcr.io/xrplf/xrpld/packaging-rhel:sha-45e4b88"
+          "image": "ghcr.io/xrplf/xrpld/packaging-rhel:sha-49cdc10"
         }
       }
     ]
diff --git a/.github/workflows/build-nix-images.yml b/.github/workflows/build-nix-images.yml
index a528786dd4..8ecf4912f5 100644
--- a/.github/workflows/build-nix-images.yml
+++ b/.github/workflows/build-nix-images.yml
@@ -5,15 +5,13 @@ on:
     branches:
       - develop
     paths:
-      - ".github/workflows/build-nix-images.yml"
       - "flake.nix"
       - "flake.lock"
       - "rust-toolchain.toml"
       - "nix/**"
       - "!nix/docker/README.md"
       - "!nix/devshell.nix"
-      - "!nix/check-tools/*.txt"
-      - "bin/check-tools.sh"
+      - "!nix/check-tools/**"
       - "bin/default-loader-path.sh"
       - "bin/install-sanitizer-libs.sh"
   pull_request:
@@ -25,7 +23,7 @@ on:
       - "nix/**"
       - "!nix/docker/README.md"
       - "!nix/devshell.nix"
-      - "!nix/check-tools/*.txt"
+      - "!nix/check-tools/**"
       - "bin/check-tools.sh"
       - "bin/default-loader-path.sh"
       - "bin/install-sanitizer-libs.sh"
@@ -60,7 +58,7 @@ jobs:
             base_image: debian:bookworm
           - name: rhel
             base_image: registry.access.redhat.com/ubi9/ubi:latest
-    uses: XRPLF/actions/.github/workflows/build-multiarch-image.yml@65d5a0bd72be4ecea95cff0673a6e0672ab5243a
+    uses: XRPLF/actions/.github/workflows/build-multiarch-image.yml@034e87065fcd0100214cf0672923bd38d193cf78
     with:
       image_name: xrpld/nix-${{ matrix.distro.name }}
       dockerfile: nix/docker/Dockerfile
diff --git a/.github/workflows/build-packaging-images.yml b/.github/workflows/build-packaging-images.yml
index fd04eae995..45fe338097 100644
--- a/.github/workflows/build-packaging-images.yml
+++ b/.github/workflows/build-packaging-images.yml
@@ -6,13 +6,13 @@ on:
       - develop
     paths:
       - ".github/workflows/build-packaging-images.yml"
-      - "package/Dockerfile"
-      - "package/install-packaging-tools.sh"
+      - "bin/install-packaging-tools.sh"
+      - "package/docker/**"
   pull_request:
     paths:
       - ".github/workflows/build-packaging-images.yml"
-      - "package/Dockerfile"
-      - "package/install-packaging-tools.sh"
+      - "bin/install-packaging-tools.sh"
+      - "package/docker/**"
   workflow_dispatch:
 
 concurrency:
@@ -41,9 +41,9 @@ jobs:
           # AlmaLinux rather than UBI, which does not ship rpm-sign.
           - name: rhel
             base_image: almalinux:10
-    uses: XRPLF/actions/.github/workflows/build-multiarch-image.yml@65d5a0bd72be4ecea95cff0673a6e0672ab5243a
+    uses: XRPLF/actions/.github/workflows/build-multiarch-image.yml@034e87065fcd0100214cf0672923bd38d193cf78
     with:
       image_name: xrpld/packaging-${{ matrix.distro.name }}
-      dockerfile: package/Dockerfile
+      dockerfile: package/docker/Dockerfile
       base_image: ${{ matrix.distro.base_image }}
       push: ${{ github.event_name == 'push' }}
diff --git a/.github/workflows/build-pre-commit-image.yml b/.github/workflows/build-pre-commit-image.yml
index 71f083b686..fc2d3f2ab2 100644
--- a/.github/workflows/build-pre-commit-image.yml
+++ b/.github/workflows/build-pre-commit-image.yml
@@ -30,7 +30,7 @@ jobs:
     permissions:
       contents: read
       packages: write
-    uses: XRPLF/actions/.github/workflows/build-multiarch-image.yml@65d5a0bd72be4ecea95cff0673a6e0672ab5243a
+    uses: XRPLF/actions/.github/workflows/build-multiarch-image.yml@034e87065fcd0100214cf0672923bd38d193cf78
     with:
       image_name: xrpld/pre-commit
       dockerfile: bin/pre-commit/Dockerfile
diff --git a/.github/workflows/cargo-audit.yml b/.github/workflows/cargo-audit.yml
index 6ddc6cdac9..6e613b822a 100644
--- a/.github/workflows/cargo-audit.yml
+++ b/.github/workflows/cargo-audit.yml
@@ -34,7 +34,7 @@ permissions:
 jobs:
   audit:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-473fe44
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-060957e
     permissions:
       contents: read
       # Needed to open an issue on scheduled failures.
diff --git a/.github/workflows/check-tools.yml b/.github/workflows/check-tools.yml
index 1169140481..4b1a81de17 100644
--- a/.github/workflows/check-tools.yml
+++ b/.github/workflows/check-tools.yml
@@ -79,7 +79,7 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@7bf7ceca5932114abdd0d43493c3c30c5a654e13
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
         with:
           enable_ccache: false
 
diff --git a/.github/workflows/pre-commit.yml b/.github/workflows/pre-commit.yml
index 1f6b69f087..25063b9dfa 100644
--- a/.github/workflows/pre-commit.yml
+++ b/.github/workflows/pre-commit.yml
@@ -14,7 +14,7 @@ on:
 jobs:
   # Call the workflow in the XRPLF/actions repo that runs the pre-commit hooks.
   run-hooks:
-    uses: XRPLF/actions/.github/workflows/pre-commit.yml@f1952595d212e86169935135efc66294b4574131
+    uses: XRPLF/actions/.github/workflows/pre-commit.yml@279ec358f4a1be4088be3e024b07916fa97c75b6
     with:
       runs_on: ubuntu-latest
       container: '{ "image": "ghcr.io/xrplf/xrpld/pre-commit:sha-473fe44" }'
diff --git a/.github/workflows/publish-docs.yml b/.github/workflows/publish-docs.yml
index 8c5d10929c..735ddfc906 100644
--- a/.github/workflows/publish-docs.yml
+++ b/.github/workflows/publish-docs.yml
@@ -41,13 +41,13 @@ env:
 jobs:
   build:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-473fe44
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-060957e
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@7bf7ceca5932114abdd0d43493c3c30c5a654e13
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
         with:
           enable_ccache: false
 
@@ -91,4 +91,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deploy
-        uses: actions/deploy-pages@cd2ce8fcbc39b97be8ca5fce6e763baed58fa128 # v5.0.0
+        uses: actions/deploy-pages@368f82528645a54fb793d4d04e342629a3f51346 # v5.0.1
diff --git a/.github/workflows/reusable-build-test-config.yml b/.github/workflows/reusable-build-test-config.yml
index dd13349d72..60d17a8705 100644
--- a/.github/workflows/reusable-build-test-config.yml
+++ b/.github/workflows/reusable-build-test-config.yml
@@ -129,7 +129,7 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@7bf7ceca5932114abdd0d43493c3c30c5a654e13
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
         with:
           enable_ccache: ${{ inputs.ccache_enabled }}
 
diff --git a/.github/workflows/reusable-clang-tidy.yml b/.github/workflows/reusable-clang-tidy.yml
index 2b72f235d0..5812e0ce46 100644
--- a/.github/workflows/reusable-clang-tidy.yml
+++ b/.github/workflows/reusable-clang-tidy.yml
@@ -34,7 +34,7 @@ jobs:
     needs: [determine-files]
     if: ${{ needs.determine-files.outputs.cpp_changed_files != '' || needs.determine-files.outputs.need_full_run == 'true' }}
     runs-on: ["self-hosted", "Linux", "X64", "heavy"]
-    container: "ghcr.io/xrplf/xrpld/nix-debian:sha-473fe44"
+    container: "ghcr.io/xrplf/xrpld/nix-debian:sha-060957e"
     permissions:
       contents: read
       issues: write
@@ -43,7 +43,7 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@7bf7ceca5932114abdd0d43493c3c30c5a654e13
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
         with:
           enable_ccache: false
 
diff --git a/.github/workflows/reusable-package.yml b/.github/workflows/reusable-package.yml
index aa9183be37..9dbc027176 100644
--- a/.github/workflows/reusable-package.yml
+++ b/.github/workflows/reusable-package.yml
@@ -1,11 +1,14 @@
-# Build Linux packages from the pre-built xrpld and validator-keys artifacts:
+# Build, verify and publish Linux packages from the pre-built xrpld and
+# validator-keys artifacts, in three stages:
 #
-#   - one job per config that carries a "package" map in linux.json
-#   - that map names the container image and the format it builds there
-#   - with 'publish: true' a job also uploads what it built
-#     (see package/publish_pkg.py)
+#   - 'package' builds and signs one format per config that carries a "package"
+#     map in linux.json; that map names the container image and the format
+#   - 'test-install' installs what was built on a range of distros and runs the
+#     binaries there, so a package that cannot be installed never reaches Nexus
+#   - 'publish' uploads with the image's publish_pkg.py, doing a --dry-run
+#     unless 'publish: true'
 #
-# Only linux/amd64 is supported; the runner is hardcoded in the job below.
+# Only linux/amd64 is supported; the runner is hardcoded in the jobs below.
 name: Package
 
 on:
@@ -39,6 +42,7 @@ defaults:
 
 env:
   BUILD_DIR: build
+  PACKAGE_DIR: packages
 
 jobs:
   generate-matrix:
@@ -70,12 +74,17 @@ jobs:
       contents: read
     runs-on: ["self-hosted", "Linux", "X64", "heavy"]
     container: ${{ matrix.image }}
-    timeout-minutes: 30
+    timeout-minutes: 10
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      - name: Prepare runner
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
+        with:
+          enable_ccache: false
+
       - name: Download pre-built xrpld binary
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -107,33 +116,194 @@ jobs:
               --pkg-release "${PKG_RELEASE}" \
               --channel "${CHANNEL}"
 
-      # Before the upload, so the artifact and the published package are the
-      # same bytes. DEBs are not signed, so the key is never set on that job.
+      # Before the upload, so the artifact, the tested package and the published
+      # package are the same bytes.
       - name: Sign RPM
         if: ${{ inputs.publish && matrix.package_type == 'rpm' }}
         env:
           PKG_SIGNING_KEY: ${{ secrets.signing_key }}
         run: ./package/sign_rpm.py --package-dir "${BUILD_DIR}"
 
+      # Split from the debug symbols, which are an order of magnitude larger, so
+      # that test-install downloads only what it installs.
       - name: Upload package artifact
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: ${{ matrix.xrpld_artifact_name }}-pkg
           path: |
-            ${{ env.BUILD_DIR }}/debbuild/*.deb
-            ${{ env.BUILD_DIR }}/debbuild/*.ddeb
-            ${{ env.BUILD_DIR }}/rpmbuild/RPMS/**/*.rpm
+            ${{ env.BUILD_DIR }}/debbuild/xrpld_*.deb
+            ${{ env.BUILD_DIR }}/rpmbuild/RPMS/**/xrpld-[0-9]*.rpm
           if-no-files-found: error
 
+      - name: Upload debug symbol artifact
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: ${{ matrix.xrpld_artifact_name }}-pkg-debug
+          path: |
+            ${{ env.BUILD_DIR }}/debbuild/xrpld-dbgsym_*.deb
+            ${{ env.BUILD_DIR }}/debbuild/xrpld-dbgsym_*.ddeb
+            ${{ env.BUILD_DIR }}/rpmbuild/RPMS/**/xrpld-debuginfo-*.rpm
+          if-no-files-found: error
+
+  # Every distro family the packages target, oldest release first, so both ends
+  # of the dependency range they declare are exercised.
+  test-install:
+    needs: [package]
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - package_type: deb
+            image: debian:11
+          - package_type: deb
+            image: debian:12
+          - package_type: deb
+            image: debian:13
+          - package_type: deb
+            image: ubuntu:20.04
+          - package_type: deb
+            image: ubuntu:22.04
+          - package_type: deb
+            image: ubuntu:24.04
+          - package_type: deb
+            image: ubuntu:26.04
+
+          - package_type: rpm
+            image: almalinux:9
+          - package_type: rpm
+            image: almalinux:10
+          - package_type: rpm
+            image: rockylinux/rockylinux:9
+          - package_type: rpm
+            image: rockylinux/rockylinux:10
+          - package_type: rpm
+            image: registry.access.redhat.com/ubi9/ubi
+          - package_type: rpm
+            image: registry.access.redhat.com/ubi10/ubi
+    name: "install ${{ matrix.package_type }} on ${{ matrix.image }}"
+    permissions:
+      contents: read
+    runs-on: ubuntu-latest
+    container: ${{ matrix.image }}
+    timeout-minutes: 5
+
+    steps:
+      # Both formats land in one directory; the step below picks its own by
+      # extension, so this stays independent of the artifact names.
+      - name: Download package artifacts
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          pattern: "*-pkg"
+          merge-multiple: true
+          path: ${{ env.PACKAGE_DIR }}
+
+      - name: Find the package
+        id: find
+        env:
+          PACKAGE_TYPE: ${{ matrix.package_type }}
+        run: |
+          package="$(find "${PACKAGE_DIR}" -type f -name "*.${PACKAGE_TYPE}" -print -quit)"
+          test -n "${package}" || {
+              echo "no .${PACKAGE_TYPE} found in ${PACKAGE_DIR}" >&2
+              exit 1
+          }
+          echo "package=${package}" >>"${GITHUB_OUTPUT}"
+
+      # Debian 11 went end-of-life on 2026-08-31
+      # (https://www.debian.org/News/2026/20260831) and its packages are
+      # already partly gone from deb.debian.org, so switch to the
+      # snapshot.debian.org entries the image ships commented out in its
+      # sources.list: they are pinned to the snapshot the image was built
+      # from, so they serve every version it needs and never go away.
+      # Snapshots keep their original, long-passed Valid-Until, hence the
+      # disabled check; the retries absorb snapshot.debian.org's throttling.
+      - name: Switch Debian 11 to snapshot.debian.org
+        if: ${{ matrix.image == 'debian:11' }}
+        run: |
+          sed -i 's|^deb |# deb |; s|^# deb http://snapshot|deb http://snapshot|' /etc/apt/sources.list
+          printf '%s\n' \
+              'Acquire::Check-Valid-Until "false";' \
+              'Acquire::Retries "3";' \
+              >/etc/apt/apt.conf.d/99snapshot
+
+      - name: Install the DEB
+        if: ${{ matrix.package_type == 'deb' }}
+        env:
+          DEBIAN_FRONTEND: noninteractive
+          PACKAGE: ${{ steps.find.outputs.package }}
+        run: |
+          # Stock Debian and Ubuntu images carry no package lists, so apt has
+          # nothing to resolve the systemd dependency from until it fetches them.
+          apt-get update -qq
+          apt-get install -y "./${PACKAGE}"
+
+      - name: Install the RPM
+        if: ${{ matrix.package_type == 'rpm' }}
+        env:
+          PACKAGE: ${{ steps.find.outputs.package }}
+        run: dnf install -y "./${PACKAGE}"
+
+      - name: Run xrpld
+        run: xrpld --version
+
+      - name: Run validator-keys
+        run: validator-keys --version
+
+      - name: Run rippled, the legacy compatibility symlink
+        run: rippled --version
+
+      - name: Check the service account
+        run: id xrpld
+
+      - name: Check the state directory
+        run: test -d /var/lib/xrpld
+
+      - name: Check the log directory
+        run: test -d /var/log/xrpld
+
+  publish:
+    needs: [generate-matrix, package, test-install]
+    strategy:
+      fail-fast: false
+      matrix: ${{ fromJson(needs.generate-matrix.outputs.matrix) }}
+    name: "publish ${{ matrix.xrpld_artifact_name }}"
+    permissions:
+      contents: read
+    runs-on: ["self-hosted", "Linux", "X64", "heavy"]
+    container: ${{ matrix.image }}
+    timeout-minutes: 30
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Prepare runner
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
+        with:
+          enable_ccache: false
+
+      # Both artifacts, so the debug symbols are published alongside the package.
+      - name: Download package artifacts
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          pattern: ${{ matrix.xrpld_artifact_name }}-pkg*
+          merge-multiple: true
+          path: ${{ env.PACKAGE_DIR }}
+
+      - name: Determine release info
+        id: release_info
+        uses: ./.github/actions/release-info
+
       - name: Publish package
-        if: ${{ inputs.publish }}
         env:
           CHANNEL: ${{ steps.release_info.outputs.channel }}
+          DRY_RUN_OPTION: ${{ !inputs.publish && '--dry-run' || '' }}
           NEXUS_URL: ${{ inputs.nexus_url }}
-          NEXUS_USERNAME: ${{ secrets.remote_username }}
-          NEXUS_PASSWORD: ${{ secrets.remote_password }}
+          NEXUS_USERNAME: ${{ inputs.publish && secrets.remote_username || '' }}
+          NEXUS_PASSWORD: ${{ inputs.publish && secrets.remote_password || '' }}
         run: |
-          ./package/publish_pkg.py \
+          publish_pkg.py \
               --channel "${CHANNEL}" \
-              --package-dir "${BUILD_DIR}" \
-              --nexus-url "${NEXUS_URL}"
+              --package-dir "${PACKAGE_DIR}" \
+              --nexus-url "${NEXUS_URL}" \
+              ${DRY_RUN_OPTION}
diff --git a/.github/workflows/reusable-rust.yml b/.github/workflows/reusable-rust.yml
index a0199f0129..12a31aacbd 100644
--- a/.github/workflows/reusable-rust.yml
+++ b/.github/workflows/reusable-rust.yml
@@ -1,8 +1,9 @@
 # Clippy, coverage and documentation for the Rust crates in crates/. Each runs
 # as an independent job on a GitHub-hosted runner, but inside the same container
 # image used to build the crates in the C++/Corrosion path, so the toolchain
-# (and therefore the lints, coverage instrumentation and the cargo cache) matches
-# what production builds use.
+# (and therefore the lints and the cargo cache) matches what production builds
+# use. Coverage is the exception: it needs the nightly rustc that honours
+# #[coverage(off)], which the image carries alongside the pinned stable.
 #
 # Rust unit tests are deliberately NOT run here. They run as part of the C++
 # build (reusable-build-test-config.yml), which already compiles the crates on a
@@ -27,7 +28,7 @@ permissions:
 jobs:
   clippy:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-473fe44
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-060957e
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -40,11 +41,14 @@ jobs:
 
   coverage:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-473fe44
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-060957e
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      - name: Use the nightly Rust toolchain
+        run: rust-nightly path >>"${GITHUB_PATH}"
+
       - name: Use cargo artifacts cache
         uses: ./.github/actions/cargo-cache
 
@@ -66,7 +70,7 @@ jobs:
 
   doc:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-473fe44
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-060957e
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
diff --git a/.github/workflows/reusable-upload-recipe.yml b/.github/workflows/reusable-upload-recipe.yml
index 608a5ea988..0511458e7f 100644
--- a/.github/workflows/reusable-upload-recipe.yml
+++ b/.github/workflows/reusable-upload-recipe.yml
@@ -40,7 +40,7 @@ defaults:
 jobs:
   upload:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-473fe44
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-060957e
     env:
       REMOTE_NAME: ${{ inputs.remote_name }}
       CONAN_LOGIN_USERNAME_XRPLF: ${{ secrets.remote_username }}
@@ -49,6 +49,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      - name: Prepare runner
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
+        with:
+          enable_ccache: false
+
       - name: Determine release info
         id: release_info
         uses: ./.github/actions/release-info
diff --git a/.github/workflows/upload-conan-deps.yml b/.github/workflows/upload-conan-deps.yml
index 184f13cc5e..526b647429 100644
--- a/.github/workflows/upload-conan-deps.yml
+++ b/.github/workflows/upload-conan-deps.yml
@@ -68,7 +68,7 @@ jobs:
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@7bf7ceca5932114abdd0d43493c3c30c5a654e13
+        uses: XRPLF/actions/prepare-runner@b3e255d74d785d053e4903da8ac90983cd7d9e82
         with:
           enable_ccache: false
 
diff --git a/.gitignore b/.gitignore
index c5af8eb7b4..5b21076af3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -72,11 +72,16 @@ DerivedData
 /.zed/
 
 # AI tools.
+# Shared/committable AI agent config (AGENTS.md, CLAUDE.md, GEMINI.md, .claude/settings.json,
+# tool-specific rules files, etc.) should be checked in — see CONTRIBUTING.md. Only the
+# personal/local variants below are ignored.
 /.agent
 /.agents
 /.augment
-/.claude
-/CLAUDE.md
+/.claude/settings.local.json
+AGENTS.override.md
+CLAUDE.local.md
+GEMINI.local.md
 
 # Python
 __pycache__
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index f223ab1684..8721ad7863 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -70,6 +70,11 @@ repos:
         language: system
         types: [rust]
         pass_filenames: false # rustfmt formats the whole workspace
+      - id: check-coverage-attrs
+        name: check Rust coverage attributes
+        entry: ./bin/pre-commit/check_rust_coverage_attrs.py
+        language: python
+        files: ^crates/.*\.rs$
 
   - repo: https://github.com/BlankSpruce/gersemi-pre-commit
     rev: e98930bdc210d3387007f9252d8c1694ea7e410f # frozen: 0.27.7
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000000..85bf9befb2
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,42 @@
+# AGENTS.md
+
+This file provides guidance to AI coding agents (Claude Code, and other AGENTS.md-compatible tools) when working with code in this repository.
+
+## Build
+
+Required on Linux/macOS: use the Nix devshell, which sets up the compiler, Conan, ccache, and (optionally) Rust automatically.
+
+```bash
+nix develop
+```
+
+For alternate devshell variants (specific compiler, no-compiler, coverage), see [docs/build/nix.md](./docs/build/nix.md). For the manual build steps, CMake options, and protocol codegen commands, see [BUILD.md](./BUILD.md) (`## Steps`, `## Options`, `## Code generation`).
+
+Rust crate tests (independent of the CMake build): `cargo test --manifest-path crates/Cargo.toml --workspace` (CI uses `cargo nextest`).
+
+## Testing
+
+Unit tests are a custom framework built into the `xrpld` binary itself (not Boost.Test/GTest/Catch); see [CONTRIBUTING.md](./CONTRIBUTING.md#unit-tests) for the basic invocation. Notes not covered there:
+
+- A suite's `--unittest` name is built from the arguments to its `BEAST_DEFINE_TESTSUITE`/`BEAST_DEFINE_TESTSUITE_PRIO` macro (usually at the bottom of the test file), in reverse order and joined with `.`: `BEAST_DEFINE_TESTSUITE(Credentials, app, xrpl)` → `xrpl.app.Credentials`.
+- `--unittest-arg` does nothing — don't use it.
+- Tests that run offline in under a minute should be automatic `--unittest` suites; anything else is a manual/integration test.
+- New tests should be written using `gtest` under `src/tests/` unless that isn't possible, in which case fall back to the legacy Beast framework under `src/test/`. `tests/` (top-level) holds integration tests exercised against `libxrpl`/`xrpld`.
+
+## Lint/Format
+
+See [CONTRIBUTING.md](./CONTRIBUTING.md#pre-commit-hooks) for `pre-commit` setup and [CONTRIBUTING.md](./CONTRIBUTING.md#clang-tidy) for `clang-tidy` (opt-in, needs local `clang-tidy` and generated headers).
+
+## Code Style
+
+New file placement and header levelization: see [CONTRIBUTING.md](./CONTRIBUTING.md#before-making-a-pull-request). Braces, whitespace, member order, and other conventions: see [docs/CodingStyle.md](./docs/CodingStyle.md). `XRPL_ASSERT`/`UNREACHABLE` contracts: see [CONTRIBUTING.md](./CONTRIBUTING.md#contracts-and-instrumentation). Commit messages: see [CONTRIBUTING.md](./CONTRIBUTING.md#good-commit-messages).
+
+## Architecture
+
+Paths below reflect the current layout; update this section if modularization moves a subsystem to a different directory.
+
+- `include/xrpl/` + `src/libxrpl/` — the core protocol library: ledger, shamap, consensus, crypto, json, resource, nodestore, rdb, peerfinder, and `tx/` (transaction application: `Transactor.cpp`, `applySteps.cpp`, invariants, payment paths). `tx/transactors/` has one file per transaction type, grouped by subsystem: `escrow/`, `vault/`, `lending/`, `sponsor/`, `nft/`, `token/` (MPT), `payment_channel/`, `permissioned_domain/`, `dex/`, `oracle/`, `did/`, `credentials/`, `bridge/`, `check/`, `delegate/`, `account/`, `system/`. Any change to transaction-processing behavior must be gated behind an Amendment.
+- `src/xrpld/` — the server application built on top of `libxrpl`: `app`, `core`, `overlay` (P2P networking), `peerfinder`, `perflog`, `rpc`, `shamap`. `main` builds an `ApplicationImp` implementing `Application`; most components hold a reference to it (`app_`), giving broad cross-component access — expect to trace call chains through `Application&`.
+- `src/test/` — unit tests mirroring the subsystems above, plus `jtx/` (the transaction-building test DSL — e.g. `jtx/escrow.h`, `jtx/vault.h`, `jtx/sponsor.h`, `jtx/permissioned_dex.h`) and `unit_test/` (the custom test framework itself, derived from Beast).
+- `src/tests/` — unit tests for `libxrpl` written in `gtest`, gradually replacing the `src/test` equivalents.
+- `crates/` — a Rust workspace (only built with `-Dxrpld -Drust=ON`) bridged into C++ via `cxxbridge`/the `cxx` crate; currently just a `hello_world` interop scaffold. Requires the Rust toolchain pinned in `rust-toolchain.toml` (the Nix devshell provides it automatically).
diff --git a/API-CHANGELOG.md b/API-CHANGELOG.md
index d521f9c024..ed27312023 100644
--- a/API-CHANGELOG.md
+++ b/API-CHANGELOG.md
@@ -22,17 +22,47 @@ API version 2 is available in `xrpld` version 2.0.0 and later. See [API-VERSION-
 
 This version is supported by all `xrpld` versions. For WebSocket and HTTP JSON-RPC requests, it is currently the default API version used when no `api_version` is specified.
 
-## Unreleased
+## XRP Ledger server version 3.4.0
 
-This section contains changes targeting a future version.
+Version 3.4.0 is not yet released. These changes are available in the 3.4.0 beta releases.
 
-### Additions
+### Additions in 3.4.0
 
-- `account_tx`: Added an optional `delegate` request object to filter delegated transactions. The object requires `delegate_filter`, which must be either `actor` for transactions owned by the requested account but signed by another account, or `authorizer` for transactions signed by the requested account on behalf of another account. The optional `counter_party` account narrows the results to a specific signer/delegate for `actor` or a specific owner/delegator for `authorizer`. Malformed `delegate`, `delegate_filter`, and `counter_party` values return standard invalid field errors, and invalid account IDs return `actMalformed`.
-  When paginating delegate-filtered queries, a marker from a delegate-filtered query includes a `delegate` flag and is only valid for follow-up requests that also supply `delegate` (mixing marker conventions returns `invalidParams`). Because filtering is applied after the ledger scan, a page may contain fewer results than `limit` (possibly zero) while still returning a marker, so callers must continue until no marker is present.
+- `ledger`: `nftoken_id`, `nftoken_ids`, and `offer_id` are now included in transaction metadata when transactions are expanded (`expand`, or admin-only `full`), matching the `tx`, `account_tx`, and `subscribe` (`transactions` stream) responses. ([#5706](https://github.com/XRPLF/rippled/pull/5706))
+
+### Bugfixes in 3.4.0
+
+- `sign`, `sign_for`, `submit`: `signature_target` now returns `invalidParams` unless it names `CounterpartySignature` or `SponsorSignature`. It previously accepted any inner object field, such as `Book` or `NFToken`, and signed into it.
+- `sign`, `sign_for`, `submit`, `submit_multisigned`: With `fixCleanup3_4_0` enabled, a signature in `CounterpartySignature` or `SponsorSignature` covers a different prefix than the transaction's own signature, so a signature can no longer be moved from one of those roles into another. Clients that build these signatures themselves must use the new prefixes: `CPT` and `CPM` (single- and multi-signing) for `CounterpartySignature`, and `SPN` and `SPM` for `SponsorSignature`.
+- `get_aggregate_price`: Duplicate entries in the `oracles` request array are now ignored. [#6586](https://github.com/XRPLF/rippled/pull/6586)
+- `vault_info`: Errors now identify what the request got wrong instead of reporting every failure as the unregistered token `malformedRequest`, and the `error`, `error_code` and `error_message` fields now agree with each other. An invalid `vault_id` or `seq` returns `invalidParams`, an invalid `owner` returns `actMalformed`, and a request that mixes `vault_id` with `owner`/`seq` or supplies neither returns `invalidParams` with a message naming the accepted combinations. [#8015](https://github.com/XRPLF/rippled/pull/8015)
+- `vault_info`: A well-formed all-zero `vault_id` now returns `entryNotFound` instead of being rejected as malformed, and `entryNotFound` responses now include `error_code` and `error_message`. Clients that request `ripplerpc` 3.0 or above therefore receive HTTP 400 with that error rather than HTTP 200. [#8015](https://github.com/XRPLF/rippled/pull/8015)
+- `vault_info`: `vault_id` and `owner` must now be strings, matching how `ledger_entry` reads the same fields. An object or an array in either field previously produced an internal error, and a number was silently converted to its decimal text; `vault_id` now returns `invalidParams` and `owner` returns `actMalformed`. [#8015](https://github.com/XRPLF/rippled/pull/8015)
+- `gateway_balances`: The `account` and `ident` fields now return an `invalidParams` error if the value is not a string, instead of an `internal` error. [#7655](https://github.com/XRPLF/rippled/pull/7655)
+- `account_lines`: The `peer` field now returns an error if the value is not a string. [#7728](https://github.com/XRPLF/rippled/pull/7728)
+- `ledger`: `delivered_amount` is now included in the metadata of successful `AccountDelete` transactions when transactions are expanded (`expand`, or admin-only `full`). Previously it was only added for `Payment` and `CheckCash`, which made `ledger` inconsistent with `tx` and `account_tx`. [#5706](https://github.com/XRPLF/rippled/pull/5706)
+
+## XRP Ledger server version 3.3.0
+
+[Version 3.3.0](https://github.com/XRPLF/rippled/releases/tag/3.3.0) was released on Aug 6, 2026.
+
+### Additions in 3.3.0
+
+- `account_tx`: Added an optional `delegate` request object to filter delegated transactions. The object requires `delegate_filter`, which must be either `actor` for transactions owned by the requested account but signed by another account, or `authorizer` for transactions signed by the requested account on behalf of another account. The optional `counter_party` account narrows the results to a specific signer/delegate for `actor` or a specific owner/delegator for `authorizer`. Malformed `delegate`, `delegate_filter`, and `counter_party` values return standard invalid field errors, and invalid account IDs return `actMalformed`. When paginating delegate-filtered queries, a marker from a delegate-filtered query includes a `delegate` flag and is only valid for follow-up requests that also supply `delegate` (mixing marker conventions returns `invalidParams`). Because filtering is applied after the ledger scan, a page may contain fewer results than `limit` (possibly zero) while still returning a marker, so callers must continue until no marker is present. ([#6126](https://github.com/XRPLF/rippled/pull/6126))
+
+## XRP Ledger server version 3.2.1
+
+[Version 3.2.1](https://github.com/XRPLF/rippled/releases/tag/3.2.1) was released on Aug 1, 2026.
+
+This release contains bug fixes only and no API changes.
+
+## XRP Ledger server version 3.2.0
+
+[Version 3.2.0](https://github.com/XRPLF/rippled/releases/tag/3.2.0) was released on Jun 16, 2026.
+
+### Additions in 3.2.0
 
 - `ledger_entry`, `account_objects`: The `Delegate` ledger entry now includes an optional `DestinationNode` field, which stores the index into the authorized account's owner directory. This field is present on entries created after bidirectional directory tracking was introduced and may appear in RPC responses for those entries. ([#6681](https://github.com/XRPLF/rippled/pull/6681))
-
 - `server_definitions`: Added the following new sections to the response ([#6321](https://github.com/XRPLF/rippled/pull/6321)):
   - `TRANSACTION_FORMATS`: Describes the fields and their optionality for each transaction type, including common fields shared across all transactions.
   - `LEDGER_ENTRY_FORMATS`: Describes the fields and their optionality for each ledger entry type, including common fields shared across all ledger entries.
@@ -40,9 +70,8 @@ This section contains changes targeting a future version.
   - `LEDGER_ENTRY_FLAGS`: Maps ledger entry type names to their flags and flag values.
   - `ACCOUNT_SET_FLAGS`: Maps AccountSet flag names (asf flags) to their numeric values.
 
-### Bugfixes
+### Bugfixes in 3.2.0
 
-- `get_aggregate_price`: Duplicate entries in the `oracles` request array are now ignored. [#6586](https://github.com/XRPLF/rippled/pull/6586)
 - Peer Crawler: The `port` field in `overlay.active[]` now consistently returns an integer instead of a string for outbound peers. [#6318](https://github.com/XRPLF/rippled/pull/6318)
 - `ping`: The `ip` field is no longer returned as an empty string for proxied connections without a forwarded-for header. It is now omitted, consistent with the behavior for identified connections. [#6730](https://github.com/XRPLF/rippled/pull/6730)
 - gRPC `GetLedgerDiff`: Fixed error message that incorrectly said "base ledger not validated" when the desired ledger was not validated. [#6730](https://github.com/XRPLF/rippled/pull/6730)
@@ -54,11 +83,24 @@ This section contains changes targeting a future version.
 - `submit`: The `fail_hard` field now returns an error if the value is not a boolean. [#6529](https://github.com/XRPLF/rippled/pull/6529)
 - `subscribe`: The `taker` field in the `books` array now returns `actMalformed` instead of `badIssuer` if the value is not a valid account. [#6529](https://github.com/XRPLF/rippled/pull/6529)
 - Fixed a bug in `Forwarded` HTTP header parsing where the extracted IP address could be incorrect when no comma or semicolon delimiter follows the address. This could cause the server to misidentify a client's IP address when operating behind a reverse proxy. [#6529](https://github.com/XRPLF/rippled/pull/6529)
-- `vault_info`: Errors now identify what the request got wrong instead of reporting every failure as the unregistered token `malformedRequest`, and the `error`, `error_code` and `error_message` fields now agree with each other. An invalid `vault_id` or `seq` returns `invalidParams`, an invalid `owner` returns `actMalformed`, and a request that mixes `vault_id` with `owner`/`seq` or supplies neither returns `invalidParams` with a message naming the accepted combinations. [#8015](https://github.com/XRPLF/rippled/pull/8015)
-- `vault_info`: A well-formed all-zero `vault_id` now returns `entryNotFound` instead of being rejected as malformed, and `entryNotFound` responses now include `error_code` and `error_message`. Clients that request `ripplerpc` 3.0 or above therefore receive HTTP 400 with that error rather than HTTP 200. [#8015](https://github.com/XRPLF/rippled/pull/8015)
-- `vault_info`: `vault_id` and `owner` must now be strings, matching how `ledger_entry` reads the same fields. An object or an array in either field previously produced an internal error, and a number was silently converted to its decimal text; `vault_id` now returns `invalidParams` and `owner` returns `actMalformed`. [#8015](https://github.com/XRPLF/rippled/pull/8015)
-- `gateway_balances`: The `account` and `ident` fields now return an `invalidParams` error if the value is not a string, instead of an `internal` error. [#7655](https://github.com/XRPLF/rippled/pull/7655)
-- `account_lines`: The `peer` field now returns an error if the value is not a string. [#7728](https://github.com/XRPLF/rippled/pull/7728)
+
+## XRP Ledger server version 3.1.3
+
+[Version 3.1.3](https://github.com/XRPLF/rippled/releases/tag/3.1.3) was released on May 8, 2026.
+
+This release contains bug fixes only and no API changes.
+
+## XRP Ledger server version 3.1.2
+
+[Version 3.1.2](https://github.com/XRPLF/rippled/releases/tag/3.1.2) was released on Mar 12, 2026.
+
+This release contains bug fixes only and no API changes.
+
+## XRP Ledger server version 3.1.1
+
+[Version 3.1.1](https://github.com/XRPLF/rippled/releases/tag/3.1.1) was released on Feb 23, 2026.
+
+This release contains bug fixes only and no API changes.
 
 ## XRP Ledger server version 3.1.0
 
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 120000
index 0000000000..47dc3e3d86
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1 @@
+AGENTS.md
\ No newline at end of file
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index de2aff5325..5fed795778 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -59,6 +59,17 @@ to an existing XLS. Neither change will be released (in an amendment's
 case, marked as `Supported::yes`) until the corresponding XLS's status
 is `Final`.
 
+## AI coding agents
+
+[`AGENTS.md`](./AGENTS.md) (and its `CLAUDE.md` symlink, for Claude Code) holds shared, checked-in guidance for AI coding agents working in this repository — build/test/lint commands and architecture notes. Additional `AGENTS.md` files may exist in subdirectories to give agents context specific to that part of the codebase; whenever you add one, also add a `CLAUDE.md` symlink pointing to it (`ln -s AGENTS.md CLAUDE.md`) so Claude Code picks it up too.
+
+If you want to give an agent personal instructions that shouldn't be shared with other contributors (e.g. your own workflow preferences), those are gitignored, not checked in:
+
+- `CLAUDE.local.md` — read by Claude Code alongside `CLAUDE.md`.
+- `AGENTS.override.md` — read by AGENTS.md-compatible tools that support a personal override file layered on top of `AGENTS.md`.
+
+Likewise, `.claude/settings.local.json` is for personal, untracked Claude Code settings, while `.claude/settings.json` is shared.
+
 ## Before making a pull request
 
 (Or marking a draft pull request as ready.)
@@ -82,7 +93,7 @@ If you create new source files, they must be organized as follows:
   under `include/xrpl`, and source (`.cpp`) files must go under
   `src/libxrpl`.
 - All other non-test files must go under `src/xrpld`.
-- All test source files must go under `src/test`.
+- New test source files should use `gtest` and go under `src/tests`, unless that isn't possible, in which case they should use our legacy test framework and go under `src/test`.
 - All benchmark source files must go under `src/benchmarks`.
 
 The source must be formatted according to the style guide below. The easiest
diff --git a/bin/check-tools.sh b/bin/check-tools.sh
index 8273375428..ed76861aa4 100755
--- a/bin/check-tools.sh
+++ b/bin/check-tools.sh
@@ -158,6 +158,7 @@ if [ "${os}" = "linux" ] || [ "${os}" = "macos" ]; then
     check cargo-nextest cargo nextest --version
     check clippy-driver
     check rust-analyzer
+    check rust-nightly rust-nightly run rustc --version
     check rustc
     check rustfmt
 fi
diff --git a/package/install-packaging-tools.sh b/bin/install-packaging-tools.sh
similarity index 88%
rename from package/install-packaging-tools.sh
rename to bin/install-packaging-tools.sh
index 36557364ae..0d1fce3055 100755
--- a/package/install-packaging-tools.sh
+++ b/bin/install-packaging-tools.sh
@@ -25,7 +25,9 @@ esac
 # Packaging runs in a vanilla distro image, so the tooling comes from the distro's
 # archive rather than from nixpkgs:
 #
-#   - debhelper and dpkg-dev build the DEB
+#   - debhelper and dpkg-dev build the DEB, and lintian checks it
+#   - binutils gives debian/rules the readelf its glibc-floor check runs; it
+#     already arrives via dpkg-dev, but that tool is called directly
 #   - rpm-build builds the RPM, with systemd-rpm-macros and redhat-rpm-config
 #     supplying the systemd and find-debuginfo macros the spec uses
 #   - rpm-sign and gnupg2 sign the built RPM
@@ -37,11 +39,13 @@ function install() {
         debian | ubuntu)
             apt-get update -y
             apt-get install -y --no-install-recommends \
+                binutils \
                 ca-certificates \
                 debhelper \
                 debhelper-compat \
                 dpkg-dev \
                 git \
+                lintian \
                 python3
             ;;
 
diff --git a/bin/pre-commit/check_rust_coverage_attrs.py b/bin/pre-commit/check_rust_coverage_attrs.py
new file mode 100755
index 0000000000..dba56d5756
--- /dev/null
+++ b/bin/pre-commit/check_rust_coverage_attrs.py
@@ -0,0 +1,149 @@
+#!/usr/bin/env python3
+"""
+Check that Rust unit tests stay out of the coverage report.
+
+cargo-llvm-cov instruments the test code along with everything else, so a test
+module that is not excluded counts its own body as covered and inflates the
+reported number. Excluding it takes two attributes:
+
+  * every `#[cfg(test)]` module carries
+    `#[cfg_attr(coverage_nightly, coverage(off))]`;
+  * every crate root (lib.rs, main.rs) carries
+    `#![cfg_attr(coverage_nightly, feature(coverage_attribute))]`, which the
+    attribute above needs in order to compile.
+
+Both are inert outside the coverage job: cargo-llvm-cov defines
+`coverage_nightly` only when it runs on a nightly toolchain.
+
+The crate-root gate is checked even in a crate that has no tests yet, because
+that is what lets the first test module added later carry the attribute without
+a build failure. Missing it is a hard error, so it cannot go unnoticed; a
+missing `coverage(off)` fails open, which is why this check exists.
+
+Matching is on exact attribute text, which works because `cargo fmt` runs over
+the whole workspace in the hook ahead of this one: rustfmt puts every attribute
+on its own line and normalizes what is inside it, turning `#[cfg( test )]`
+and `#[cfg(test,)]` alike into `#[cfg(test)]`. So there is nothing here that
+parses Rust. The price is that a cfg this file does not spell out literally --
+`all(test, ...)`, `any(test, ...)`, `not(test)` -- is reported rather than
+classified, on the grounds that guessing at coverage semantics is how a check
+like this ends up quietly wrong.
+
+Usage: ./bin/pre-commit/check_rust_coverage_attrs.py <file1> <file2> ...
+
+Exit status is non-zero if any violation is found.
+"""
+
+import re
+import sys
+from dataclasses import dataclass
+from pathlib import Path
+
+CRATE_ROOTS = {"lib.rs", "main.rs"}
+
+FEATURE_ATTR = "#![cfg_attr(coverage_nightly, feature(coverage_attribute))]"
+COVERAGE_OFF_ATTR = "#[cfg_attr(coverage_nightly, coverage(off))]"
+CFG_TEST_ATTR = "#[cfg(test)]"
+
+# Any other cfg that mentions `test`. String literals are blanked before this
+# runs, so `feature = "test"` does not read as the `test` cfg.
+RE_CFG_MENTIONS_TEST = re.compile(r"^#\[cfg\(.*\btest\b.*\)\]$")
+RE_STRING = re.compile(r'"(?:[^"\\]|\\.)*"')
+RE_MOD = re.compile(r"^(?:pub(?:\([^)]*\))?\s+)?mod\s+([A-Za-z_]\w*)")
+
+
+@dataclass(frozen=True)
+class Finding:
+    line: int
+    label: str
+    message: str
+
+
+def _check_module(attrs: list[str], line: int, name: str) -> list[Finding]:
+    """Findings for one module, given the attributes attached to it."""
+    if COVERAGE_OFF_ATTR in attrs:
+        return []  # excluded from coverage; which cfg gates it does not matter
+    if CFG_TEST_ATTR in attrs:
+        return [
+            Finding(
+                line,
+                "missing-coverage-off",
+                f"`mod {name}` is #[cfg(test)] but not excluded from coverage; "
+                f"add {COVERAGE_OFF_ATTR}",
+            )
+        ]
+    unclassified = [
+        attr for attr in attrs if RE_CFG_MENTIONS_TEST.match(RE_STRING.sub('""', attr))
+    ]
+    if unclassified:
+        return [
+            Finding(
+                line,
+                "unclassified-cfg",
+                f"`mod {name}` is gated on {unclassified[0]}, which this check "
+                f"cannot tell apart from a module that ships in the library; "
+                f"add {COVERAGE_OFF_ATTR} if it is test-only, or teach this "
+                f"check the cfg if it is not",
+            )
+        ]
+    return []
+
+
+def _check_test_modules(lines: list[str]) -> list[Finding]:
+    """Findings for every test module that is not excluded from coverage."""
+    findings: list[Finding] = []
+    attrs: list[str] = []
+    attrs_line = 0
+    for number, raw in enumerate(lines, start=1):
+        stripped = raw.strip()
+        # Blank lines and comments are allowed between an attribute and its item.
+        if not stripped or stripped.startswith("//"):
+            continue
+        if stripped.startswith("#["):
+            if not attrs:
+                attrs_line = number
+            attrs.append(stripped)
+            continue
+        module = RE_MOD.match(stripped)
+        if module is not None and attrs:
+            findings += _check_module(attrs, attrs_line, module.group(1))
+        attrs = []
+    return findings
+
+
+def _check_crate_root(name: str, lines: list[str]) -> list[Finding]:
+    """A finding if a crate root is missing the coverage_attribute feature gate."""
+    if name not in CRATE_ROOTS:
+        return []
+    if any(line.strip() == FEATURE_ATTR for line in lines):
+        return []
+    return [
+        Finding(
+            1,
+            "missing-feature-gate",
+            f"crate root is missing {FEATURE_ATTR}",
+        )
+    ]
+
+
+def check_source(name: str, text: str) -> list[Finding]:
+    """Findings for one file's contents; `name` is its base name (lib.rs, ...)."""
+    lines = text.splitlines()
+    return _check_crate_root(name, lines) + _check_test_modules(lines)
+
+
+def check_file(path: Path) -> list[Finding]:
+    return check_source(path.name, path.read_text(encoding="utf-8"))
+
+
+def main() -> int:
+    total = 0
+    for path in (Path(name) for name in sys.argv[1:]):
+        for finding in check_file(path):
+            total += 1
+            print(f"{path}:{finding.line}: {finding.label}: {finding.message}")
+    return 1 if total else 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/crates/Cargo.toml b/crates/Cargo.toml
index d08f4da233..37dde89213 100644
--- a/crates/Cargo.toml
+++ b/crates/Cargo.toml
@@ -14,6 +14,9 @@ cxx = { version = "1.0.199", features = ["c++20"] }
 [workspace.package]
 edition = "2024"
 
+[workspace.lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = [ 'cfg(coverage)', 'cfg(coverage_nightly)' ] }
+
 [profile.release]
 opt-level = 3
 overflow-checks = true
diff --git a/crates/xrpl-host-functions-macros/Cargo.toml b/crates/xrpl-host-functions-macros/Cargo.toml
index d24ca268d0..db9ec19da7 100644
--- a/crates/xrpl-host-functions-macros/Cargo.toml
+++ b/crates/xrpl-host-functions-macros/Cargo.toml
@@ -16,3 +16,6 @@ proc-macro2 = "1"
 # the library build graph.
 [dev-dependencies]
 xrpl-host-functions.path = "../xrpl-host-functions"
+
+[lints]
+workspace = true
diff --git a/crates/xrpl-host-functions/Cargo.toml b/crates/xrpl-host-functions/Cargo.toml
index ac67c8b465..422085fd80 100644
--- a/crates/xrpl-host-functions/Cargo.toml
+++ b/crates/xrpl-host-functions/Cargo.toml
@@ -18,3 +18,6 @@ xrpl-host-functions-macros.path = "../xrpl-host-functions-macros"
 [features]
 default = []
 wasmi_glue = []
+
+[lints]
+workspace = true
diff --git a/crates/xrpl-wasm-testkit/Cargo.toml b/crates/xrpl-wasm-testkit/Cargo.toml
index 21b929bae1..4bf6505efb 100644
--- a/crates/xrpl-wasm-testkit/Cargo.toml
+++ b/crates/xrpl-wasm-testkit/Cargo.toml
@@ -10,3 +10,6 @@ crate-type = ["staticlib", "rlib"]
 cxx.workspace = true
 wat = "1"
 xrpl-host-functions = { path = "../xrpl-host-functions" }
+
+[lints]
+workspace = true
diff --git a/crates/xrpl-wasm-vm-ffi/Cargo.toml b/crates/xrpl-wasm-vm-ffi/Cargo.toml
index c301eb707a..2a3b371d92 100644
--- a/crates/xrpl-wasm-vm-ffi/Cargo.toml
+++ b/crates/xrpl-wasm-vm-ffi/Cargo.toml
@@ -10,3 +10,6 @@ crate-type = ["staticlib", "rlib"]
 cxx.workspace = true
 xrpl-host-functions = { path = "../xrpl-host-functions" }
 xrpl-wasm-vm = { path = "../xrpl-wasm-vm" }
+
+[lints]
+workspace = true
diff --git a/docs/install.md b/docs/install.md
index 01cfc144a1..4c52b587b6 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -13,7 +13,7 @@ To build from source instead, see [BUILD.md](../BUILD.md).
 
 Packages are published to four channels:
 
-- `stable` - the latest production release
+- `stable` - production releases
 - `rc` - release candidates
 - `beta` - beta builds
 - `develop` - every push to the [`develop` branch](https://github.com/XRPLF/rippled/tree/develop)
diff --git a/include/xrpl/core/HashRouter.h b/include/xrpl/core/HashRouter.h
index 20aafecc5f..25e4df3d0d 100644
--- a/include/xrpl/core/HashRouter.h
+++ b/include/xrpl/core/HashRouter.h
@@ -34,7 +34,10 @@ enum class HashRouterFlags : std::uint16_t {
     PRIVATE4 = 0x0800,
     // Used in EscrowFinish.cpp
     PRIVATE5 = 0x1000,
-    PRIVATE6 = 0x2000
+    PRIVATE6 = 0x2000,
+    // Used in apply.cpp
+    PRIVATE7 = 0x4000,
+    PRIVATE8 = 0x8000
 };
 
 constexpr HashRouterFlags
diff --git a/include/xrpl/ledger/helpers/AccountRootHelpers.h b/include/xrpl/ledger/helpers/AccountRootHelpers.h
index 350fc6ca85..452d402d14 100644
--- a/include/xrpl/ledger/helpers/AccountRootHelpers.h
+++ b/include/xrpl/ledger/helpers/AccountRootHelpers.h
@@ -15,7 +15,6 @@
 #include <cstdint>
 #include <expected>
 #include <optional>
-#include <set>
 #include <vector>
 
 namespace xrpl {
@@ -353,14 +352,14 @@ pseudoAccountAddress(ReadView const& view, uint256 const& pseudoOwnerKey);
  *
  * The list is constructed during initialization and is const after that.
  * Pseudo-account designator fields MUST be maintained by including the
- * SField::sMD_PseudoAccount flag in the SField definition.
+ * SField::kSmdPseudoAccount flag in the SField definition.
  */
 [[nodiscard]] std::vector<SField const*> const&
 getPseudoAccountFields();
 
 /**
- * Returns true if and only if sleAcct is a pseudo-account or specific
- * pseudo-accounts in pseudoFieldFilter.
+ * Returns true if and only if sleAcct is a pseudo-account of any kind
+ * (i.e. carries at least one field flagged with SField::kSmdPseudoAccount).
  *
  * Returns false if sleAcct is:
  * - NOT a pseudo-account OR
@@ -368,18 +367,15 @@ getPseudoAccountFields();
  * - null pointer
  */
 [[nodiscard]] bool
-isPseudoAccount(SLE::const_pointer sleAcct, std::set<SField const*> const& pseudoFieldFilter = {});
+isPseudoAccount(SLE::const_pointer sleAcct);
 
 /**
  * Convenience overload that reads the account from the view.
  */
 [[nodiscard]] inline bool
-isPseudoAccount(
-    ReadView const& view,
-    AccountID const& accountId,
-    std::set<SField const*> const& pseudoFieldFilter = {})
+isPseudoAccount(ReadView const& view, AccountID const& accountId)
 {
-    return isPseudoAccount(view.read(keylet::account(accountId)), pseudoFieldFilter);
+    return isPseudoAccount(view.read(keylet::account(accountId)));
 }
 
 /**
diff --git a/include/xrpl/ledger/helpers/CredentialHelpers.h b/include/xrpl/ledger/helpers/CredentialHelpers.h
index 6d235b4316..8b1c819bf4 100644
--- a/include/xrpl/ledger/helpers/CredentialHelpers.h
+++ b/include/xrpl/ledger/helpers/CredentialHelpers.h
@@ -14,7 +14,6 @@
 #include <xrpl/protocol/STVector256.h>
 #include <xrpl/protocol/TER.h>
 
-#include <cstdint>
 #include <memory>
 #include <set>
 #include <utility>
@@ -34,32 +33,6 @@ checkExpired(SLE const& sleCredential, NetClock::time_point const& closed);
 [[nodiscard]] TER
 deleteSLE(ApplyView& view, SLE::ref sleCredential, beast::Journal j);
 
-/**
- * @brief Remove credentials pinned to a pseudo-account's owner directory.
- *
- * Cleans up credentials that were linked to a pseudo-account (Vault, LoanBroker,
- * AMM), which such an account can neither accept nor delete. Only credentials
- * are removed; every other object is left in place. The walk visits at most
- * @p maxNodesToDelete directory entries and charges the ones it leaves alone
- * against that budget too, so a directory holding other objects yields fewer
- * than @p maxNodesToDelete deletions. On reaching the bound the result is
- * `tecINCOMPLETE` and the caller must propagate it so a later transaction
- * resumes.
- *
- * @param view Mutable ledger view.
- * @param pseudoAcct The pseudo-account whose directory is cleaned.
- * @param maxNodesToDelete Upper bound on directory entries processed in one call.
- * @param j Journal for diagnostics.
- * @return tesSUCCESS once no credentials remain, tecINCOMPLETE if the bound was
- *         reached, or a deletion error.
- */
-[[nodiscard]] TER
-deletePseudoAccountCredentials(
-    ApplyView& view,
-    AccountID const& pseudoAcct,
-    std::uint16_t maxNodesToDelete,
-    beast::Journal j);
-
 // Amendment and parameters checks for sfCredentialIDs field
 NotTEC
 checkFields(STTx const& tx, Rules const& rules, beast::Journal j);
diff --git a/include/xrpl/ledger/helpers/RippleStateHelpers.h b/include/xrpl/ledger/helpers/RippleStateHelpers.h
index a0508d074f..1a0f92a94b 100644
--- a/include/xrpl/ledger/helpers/RippleStateHelpers.h
+++ b/include/xrpl/ledger/helpers/RippleStateHelpers.h
@@ -239,8 +239,13 @@ canTransfer(ReadView const& view, Issue const& issue, AccountID const& from, Acc
 //------------------------------------------------------------------------------
 
 /**
- * Any transactors that call addEmptyHolding() in doApply must call
- * canAddHolding() in preflight with the same View and Asset
+ * XRP and the issuer itself are always tesSUCCESS. Otherwise, after
+ * fixCleanup3_4_0, an existing trust line returns tecDUPLICATE without
+ * consulting issuer freeze or DefaultRipple; both still apply on the create
+ * path (DefaultRipple off is terNO_RIPPLE). canAddHolding() ignores existing
+ * holdings, so transactors that may create a holding in doApply should gate
+ * their preclaim call on it: after the amendment only when no holding
+ * exists, before it always.
  */
 [[nodiscard]] TER
 addEmptyHolding(
diff --git a/include/xrpl/ledger/helpers/TokenHelpers.h b/include/xrpl/ledger/helpers/TokenHelpers.h
index 501101136a..12fa8a105e 100644
--- a/include/xrpl/ledger/helpers/TokenHelpers.h
+++ b/include/xrpl/ledger/helpers/TokenHelpers.h
@@ -38,6 +38,12 @@ enum class FreezeHandling { IgnoreFreeze, ZeroIfFrozen };
  */
 enum class AuthHandling { IgnoreAuth, ZeroIfUnauthorized };
 
+/**
+ * Controls whether the recipient owner-reserve check is enforced when
+ * auto-creating a trustline or MPToken during AMMWithdraw or AMMClawback.
+ */
+enum class ReserveHandling : bool { EnforceReserve, IgnoreReserve };
+
 /**
  * Controls whether to include the account's full spendable balance
  */
@@ -294,6 +300,14 @@ accountFunds(
     AuthHandling authHandling,
     beast::Journal j);
 
+/**
+ * Returns the transfer fee as Rate based on the type of token
+ * @param view The ledger view
+ * @param asset The asset being transferred
+ */
+[[nodiscard]] Rate
+transferRate(ReadView const& view, Asset const& asset);
+
 /**
  * Returns the transfer fee as Rate based on the type of token
  * @param view The ledger view
@@ -311,6 +325,12 @@ transferRate(ReadView const& view, STAmount const& amount);
 [[nodiscard]] TER
 canAddHolding(ReadView const& view, Asset const& asset);
 
+/**
+ * True if the account already holds this asset (or is the issuer / XRP).
+ */
+[[nodiscard]] bool
+holdingExists(ReadView const& view, AccountID const& account, Asset const& asset);
+
 [[nodiscard]] TER
 addEmptyHolding(
     ApplyViewContext ctx,
diff --git a/include/xrpl/ledger/helpers/VaultHelpers.h b/include/xrpl/ledger/helpers/VaultHelpers.h
index e4ed6de0ef..b42f349b95 100644
--- a/include/xrpl/ledger/helpers/VaultHelpers.h
+++ b/include/xrpl/ledger/helpers/VaultHelpers.h
@@ -10,6 +10,7 @@
 #include <xrpl/protocol/TER.h>
 
 #include <cstdint>
+#include <expected>
 #include <optional>
 
 namespace xrpl {
@@ -44,6 +45,32 @@ assetsToSharesDeposit(SLE::const_ref vault, SLE::const_ref issuance, STAmount co
 [[nodiscard]] std::optional<STAmount>
 sharesToAssetsDeposit(SLE::const_ref vault, SLE::const_ref issuance, STAmount const& shares);
 
+/**
+ * Adjusts a requested asset change (`delta`) to match the decimal scale of the
+ * updated total vault assets. This ensures `sfAssetsTotal`, `sfAssetsAvailable`,
+ * and the actual asset transfer change by the exact same representable amount.
+ *
+ * Rounding strategy:
+ * - Debits (withdrawals): Rounds down `|delta|` on the new scale to prevent
+ *   paying out more than requested.
+ * - Credits (deposits): Floors the resulting total asset balance and returns the
+ *   difference from the current total. This prevents crediting the vault with
+ *   more assets than the user deposited.
+ *
+ * Key rules:
+ * - The returned magnitude never exceeds `|delta|`.
+ * - Returns `tecPRECISION_LOSS` if the change is smaller than 1 ULP of the target scale
+ *   (prevents share operations when totals cannot change).
+ * - For integer assets (XRP, MPT), rounding is a no-op.
+ *
+ * @param vault The vault ledger entry.
+ * @param delta The requested signed change to sfAssetsTotal.
+ * @return The rounded, positive magnitude, or `tecPRECISION_LOSS` if the
+ *         change is below representable precision.
+ */
+[[nodiscard]] std::expected<STAmount, TER>
+clampToAssetsTotalScale(SLE::const_ref vault, STAmount const& delta);
+
 /**
  * Controls whether to truncate shares instead of rounding.
  */
@@ -59,33 +86,30 @@ enum class TruncateShares : bool { No = false, Yes = true };
 enum class WaiveUnrealizedLoss : bool { No = false, Yes = true };
 
 /**
- * Returns the effective total of assets backing outstanding shares for the
- * purposes of a withdrawal, i.e. sfAssetsTotal, discounted by sfLossUnrealized
- * unless waived. This is the numerator used by both withdraw conversion
- * helpers (assetsToSharesWithdraw and sharesToAssetsWithdraw) to compute the
- * share/asset exchange rate.
+ * Returns the assets backing outstanding shares for a withdrawal:
+ * sfAssetsTotal minus sfLossUnrealized, or sfAssetsTotal alone when the
+ * unrealized loss is waived. Used by assetsToSharesWithdraw and
+ * sharesToAssetsWithdraw as the numerator of the share/asset exchange rate.
  *
  * @param vault The vault SLE.
- * @param waive Whether to waive (i.e. not subtract) the vault's unrealized
- *              loss.
+ * @param waive Whether to skip subtracting the unrealized loss.
  */
 [[nodiscard]] Number
 assetsTotalForWithdrawal(SLE::const_ref vault, WaiveUnrealizedLoss waive);
 
 /**
- * Returns whether debiting `amount` from `total` — the current value of a
- * vault's sfAssetsTotal or sfAssetsAvailable field — would canonicalize back
- * to the exact same STAmount value it started at. This happens when a
- * genuinely non-zero debit is dust relative to a `total` large enough to
- * exceed STAmount's significant-digit precision: the shares still move, but
- * the stored total doesn't change, which otherwise trips the ValidVault
- * invariant after the fact instead of failing cleanly upfront.
+ * Returns true if debiting `amount` from `total` (the current value of a
+ * vault's sfAssetsTotal or sfAssetsAvailable) would canonicalize to the
+ * same STAmount value. This happens when `amount` is non-zero but too small
+ * to change the stored total at STAmount's precision. Shares would still
+ * move, so the ValidVault invariant would fail after apply; callers use
+ * this to reject the transaction upfront instead.
  *
- * @param asset The vault's underlying asset, used to canonicalize both sides
- *              the same way the ledger will when the field is stored.
+ * @param asset The vault's underlying asset, used to canonicalize both
+ *              sides the same way the ledger will when the field is stored.
  * @param total The field's current value.
- * @param amount The amount to debit. A value of zero always returns false;
- *               that case is rejected separately and unconditionally.
+ * @param amount The amount to debit. Zero always returns false; that case
+ *               is rejected separately.
  */
 [[nodiscard]] bool
 debitIsNonZeroDust(Asset const& asset, Number const& total, Number const& amount);
diff --git a/include/xrpl/protocol/HashPrefix.h b/include/xrpl/protocol/HashPrefix.h
index 9d4471d05c..e77e891b04 100644
--- a/include/xrpl/protocol/HashPrefix.h
+++ b/include/xrpl/protocol/HashPrefix.h
@@ -92,6 +92,26 @@ enum class HashPrefix : std::uint32_t {
      * Batch
      */
     Batch = detail::makeHashPrefix('B', 'C', 'H'),
+
+    /**
+     * inner transaction to sign as the counterparty
+     */
+    CounterpartyTxSign = detail::makeHashPrefix('C', 'P', 'T'),
+
+    /**
+     * inner transaction to multi-sign as the counterparty
+     */
+    CounterpartyTxMultiSign = detail::makeHashPrefix('C', 'P', 'M'),
+
+    /**
+     * inner transaction to sign as the sponsor
+     */
+    SponsorTxSign = detail::makeHashPrefix('S', 'P', 'N'),
+
+    /**
+     * inner transaction to multi-sign as the sponsor
+     */
+    SponsorTxMultiSign = detail::makeHashPrefix('S', 'P', 'M'),
 };
 
 template <class Hasher>
diff --git a/include/xrpl/protocol/MPTAmount.h b/include/xrpl/protocol/MPTAmount.h
index 462092f7dd..68a7926256 100644
--- a/include/xrpl/protocol/MPTAmount.h
+++ b/include/xrpl/protocol/MPTAmount.h
@@ -9,6 +9,7 @@
 
 #include <cstdint>
 #include <limits>
+#include <optional>
 #include <ostream>
 #include <stdexcept>
 #include <string>
@@ -174,4 +175,17 @@ mulRatio(MPTAmount const& amt, std::uint32_t num, std::uint32_t den, bool roundU
     return MPTAmount(r.convert_to<MPTAmount::value_type>());
 }
 
+inline std::optional<MPTAmount>
+tryMulRatio(MPTAmount const& amt, std::uint32_t num, std::uint32_t den, bool roundUp)
+{
+    try
+    {
+        return mulRatio(amt, num, den, roundUp);
+    }
+    catch (std::overflow_error const&)
+    {
+        return std::nullopt;
+    }
+}
+
 }  // namespace xrpl
diff --git a/include/xrpl/protocol/NFTSyntheticSerializer.h b/include/xrpl/protocol/NFTSyntheticSerializer.h
deleted file mode 100644
index df4fedb707..0000000000
--- a/include/xrpl/protocol/NFTSyntheticSerializer.h
+++ /dev/null
@@ -1,19 +0,0 @@
-#pragma once
-
-#include <xrpl/json/json_forwards.h>
-#include <xrpl/protocol/STTx.h>
-#include <xrpl/protocol/TxMeta.h>
-
-#include <memory>
-
-namespace xrpl::rpc {
-
-/**
- * Adds common synthetic fields to transaction-related JSON responses
- */
-/** @{ */
-void
-insertNFTSyntheticInJson(json::Value&, std::shared_ptr<STTx const> const&, TxMeta const&);
-/** @} */
-
-}  // namespace xrpl::rpc
diff --git a/include/xrpl/protocol/Protocol.h b/include/xrpl/protocol/Protocol.h
index 2816414890..d0de17787c 100644
--- a/include/xrpl/protocol/Protocol.h
+++ b/include/xrpl/protocol/Protocol.h
@@ -12,6 +12,7 @@
 #include <chrono>
 #include <cstddef>
 #include <cstdint>
+#include <limits>
 
 namespace xrpl {
 
@@ -348,13 +349,24 @@ enum class VaultPhase : std::uint8_t {
     Redemption,
 };
 
+/**
+ * Minimum gap between a closed-ended loan's final scheduled payment and the
+ * vault's RedemptionDate. LoanSet rejects a schedule whose final payment is
+ * fewer than this many seconds before RedemptionDate.
+ */
+constexpr std::uint32_t kLoanRedemptionBuffer = std::chrono::seconds{60}.count();
+
 /**
  * Bounds on the length of a closed-ended vault's Investment phase
  * (RedemptionDate - SubscriptionDate). At vault creation the gap must satisfy
  * kMinInvestmentPeriod <= gap < kMaxInvestmentPeriod.
+ *
+ * 180s is enough to originate a loan that uses the minimum payment interval
+ * and kLoanRedemptionBuffer after StartDate, which is strictly after
+ * SubscriptionDate. The interval and buffer need not be equal; only their
+ * sum plus one second must fit in this floor.
  */
-constexpr std::uint32_t kMinInvestmentPeriod =
-    std::chrono::seconds{std::chrono::minutes{1}}.count();
+constexpr std::uint32_t kMinInvestmentPeriod = std::chrono::seconds{180}.count();
 // This is 946708560 seconds which 30 x 365.2425 days (the average length of a Gregorian year).
 constexpr std::uint32_t kMaxInvestmentPeriod = std::chrono::seconds{std::chrono::years{30}}.count();
 
@@ -406,16 +418,6 @@ using TxID = uint256;
  */
 constexpr std::uint16_t kMaxDeletableAmmTrustLines = 512;
 
-/**
- * The maximum number of owner-directory entries to walk when clearing
- * credentials pinned to a pseudo-account, in a single transaction.
- *
- * The walk stops after this many entries whether or not each one turns out to
- * be a credential, so a directory that also holds other objects yields fewer
- * deletions per transaction.
- */
-constexpr std::uint16_t kMaxDeletablePseudoAccountCredentials = 512;
-
 /**
  * The maximum length of a URI inside an Oracle
  */
@@ -553,6 +555,11 @@ constexpr std::size_t kEcClawbackProofLength = SECP256K1_COMPACT_CLAWBACK_PROOF_
  */
 constexpr std::uint32_t kConfidentialFeeMultiplier = 9;
 
+/**
+ * Maximum value a confidential MPT key epoch may reach.
+ */
+constexpr std::uint32_t kMaxKeyEpoch = std::numeric_limits<std::uint32_t>::max();
+
 /**
  * Compressed EC point prefix for even y-coordinate
  */
diff --git a/include/xrpl/protocol/STTx.h b/include/xrpl/protocol/STTx.h
index e213d4e0b7..e6291ae950 100644
--- a/include/xrpl/protocol/STTx.h
+++ b/include/xrpl/protocol/STTx.h
@@ -5,6 +5,7 @@
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/PublicKey.h>
 #include <xrpl/protocol/Rules.h>
 #include <xrpl/protocol/SField.h>
@@ -13,6 +14,7 @@
 #include <xrpl/protocol/SecretKey.h>
 #include <xrpl/protocol/SeqProxy.h>
 #include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/Sign.h>
 #include <xrpl/protocol/TxFormats.h>
 
 #include <boost/container/flat_set.hpp>
@@ -105,14 +107,36 @@ public:
     [[nodiscard]] json::Value
     getJson(JsonOptions options, bool binary) const;
 
+    /**
+     * Sign the transaction as its account.
+     *
+     * @param publicKey The public key for signing.
+     * @param secretKey The secret key for signing.
+     */
+    void
+    sign(PublicKey const& publicKey, SecretKey const& secretKey);
+
+    /**
+     * Sign the transaction in one of its signature fields.
+     *
+     * The signature is bound to the role that made it, so it cannot be moved
+     * into another role.
+     *
+     * @param publicKey The public key for signing.
+     * @param secretKey The secret key for signing.
+     * @param role The role signing the transaction.
+     * @param rules The current ledger rules.
+     */
     void
     sign(
         PublicKey const& publicKey,
         SecretKey const& secretKey,
-        std::optional<std::reference_wrapper<SField const>> signatureTarget = {});
+        SignatureRole role,
+        Rules const& rules);
 
     /**
      * Check the signature.
+     *
      * @param rules The current ledger rules.
      * @return `true` if valid signature. If invalid, the error message string.
      */
@@ -120,7 +144,7 @@ public:
     checkSign(Rules const& rules) const;
 
     [[nodiscard]] std::expected<void, std::string>
-    checkBatchSign(Rules const& rules) const;
+    checkBatchSign() const;
 
     // SQL Functions with metadata.
     static std::string const&
@@ -162,28 +186,28 @@ public:
 private:
     /**
      * Check the signature.
+     *
      * @param rules The current ledger rules.
      * @param sigObject Reference to object that contains the signature fields.
      *     Will be *this more often than not.
+     * @param role The role that made the signature in sigObject. Determines
+     *     the signing prefix, which binds the signature to that role.
      * @return `true` if valid signature. If invalid, the error message string.
      */
     [[nodiscard]] std::expected<void, std::string>
-    checkSign(Rules const& rules, STObject const& sigObject) const;
+    checkSign(Rules const& rules, STObject const& sigObject, SignatureRole role) const;
 
     [[nodiscard]] std::expected<void, std::string>
-    checkSingleSign(STObject const& sigObject) const;
+    checkSingleSign(STObject const& sigObject, HashPrefix prefix) const;
 
     [[nodiscard]] std::expected<void, std::string>
-    checkMultiSign(Rules const& rules, STObject const& sigObject) const;
+    checkMultiSign(STObject const& sigObject, HashPrefix prefix) const;
 
     [[nodiscard]] std::expected<void, std::string>
     checkBatchSingleSign(STObject const& batchSigner, std::vector<uint256> const& txIds) const;
 
     [[nodiscard]] std::expected<void, std::string>
-    checkBatchMultiSign(
-        STObject const& batchSigner,
-        Rules const& rules,
-        std::vector<uint256> const& txIds) const;
+    checkBatchMultiSign(STObject const& batchSigner, std::vector<uint256> const& txIds) const;
 
     void
     buildBatchTxns();
diff --git a/include/xrpl/protocol/Sign.h b/include/xrpl/protocol/Sign.h
index fad2c35c9e..b7a318eb35 100644
--- a/include/xrpl/protocol/Sign.h
+++ b/include/xrpl/protocol/Sign.h
@@ -4,13 +4,65 @@
 #include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/KeyType.h>
 #include <xrpl/protocol/PublicKey.h>
+#include <xrpl/protocol/Rules.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STObject.h>
 #include <xrpl/protocol/SecretKey.h>
 #include <xrpl/protocol/Serializer.h>
 
+#include <optional>
+
 namespace xrpl {
 
+/**
+ * The signature slots on a transaction.
+ *
+ * Each role signs different bytes, so a signature cannot be moved from the
+ * role that made it into another role. See signingPrefix.
+ */
+enum class SignatureRole {
+    /**
+     * The transaction's own signature, in sfTxnSignature or sfSigners.
+     */
+    Transaction,
+    /**
+     * The counterparty's signature, in sfCounterpartySignature.
+     */
+    Counterparty,
+    /**
+     * The sponsor's signature, in sfSponsorSignature.
+     */
+    Sponsor
+};
+
+/**
+ * The field that holds this role's signature.
+ *
+ * @return The signature field, or nullptr for SignatureRole::Transaction,
+ * whose signature lives at the top level of the transaction.
+ */
+[[nodiscard]] SField const*
+signatureField(SignatureRole role);
+
+/**
+ * The role that signs into the given field.
+ *
+ * @return The role, or an unseated optional if the field does not hold a
+ * transaction signature.
+ */
+[[nodiscard]] std::optional<SignatureRole>
+signatureRole(SField const& sigField);
+
+/**
+ * The hash prefix that binds a transaction signature to the role that made it.
+ *
+ * @param role The role making the signature.
+ * @param multiSigning Whether the signature is a multi-signature.
+ * @param rules The current ledger rules.
+ */
+[[nodiscard]] HashPrefix
+signingPrefix(SignatureRole role, bool multiSigning, Rules const& rules);
+
 /**
  * Sign an STObject
  *
@@ -49,9 +101,12 @@ verify(
 
 /**
  * Return a Serializer suitable for computing a multisigning TxnSignature.
+ *
+ * @param prefix Prefix to insert before the serialized object. Get it from
+ * signingPrefix, so that the signature is bound to the role making it.
  */
 Serializer
-buildMultiSigningData(STObject const& obj, AccountID const& signingID);
+buildMultiSigningData(STObject const& obj, AccountID const& signingID, HashPrefix prefix);
 
 /**
  * Break the multi-signing hash computation into 2 parts for optimization.
@@ -67,7 +122,7 @@ buildMultiSigningData(STObject const& obj, AccountID const& signingID);
  *     signer's unique data.
  */
 Serializer
-startMultiSigningData(STObject const& obj);
+startMultiSigningData(STObject const& obj, HashPrefix prefix);
 
 inline void
 finishMultiSigningData(AccountID const& signingID, Serializer& s)
diff --git a/include/xrpl/protocol/detail/features.macro b/include/xrpl/protocol/detail/features.macro
index 05c9fc82d0..e63a7f515d 100644
--- a/include/xrpl/protocol/detail/features.macro
+++ b/include/xrpl/protocol/detail/features.macro
@@ -15,11 +15,14 @@
 // Add new amendments to the top of this list.
 // Keep it sorted in reverse chronological order.
 
-XRPL_FIX    (Cleanup3_4_0,                Supported::Yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(SmartEscrow,                 Supported::No,  VoteBehavior::DefaultNo)
+XRPL_FEATURE(LendingProtocolV1_2,         Supported::No,  VoteBehavior::DefaultNo)
+XRPL_FIX    (Cleanup3_5_0,                Supported::Yes, VoteBehavior::DefaultNo)
+XRPL_FEATURE(ConfidentialMPTKeyRotation,  Supported::No,  VoteBehavior::DefaultNo)
+XRPL_FIX    (Cleanup3_4_0,                Supported::Yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(Sponsor,                     Supported::Yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(BatchV1_1,                   Supported::Yes, VoteBehavior::DefaultNo)
-XRPL_FEATURE(LendingProtocolV1_1,         Supported::No,  VoteBehavior::DefaultNo)
+XRPL_FEATURE(LendingProtocolV1_1,         Supported::Yes,  VoteBehavior::DefaultNo)
 XRPL_FEATURE(ConfidentialTransfer,        Supported::Yes, VoteBehavior::DefaultNo)
 XRPL_FIX    (Cleanup3_3_0,                Supported::Yes, VoteBehavior::DefaultNo)
 XRPL_FIX    (Cleanup3_2_0,                Supported::Yes, VoteBehavior::DefaultNo)
diff --git a/include/xrpl/protocol/detail/ledger_entries.macro b/include/xrpl/protocol/detail/ledger_entries.macro
index 1045ab6426..18c71b572c 100644
--- a/include/xrpl/protocol/detail/ledger_entries.macro
+++ b/include/xrpl/protocol/detail/ledger_entries.macro
@@ -415,6 +415,8 @@ LEDGER_ENTRY(ltMPTOKEN_ISSUANCE, 0x007e, MPTokenIssuance, mpt_issuance, ({
     {sfReferenceHolding,         SoeOptional},
     {sfIssuerEncryptionKey,      SoeOptional},
     {sfAuditorEncryptionKey,     SoeOptional},
+    {sfIssuerKeyEpoch,           SoeOptional},
+    {sfAuditorKeyEpoch,          SoeOptional},
     {sfConfidentialOutstandingAmount, SoeDefault},
 }))
 
diff --git a/include/xrpl/protocol/detail/sfields.macro b/include/xrpl/protocol/detail/sfields.macro
index 2166be2a9c..2cf35743ae 100644
--- a/include/xrpl/protocol/detail/sfields.macro
+++ b/include/xrpl/protocol/detail/sfields.macro
@@ -119,11 +119,15 @@ TYPED_SFIELD(sfRemainingOwnerCount,      UINT32,    73)
 TYPED_SFIELD(sfSponsorFlags,             UINT32,    74)
 TYPED_SFIELD(sfSubscriptionDate,         UINT32,    75)
 TYPED_SFIELD(sfRedemptionDate,           UINT32,    76)
-TYPED_SFIELD(sfGasLimit,                 UINT32,    77)
-TYPED_SFIELD(sfBytecodeSizeLimit,        UINT32,    78)
-TYPED_SFIELD(sfGasPrice,                 UINT32,    79)
-TYPED_SFIELD(sfGas,                      UINT32,    80)
-TYPED_SFIELD(sfGasUsed,                  UINT32,    81)
+TYPED_SFIELD(sfIssuerKeyEpoch,           UINT32,    77)
+TYPED_SFIELD(sfAuditorKeyEpoch,          UINT32,    78)
+TYPED_SFIELD(sfIssuerKeyMirrorEpoch,     UINT32,    79)
+TYPED_SFIELD(sfAuditorKeyMirrorEpoch,    UINT32,    80)
+TYPED_SFIELD(sfGasLimit,                 UINT32,    81)
+TYPED_SFIELD(sfBytecodeSizeLimit,        UINT32,    82)
+TYPED_SFIELD(sfGasPrice,                 UINT32,    83)
+TYPED_SFIELD(sfGas,                      UINT32,    84)
+TYPED_SFIELD(sfGasUsed,                  UINT32,    85)
 
 // 64-bit integers (common)
 TYPED_SFIELD(sfIndexNext,                UINT64,     1)
diff --git a/include/xrpl/protocol/detail/transactions.macro b/include/xrpl/protocol/detail/transactions.macro
index e812711f70..454aa85ffd 100644
--- a/include/xrpl/protocol/detail/transactions.macro
+++ b/include/xrpl/protocol/detail/transactions.macro
@@ -72,7 +72,7 @@ TRANSACTION(ttESCROW_CREATE, 1, EscrowCreate, ({.delegable = Delegation::Delegab
     {sfCancelAfter, SoeOptional},
     {sfFinishAfter, SoeOptional},
     {sfBytecode, SoeOptional},
-    {sfData,           SoeOptional},
+    {sfData, SoeOptional},
 }))
 
 /** This transaction type completes an existing escrow. */
diff --git a/include/xrpl/protocol_autogen/ledger_entries/MPTokenIssuance.h b/include/xrpl/protocol_autogen/ledger_entries/MPTokenIssuance.h
index 6a2caf52ae..74b5e3c4eb 100644
--- a/include/xrpl/protocol_autogen/ledger_entries/MPTokenIssuance.h
+++ b/include/xrpl/protocol_autogen/ledger_entries/MPTokenIssuance.h
@@ -351,6 +351,54 @@ public:
         return this->sle_->isFieldPresent(sfAuditorEncryptionKey);
     }
 
+    /**
+     * @brief Get sfIssuerKeyEpoch (SoeOptional)
+     * @return The field value, or std::nullopt if not present.
+     */
+    [[nodiscard]]
+    protocol_autogen::Optional<SF_UINT32::type::value_type>
+    getIssuerKeyEpoch() const
+    {
+        if (hasIssuerKeyEpoch())
+            return this->sle_->at(sfIssuerKeyEpoch);
+        return std::nullopt;
+    }
+
+    /**
+     * @brief Check if sfIssuerKeyEpoch is present.
+     * @return True if the field is present, false otherwise.
+     */
+    [[nodiscard]]
+    bool
+    hasIssuerKeyEpoch() const
+    {
+        return this->sle_->isFieldPresent(sfIssuerKeyEpoch);
+    }
+
+    /**
+     * @brief Get sfAuditorKeyEpoch (SoeOptional)
+     * @return The field value, or std::nullopt if not present.
+     */
+    [[nodiscard]]
+    protocol_autogen::Optional<SF_UINT32::type::value_type>
+    getAuditorKeyEpoch() const
+    {
+        if (hasAuditorKeyEpoch())
+            return this->sle_->at(sfAuditorKeyEpoch);
+        return std::nullopt;
+    }
+
+    /**
+     * @brief Check if sfAuditorKeyEpoch is present.
+     * @return True if the field is present, false otherwise.
+     */
+    [[nodiscard]]
+    bool
+    hasAuditorKeyEpoch() const
+    {
+        return this->sle_->isFieldPresent(sfAuditorKeyEpoch);
+    }
+
     /**
      * @brief Get sfConfidentialOutstandingAmount (SoeDefault)
      * @return The field value, or std::nullopt if not present.
@@ -600,6 +648,28 @@ public:
         return *this;
     }
 
+    /**
+     * @brief Set sfIssuerKeyEpoch (SoeOptional)
+     * @return Reference to this builder for method chaining.
+     */
+    MPTokenIssuanceBuilder&
+    setIssuerKeyEpoch(std::decay_t<typename SF_UINT32::type::value_type> const& value)
+    {
+        object_[sfIssuerKeyEpoch] = value;
+        return *this;
+    }
+
+    /**
+     * @brief Set sfAuditorKeyEpoch (SoeOptional)
+     * @return Reference to this builder for method chaining.
+     */
+    MPTokenIssuanceBuilder&
+    setAuditorKeyEpoch(std::decay_t<typename SF_UINT32::type::value_type> const& value)
+    {
+        object_[sfAuditorKeyEpoch] = value;
+        return *this;
+    }
+
     /**
      * @brief Set sfConfidentialOutstandingAmount (SoeDefault)
      * @return Reference to this builder for method chaining.
diff --git a/include/xrpl/tx/Transactor.h b/include/xrpl/tx/Transactor.h
index 96ad7e00bc..aabde69ff9 100644
--- a/include/xrpl/tx/Transactor.h
+++ b/include/xrpl/tx/Transactor.h
@@ -259,6 +259,13 @@ public:
     static XRPAmount
     calculateBaseFee(ReadView const& view, STTx const& tx, std::uint32_t extraBaseFeeMultiplier);
 
+    // Exposed for invariant checks (e.g. ValidVault) that need to know which
+    // ledger entry actually pays a transaction's fee, distinguishing an
+    // ordinary sender, a delegate, and pre-funded vs. co-signed fee
+    // sponsorship.
+    static FeePayer
+    getFeePayer(ReadView const& view, STTx const& tx);
+
     /* Do NOT define an invokePreflight function in a derived class.
        Instead, define:
 
@@ -525,9 +532,6 @@ private:
     std::pair<TER, XRPAmount>
     reset(XRPAmount fee);
 
-    static FeePayer
-    getFeePayer(ReadView const& view, STTx const& tx);
-
     TER
     consumeSeqProxy(SLE::pointer const& sleAccount);
     TER
diff --git a/include/xrpl/tx/invariants/LoanBrokerInvariant.h b/include/xrpl/tx/invariants/LoanBrokerInvariant.h
index 979f57de35..2b8713fb90 100644
--- a/include/xrpl/tx/invariants/LoanBrokerInvariant.h
+++ b/include/xrpl/tx/invariants/LoanBrokerInvariant.h
@@ -19,6 +19,11 @@ namespace xrpl {
  * 1. If `LoanBroker.OwnerCount = 0` the `DirectoryNode` will have at most one
  *    node (the root), which will only hold entries for `RippleState` or
  * `MPToken` objects.
+ * 2. Under featureLendingProtocolV1_1, an `ltLOAN_BROKER` may only be deleted
+ *    by a `ttLOAN_BROKER_DELETE` transaction, and only when its pre-state
+ *    `OwnerCount` is zero and its pre-state `DebtTotal` rounds to zero at the
+ *    vault's `AssetsTotal` scale, as `LoanBrokerDelete::preclaim` requires.
+ * 3. At most one `ltLOAN_BROKER` may be deleted in a single transaction.
  *
  */
 class ValidLoanBroker
@@ -36,6 +41,15 @@ class ValidLoanBroker
     // pseudo-accounts. Key is the brokerID / index. It will be used to find the
     // LoanBroker object if brokerBefore and brokerAfter are nullptr
     std::map<uint256, BrokerInfo> brokers_;
+    // The broker whose ledger entry was deleted by this transaction, if any.
+    // Only ttLOAN_BROKER_DELETE removes a broker, and it removes exactly one.
+    // This is the pre-transaction state, which is what LoanBrokerDelete::preclaim
+    // reads when it decides whether the broker may be deleted, so the deletion invariants inspect
+    // the same DebtTotal and OwnerCount that the transactor did.
+    SLE::const_pointer deletedBroker_ = nullptr;
+    // Set if visitEntry observes more than one ltLOAN_BROKER deletion in the
+    // same transaction. Enforced as its own invariant in finalize.
+    bool multipleBrokerDeletions_ = false;
     // Collect all the modified trust lines. Their high and low accounts will be
     // loaded to look for LoanBroker pseudo-accounts.
     std::vector<SLE::const_pointer> lines_;
diff --git a/include/xrpl/tx/invariants/LoanInvariant.h b/include/xrpl/tx/invariants/LoanInvariant.h
index fc72b8d420..34ce1a4dc2 100644
--- a/include/xrpl/tx/invariants/LoanInvariant.h
+++ b/include/xrpl/tx/invariants/LoanInvariant.h
@@ -15,9 +15,33 @@ namespace xrpl {
 /**
  * @brief Invariants: Loans are internally consistent
  *
- * 1. If `Loan.PaymentRemaining = 0` then `Loan.PrincipalOutstanding = 0`
+ * 1. If `Loan.PaymentRemaining = 0` then `Loan.PrincipalOutstanding = 0`.
  * 2. A newly-created Loan against a closed-ended vault must satisfy
  *    `StartDate + PaymentInterval * PaymentRemaining < Vault.RedemptionDate`.
+ * 3. An `ltLOAN` may only be created by a `ttLOAN_SET` transaction.
+ * 4. Prior to `featureLendingProtocolV1_1`, the `lsfLoanOverpayment` flag on a
+ *    Loan must not change. From `featureLendingProtocolV1_1` onward the same
+ *    rule is enforced by `NoModifiedUnmodifiableFields`.
+ * 5. Under `featureLendingProtocolV1_1`:
+ *    a. An `ltLOAN` may only be deleted by a `ttLOAN_DELETE` transaction.
+ *    b. If `Loan.PaymentRemaining = 0` then `Loan.NextPaymentDueDate = 0`.
+ *    c. The `lsfLoanImpaired` flag may only change through a `ttLOAN_MANAGE`
+ *       or `ttLOAN_PAY` transaction.
+ *    d. The `lsfLoanDefault` flag may only change through a `ttLOAN_MANAGE`
+ *       transaction. Combined with `NoModifiedUnmodifiableFields`, which
+ *       rejects any clearing of `lsfLoanDefault`, this makes the flag
+ *       write-once: `ttLOAN_MANAGE` may set it, and no transaction may
+ *       clear it.
+ *    e. Interest due, computed as `TotalValueOutstanding -
+ *       PrincipalOutstanding - ManagementFeeOutstanding`, must not be
+ *       negative.
+ *    f. A Loan must reference a live `ltLOAN_BROKER`, and that broker must
+ *       reference a live `ltVAULT`.
+ *    g. Post-conditions for the Loan paid down by a successful `ttLOAN_PAY`:
+ *       `PaymentRemaining > 0` after: `PrincipalOutstanding` and
+ *          `PaymentRemaining` strictly decrease; `NextPaymentDueDate`
+ *          advances by N * `PaymentInterval`, N > 0.
+ *       `PaymentRemaining == 0` after: pinned by checks 1 and 5b.
  *
  */
 class ValidLoan
@@ -25,6 +49,9 @@ class ValidLoan
     // Pair is <before, after>. After is used for most of the checks, except
     // those that check changed values.
     std::vector<std::pair<SLE::const_pointer, SLE::const_pointer>> loans_;
+    // Loans removed from the ledger, in the same <before, after> form as loans_.
+    // Note that `after` holds the erased entry, so it is not null.
+    std::vector<std::pair<SLE::const_pointer, SLE::const_pointer>> deletedLoans_;
 
 public:
     void
diff --git a/include/xrpl/tx/invariants/MPTInvariant.h b/include/xrpl/tx/invariants/MPTInvariant.h
index 5740cd5be2..ddda348d2e 100644
--- a/include/xrpl/tx/invariants/MPTInvariant.h
+++ b/include/xrpl/tx/invariants/MPTInvariant.h
@@ -215,6 +215,13 @@ class ValidMPTTransfer
     // Deleted MPToken
     // MPToken key: true if MPTAuthorized is set
     hash_map<uint256, bool> deletedAuthorized_;
+    // Every touched AccountRoot (not only pseudos):
+    // AccountID -> whether it was a pseudo-account BEFORE this transaction
+    // applied. Needed because a transaction may erase a pseudo-account and
+    // move MPT out of it in the same transaction; by finalize() time the
+    // view no longer shows it as a pseudo-account (or as existing at all).
+    // False entries freeze the pre-tx classification for touched non-pseudos.
+    hash_map<AccountID, bool> pseudoAccountsBefore_;
 
 public:
     /**
diff --git a/include/xrpl/tx/invariants/VaultInvariant.h b/include/xrpl/tx/invariants/VaultInvariant.h
index 2ba42f0ab4..ee52f4edb3 100644
--- a/include/xrpl/tx/invariants/VaultInvariant.h
+++ b/include/xrpl/tx/invariants/VaultInvariant.h
@@ -48,7 +48,10 @@ namespace xrpl {
  *   vault phase is Investment
  *
  * Immutability of VaultKind, SubscriptionDate and RedemptionDate is enforced
- * by NoModifiedUnmodifiableFields (see InvariantCheck.cpp).
+ * by NoModifiedUnmodifiableFields (see InvariantCheck.cpp). From
+ * featureLendingProtocolV1_1 onwards, immutability of the vault's Asset,
+ * pseudo-account and ShareMPTID is likewise enforced by
+ * NoModifiedUnmodifiableFields; prior to that amendment it is checked here.
  */
 class ValidVault
 {
@@ -128,20 +131,57 @@ private:
     deltaAssets(AccountID const& id) const;
 
     /**
-     * @brief Return the vault-asset delta for the transaction's sending
-     *        account, adjusted for the fee.
+     * @brief Return the AccountRoot whose XRP balance actually absorbed a
+     *        transaction's fee, if any.
      *
-     * Calls @c deltaAssets for @c tx[sfAccount] and, for non-delegated XRP
-     * transactions, adds the consumed fee back so the invariant sees the net
-     * asset movement rather than the fee-reduced balance change.
+     * Mirrors @c Transactor::getFeePayer, but resolves to @c std::nullopt for
+     * a pre-funded sponsorship: that fee is drawn from the @c ltSponsorship
+     * object's @c sfFeeAmount, never from the sponsor's own AccountRoot, so
+     * there is no balance to add back there.
      *
-     * @param tx  The transaction being applied.
-     * @param fee Fee charged by this transaction.
+     * @param view Read-only view of the ledger after the transaction.
+     * @param tx   The transaction being applied.
+     * @return The fee-paying AccountRoot's id, or @c std::nullopt when the
+     *         fee was not drawn from any AccountRoot balance.
+     */
+    [[nodiscard]] static std::optional<AccountID>
+    feePayerAccountRoot(ReadView const& view, STTx const& tx);
+
+    /**
+     * @brief Return the vault-asset delta for a party inspected as a
+     *        withdrawal/deposit counterparty, adjusted for the fee.
+     *
+     * Calls @c deltaAssets for @p id and, for XRP transactions, adds the
+     * consumed fee back only when @p id is the AccountRoot that actually
+     * paid it (per @c feePayerAccountRoot) -- so the invariant sees the net
+     * asset movement rather than a fee-reduced balance change, regardless of
+     * whether @p id is the sender, a distinct destination, a delegate, or a
+     * co-signed fee sponsor. Post-@c fixCleanup3_4_0, any resulting
+     * economically-zero delta is always normalized to absence.
+     *
+     * Pre-@c fixCleanup3_4_0 this replicates the legacy behaviour exactly:
+     * only @c tx[sfAccount] could ever receive a fee correction (and only
+     * when it was itself, per @c STTx::getFeePayerID, the fee payer). After
+     * that sender-only correction a zero delta is collapsed to absence; if
+     * the correction does not apply, a present-zero delta is kept as-is.
+     *
+     * @param view          Read-only view of the ledger after the transaction.
+     * @param id            Account being inspected as sender or destination.
+     * @param tx            The transaction being applied.
+     * @param fee           Fee charged by this transaction.
+     * @param fix340Enabled Whether @c fixCleanup3_4_0 is enabled, as already
+     *                      determined once by @c finalize.
      * @return The fee-adjusted delta, or @c std::nullopt if the net delta is
-     *         zero or the account entry was not touched.
+     *         zero (always post-amendment; pre-amendment only after the
+     *         sender-only fee correction) or the entry was not touched.
      */
     [[nodiscard]] std::optional<DeltaInfo>
-    deltaAssetsTxAccount(STTx const& tx, XRPAmount fee) const;
+    deltaAssetsForParty(
+        ReadView const& view,
+        AccountID const& id,
+        STTx const& tx,
+        XRPAmount fee,
+        bool fix340Enabled) const;
 
     /**
      * @brief Return the vault-share balance-change delta for an account.
@@ -171,8 +211,8 @@ private:
      *
      * For a closed-ended vault, a loan may only be originated while the vault is in the Investment
      * phase (strictly past @c SubscriptionDate and before @c RedemptionDate). Open-ended vaults (@c
-     * NoPhase) are unaffected. The complementary maturity bound (final payment strictly precedes @c
-     * RedemptionDate) is enforced by @c ValidLoan.
+     * NoPhase) are unaffected. The complementary maturity bound (final payment precedes @c
+     * RedemptionDate by at least @c kLoanRedemptionBuffer) is enforced by @c ValidLoan.
      */
     [[nodiscard]] bool
     finalizeLoanSet(ReadView const& view, beast::Journal const& j) const;
diff --git a/include/xrpl/tx/transactors/dex/AMMWithdraw.h b/include/xrpl/tx/transactors/dex/AMMWithdraw.h
index 6861fa7bc4..ea0ad3b253 100644
--- a/include/xrpl/tx/transactors/dex/AMMWithdraw.h
+++ b/include/xrpl/tx/transactors/dex/AMMWithdraw.h
@@ -109,6 +109,11 @@ public:
      * @param lpTokens current LPT balance
      * @param lpTokensWithdraw amount of tokens to withdraw
      * @param tfee trading fee in basis points
+     * @param freezeHandling whether a frozen balance is reported as zero
+     * @param authHandling whether an unauthorized MPT balance is reported as
+     *        zero
+     * @param reserveHandling whether the recipient owner-reserve check is
+     *        enforced when a trustline or MPToken has to be auto-created
      * @param withdrawAll if withdrawing all lptokens
      * @param priorBalance balance before fees
      * @return
@@ -128,6 +133,7 @@ public:
         std::uint16_t tfee,
         FreezeHandling freezeHandling,
         AuthHandling authHandling,
+        ReserveHandling reserveHandling,
         WithdrawAll withdrawAll,
         XRPAmount const& priorBalance,
         beast::Journal const& journal);
@@ -150,6 +156,11 @@ public:
      * @param lpTokensAMMBalance current AMM LPT balance
      * @param lpTokensWithdraw amount of lptokens to withdraw
      * @param tfee trading fee in basis points
+     * @param freezeHandling whether a frozen balance is reported as zero
+     * @param authHandling whether an unauthorized MPT balance is reported as
+     *        zero
+     * @param reserveHandling whether the recipient owner-reserve check is
+     *        enforced when a trustline or MPToken has to be auto-created
      * @param withdrawAll if withdraw all lptokens
      * @param priorBalance balance before fees
      * @return
@@ -169,6 +180,7 @@ public:
         std::uint16_t tfee,
         FreezeHandling freezeHandling,
         AuthHandling authHandling,
+        ReserveHandling reserveHandling,
         WithdrawAll withdrawAll,
         XRPAmount const& priorBalance,
         beast::Journal const& journal);
diff --git a/nix/check-tools/macos.txt b/nix/check-tools/macos.txt
index 8edfeef311..d2dee651f1 100644
--- a/nix/check-tools/macos.txt
+++ b/nix/check-tools/macos.txt
@@ -131,6 +131,9 @@ Rust toolchain:
   ✅ rust-analyzer
      rust-analyzer 1.97.1 (8bab26f4 2026-07-14)
      /nix/store/j6apc5pmd0giy15da9p650r8zklslmvi-rust-analyzer-preview-1.97.1-aarch64-apple-darwin/bin/rust-analyzer
+  ✅ rust-nightly
+     rustc 1.99.0-nightly (87e5904f5 2026-07-20)
+     /nix/store/fqpjz4l0nsnji8b2pz57mnj0akbp6hcl-rust-nightly/bin/rust-nightly
   ✅ rustc
      rustc 1.97.1 (8bab26f4f 2026-07-14)
      /nix/store/bnfk1sl4s9angb0vj1cj9a5y5zvqinwy-rust-minimal-1.97.1/bin/rustc
@@ -140,4 +143,4 @@ Rust toolchain:
 
 Skipping git-over-HTTPS check (CHECK_TOOLS_SKIP_CLONE is set).
 
-✅ All 44 checked tools are present and runnable.
+✅ All 45 checked tools are present and runnable.
diff --git a/nix/check-tools/nix-ubuntu-amd64.txt b/nix/check-tools/nix-ubuntu-amd64.txt
index 28b6c38014..ba5d5e65b1 100644
--- a/nix/check-tools/nix-ubuntu-amd64.txt
+++ b/nix/check-tools/nix-ubuntu-amd64.txt
@@ -131,6 +131,9 @@ Rust toolchain:
   ✅ rust-analyzer
      rust-analyzer 1.97.1 (8bab26f 2026-07-14)
      /nix/store/lr3m97p3hx1k22a7c44pb0wa7rbayhfi-rust-analyzer-preview-1.97.1-x86_64-unknown-linux-gnu/bin/rust-analyzer
+  ✅ rust-nightly
+     rustc 1.99.0-nightly (87e5904f5 2026-07-20)
+     /nix/store/j7kf7a5h4xypzp6x1skg4dsdx2k4fwb3-rust-nightly/bin/rust-nightly
   ✅ rustc
      rustc 1.97.1 (8bab26f4f 2026-07-14)
      /nix/store/40d3mzka7r1ps71l0yv2fs6616nbw85m-rust-minimal-1.97.1/bin/rustc
@@ -168,4 +171,4 @@ Mold:
 
 Skipping git-over-HTTPS check (CHECK_TOOLS_SKIP_CLONE is set).
 
-✅ All 52 checked tools are present and runnable.
+✅ All 53 checked tools are present and runnable.
diff --git a/nix/check-tools/nix-ubuntu-arm64.txt b/nix/check-tools/nix-ubuntu-arm64.txt
index b3b5885a7f..2b45230327 100644
--- a/nix/check-tools/nix-ubuntu-arm64.txt
+++ b/nix/check-tools/nix-ubuntu-arm64.txt
@@ -131,6 +131,9 @@ Rust toolchain:
   ✅ rust-analyzer
      rust-analyzer 1.97.1 (8bab26f 2026-07-14)
      /nix/store/262830dlw2517lnagfx7i7agqgl4fmsd-rust-analyzer-preview-1.97.1-aarch64-unknown-linux-gnu/bin/rust-analyzer
+  ✅ rust-nightly
+     rustc 1.99.0-nightly (87e5904f5 2026-07-20)
+     /nix/store/c59pxk1yikdlf129qwyg4fplmxcrha0k-rust-nightly/bin/rust-nightly
   ✅ rustc
      rustc 1.97.1 (8bab26f4f 2026-07-14)
      /nix/store/a6p27cg6b8szfixfyvkssx6l0c345zw8-rust-minimal-1.97.1/bin/rustc
@@ -168,4 +171,4 @@ Mold:
 
 Skipping git-over-HTTPS check (CHECK_TOOLS_SKIP_CLONE is set).
 
-✅ All 52 checked tools are present and runnable.
+✅ All 53 checked tools are present and runnable.
diff --git a/nix/docker/Dockerfile b/nix/docker/Dockerfile
index 5506bc3c77..7eae693ad2 100644
--- a/nix/docker/Dockerfile
+++ b/nix/docker/Dockerfile
@@ -10,6 +10,8 @@ RUN mkdir -p ~/.config/nix && \
 COPY nix/ci-env.nix /tmp/build/nix/ci-env.nix
 COPY nix/linux.nix /tmp/build/nix/linux.nix
 COPY nix/packages.nix /tmp/build/nix/packages.nix
+COPY nix/rust-nightly.sh /tmp/build/nix/rust-nightly.sh
+COPY nix/rust.nix /tmp/build/nix/rust.nix
 COPY nix/utils.nix /tmp/build/nix/utils.nix
 COPY flake.nix /tmp/build/
 COPY flake.lock /tmp/build/
diff --git a/nix/packages.nix b/nix/packages.nix
index c7972c9843..9af230097d 100644
--- a/nix/packages.nix
+++ b/nix/packages.nix
@@ -16,23 +16,7 @@ let
     exec ${pkgs.python3}/bin/python3 ${llvmPackages.clang-unwrapped}/bin/run-clang-tidy "$@"
   '';
 
-  # rust-overlay's toolchain propagates the *default* stdenv.cc onto the PATH (so
-  # cargo has a linker). That default may be different from the clang we pin here,
-  # so it shadows our clang and the build can silently use a different compiler
-  # version. Drop that cc from every propagation channel instead of pinning a
-  # replacement: the toolchain then carries no compiler and cargo just uses the
-  # active shell's stdenv cc. Must cover all channels — rust-overlay uses both
-  # propagatedBuildInputs and depsHostHostPropagated.
-  rustToolchainBase = pkgs.rust-bin.fromRustupToolchainFile ../rust-toolchain.toml;
-  rustToolchain =
-    let
-      defaultCc = pkgs.stdenv.cc; # default compiler from nixpkgs stdenv
-      withoutDefaultCc = builtins.filter (dep: (dep.outPath or "") != defaultCc.outPath);
-    in
-    rustToolchainBase.overrideAttrs (old: {
-      propagatedBuildInputs = withoutDefaultCc (old.propagatedBuildInputs or [ ]);
-      depsHostHostPropagated = withoutDefaultCc (old.depsHostHostPropagated or [ ]);
-    });
+  rust = import ./rust.nix { inherit pkgs; };
 
   # Nix wraps its toolchain so that binaries are exposed only under unsuffixed
   # names (gcc, g++, clang-tidy, ...). Several tools probe for a
@@ -108,41 +92,38 @@ in
     mkGcov
     ;
 
-  commonPackages = with pkgs; [
-    clangToolLinks
-    runClangTidyLink
-    ccache
-    clangbuildanalyzer
-    clangTools
-    cmake
-    conan
-    curlMinimal # needed for codecov/codecov-action
-    doxygen
-    file # needed for cpack in Clio
-    gcovr
-    gh
-    git
-    git-cliff
-    git-lfs
-    gnumake
-    gnupg # needed for signing commits & codecov/codecov-action
-    graphviz
-    less # needed for git diff
-    mold
-    nettools # provides netstat, used to debug failures in CI
-    ninja
-    patchelf
-    perl # needed for openssl
-    pkg-config
-    pre-commit
-    python3
-    runClangTidy
-    vim
-    zip
-    # Rust packages
-    cargo-audit
-    cargo-llvm-cov
-    cargo-nextest
-    rustToolchain
-  ];
+  commonPackages =
+    (with pkgs; [
+      clangToolLinks
+      runClangTidyLink
+      ccache
+      clangbuildanalyzer
+      clangTools
+      cmake
+      conan
+      curlMinimal # needed for codecov/codecov-action
+      doxygen
+      file # needed for cpack in Clio
+      gcovr
+      gh
+      git
+      git-cliff
+      git-lfs
+      gnumake
+      gnupg # needed for signing commits & codecov/codecov-action
+      graphviz
+      less # needed for git diff
+      mold
+      nettools # provides netstat, used to debug failures in CI
+      ninja
+      patchelf
+      perl # needed for openssl
+      pkg-config
+      pre-commit
+      python3
+      runClangTidy
+      vim
+      zip
+    ])
+    ++ rust.packages;
 }
diff --git a/nix/rust-nightly.sh b/nix/rust-nightly.sh
new file mode 100644
index 0000000000..263e647d8e
--- /dev/null
+++ b/nix/rust-nightly.sh
@@ -0,0 +1,23 @@
+#!@runtimeShell@
+# Reaches the nightly Rust toolchain, which is deliberately kept off PATH.
+# Packaged by nix/rust.nix, which explains why.
+
+set -euo pipefail
+
+usage() {
+    echo "usage: rust-nightly (path | run <command>...)" >&2
+    exit 2
+}
+
+case "${1-}" in
+    path) printf '%s\n' "@rustNightlyBin@" ;;
+    run)
+        shift
+        if [[ $# -eq 0 ]]; then
+            usage
+        fi
+        export PATH="@rustNightlyBin@:${PATH}"
+        exec "$@"
+        ;;
+    *) usage ;;
+esac
diff --git a/nix/rust.nix b/nix/rust.nix
new file mode 100644
index 0000000000..8be48dcad0
--- /dev/null
+++ b/nix/rust.nix
@@ -0,0 +1,84 @@
+# The Rust half of the tool set shared by the CI environment and the dev shell:
+# the stable toolchain pinned by rust-toolchain.toml, the nightly the Rust
+# coverage job needs, and the cargo plugins. Consumed by packages.nix.
+{ pkgs }:
+let
+  # rust-overlay's toolchain propagates the *default* stdenv.cc onto the PATH (so
+  # cargo has a linker). That default may be different from the clang we pin
+  # elsewhere, so it shadows our clang and the build can silently use a different
+  # compiler version. Drop that cc from every propagation channel instead of
+  # pinning a replacement: the toolchain then carries no compiler and cargo just
+  # uses the active shell's stdenv cc.
+  #
+  # The channel list is every list mkDerivation propagates to a dependent's
+  # environment (including the two legacy aliases). rust-overlay currently only
+  # uses propagatedBuildInputs and depsHostHostPropagated, but covering all of
+  # them means an upstream switch to another channel cannot quietly put the
+  # compiler back on PATH.
+  dropDefaultCc =
+    toolchain:
+    let
+      defaultCc = pkgs.stdenv.cc; # default compiler from nixpkgs stdenv
+      withoutDefaultCc = builtins.filter (dep: (dep.outPath or "") != defaultCc.outPath);
+    in
+    toolchain.overrideAttrs (
+      old:
+      pkgs.lib.genAttrs [
+        "depsBuildBuildPropagated"
+        "propagatedNativeBuildInputs" # alias of depsBuildHostPropagated
+        "depsBuildTargetPropagated"
+        "depsHostHostPropagated"
+        "propagatedBuildInputs" # alias of depsHostTargetPropagated
+        "depsTargetTargetPropagated"
+      ] (channel: withoutDefaultCc (old.${channel} or [ ]))
+    );
+
+  rustToolchain = dropDefaultCc (pkgs.rust-bin.fromRustupToolchainFile ../rust-toolchain.toml);
+
+  # cargo-llvm-cov honours the #[coverage(off)] that keeps unit tests out of the
+  # coverage report only under a nightly rustc, and looks for llvm-profdata and
+  # llvm-cov in that same toolchain's sysroot — hence llvm-tools-preview.
+  #
+  # Not every nightly ships every component, so `nightly.latest` breaks on the
+  # days llvm-tools-preview is absent; selectLatestNightlyWith walks back to the
+  # newest one that has it. The result is the newest such nightly *known to the
+  # locked rust-overlay*, which means updating flake.lock moves the compiler that
+  # produces the coverage numbers — and with it the rustc version recorded in
+  # nix/check-tools/*.txt, so those snapshots need regenerating alongside.
+  rustNightly = dropDefaultCc (
+    pkgs.rust-bin.selectLatestNightlyWith (
+      toolchain: toolchain.minimal.override { extensions = [ "llvm-tools-preview" ]; }
+    )
+  );
+
+  # A second toolchain cannot go on PATH: its cargo and rustc would collide with
+  # the pinned stable's in the ci-env buildEnv, which resolves collisions by
+  # picking one silently. Reaching the nightly only through this wrapper keeps it
+  # in the image closure (the Docker build copies the whole closure, not just
+  # what is linked into /bin) while leaving it inactive everywhere that does not
+  # ask for it.
+  #
+  # The script's `path` subcommand exists for scopes wider than one command — a
+  # CI job appending to $GITHUB_PATH, so that the cargo cache action's own
+  # `rustc -vV` probe, which runs in a step of its own, agrees with the toolchain
+  # the build will use.
+  rustNightlyScript = pkgs.replaceVarsWith {
+    name = "rust-nightly";
+    src = ./rust-nightly.sh;
+    dir = "bin";
+    isExecutable = true;
+    replacements = {
+      inherit (pkgs) runtimeShell;
+      rustNightlyBin = "${rustNightly}/bin";
+    };
+  };
+in
+{
+  packages = [
+    pkgs.cargo-audit
+    pkgs.cargo-llvm-cov
+    pkgs.cargo-nextest
+    rustNightlyScript
+    rustToolchain
+  ];
+}
diff --git a/package/Dockerfile b/package/Dockerfile
deleted file mode 100644
index 978b569bd8..0000000000
--- a/package/Dockerfile
+++ /dev/null
@@ -1,7 +0,0 @@
-ARG BASE_IMAGE=debian:bookworm
-
-FROM ${BASE_IMAGE}
-
-COPY package/install-packaging-tools.sh /tmp/install-packaging-tools.sh
-
-RUN /tmp/install-packaging-tools.sh
diff --git a/package/README.md b/package/README.md
index 8295a8a38e..6e88309ecd 100644
--- a/package/README.md
+++ b/package/README.md
@@ -10,10 +10,12 @@ a build configured with `-Dvalidator_keys=ON`.
 package/
   build_pkg.py        Staging and build script (called by the CMake `package` target and CI)
   sign_rpm.py         Signs the built RPMs (called by CI when publishing)
-  publish_pkg.py      Uploads built packages to the XRPLF Nexus repositories (called by CI)
+  docker/
+    Dockerfile          Packaging image, built by `build-packaging-images.yml`; installs its tooling with `bin/install-packaging-tools.sh`
+    publish_pkg.py      Uploads built packages to the XRPLF Nexus repositories (called by CI, and shipped in that image)
   rpm/
     xrpld.spec      RPM spec
-  debian/           Debian control files (control, rules, copyright, xrpld.docs, xrpld.links, source/format)
+  debian/           Debian control files (control, rules, copyright, xrpld.docs, xrpld.links, xrpld.lintian-overrides, source/format)
   shared/
     xrpld.service       systemd unit file (used by both RPM and DEB)
     xrpld.sysusers      sysusers.d config (used by both RPM and DEB)
@@ -32,10 +34,10 @@ image and both CI and local builds pick it up — and names the format that imag
 builds in `type`, which CI passes to `build_pkg.py` as `--package-type`; the two
 have to stay in step.
 
-| Package type | Image (`configs.<distro>[].package.image` in `linux.json`) | Tools required                                      |
-| ------------ | ---------------------------------------------------------- | --------------------------------------------------- |
-| RPM          | `ghcr.io/xrplf/xrpld/packaging-rhel:sha-<sha>`             | `rpmbuild`, `rpmsign`                               |
-| DEB          | `ghcr.io/xrplf/xrpld/packaging-debian:sha-<sha>`           | `dpkg-buildpackage`, debhelper with compat level 13 |
+| Package type | Image (`configs.<distro>[].package.image` in `linux.json`) | Tools required                                                 |
+| ------------ | ---------------------------------------------------------- | -------------------------------------------------------------- |
+| RPM          | `ghcr.io/xrplf/xrpld/packaging-rhel:sha-<sha>`             | `rpmbuild`, `rpmsign`                                          |
+| DEB          | `ghcr.io/xrplf/xrpld/packaging-debian:sha-<sha>`           | `dpkg-buildpackage`, debhelper with compat level 13, `lintian` |
 
 To print the full packaging matrix (artifact names and images) for the current
 `linux.json`:
@@ -49,13 +51,19 @@ To print the full packaging matrix (artifact names and images) for the current
 ### Via CI
 
 Caller workflows (`on-pr.yml`, `on-tag.yml`, `on-trigger.yml`) call
-`reusable-package.yml`. That workflow generates its own packaging matrix from
-the configs that carry a `package` map (via `generate.py --packaging`) and fans
-out one job per distro. Each job downloads the pre-built `xrpld` and
-`validator-keys` binary artifacts and runs in that distro's container, building
-the format `package.type` declares. The packaging script derives the package
-version from the downloaded binary's `xrpld --version` output; no CMake
-configure or build step is needed inside the packaging job.
+`reusable-package.yml`, which runs in three stages:
+
+1. `package` fans out one job per config carrying a `package` map, building and
+   signing in that config's container, and uploading `<config>-pkg` alongside
+   `<config>-pkg-debug` for the much larger debug symbols.
+2. `test-install` installs `<config>-pkg` in the container of every distro the
+   packages target and runs the binaries there, so one that cannot be installed
+   never reaches Nexus.
+3. `publish` uploads both artifacts, or lists what it would upload.
+
+The packaging script derives the package version from the downloaded binary's
+`xrpld --version` output; no CMake configure or build step is needed inside the
+packaging job.
 
 The binaries come from the `debian` and `rhel` build configs themselves — the
 ones carrying the `package` map — which pass `-Dvalidator_keys=ON` so that the
@@ -92,8 +100,7 @@ docker run --rm \
     --pkg-release "${PKG_RELEASE}" \
     --channel UNRELEASED
 
-# Output:
-#   build/debbuild/*.deb         (DEB + dbgsym; Debian names both .deb)
+# Output (the deb image writes build/debbuild/*.deb instead):
 #   build/rpmbuild/RPMS/x86_64/*.rpm
 ```
 
@@ -147,15 +154,21 @@ Versions sort in row order, so moving to a more mature channel never downgrades.
 
 The action decides the package release number on the same split: a tag's version
 is unique, so its packages are release 1, while develop repeats the same version
-and takes `github.run_number` so each push supersedes the last. Both reach the
-packaging scripts as arguments, so neither script derives anything itself.
+and takes `<run number>.<commit date>git<commit hash>`, e.g.
+`857.20260826gitb6a8995` — the leading run number keeps each push superseding
+the last, and the date and hash say which commit a package on
+`packages.xrplf.org` came from. Both reach the packaging scripts as arguments,
+so neither script derives anything itself.
 
-Publishing is the last step of each packaging job, uploading from the container
-that built the packages. It runs when the caller passes `publish: true`:
-`on-trigger.yml` for develop pushes in `XRPLF/rippled`, `on-tag.yml` for tags in
-any `XRPLF` repository, `on-pr.yml` never. Both authenticate with the
+Publishing is its own job, gated behind `test-install`, uploading from the same
+image that built the packages with the `publish_pkg.py` shipped in it — the
+same copy other repositories run. Without `publish: true` the job is a
+`--dry-run`, listing the uploads it would make without needing credentials, so
+any run that builds packages also exercises the upload routing. `on-trigger.yml`
+passes `publish: true` for develop pushes in `XRPLF/rippled` and `on-tag.yml`
+for tags in any `XRPLF` repository, both authenticating with the
 `NEXUS_REMOTE_USERNAME` / `NEXUS_REMOTE_PASSWORD` secrets already used for the
-Conan remote.
+Conan remote; `on-pr.yml` never publishes.
 
 Nexus owns the repository metadata; nothing here indexes anything. Worth knowing:
 
@@ -176,6 +189,12 @@ Nexus owns the repository metadata; nothing here indexes anything. Worth knowing
 - The `develop` repositories gain a package per push, so they need a cleanup
   policy to stay bounded; tagged channels publish each version once.
 
+### Publishing from other repositories
+
+`publish_pkg.py` knows nothing about `xrpld`, so the packaging image
+installs it at `/usr/local/bin/publish_pkg.py` for other XRPLF repositories that
+build their packages elsewhere.
+
 ## How `build_pkg.py` works
 
 `build_pkg.py` derives the `xrpld` software version from
@@ -188,6 +207,9 @@ the final release. If that normalized package version still contains `-`,
 packaging fails because RPM forbids `-` in `Version`, and Debian uses `-` as
 the upstream/revision separator.
 
+> [!NOTE]
+> Debug and sanitizer builds are not packaged yet.
+
 `pkg_version` is the normalized package metadata version derived inside
 `build_pkg.py` from the binary-reported `xrpld` version (`-` pre-release
 separator converted to `~`). It is not a separate user input.
@@ -265,37 +287,45 @@ service restart.
 2. Stages the binaries, configs, `README.md`, `LICENSE.md`, and
    `validator-keys-LICENSE`.
 3. Copies `package/debian/` control files into `debbuild/source/debian/`.
-4. Copies shared service/sysusers/tmpfiles into `debian/` where `dh_installsystemd`, `dh_installsysusers`, and `dh_installtmpfiles` pick them up automatically.
+4. Copies shared service/sysusers/tmpfiles/logrotate into `debian/` where `dh_installsystemd`, `dh_installsysusers`, `dh_installtmpfiles` and `dh_installlogrotate` pick them up automatically.
 5. Generates a minimal `debian/changelog` using `${pkg_version}-${PKG_RELEASE}`,
    where `pkg_version` is derived from the binary-reported `xrpld` version.
 6. Runs `dpkg-buildpackage -b --no-sign -d` (`-d` skips the build-dependency check, since the binary is already built). `debian/rules` uses manual `install` commands.
+
+   It also rewrites the `libc6` bound to `LIBC_MIN` in `debian/rules`, the glibc
+   the Nix toolchain builds against. `dpkg-shlibdeps` would otherwise derive it
+   from the build host's symbols file — on trixie that yields `libc6 (>= 2.34)`
+   because of `sysconf`, locking out distros the binaries run on. A check fails
+   the build if either binary outgrows `LIBC_MIN`.
+
 7. Output: `debbuild/*.deb`, the binary package and the `-dbgsym` package.
    Debian gives dbgsym packages a `.deb` extension; only Ubuntu uses `.ddeb`.
 
 ## Post-build verification
 
 ```bash
-# DEB
-dpkg-deb -c debbuild/*.deb | grep -E 'systemd|sysusers|tmpfiles'
+# DEB (one invocation per package: the dbgsym package is a .deb too)
+for deb in debbuild/*.deb; do dpkg-deb -c "${deb}"; done | grep -E 'systemd|sysusers|tmpfiles'
+lintian -I debbuild/*.deb
 
 # RPM
 rpm -qlp rpmbuild/RPMS/x86_64/*.rpm
-
-# Optional, and not in the packaging image: apt-get install -y lintian
-lintian -I debbuild/*.deb
 ```
 
+`lintian` still reports `embedded-library zlib`, `no-manual-page` and
+`initial-upload-closes-no-bugs`; only the `/usr/local` tags are overridden.
+
 ## Reproducibility
 
-`build_pkg.py` sets `SOURCE_DATE_EPOCH` from the latest git commit time and
-exports it; the RPM spec clamps file modification times to it via
-`%build_mtime_policy`. The remaining variables
-below further improve reproducibility but are _not_ set by the script — export
-them yourself if needed:
+Both formats build reproducibly as they are: the same binaries at the same
+commit give byte-identical packages on a rebuild, and nothing has to be
+exported by hand.
 
-```bash
-export TZ=UTC
-export LC_ALL=C.UTF-8
-export GZIP=-n
-export DEB_BUILD_OPTIONS="noautodbgsym reproducible=+fixfilepath"
-```
+`build_pkg.py` sets `SOURCE_DATE_EPOCH` from the latest git commit time.
+`dpkg-buildpackage` honours it on its own; the RPM spec sets three macros:
+
+- `%clamp_mtime_to_source_date_epoch` — file modification times, from
+  `SOURCE_DATE_EPOCH`.
+- `%use_source_date_epoch_as_buildtime` — the `BUILDTIME` header, from the
+  same.
+- `%_buildhost` — pinned, so the builder's hostname stays out of the header.
diff --git a/package/build_pkg.py b/package/build_pkg.py
index 2518d8c1db..1aaf53d5ff 100755
--- a/package/build_pkg.py
+++ b/package/build_pkg.py
@@ -19,7 +19,7 @@ from pathlib import Path
 # This script lives in the repository it packages.
 SRC_DIR = Path(__file__).resolve().parents[1]
 
-PRE_RELEASE = re.compile(r"^(b0|b[1-9][0-9]*|rc[0-9]+)(\+.*)?$")
+PRE_RELEASE = re.compile(r"^(b|rc)(0|[1-9][0-9]*)(\+.*)?$")
 
 # Files both packaging systems consume, staged under the same names.
 STAGED_FROM_BUILD = ("xrpld", "validator-keys", "validator-keys-LICENSE")
@@ -133,6 +133,14 @@ def stage_common(build_dir: Path, dest: Path) -> None:
         shutil.copy2(build_dir / name, dest / name)
     for source, name in STAGED_FROM_SRC.items():
         shutil.copy2(SRC_DIR / source, dest / name)
+
+
+def stage_units(dest: Path) -> None:
+    """Copy the systemd, sysusers, tmpfiles and logrotate files into dest.
+
+    Each format wants them somewhere else: rpmbuild reads them from SOURCES,
+    debhelper from debian/.
+    """
     for name in STAGED_UNITS:
         shutil.copy2(SRC_DIR / "package" / "shared" / name, dest / name)
 
@@ -146,6 +154,7 @@ def build_rpm(build_dir: Path, *, version: str, pkg_release: str) -> None:
     spec = topdir / "SPECS" / "xrpld.spec"
     shutil.copy2(SRC_DIR / "package" / "rpm" / "xrpld.spec", spec)
     stage_common(build_dir, topdir / "SOURCES")
+    stage_units(topdir / "SOURCES")
 
     run(
         "rpmbuild",
@@ -178,8 +187,7 @@ def build_deb(
     shutil.copytree(SRC_DIR / "package" / "debian", staging / "debian")
 
     # debhelper picks these up from debian/ automatically.
-    for name in STAGED_UNITS:
-        shutil.copy2(staging / name, staging / "debian" / name)
+    stage_units(staging / "debian")
 
     date = datetime.fromtimestamp(epoch, timezone.utc).strftime(
         "%a, %d %b %Y %H:%M:%S %z"
@@ -193,8 +201,6 @@ def build_deb(
         """)
     (staging / "debian" / "changelog").write_text(changelog)
 
-    (staging / "debian" / "rules").chmod(0o755)
-
     run("dpkg-buildpackage", "-b", "--no-sign", "-d", cwd=staging)
 
 
diff --git a/package/debian/control b/package/debian/control
index 62e5d79ef1..359f39f770 100644
--- a/package/debian/control
+++ b/package/debian/control
@@ -4,6 +4,7 @@ Priority: optional
 Maintainer: XRPL Foundation <contact@xrplf.org>
 Rules-Requires-Root: no
 Build-Depends:
+ binutils,
  debhelper-compat (= 13)
 Standards-Version: 4.7.0
 Homepage: https://github.com/XRPLF/rippled
@@ -11,8 +12,6 @@ Vcs-Git: https://github.com/XRPLF/rippled.git
 Vcs-Browser: https://github.com/XRPLF/rippled
 
 Package: xrpld
-Section: net
-Priority: optional
 Architecture: any
 Depends:
  ${shlibs:Depends},
diff --git a/package/debian/copyright b/package/debian/copyright
index 2cf673854a..baaa12e13c 100644
--- a/package/debian/copyright
+++ b/package/debian/copyright
@@ -1,5 +1,5 @@
 Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
-Upstream-Name: rippled
+Upstream-Name: xrpld
 Source: https://github.com/XRPLF/rippled
 
 Files: *
@@ -15,7 +15,7 @@ Copyright: 2016, Ripple Labs Inc.
  2009-2010, Satoshi Nakamoto
  2011, The Bitcoin developers
  2003-2005, Tom Wu
-License: ISC
+License: ISC and BSL-1.0 and MIT and Tom-Wu
 Comment: Built from https://github.com/ripple/validator-keys-tool at the commit
  pinned in cmake/XrplValidatorKeys.cmake. Besides ISC-licensed code it
  incorporates work under the Boost Software License 1.0 (ASIO), the MIT/X11
@@ -35,3 +35,74 @@ License: ISC
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+License: BSL-1.0
+ Boost Software License - Version 1.0 - August 17th, 2003
+ .
+ Permission is hereby granted, free of charge, to any person or organization
+ obtaining a copy of the software and accompanying documentation covered by
+ this license (the "Software") to use, reproduce, display, distribute,
+ execute, and transmit the Software, and to prepare derivative works of the
+ Software, and to permit third-parties to whom the Software is furnished to
+ do so, all subject to the following:
+ .
+ The copyright notices in the Software and this entire statement, including
+ the above license grant, this restriction and the following disclaimer,
+ must be included in all copies of the Software, in whole or in part, and
+ all derivative works of the Software, unless such copies or derivative
+ works are solely in the form of machine-executable object code generated by
+ a source language processor.
+ .
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+ SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+ FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ DEALINGS IN THE SOFTWARE.
+
+License: MIT
+ Permission is hereby granted, free of charge, to any person obtaining a
+ copy of this software and associated documentation files (the "Software"),
+ to deal in the Software without restriction, including without limitation
+ the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ and/or sell copies of the Software, and to permit persons to whom the
+ Software is furnished to do so, subject to the following conditions:
+ .
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+ .
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ DEALINGS IN THE SOFTWARE.
+
+License: Tom-Wu
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ "Software"), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject to
+ the following conditions:
+ .
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+ .
+ THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
+ WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+ .
+ IN NO EVENT SHALL TOM WU BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
+ INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
+ RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF
+ THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT
+ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ .
+ In addition, the following condition applies:
+ .
+ All redistributions must retain an intact copy of this copyright notice
+ and disclaimer.
diff --git a/package/debian/rules b/package/debian/rules
old mode 100644
new mode 100755
index 8f880b8192..dd6d1e66b9
--- a/package/debian/rules
+++ b/package/debian/rules
@@ -2,6 +2,12 @@
 
 export DH_VERBOSE = 1
 
+# The glibc the Nix toolchain builds against, and so the real floor for the
+# binaries. dpkg-shlibdeps would instead derive libc6 (>= 2.34) from the build
+# host's symbols file, where sysconf carries that minver, locking out distros
+# the binaries actually run on.
+LIBC_MIN = 2.31
+
 %:
 	dh $@
 
@@ -11,6 +17,8 @@ override_dh_auto_configure override_dh_auto_build override_dh_auto_test:
 override_dh_installsystemd:
 	dh_installsystemd --no-stop-on-upgrade xrpld.service
 
+# The tmpfiles snippet sets ownership to the xrpld user, so the sysusers snippet
+# has to be emitted first: run it early and make its own sequence slot a no-op.
 execute_before_dh_installtmpfiles:
 	dh_installsysusers
 
@@ -22,5 +30,23 @@ override_dh_install:
 	install -D -m 0644 xrpld.cfg        debian/xrpld/etc/xrpld/xrpld.cfg
 	install -D -m 0644 validators.txt   debian/xrpld/etc/xrpld/validators.txt
 
+override_dh_shlibdeps:
+	dh_shlibdeps
+	# Guards against the toolchain moving past LIBC_MIN and the packages then
+	# claiming a floor they do not meet.
+	for binary in xrpld validator-keys; do \
+		needed=$$(readelf --dyn-syms --wide $$binary \
+			| grep -o 'GLIBC_[0-9.]*' | sed 's/GLIBC_//' | sort -uV | tail -1); \
+		if [ -z "$$needed" ]; then \
+			echo "$$binary: no GLIBC_ symbol versions read, cannot check LIBC_MIN" >&2; \
+			exit 1; \
+		fi; \
+		if dpkg --compare-versions "$$needed" gt "$(LIBC_MIN)"; then \
+			echo "$$binary needs glibc $$needed, above LIBC_MIN $(LIBC_MIN)" >&2; \
+			exit 1; \
+		fi; \
+	done
+	sed -i 's/libc6 (>= [0-9.]*)/libc6 (>= $(LIBC_MIN))/' debian/xrpld.substvars
+
 override_dh_dwz:
 	@:
diff --git a/package/debian/xrpld.docs b/package/debian/xrpld.docs
index 77681ddc6e..97325dfcf5 100644
--- a/package/debian/xrpld.docs
+++ b/package/debian/xrpld.docs
@@ -1,2 +1,3 @@
 README.md
+LICENSE.md
 validator-keys-LICENSE
diff --git a/package/debian/xrpld.links b/package/debian/xrpld.links
index 10d34f5b8c..6dea4f28f3 100644
--- a/package/debian/xrpld.links
+++ b/package/debian/xrpld.links
@@ -1,2 +1,3 @@
-# Legacy compat symlinks (remove next major release)
+# Legacy compatibility for pre-FHS package layouts.
+# TODO: remove after rippled fully deprecated.
 usr/bin/xrpld          usr/local/bin/rippled
diff --git a/package/debian/xrpld.lintian-overrides b/package/debian/xrpld.lintian-overrides
new file mode 100644
index 0000000000..a0b3f583ed
--- /dev/null
+++ b/package/debian/xrpld.lintian-overrides
@@ -0,0 +1,6 @@
+# The /usr/local/bin/rippled symlink is deliberate compatibility for pre-FHS
+# layouts, so the Policy 9.1.2 tags it raises are expected.
+# TODO: remove alongside debian/xrpld.links after rippled fully deprecated.
+xrpld: dir-in-usr-local [usr/local/bin/]
+xrpld: file-in-usr-local [usr/local/bin/rippled]
+xrpld: file-in-unusual-dir [usr/local/bin/rippled]
diff --git a/package/docker/Dockerfile b/package/docker/Dockerfile
new file mode 100644
index 0000000000..adf372b6fa
--- /dev/null
+++ b/package/docker/Dockerfile
@@ -0,0 +1,10 @@
+ARG BASE_IMAGE=debian:trixie
+
+FROM ${BASE_IMAGE}
+
+# Bind-mounted rather than copied in, so the installer never lands in a layer.
+RUN --mount=type=bind,source=bin/install-packaging-tools.sh,target=/install-packaging-tools.sh \
+    /install-packaging-tools.sh
+
+# See ../README.md, "Publishing from other repositories".
+COPY package/docker/publish_pkg.py /usr/local/bin/publish_pkg.py
diff --git a/package/publish_pkg.py b/package/docker/publish_pkg.py
similarity index 87%
rename from package/publish_pkg.py
rename to package/docker/publish_pkg.py
index 0bd39d0845..84a0448e7b 100755
--- a/package/publish_pkg.py
+++ b/package/docker/publish_pkg.py
@@ -1,5 +1,8 @@
 #!/usr/bin/env python3
-"""Publish the packages built by build_pkg.py to the XRPLF repositories on Nexus.
+"""Publish built DEB and RPM packages to the XRPLF repositories on Nexus.
+
+Knows nothing about what it uploads beyond the channel, so it publishes whatever
+built the packages; see package/README.md, "Publishing from other repositories".
 
 RPMs are uploaded to the hosted repository, but yum clients install from the
 'rpm-<channel>' group repository in front of it, which serves signed metadata.
@@ -26,6 +29,9 @@ STALL_TIMEOUT = 300
 ATTEMPTS = 4
 RETRY_DELAY = 5
 
+# 429 is Nexus asking to slow down, not a rejection, so it retries like a 5xx.
+RETRYABLE_STATUSES = (429,)
+
 
 def build_opener() -> urllib.request.OpenerDirector:
     """An opener with no redirect handler, so a 3xx raises instead of being followed.
@@ -44,9 +50,9 @@ def build_opener() -> urllib.request.OpenerDirector:
 def upload(url: str, method: str, headers: dict[str, str], package: Path) -> None:
     """Send one package, retrying only what is worth retrying.
 
-    A 4xx is a deterministic rejection, so it is reported at once rather than
-    re-sending the whole body three more times. Nexus explains what it rejected
-    in the response body, so that body is always surfaced.
+    A 4xx other than 429 is a deterministic rejection, so it is reported at once
+    rather than re-sending the whole body three more times. Nexus explains what
+    it rejected in the response body, so that body is always surfaced.
     """
     opener = build_opener()
 
@@ -64,7 +70,7 @@ def upload(url: str, method: str, headers: dict[str, str], package: Path) -> Non
         except urllib.error.HTTPError as error:
             detail = error.read().decode(errors="replace").strip()
             reason = f"HTTP {error.code}: {detail}"
-            retryable = error.code >= 500
+            retryable = error.code >= 500 or error.code in RETRYABLE_STATUSES
         except (urllib.error.URLError, OSError) as error:
             reason = str(error)
             retryable = True
@@ -118,6 +124,8 @@ def main() -> None:
         token = base64.b64encode(f"{username}:{password}".encode()).decode()
         auth = {"Authorization": f"Basic {token}"}
 
+    # Deliberately not shared with sign_rpm.py: this script ships standalone in
+    # the packaging image for other repositories to run.
     packages = sorted(
         path
         for path in package_dir.rglob("*")
diff --git a/package/rpm/xrpld.spec b/package/rpm/xrpld.spec
index 23974c8900..5139cd54e5 100644
--- a/package/rpm/xrpld.spec
+++ b/package/rpm/xrpld.spec
@@ -17,6 +17,11 @@ URL:      https://github.com/XRPLF/rippled
 ExclusiveArch: x86_64 aarch64
 BuildRequires: systemd-rpm-macros
 
+# These have to precede %%debug_package: it opens the debuginfo subpackage, and
+# any tag after it is silently dropped from the main package.
+%{?systemd_requires}
+%{?sysusers_requires_compat}
+
 %undefine _debugsource_packages
 %debug_package
 # Level 3 rather than the el9 default of 19: it shrinks the multi-gigabyte
@@ -25,10 +30,13 @@ BuildRequires: systemd-rpm-macros
 %global _binary_payload w3.zstdio
 %global _find_debuginfo_dwz_opts %{nil}
 
-%build_mtime_policy clamp_to_source_date_epoch
+# Reproducibility: the first two take their value from the SOURCE_DATE_EPOCH
+# build_pkg.py exports. Without these the header records the wall clock and the
+# build container's hostname, so two builds of the same commit differ.
+%global clamp_mtime_to_source_date_epoch 1
+%global use_source_date_epoch_as_buildtime 1
+%global _buildhost xrplf.org
 
-%{?systemd_requires}
-%{?sysusers_requires_compat}
 
 %description
 xrpld is the reference implementation of the XRP Ledger protocol. It
@@ -53,7 +61,7 @@ install -Dm0644 %{_sourcedir}/validators.txt       %{buildroot}%{_sysconfdir}/%{
 install -Dm0644 %{_sourcedir}/xrpld.service        %{buildroot}%{_unitdir}/xrpld.service
 install -Dm0644 %{_sourcedir}/xrpld.sysusers       %{buildroot}%{_sysusersdir}/xrpld.conf
 install -Dm0644 %{_sourcedir}/xrpld.tmpfiles       %{buildroot}%{_tmpfilesdir}/xrpld.conf
-install -Dm0644 /dev/null %{buildroot}%{_presetdir}/50-xrpld.preset
+install -d %{buildroot}%{_presetdir}
 cat >%{buildroot}%{_presetdir}/50-xrpld.preset <<'EOF'
 enable xrpld.service
 EOF
@@ -76,7 +84,7 @@ ln -s %{_bindir}/%{name} %{buildroot}/usr/local/bin/rippled
 %sysusers_create_package %{name} %{_sourcedir}/xrpld.sysusers
 
 %post
-systemd-tmpfiles --create %{_tmpfilesdir}/xrpld.conf || :
+%tmpfiles_create_package %{name} %{_sourcedir}/xrpld.tmpfiles
 %systemd_post xrpld.service
 
 %preun
@@ -86,11 +94,12 @@ systemd-tmpfiles --create %{_tmpfilesdir}/xrpld.conf || :
 %systemd_postun xrpld.service
 
 %files
+%attr(0755,root,root) %dir %{_docdir}/%{name}
 %license %{_docdir}/%{name}/LICENSE.md
 %license %{_docdir}/%{name}/validator-keys-LICENSE
 %doc %{_docdir}/%{name}/README.md
 
-%dir %{_sysconfdir}/%{name}
+%attr(0755,root,root) %dir %{_sysconfdir}/%{name}
 
 %{_bindir}/%{name}
 %{_bindir}/validator-keys
@@ -101,7 +110,7 @@ systemd-tmpfiles --create %{_tmpfilesdir}/xrpld.conf || :
 
 
 %{_unitdir}/xrpld.service
-%{_presetdir}/50-xrpld.preset
+%attr(0644,root,root) %{_presetdir}/50-xrpld.preset
 %{_sysusersdir}/xrpld.conf
 %{_tmpfilesdir}/xrpld.conf
 %ghost %dir /var/lib/xrpld
diff --git a/package/shared/xrpld.service b/package/shared/xrpld.service
index 22e6359ef0..27dd6a5a3a 100644
--- a/package/shared/xrpld.service
+++ b/package/shared/xrpld.service
@@ -17,6 +17,8 @@ ProtectHome=true
 PrivateTmp=true
 User=xrpld
 Group=xrpld
+# xrpld.tmpfiles creates these at install and boot; these recreate them on
+# every start, so a removed directory does not stop the service.
 StateDirectory=xrpld
 StateDirectoryMode=0750
 LogsDirectory=xrpld
diff --git a/package/sign_rpm.py b/package/sign_rpm.py
index 05c719b710..07bda9f392 100755
--- a/package/sign_rpm.py
+++ b/package/sign_rpm.py
@@ -107,6 +107,8 @@ def main() -> None:
     args = parser.parse_args()
     package_dir: Path = args.package_dir
 
+    # Deliberately not shared with publish_pkg.py, which ships standalone in the
+    # packaging image.
     rpms = sorted(path for path in package_dir.rglob("*.rpm") if path.is_file())
     # Signing nothing would otherwise look like a successful signing.
     assert rpms, f"no RPMs found in {package_dir}"
diff --git a/src/libxrpl/ledger/View.cpp b/src/libxrpl/ledger/View.cpp
index 0cd082ff47..75a49187b4 100644
--- a/src/libxrpl/ledger/View.cpp
+++ b/src/libxrpl/ledger/View.cpp
@@ -543,12 +543,19 @@ doWithdraw(
 {
     auto const dstSle = ctx.view.read(keylet::account(dstAcct));
 
-    // Create trust line or MPToken for the receiving account
+    // Create a trust line or MPToken for a self-destination only when there
+    // is a payout to credit. Post-fixCleanup3_4_0, a zero-value withdraw
+    // (e.g. share redemption from a fully impaired vault) must not insert
+    // an empty holding: that records a one-sided zero delta and can also
+    // create+delete MPTokens in the same transaction.
     if (dstAcct == senderAcct)
     {
-        if (auto const ter = addEmptyHolding(ctx, senderAcct, priorBalance, amount.asset(), j);
-            !isTesSuccess(ter) && ter != tecDUPLICATE)
-            return ter;
+        if (amount > beast::kZero || !ctx.view.rules().enabled(fixCleanup3_4_0))
+        {
+            if (auto const ter = addEmptyHolding(ctx, senderAcct, priorBalance, amount.asset(), j);
+                !isTesSuccess(ter) && ter != tecDUPLICATE)
+                return ter;
+        }
     }
     else
     {
diff --git a/src/libxrpl/ledger/helpers/AMMHelpers.cpp b/src/libxrpl/ledger/helpers/AMMHelpers.cpp
index 20a793e4cb..fcad22d2d5 100644
--- a/src/libxrpl/ledger/helpers/AMMHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/AMMHelpers.cpp
@@ -11,7 +11,6 @@
 #include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/Sandbox.h>
 #include <xrpl/ledger/View.h>
-#include <xrpl/ledger/helpers/CredentialHelpers.h>
 #include <xrpl/ledger/helpers/MPTokenHelpers.h>
 #include <xrpl/ledger/helpers/RippleStateHelpers.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
@@ -691,12 +690,6 @@ deleteAMMTrustLines(
 
                 return {deleteAMMTrustLine(sb, sleItem, ammAccountID, j), SkipEntry::No};
             }
-            // A credential naming the pseudo-account as subject can't be
-            // accepted or deleted by it and would otherwise permanently pin the
-            // AMM. Clean it up here, inside the same bounded walk, so the
-            // pinned AMM can still be deleted.
-            if (sb.rules().enabled(fixCleanup3_4_0) && nodeType == ltCREDENTIAL)
-                return {credentials::deleteSLE(sb, sleItem, j), SkipEntry::No};
             // LCOV_EXCL_START
             JLOG(j.error()) << "deleteAMMObjects: deleting non-trustline or non-MPT " << nodeType;
             return {tecINTERNAL, SkipEntry::No};
@@ -774,8 +767,6 @@ deleteAMMAccount(Sandbox& sb, Asset const& asset, Asset const& asset2, beast::Jo
         // LCOV_EXCL_STOP
     }
 
-    // deleteAMMTrustLines also removes any credentials pinned to the AMM
-    // pseudo-account, within its bounded walk.
     if (auto const ter = deleteAMMTrustLines(sb, ammAccountID, kMaxDeletableAmmTrustLines, j);
         !isTesSuccess(ter))
         return ter;
@@ -917,11 +908,6 @@ isOnlyLiquidityProvider(ReadView const& view, Issue const& ammIssue, AccountID c
                 ++nMPT;
                 continue;
             }
-            // A credential naming the pseudo-account as subject can be pinned
-            // to its owner directory. Ignore it here; deleteAMMTrustLines
-            // removes it when the AMM is deleted.
-            if (view.rules().enabled(fixCleanup3_4_0) && entryType == ltCREDENTIAL)
-                continue;
             if (entryType != ltRIPPLE_STATE)
                 return std::unexpected<TER>(tecINTERNAL);  // LCOV_EXCL_LINE
             auto const lowLimit = sle->getFieldAmount(sfLowLimit);
diff --git a/src/libxrpl/ledger/helpers/AccountRootHelpers.cpp b/src/libxrpl/ledger/helpers/AccountRootHelpers.cpp
index faca4ebfb6..819ebb04d1 100644
--- a/src/libxrpl/ledger/helpers/AccountRootHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/AccountRootHelpers.cpp
@@ -28,7 +28,6 @@
 #include <limits>
 #include <memory>
 #include <optional>
-#include <set>
 #include <stdexcept>
 #include <vector>
 
@@ -515,8 +514,8 @@ pseudoAccountAddress(ReadView const& view, uint256 const& pseudoOwnerKey)
 }
 
 // Pseudo-account designator fields MUST be maintained by including the
-// SField::sMD_PseudoAccount flag in the SField definition. (Don't forget to
-// "| SField::sMD_Default"!) The fields do NOT need to be amendment-gated,
+// SField::kSmdPseudoAccount flag in the SField definition. (Don't forget to
+// "| SField::kSmdDefault"!) The fields do NOT need to be amendment-gated,
 // since a non-active amendment will not set any field, by definition.
 // Specific properties of a pseudo-account are NOT checked here, that's what
 // InvariantCheck is for.
@@ -547,18 +546,14 @@ getPseudoAccountFields()
 }
 
 [[nodiscard]] bool
-isPseudoAccount(SLE::const_pointer sleAcct, std::set<SField const*> const& pseudoFieldFilter)
+isPseudoAccount(SLE::const_pointer sleAcct)
 {
-    auto const& fields = getPseudoAccountFields();
-
     // Intentionally use defensive coding here because it's cheap and makes the
     // semantics of true return value clean.
     return sleAcct && sleAcct->getType() == ltACCOUNT_ROOT &&
-        std::count_if(
-            fields.begin(), fields.end(), [&sleAcct, &pseudoFieldFilter](SField const* sf) -> bool {
-                return sleAcct->isFieldPresent(*sf) &&
-                    (pseudoFieldFilter.empty() || pseudoFieldFilter.contains(sf));
-            }) > 0;
+        std::ranges::any_of(getPseudoAccountFields(), [&sleAcct](SField const* sf) {
+               return sleAcct->isFieldPresent(*sf);
+           });
 }
 
 std::expected<SLE::pointer, TER>
diff --git a/src/libxrpl/ledger/helpers/CredentialHelpers.cpp b/src/libxrpl/ledger/helpers/CredentialHelpers.cpp
index 9c3ca4ec78..5ba832957d 100644
--- a/src/libxrpl/ledger/helpers/CredentialHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/CredentialHelpers.cpp
@@ -5,10 +5,8 @@
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/beast/utility/Journal.h>
-#include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/ledger/ApplyView.h>
 #include <xrpl/ledger/ReadView.h>
-#include <xrpl/ledger/View.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/Feature.h>
@@ -129,36 +127,6 @@ deleteSLE(ApplyView& view, SLE::ref sleCredential, beast::Journal j)
     return tesSUCCESS;
 }
 
-TER
-deletePseudoAccountCredentials(
-    ApplyView& view,
-    AccountID const& pseudoAcct,
-    std::uint16_t maxNodesToDelete,
-    beast::Journal j)
-{
-    XRPL_ASSERT(
-        isPseudoAccount(view.read(keylet::account(pseudoAcct))),
-        "xrpl::credentials::deletePseudoAccountCredentials : is a pseudo-account");
-
-    // Delete the credentials linked into the pseudo-account's owner directory,
-    // visiting at most maxNodesToDelete entries. Any other object is left in
-    // place; the caller's own checks decide whether the remaining directory
-    // blocks deletion. If the bound is reached, cleanupOnAccountDelete returns
-    // tecINCOMPLETE and the caller propagates it so a later transaction resumes.
-    return cleanupOnAccountDelete(
-        view,
-        keylet::ownerDir(pseudoAcct),
-        [&view, &j](LedgerEntryType nodeType, uint256 const&, SLE::pointer& sleItem)
-            -> std::pair<TER, SkipEntry> {
-            if (nodeType == ltCREDENTIAL)
-                return {deleteSLE(view, sleItem, j), SkipEntry::No};
-
-            return {tesSUCCESS, SkipEntry::Yes};
-        },
-        j,
-        maxNodesToDelete);
-}
-
 NotTEC
 checkFields(STTx const& tx, Rules const& rules, beast::Journal j)
 {
diff --git a/src/libxrpl/ledger/helpers/MPTokenHelpers.cpp b/src/libxrpl/ledger/helpers/MPTokenHelpers.cpp
index 73d5fdb1d5..27dcd84675 100644
--- a/src/libxrpl/ledger/helpers/MPTokenHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/MPTokenHelpers.cpp
@@ -184,6 +184,8 @@ addEmptyHolding(
     auto const mpt = ctx.view.peek(keylet::mptokenIssuance(mptID));
     if (!mpt)
         return tefINTERNAL;  // LCOV_EXCL_LINE
+    // Unlike IOU addEmptyHolding (post-fixCleanup3_4_0), a locked issuance is
+    // still rejected before the "MPToken already exists" short circuit.
     if (mpt->isFlag(lsfMPTLocked))
         return tefINTERNAL;  // LCOV_EXCL_LINE
     if (ctx.view.peek(keylet::mptoken(mptID, accountID)))
@@ -384,8 +386,7 @@ requireAuth(
     // They are implicitly authorized for any MPT they hold, including vault shares whose
     // underlying asset would otherwise require auth.
     auto const isPseudoAccountExempt = [&] {
-        return (featureSAVEnabled || featureMPTV2Enabled) &&
-            isPseudoAccount(view, account, {&sfVaultID, &sfLoanBrokerID, &sfAMMID});
+        return (featureSAVEnabled || featureMPTV2Enabled) && isPseudoAccount(view, account);
     };
 
     auto const mptID = keylet::mptokenIssuance(mptIssue.getMptID());
diff --git a/src/libxrpl/ledger/helpers/RippleStateHelpers.cpp b/src/libxrpl/ledger/helpers/RippleStateHelpers.cpp
index 706564db6f..cc02b56305 100644
--- a/src/libxrpl/ledger/helpers/RippleStateHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/RippleStateHelpers.cpp
@@ -652,21 +652,32 @@ addEmptyHolding(
 
     auto const& issuerId = issue.getIssuer();
     auto const& currency = issue.currency;
-    if (isGlobalFrozen(ctx.view, issuerId))
-        return tecFROZEN;  // LCOV_EXCL_LINE
-
     auto const& srcId = issuerId;
     auto const& dstId = accountID;
     auto const high = srcId > dstId;
     auto const index = keylet::trustLine(srcId, dstId, currency);
+    // Post-fixCleanup3_4_0: an existing line is a no-op. Issuer freeze and
+    // DefaultRipple only matter when this function has to create a line.
+    bool const fix340Enabled = ctx.view.rules().enabled(fixCleanup3_4_0);
+    if (fix340Enabled && ctx.view.exists(index))
+        return tecDUPLICATE;
+
+    if (isGlobalFrozen(ctx.view, issuerId))
+        return tecFROZEN;  // LCOV_EXCL_LINE
+
     auto const sleSrc = ctx.view.peek(keylet::account(srcId));
     auto const sleDst = ctx.view.peek(keylet::account(dstId));
     if (!sleDst || !sleSrc)
         return tefINTERNAL;  // LCOV_EXCL_LINE
+    // Create path: DefaultRipple is still required. terNO_RIPPLE is
+    // intentional so VaultWithdraw / CoverWithdraw fail in preclaim via
+    // canAddHolding (retryable, no fee) rather than claiming a tec* fee
+    // in doApply. Transactor::operator() will not apply and will not
+    // convert it to tefINTERNAL.
     if (!sleSrc->isFlag(lsfDefaultRipple))
-        return tecINTERNAL;  // LCOV_EXCL_LINE
+        return fix340Enabled ? TER{terNO_RIPPLE} : tecINTERNAL;
     // If the line already exists, don't create it again.
-    if (ctx.view.read(index))
+    if (!fix340Enabled && ctx.view.exists(index))
         return tecDUPLICATE;
 
     // A reserve sponsor only covers tx.Account's own objects.
diff --git a/src/libxrpl/ledger/helpers/TokenHelpers.cpp b/src/libxrpl/ledger/helpers/TokenHelpers.cpp
index 7ebfa64bcf..2c2c943a9f 100644
--- a/src/libxrpl/ledger/helpers/TokenHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/TokenHelpers.cpp
@@ -535,13 +535,19 @@ accountFunds(
 }
 
 Rate
-transferRate(ReadView const& view, STAmount const& amount)
+transferRate(ReadView const& view, Asset const& asset)
 {
-    return amount.asset().visit(
+    return asset.visit(
         [&](Issue const& issue) { return transferRate(view, issue.getIssuer()); },
         [&](MPTIssue const& issue) { return transferRate(view, issue.getMptID()); });
 }
 
+Rate
+transferRate(ReadView const& view, STAmount const& amount)
+{
+    return transferRate(view, amount.asset());
+}
+
 //------------------------------------------------------------------------------
 //
 // Holding operations
@@ -577,6 +583,32 @@ canAddHolding(ReadView const& view, Asset const& asset)
         asset.value());
 }
 
+[[nodiscard]] bool
+holdingExists(ReadView const& view, AccountID const& account, Issue const& issue)
+{
+    if (issue.native() || account == issue.getIssuer())
+        return true;
+    return view.exists(keylet::trustLine(account, issue));
+}
+
+[[nodiscard]] bool
+holdingExists(ReadView const& view, AccountID const& account, MPTIssue const& mptIssue)
+{
+    if (account == mptIssue.getIssuer())
+        return true;
+    return view.exists(keylet::mptoken(mptIssue.getMptID(), account));
+}
+
+[[nodiscard]] bool
+holdingExists(ReadView const& view, AccountID const& account, Asset const& asset)
+{
+    return std::visit(
+        [&]<ValidIssueType TIss>(TIss const& issue) -> bool {
+            return holdingExists(view, account, issue);
+        },
+        asset.value());
+}
+
 TER
 addEmptyHolding(
     ApplyViewContext ctx,
diff --git a/src/libxrpl/ledger/helpers/VaultHelpers.cpp b/src/libxrpl/ledger/helpers/VaultHelpers.cpp
index 7f4a7ac03c..941b94143d 100644
--- a/src/libxrpl/ledger/helpers/VaultHelpers.cpp
+++ b/src/libxrpl/ledger/helpers/VaultHelpers.cpp
@@ -1,6 +1,7 @@
 #include <xrpl/ledger/helpers/VaultHelpers.h>
 
 #include <xrpl/basics/Number.h>
+#include <xrpl/beast/utility/Zero.h>
 #include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/View.h>
@@ -17,6 +18,7 @@
 #include <xrpl/protocol/TER.h>
 
 #include <cstdint>
+#include <expected>
 #include <optional>
 #include <utility>
 
@@ -69,6 +71,65 @@ sharesToAssetsDeposit(SLE::const_ref vault, SLE::const_ref issuance, STAmount co
     return assets;
 }
 
+[[nodiscard]] std::expected<STAmount, TER>
+clampToAssetsTotalScale(SLE::const_ref vault, STAmount const& delta)
+{
+    XRPL_ASSERT(
+        delta.asset() == vault->at(sfAsset),
+        "xrpl::clampToAssetsTotalScale : delta and vault asset match");
+
+    Asset const asset = vault->at(sfAsset);
+
+    STAmount magnitude = delta.negative() ? -delta : delta;
+    if (asset.integral())
+    {
+        return magnitude;
+    }
+    Number const assetsTotal = vault->at(sfAssetsTotal);
+
+    // Calculate the scale after applying the delta using ToNearest rounding.
+    // This aligns the delta with scale checks used by vault invariants.
+    int const postScale = [&] {
+        NumberRoundModeGuard const rg(Number::RoundingMode::ToNearest);
+        return scale(assetsTotal + delta, asset);
+    }();
+
+    STAmount actualDelta;
+    if (delta.negative())
+    {
+        // For withdrawals (debits), floor the magnitude to the target scale
+        // to ensure exact grid alignment without paying out extra assets.
+        actualDelta = roundToScale(magnitude, postScale, Number::RoundingMode::Downward);
+    }
+    else
+    {
+        // For deposits (credits), derive actualDelta from the floored posterior total.
+        // This prevents grid alignment issues from crediting the vault more than deposited.
+        //
+        // Sum using Downward rounding so intermediate precision doesn't round up
+        // and exceed the original requested amount.
+        Number const posterior = [&] {
+            NumberRoundModeGuard const rg(Number::RoundingMode::Downward);
+            return assetsTotal + magnitude;
+        }();
+
+        Number const roundedPosterior =
+            roundToAsset(asset, posterior, postScale, Number::RoundingMode::Downward);
+        actualDelta = STAmount{asset, roundedPosterior - assetsTotal};
+    }
+
+    XRPL_ASSERT(
+        abs(actualDelta) <= abs(delta),
+        "xrpl::clampToAssetsTotalScale : actual delta smaller or equal to calculated delta");
+
+    // Reject changes below scale precision (1 ULP) to prevent share balance changes
+    // without corresponding asset movements.
+    if (actualDelta <= beast::kZero)
+        return std::unexpected(tecPRECISION_LOSS);
+
+    return actualDelta;
+}
+
 [[nodiscard]] Number
 assetsTotalForWithdrawal(SLE::const_ref vault, WaiveUnrealizedLoss waive)
 {
diff --git a/src/libxrpl/protocol/BuildInfo.cpp b/src/libxrpl/protocol/BuildInfo.cpp
index f1917eccff..bf67defa3b 100644
--- a/src/libxrpl/protocol/BuildInfo.cpp
+++ b/src/libxrpl/protocol/BuildInfo.cpp
@@ -23,7 +23,7 @@ namespace {
 //------------------------------------------------------------------------------
 // clang-format off
 // NOLINTNEXTLINE(readability-identifier-naming)
-char const* const versionString = "3.4.0-b2"
+char const* const versionString = "3.4.0-rc1"
     // clang-format on
     ;
 
diff --git a/src/libxrpl/protocol/Indexes.cpp b/src/libxrpl/protocol/Indexes.cpp
index 66fdfd453b..91ed5c893f 100644
--- a/src/libxrpl/protocol/Indexes.cpp
+++ b/src/libxrpl/protocol/Indexes.cpp
@@ -123,6 +123,10 @@ getBookBase(Book const& book)
 {
     XRPL_ASSERT(isConsistent(book), "xrpl::getBookBase : input is consistent");
 
+    constexpr std::uint8_t kIssueToMPTTag = 0x01;
+    constexpr std::uint8_t kMPTToIssueTag = 0x02;
+    constexpr std::uint8_t kMPTToMPTTag = 0x03;
+
     auto getIndexHash = [&book]<typename... Args>(Args... args) {
         if (book.domain)
             return indexHash(std::forward<Args>(args)..., *book.domain);
@@ -136,19 +140,36 @@ getBookBase(Book const& book)
                 return getIndexHash(
                     LedgerNameSpace::BookDir, in.currency, out.currency, in.account, out.account);
             }
+            // The three MPT-involving branches are new under MPTokensV2 and
+            // each gets a 1-byte discriminator to prevent preimage collisions
+            // between branches: the (Issue,MPT) and (MPT,Issue) preimages
+            // are both 64 bytes of raw concatenation, so without a
+            // per-branch tag chosen Currency / MPTID / AccountID values can
+            // align byte-for-byte and produce the same BookDir keylet for
+            // two distinct markets. (Issue,Issue) is left untagged to
+            // preserve existing mainnet order-book keylets.
             else if constexpr (std::is_same_v<TIn, Issue> && std::is_same_v<TOut, MPTIssue>)
             {
                 return getIndexHash(
-                    LedgerNameSpace::BookDir, in.currency, out.getMptID(), in.account);
+                    LedgerNameSpace::BookDir,
+                    kIssueToMPTTag,
+                    in.currency,
+                    out.getMptID(),
+                    in.account);
             }
             else if constexpr (std::is_same_v<TIn, MPTIssue> && std::is_same_v<TOut, Issue>)
             {
                 return getIndexHash(
-                    LedgerNameSpace::BookDir, in.getMptID(), out.currency, out.account);
+                    LedgerNameSpace::BookDir,
+                    kMPTToIssueTag,
+                    in.getMptID(),
+                    out.currency,
+                    out.account);
             }
             else
             {
-                return getIndexHash(LedgerNameSpace::BookDir, in.getMptID(), out.getMptID());
+                return getIndexHash(
+                    LedgerNameSpace::BookDir, kMPTToMPTTag, in.getMptID(), out.getMptID());
             }
         },
         book.in.value(),
diff --git a/src/libxrpl/protocol/NFTSyntheticSerializer.cpp b/src/libxrpl/protocol/NFTSyntheticSerializer.cpp
deleted file mode 100644
index fd44ae1f33..0000000000
--- a/src/libxrpl/protocol/NFTSyntheticSerializer.cpp
+++ /dev/null
@@ -1,24 +0,0 @@
-#include <xrpl/protocol/NFTSyntheticSerializer.h>
-
-#include <xrpl/json/json_value.h>
-#include <xrpl/protocol/NFTokenID.h>
-#include <xrpl/protocol/NFTokenOfferID.h>
-#include <xrpl/protocol/STTx.h>
-#include <xrpl/protocol/TxMeta.h>
-#include <xrpl/protocol/jss.h>
-
-#include <memory>
-
-namespace xrpl::rpc {
-
-void
-insertNFTSyntheticInJson(
-    json::Value& response,
-    std::shared_ptr<STTx const> const& transaction,
-    TxMeta const& transactionMeta)
-{
-    insertNFTokenID(response[jss::meta], transaction, transactionMeta);
-    insertNFTokenOfferID(response[jss::meta], transaction, transactionMeta);
-}
-
-}  // namespace xrpl::rpc
diff --git a/src/libxrpl/protocol/STTx.cpp b/src/libxrpl/protocol/STTx.cpp
index ce672b515d..3db6a3dc6c 100644
--- a/src/libxrpl/protocol/STTx.cpp
+++ b/src/libxrpl/protocol/STTx.cpp
@@ -168,10 +168,10 @@ STTx::getMentionedAccounts() const
 }
 
 static Blob
-getSigningData(STTx const& that)
+getSigningData(STTx const& that, HashPrefix prefix)
 {
     Serializer s;
-    s.add32(HashPrefix::TxSign);
+    s.add32(prefix);
     that.addWithoutSigningFields(s);
     return s.getData();
 }
@@ -212,30 +212,42 @@ STTx::getSeqProxy() const
     return SeqProxy::rawTicket(*ticketSeq);
 }
 
+void
+STTx::sign(PublicKey const& publicKey, SecretKey const& secretKey)
+{
+    // The account's own signature always covers the plain transaction prefix;
+    // see signingPrefix for the role signatures that do not.
+    auto const data = getSigningData(*this, HashPrefix::TxSign);
+
+    setFieldVL(sfTxnSignature, xrpl::sign(publicKey, secretKey, makeSlice(data)));
+    tid_ = getHash(HashPrefix::TransactionId);
+}
+
 void
 STTx::sign(
     PublicKey const& publicKey,
     SecretKey const& secretKey,
-    std::optional<std::reference_wrapper<SField const>> signatureTarget)
+    SignatureRole role,
+    Rules const& rules)
 {
-    auto const data = getSigningData(*this);
+    auto const data = getSigningData(*this, signingPrefix(role, false, rules));
 
     auto const sig = xrpl::sign(publicKey, secretKey, makeSlice(data));
 
-    if (signatureTarget)
+    if (auto const target = signatureField(role))
     {
-        auto& target = peekFieldObject(*signatureTarget);
-        target.setFieldVL(sfTxnSignature, sig);
+        peekFieldObject(*target).setFieldVL(sfTxnSignature, sig);
     }
     else
     {
         setFieldVL(sfTxnSignature, sig);
     }
+
     tid_ = getHash(HashPrefix::TransactionId);
 }
 
 std::expected<void, std::string>
-STTx::checkSign(Rules const& rules, STObject const& sigObject) const
+STTx::checkSign(Rules const& rules, STObject const& sigObject, SignatureRole role) const
 {
     try
     {
@@ -244,8 +256,10 @@ STTx::checkSign(Rules const& rules, STObject const& sigObject) const
         // multi-signing.  Otherwise we're single-signing.
 
         Blob const& signingPubKey = sigObject.getFieldVL(sfSigningPubKey);
-        return signingPubKey.empty() ? checkMultiSign(rules, sigObject)
-                                     : checkSingleSign(sigObject);
+        bool const multiSigning = signingPubKey.empty();
+        auto const prefix = signingPrefix(role, multiSigning, rules);
+        return multiSigning ? checkMultiSign(sigObject, prefix)
+                            : checkSingleSign(sigObject, prefix);
     }
     catch (...)
     {
@@ -256,20 +270,20 @@ STTx::checkSign(Rules const& rules, STObject const& sigObject) const
 std::expected<void, std::string>
 STTx::checkSign(Rules const& rules) const
 {
-    if (auto const ret = checkSign(rules, *this); !ret)
+    if (auto const ret = checkSign(rules, *this, SignatureRole::Transaction); !ret)
         return ret;
 
     if (isFieldPresent(sfCounterpartySignature))
     {
         auto const counterSig = getFieldObject(sfCounterpartySignature);
-        if (auto const ret = checkSign(rules, counterSig); !ret)
+        if (auto const ret = checkSign(rules, counterSig, SignatureRole::Counterparty); !ret)
             return std::unexpected("Counterparty: " + ret.error());
     }
 
     if (isFieldPresent(sfSponsorSignature))
     {
         auto const sponsorSignatureObj = getFieldObject(sfSponsorSignature);
-        if (auto const ret = checkSign(rules, sponsorSignatureObj); !ret)
+        if (auto const ret = checkSign(rules, sponsorSignatureObj, SignatureRole::Sponsor); !ret)
             return std::unexpected("Sponsor: " + ret.error());
     }
 
@@ -277,14 +291,14 @@ STTx::checkSign(Rules const& rules) const
     // of signature checking.
     if (isFieldPresent(sfBatchSigners))
     {
-        if (auto const ret = checkBatchSign(rules); !ret)
+        if (auto const ret = checkBatchSign(); !ret)
             return ret;
     }
     return {};
 }
 
 std::expected<void, std::string>
-STTx::checkBatchSign(Rules const& rules) const
+STTx::checkBatchSign() const
 {
     try
     {
@@ -318,7 +332,7 @@ STTx::checkBatchSign(Rules const& rules) const
         for (auto const& signer : signers)
         {
             Blob const& signingPubKey = signer.getFieldVL(sfSigningPubKey);
-            auto const result = signingPubKey.empty() ? checkBatchMultiSign(signer, rules, txIds)
+            auto const result = signingPubKey.empty() ? checkBatchMultiSign(signer, txIds)
                                                       : checkBatchSingleSign(signer, txIds);
 
             if (!result)
@@ -447,9 +461,9 @@ singleSignHelper(STObject const& sigObject, Slice const& data)
 }
 
 std::expected<void, std::string>
-STTx::checkSingleSign(STObject const& sigObject) const
+STTx::checkSingleSign(STObject const& sigObject, HashPrefix prefix) const
 {
-    auto const data = getSigningData(*this);
+    auto const data = getSigningData(*this, prefix);
     return singleSignHelper(sigObject, makeSlice(data));
 }
 
@@ -467,8 +481,7 @@ std::expected<void, std::string>
 multiSignHelper(
     STObject const& sigObject,
     std::optional<AccountID> txnAccountID,
-    std::function<Serializer(AccountID const&)> makeMsg,
-    Rules const& rules)
+    std::function<Serializer(AccountID const&)> makeMsg)
 {
     // Make sure the MultiSigners are present.  Otherwise they are not
     // attempting multi-signing and we just have a bad SigningPubKey.
@@ -541,10 +554,7 @@ multiSignHelper(
 }
 
 std::expected<void, std::string>
-STTx::checkBatchMultiSign(
-    STObject const& batchSigner,
-    Rules const& rules,
-    std::vector<uint256> const& txIds) const
+STTx::checkBatchMultiSign(STObject const& batchSigner, std::vector<uint256> const& txIds) const
 {
     XRPL_ASSERT(getTxnType() == ttBATCH, "STTx::checkBatchMultiSign : batch transaction");
     // We can ease the computational load inside the loop a bit by
@@ -555,18 +565,15 @@ STTx::checkBatchMultiSign(
     serializeBatch(dataStart, getAccountID(sfAccount), getSeqProxy().value(), getFlags(), txIds);
     dataStart.addBitString(batchSignerAccount);
     return multiSignHelper(
-        batchSigner,
-        batchSignerAccount,
-        [&dataStart](AccountID const& accountID) -> Serializer {
+        batchSigner, batchSignerAccount, [&dataStart](AccountID const& accountID) -> Serializer {
             Serializer s = dataStart;
             finishMultiSigningData(accountID, s);
             return s;
-        },
-        rules);
+        });
 }
 
 std::expected<void, std::string>
-STTx::checkMultiSign(Rules const& rules, STObject const& sigObject) const
+STTx::checkMultiSign(STObject const& sigObject, HashPrefix prefix) const
 {
     // Used inside the loop in multiSignHelper to enforce that
     // the account owner may not multisign for themselves.
@@ -578,16 +585,13 @@ STTx::checkMultiSign(Rules const& rules, STObject const& sigObject) const
     // We can ease the computational load inside the loop a bit by
     // pre-constructing part of the data that we hash.  Fill a Serializer
     // with the stuff that stays constant from signature to signature.
-    Serializer dataStart = startMultiSigningData(*this);
+    Serializer dataStart = startMultiSigningData(*this, prefix);
     return multiSignHelper(
-        sigObject,
-        txnAccountID,
-        [&dataStart](AccountID const& accountID) -> Serializer {
+        sigObject, txnAccountID, [&dataStart](AccountID const& accountID) -> Serializer {
             Serializer s = dataStart;
             finishMultiSigningData(accountID, s);
             return s;
-        },
-        rules);
+        });
 }
 
 void
diff --git a/src/libxrpl/protocol/Sign.cpp b/src/libxrpl/protocol/Sign.cpp
index 9e7ef7f999..ce3dabde33 100644
--- a/src/libxrpl/protocol/Sign.cpp
+++ b/src/libxrpl/protocol/Sign.cpp
@@ -1,17 +1,77 @@
 #include <xrpl/protocol/Sign.h>
 
+#include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/KeyType.h>
 #include <xrpl/protocol/PublicKey.h>
+#include <xrpl/protocol/Rules.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STExchange.h>
 #include <xrpl/protocol/STObject.h>
 #include <xrpl/protocol/SecretKey.h>
 #include <xrpl/protocol/Serializer.h>
 
+#include <optional>
+
 namespace xrpl {
 
+SField const*
+signatureField(SignatureRole role)
+{
+    switch (role)
+    {
+        case SignatureRole::Transaction:
+            return nullptr;
+        case SignatureRole::Counterparty:
+            return &sfCounterpartySignature;
+        case SignatureRole::Sponsor:
+            return &sfSponsorSignature;
+    }
+    UNREACHABLE("xrpl::signatureField : unknown SignatureRole");
+    return nullptr;
+}
+
+std::optional<SignatureRole>
+signatureRole(SField const& sigField)
+{
+    if (sigField == sfCounterpartySignature)
+        return SignatureRole::Counterparty;
+    if (sigField == sfSponsorSignature)
+        return SignatureRole::Sponsor;
+    return std::nullopt;
+}
+
+// Signature validity depends on fixCleanup3_4_0: a role signature covers
+// different bytes before and after the amendment activates. checkValidity
+// caches its verdict per transaction ID, so it keeps two separate cache slots
+// for role-signature transactions (kSfSiggoodOldPrefix / kSfSigbadOldPrefix in
+// tx/apply.cpp) to keep a pre-fix verdict from being reused in the post-fix
+// era, and vice versa. See the block comment in tx/apply.cpp for the details
+// and the reason both directions matter.
+HashPrefix
+signingPrefix(SignatureRole role, bool multiSigning, Rules const& rules)
+{
+    // Before fixCleanup3_4_0 every signature on a transaction covered the same
+    // bytes, so a signature could be moved from one role to another.
+    if (!rules.enabled(fixCleanup3_4_0))
+        return multiSigning ? HashPrefix::TxMultiSign : HashPrefix::TxSign;
+
+    switch (role)
+    {
+        case SignatureRole::Transaction:
+            return multiSigning ? HashPrefix::TxMultiSign : HashPrefix::TxSign;
+        case SignatureRole::Counterparty:
+            return multiSigning ? HashPrefix::CounterpartyTxMultiSign
+                                : HashPrefix::CounterpartyTxSign;
+        case SignatureRole::Sponsor:
+            return multiSigning ? HashPrefix::SponsorTxMultiSign : HashPrefix::SponsorTxSign;
+    }
+    UNREACHABLE("xrpl::signingPrefix : unknown SignatureRole");
+    return multiSigning ? HashPrefix::TxMultiSign : HashPrefix::TxSign;
+}
+
 void
 sign(
     STObject& st,
@@ -70,18 +130,18 @@ verify(STObject const& st, HashPrefix const& prefix, PublicKey const& pk, SF_VL
 // So, if we support multiple levels of signing, then we'll need to
 // incorporate the "signing for" accounts into the signing data as well.
 Serializer
-buildMultiSigningData(STObject const& obj, AccountID const& signingID)
+buildMultiSigningData(STObject const& obj, AccountID const& signingID, HashPrefix prefix)
 {
-    Serializer s{startMultiSigningData(obj)};
+    Serializer s{startMultiSigningData(obj, prefix)};
     finishMultiSigningData(signingID, s);
     return s;
 }
 
 Serializer
-startMultiSigningData(STObject const& obj)
+startMultiSigningData(STObject const& obj, HashPrefix prefix)
 {
     Serializer s;
-    s.add32(HashPrefix::TxMultiSign);
+    s.add32(prefix);
     obj.addWithoutSigningFields(s);
     return s;
 }
diff --git a/src/libxrpl/protocol/TER.cpp b/src/libxrpl/protocol/TER.cpp
index dcc87a5fa9..c6ebe98642 100644
--- a/src/libxrpl/protocol/TER.cpp
+++ b/src/libxrpl/protocol/TER.cpp
@@ -136,7 +136,7 @@ transResults()
         MAKE_ERROR(tefNO_DST_PARTIAL,              "Partial payment to create account not allowed."),
         MAKE_ERROR(tefBAD_PATH_COUNT,              "Malformed: Too many paths."),
         MAKE_ERROR(tefNO_BYTECODE,                 "There is no WASM code to run, but a WASM-specific field was included."),
-        MAKE_ERROR(tefBYTECODE_NOT_INCLUDED,       "WASM code requires a field to be included that was not included."),
+        MAKE_ERROR(tefBYTECODE_NOT_INCLUDED,       "WASM code requires a field that was not included."),
 
         MAKE_ERROR(telLOCAL_ERROR,            "Local failure."),
         MAKE_ERROR(telBAD_DOMAIN,             "Domain too long."),
diff --git a/src/libxrpl/shamap/SHAMapNodeID.cpp b/src/libxrpl/shamap/SHAMapNodeID.cpp
index 8fd7afe8fc..42b946b921 100644
--- a/src/libxrpl/shamap/SHAMapNodeID.cpp
+++ b/src/libxrpl/shamap/SHAMapNodeID.cpp
@@ -6,6 +6,7 @@
 #include <xrpl/protocol/Serializer.h>
 #include <xrpl/shamap/SHAMap.h>
 
+#include <algorithm>
 #include <cstddef>
 #include <optional>
 #include <stdexcept>
@@ -40,11 +41,41 @@ depthMask(unsigned int depth)
     return kMasks.entry[depth];
 }
 
+// The prefix of `key` at `depth`: the leading nibbles naming the subtree a node at that depth
+// identifies, with the remainder of the key masked off.
+static uint256
+maskedToDepth(uint256 const& key, unsigned int depth)
+{
+    return key & depthMask(depth);
+}
+
+// Whether `id` at `depth` is what `key` looks like once masked down to that depth, i.e.
+// whether an ID with this depth and id names a subtree that `key` falls under.
+static bool
+isPrefixOfAtDepth(uint256 const& id, unsigned int depth, uint256 const& key)
+{
+    return maskedToDepth(key, depth) == id;
+}
+
 // canonicalize the hash to a node ID for this depth
 SHAMapNodeID::SHAMapNodeID(unsigned int depth, uint256 const& hash) : id_(hash), depth_(depth)
 {
-    XRPL_ASSERT(
-        depth <= SHAMap::kLeafDepth, "xrpl::SHAMapNodeID::SHAMapNodeID : maximum depth input");
+    // Every SHAMapNodeID's depth is stored here, so this is the one place that can stop an
+    // out-of-range one from being kept: a depth past kLeafDepth would go on to index depthMask
+    // out of bounds, and getRawString would narrow it to a byte, silently renaming the node.
+    // Clamp rather than throw, since node IDs are built from peer-supplied depths on the ledger
+    // data path, where no caller catches an exception before it reaches a thread boundary.
+    if (depth_ > SHAMap::kLeafDepth)
+    {
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::SHAMapNodeID::SHAMapNodeID : depth within tree");
+        depth_ = SHAMap::kLeafDepth;
+        id_ = maskedToDepth(id_, depth_);
+        // LCOV_EXCL_STOP
+    }
+
+    // Reads the clamped member rather than the depth argument, so it cannot index depthMask past
+    // its last entry even once the clamp above has reported the bad input and carried on.
     XRPL_ASSERT(
         isPrefixOf(id_), "xrpl::SHAMapNodeID::SHAMapNodeID : hash and depth inputs do match");
 }
@@ -89,7 +120,7 @@ SHAMapNodeID::getChildNodeID(unsigned int branch) const
 bool
 SHAMapNodeID::isPrefixOf(uint256 const& key) const
 {
-    return (key & depthMask(depth_)) == id_;
+    return isPrefixOfAtDepth(id_, depth_, key);
 }
 
 [[nodiscard]] std::optional<SHAMapNodeID>
@@ -102,9 +133,9 @@ deserializeSHAMapNodeID(void const* data, std::size_t size)
         unsigned int const depth = *(static_cast<unsigned char const*>(data) + 32);
         if (depth <= SHAMap::kLeafDepth)
         {
-            auto const id = uint256::fromVoid(data);
-
-            if (id == (id & depthMask(depth)))
+            // Reject a serialized ID carrying bits below its own depth. Checked before
+            // constructing, since the constructor asserts that same property.
+            if (auto const id = uint256::fromVoid(data); isPrefixOfAtDepth(id, depth, id))
                 ret.emplace(depth, id);
         }
     }
@@ -115,7 +146,11 @@ deserializeSHAMapNodeID(void const* data, std::size_t size)
 [[nodiscard]] unsigned int
 selectBranch(SHAMapNodeID const& id, uint256 const& hash)
 {
-    auto const depth = id.getDepth();
+    XRPL_ASSERT(id.getDepth() < SHAMap::kLeafDepth, "xrpl::selectBranch : depth below leaf depth");
+
+    // A depth-64 ID has no nibble left to select. Callers must not ask, but clamp anyway to keep
+    // the read below the end of the 32-byte key.
+    auto const depth = std::min(id.getDepth(), SHAMap::kLeafDepth - 1u);
     auto branch = static_cast<unsigned int>(*(hash.begin() + (depth / 2)));
 
     if ((depth & 1) != 0u)
@@ -134,8 +169,18 @@ selectBranch(SHAMapNodeID const& id, uint256 const& hash)
 SHAMapNodeID
 SHAMapNodeID::createID(unsigned int depth, uint256 const& key)
 {
-    XRPL_ASSERT(depth <= SHAMap::kLeafDepth, "xrpl::SHAMapNodeID::createID : valid depth");
-    return SHAMapNodeID(depth, key & depthMask(depth));
+    // The mask is chosen here, before the constructor runs, so the clamp there cannot cover this
+    // call: an out-of-range depth would index depthMask's table while still evaluating this
+    // argument. A public factory has to hold its own bound.
+    if (depth > SHAMap::kLeafDepth)
+    {
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::SHAMapNodeID::createID : depth within tree");
+        depth = SHAMap::kLeafDepth;
+        // LCOV_EXCL_STOP
+    }
+
+    return SHAMapNodeID(depth, maskedToDepth(key, depth));
 }
 
 }  // namespace xrpl
diff --git a/src/libxrpl/tx/AGENTS.md b/src/libxrpl/tx/AGENTS.md
new file mode 100644
index 0000000000..e2261fc1ad
--- /dev/null
+++ b/src/libxrpl/tx/AGENTS.md
@@ -0,0 +1,5 @@
+# AGENTS.md — tx
+
+See the repo-level [AGENTS.md](../../../AGENTS.md) for general build/test/style guidance.
+
+Any change to transaction-processing behavior must be gated behind an amendment. New amendments (and fixes, i.e. `fix*` amendments) are added to [`include/xrpl/protocol/detail/features.macro`](../../../include/xrpl/protocol/detail/features.macro), as an `XRPL_FEATURE(...)` or `XRPL_FIX(...)` entry added to the top of the list (the list is kept in reverse chronological order). Once the pre-amendment code path for a retired amendment is removed, move its entry to `XRPL_RETIRE_FEATURE(...)`/`XRPL_RETIRE_FIX(...)` instead of deleting it.
diff --git a/src/libxrpl/tx/CLAUDE.md b/src/libxrpl/tx/CLAUDE.md
new file mode 120000
index 0000000000..47dc3e3d86
--- /dev/null
+++ b/src/libxrpl/tx/CLAUDE.md
@@ -0,0 +1 @@
+AGENTS.md
\ No newline at end of file
diff --git a/src/libxrpl/tx/Transactor.cpp b/src/libxrpl/tx/Transactor.cpp
index 1170b855d2..95ed2cc483 100644
--- a/src/libxrpl/tx/Transactor.cpp
+++ b/src/libxrpl/tx/Transactor.cpp
@@ -1246,7 +1246,7 @@ removeExpiredNFTokenOffers(
 }
 
 static void
-removeDeletedCredentials(ApplyView& view, std::vector<uint256> const& creds, beast::Journal viewJ)
+removeExpiredCredentials(ApplyView& view, std::vector<uint256> const& creds, beast::Journal viewJ)
 {
     for (auto const& index : creds)
     {
@@ -1255,7 +1255,7 @@ removeDeletedCredentials(ApplyView& view, std::vector<uint256> const& creds, bea
             if (auto const ter = credentials::deleteSLE(view, sle, viewJ); !isTesSuccess(ter))
             {
                 JLOG(viewJ.error())
-                    << "removeDeletedCredentials: failed to delete credential. Err: "
+                    << "removeExpiredCredentials: failed to delete expired credential. Err: "
                     << transToken(ter);
             }
         }
@@ -1454,8 +1454,7 @@ Transactor::processPersistentChanges(TER result, XRPAmount fee)
     //        should be used, making it possible to do more useful work
     //        when transactions fail with a `tec` code.
 
-    auto typesForResult = [credentialCleanup =
-                               view().rules().enabled(fixCleanup3_4_0)](TER const ter) {
+    auto typesForResult = [](TER const ter) {
         std::unordered_set<LedgerEntryType> types;
         if ((ter == tecOVERSIZE) || (ter == tecKILLED))
         {
@@ -1464,11 +1463,6 @@ Transactor::processPersistentChanges(TER result, XRPAmount fee)
         else if (ter == tecINCOMPLETE)
         {
             types.insert(ltRIPPLE_STATE);
-            // A bounded pseudo-account credential cleanup (VaultDelete /
-            // LoanBrokerDelete) persists its partial credential deletions so a
-            // later transaction can resume.
-            if (credentialCleanup)
-                types.insert(ltCREDENTIAL);
         }
         else if (ter == tecEXPIRED)
         {
@@ -1561,7 +1555,7 @@ Transactor::processPersistentChanges(TER result, XRPAmount fee)
                     removeDeletedTrustLines(view(), ids, viewJ);
                     break;
                 case ltCREDENTIAL:
-                    removeDeletedCredentials(view(), ids, viewJ);
+                    removeExpiredCredentials(view(), ids, viewJ);
                     break;
                 // LCOV_EXCL_START
                 default:
diff --git a/src/libxrpl/tx/apply.cpp b/src/libxrpl/tx/apply.cpp
index f93b19a158..688c585e2a 100644
--- a/src/libxrpl/tx/apply.cpp
+++ b/src/libxrpl/tx/apply.cpp
@@ -8,6 +8,7 @@
 #include <xrpl/core/ServiceRegistry.h>
 #include <xrpl/ledger/ApplyView.h>
 #include <xrpl/ledger/OpenView.h>
+#include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Rules.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STObject.h>
@@ -23,13 +24,38 @@
 
 namespace xrpl {
 
-// These are the same flags defined as HashRouterFlags::PRIVATE1-4 in
-// HashRouter.h
+// This file owns HashRouterFlags::PRIVATE1-4 and PRIVATE7-8 in HashRouter.h.
+// These are the first four; the other two are below.
 constexpr HashRouterFlags kSfSigbad = HashRouterFlags::PRIVATE1;     // Signature is bad
 constexpr HashRouterFlags kSfSiggood = HashRouterFlags::PRIVATE2;    // Signature is good
 constexpr HashRouterFlags kSfLocalbad = HashRouterFlags::PRIVATE3;   // Local checks failed
 constexpr HashRouterFlags kSfLocalgood = HashRouterFlags::PRIVATE4;  // Local checks passed
 
+// Before fixCleanup3_4_0, a signature in an alternate role field, such as
+// sfSponsorSignature, covered the same bytes as the top level signature. Which
+// bytes a role signature must cover therefore depends on whether the fix is
+// enabled, but the four flags above record only the verdict, not the rules that
+// produced it. A verdict reached under one prefix would otherwise be reused
+// under the other.
+//
+// The two flags below hold the verdict for the pre-fix prefixes, so the pre-fix
+// and post-fix verdicts occupy separate slots and neither is ever read in the
+// other's era. Nothing is cleared when the amendment activates: setFlags only
+// sets bits, so a stale pre-fix verdict simply stops being read and ages out
+// with the rest of the routing table.
+//
+// This is not one switchover at a single instant. The era is chosen per call
+// from the rules passed in, and callers do not agree on the rules: relay and
+// submit verify against the validated rules, which lag the open ledger rules
+// that preflight2 verifies against. At the amendment's flag ledger the same
+// transaction can therefore be checked under both prefixes, on the same node,
+// at the same time.
+//
+// Remove these two flags, and oldPrefixSig below, when Cleanup3_4_0 is retired
+// in features.macro.
+constexpr HashRouterFlags kSfSigbadOldPrefix = HashRouterFlags::PRIVATE7;
+constexpr HashRouterFlags kSfSiggoodOldPrefix = HashRouterFlags::PRIVATE8;
+
 //------------------------------------------------------------------------------
 
 std::pair<Validity, std::string>
@@ -48,21 +74,41 @@ checkValidity(HashRouter& router, STTx const& tx, Rules const& rules)
         return {Validity::SigBad, "Batch inner transactions are never considered validly signed."};
     }
 
-    if (any(flags & kSfSigbad))
+    // Pick the cache slot for this call's era; see kSfSiggoodOldPrefix above.
+    // Only a transaction that carries a role signature, and only while the fix
+    // is disabled, uses the separate slot. Every other transaction, and every
+    // transaction once the fix is enabled, uses the ordinary flags and verifies
+    // exactly once, so there is no steady state cost.
+    //
+    // Both directions matter. A good verdict from before the fix must not let a
+    // signature moved between roles survive the amendment, and a bad verdict
+    // from before the fix must not condemn a transaction that the new prefixes
+    // accept.
+    //
+    // Whether a transaction carries a role signature is fixed for its ID: the
+    // fields are kNotSigning, so they are excluded from the signed bytes, but
+    // they are still covered by the transaction ID. Repeat calls for one ID
+    // therefore always agree on which slot pair to use.
+    bool const oldPrefixSig = !rules.enabled(fixCleanup3_4_0) &&
+        (tx.isFieldPresent(sfSponsorSignature) || tx.isFieldPresent(sfCounterpartySignature));
+    auto const sigbadFlag = oldPrefixSig ? kSfSigbadOldPrefix : kSfSigbad;
+    auto const siggoodFlag = oldPrefixSig ? kSfSiggoodOldPrefix : kSfSiggood;
+
+    if (any(flags & sigbadFlag))
     {
         // Signature is known bad
         return {Validity::SigBad, "Transaction has bad signature."};
     }
 
-    if (!any(flags & kSfSiggood))
+    if (!any(flags & siggoodFlag))
     {
         auto const sigVerify = tx.checkSign(rules);
         if (!sigVerify)
         {
-            router.setFlags(id, kSfSigbad);
+            router.setFlags(id, sigbadFlag);
             return {Validity::SigBad, sigVerify.error()};
         }
-        router.setFlags(id, kSfSiggood);
+        router.setFlags(id, siggoodFlag);
     }
 
     // Signature is now known good
@@ -94,6 +140,19 @@ checkValidity(HashRouter& router, STTx const& tx, Rules const& rules)
 void
 forceValidity(HashRouter& router, uint256 const& txid, Validity validity)
 {
+    // Callers reach here when they deliberately skip signature verification,
+    // such as a cluster peer that trusts its neighbor's checks, or a
+    // configuration that turns signature checks off. Nothing was verified, so
+    // there is no prefix era to record. Mark both of checkValidity's signature
+    // slots good: otherwise the forced verdict is ignored for a role-signature
+    // transaction until fixCleanup3_4_0 is enabled, and the signature the
+    // caller meant to skip gets verified after all. Marking both cannot leak a
+    // verdict across eras, because no verdict was reached, and this is the only
+    // place the distinction can be recorded: kSfSiggood alone does not say
+    // whether checkValidity verified a post-fix signature or a caller forced
+    // the result. An already cached bad verdict still wins, since checkValidity
+    // tests its bad flag first. Drop kSfSiggoodOldPrefix when Cleanup3_4_0 is
+    // retired.
     HashRouterFlags flags = HashRouterFlags::UNDEFINED;
     switch (validity)
     {
@@ -101,7 +160,7 @@ forceValidity(HashRouter& router, uint256 const& txid, Validity validity)
             flags |= kSfLocalgood;
             [[fallthrough]];
         case Validity::SigGoodOnly:
-            flags |= kSfSiggood;
+            flags |= kSfSiggood | kSfSiggoodOldPrefix;
             [[fallthrough]];
         case Validity::SigBad:
             // would be silly to call directly
diff --git a/src/libxrpl/tx/invariants/InvariantCheck.cpp b/src/libxrpl/tx/invariants/InvariantCheck.cpp
index aa4df8db42..96820d00bb 100644
--- a/src/libxrpl/tx/invariants/InvariantCheck.cpp
+++ b/src/libxrpl/tx/invariants/InvariantCheck.cpp
@@ -1123,10 +1123,17 @@ NoModifiedUnmodifiableFields::finalize(
     ReadView const& view,
     beast::Journal const& j)
 {
-    static auto const kFieldChanged = [](auto const& before, auto const& after, auto const& field) {
+    auto const kFieldChanged = [&j, &tx](auto const& before, auto const& after, auto const& field) {
         bool const beforeField = before->isFieldPresent(field);
         bool const afterField = after->isFieldPresent(field);
-        return beforeField != afterField || (afterField && before->at(field) != after->at(field));
+        bool const changed =
+            beforeField != afterField || (afterField && before->at(field) != after->at(field));
+        if (changed)
+        {
+            JLOG(j.fatal()) << "Invariant failed: " << field.getName()
+                            << " changed on immutable ledger entry in " << tx.getTransactionID();
+        }
+        return changed;
     };
     for (auto const& slePair : changedEntries_)
     {
@@ -1172,13 +1179,40 @@ NoModifiedUnmodifiableFields::finalize(
                     kFieldChanged(before, after, sfPaymentInterval) ||
                     kFieldChanged(before, after, sfGracePeriod) ||
                     kFieldChanged(before, after, sfLoanScale);
+
+                // lsfLoanOverpayment must never toggle. lsfLoanDefault may only
+                // transition from unset to set, which combined with ValidLoan's rule that
+                // only LoanManage may change it makes the flag write-once.
+                if (view.rules().enabled(featureLendingProtocolV1_1))
+                {
+                    std::uint32_t const beforeFlags = before->getFlags();
+                    std::uint32_t const afterFlags = after->getFlags();
+                    bool const overpaymentChanged =
+                        (beforeFlags & lsfLoanOverpayment) != (afterFlags & lsfLoanOverpayment);
+                    if (overpaymentChanged)
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: lsfLoanOverpayment flag "
+                                           "toggled on immutable ledger entry in "
+                                        << tx.getTransactionID();
+                    }
+                    bad = bad || overpaymentChanged;
+                    bool const defaultCleared =
+                        (beforeFlags & lsfLoanDefault) != 0 && (afterFlags & lsfLoanDefault) == 0;
+                    if (defaultCleared)
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: lsfLoanDefault flag "
+                                           "cleared on immutable ledger entry in "
+                                        << tx.getTransactionID();
+                    }
+                    bad = bad || defaultCleared;
+                }
                 break;
             case ltVAULT:
                 /*
-                 * sfAccount, sfAsset and sfShareMPTID are already
-                 * captured by VaultInvariant. The additional fields
-                 * below are introduced by featureLendingProtocolV1_1
-                 * and only exist on V1_1 vaults.
+                 * All the fields below are only immutable from
+                 * featureLendingProtocolV1_1 onwards; some of them only exist on
+                 * V1_1 vaults. Before that amendment, sfAsset, sfAccount and
+                 * sfShareMPTID are checked by VaultInvariant instead.
                  */
                 if (view.rules().enabled(featureLendingProtocolV1_1))
                 {
@@ -1190,7 +1224,10 @@ NoModifiedUnmodifiableFields::finalize(
                         kFieldChanged(before, after, sfOwner) ||
                         kFieldChanged(before, after, sfWithdrawalPolicy) ||
                         kFieldChanged(before, after, sfScale) ||
-                        kFieldChanged(before, after, sfLEVersion);
+                        kFieldChanged(before, after, sfLEVersion) ||
+                        kFieldChanged(before, after, sfAsset) ||
+                        kFieldChanged(before, after, sfAccount) ||
+                        kFieldChanged(before, after, sfShareMPTID);
                 }
                 break;
             default:
diff --git a/src/libxrpl/tx/invariants/LoanBrokerInvariant.cpp b/src/libxrpl/tx/invariants/LoanBrokerInvariant.cpp
index b70c02947f..e15921b7b2 100644
--- a/src/libxrpl/tx/invariants/LoanBrokerInvariant.cpp
+++ b/src/libxrpl/tx/invariants/LoanBrokerInvariant.cpp
@@ -1,13 +1,18 @@
 #include <xrpl/tx/invariants/LoanBrokerInvariant.h>
 
 #include <xrpl/basics/Log.h>
+#include <xrpl/basics/Number.h>
 #include <xrpl/beast/utility/Journal.h>
+#include <xrpl/beast/utility/Zero.h>
 #include <xrpl/ledger/ReadView.h>
+#include <xrpl/ledger/helpers/LendingHelpers.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
+#include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/LedgerFormats.h>
 #include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STLedgerEntry.h>
 #include <xrpl/protocol/STNumber.h>  // IWYU pragma: keep
 #include <xrpl/protocol/STTx.h>
@@ -22,6 +27,24 @@ namespace xrpl {
 void
 ValidLoanBroker::visitEntry(bool isDelete, SLE::const_ref before, SLE::const_ref after)
 {
+    // Track LoanBroker deletions so finalize() can enforce:
+    //   (a) only ttLOAN_BROKER_DELETE removes a broker
+    //   (b) at most one broker is removed per transaction
+    //   (c) DebtTotal and OwnerCount were zero before deletion
+    // `before` is the pre-transaction state, which is what
+    // LoanBrokerDelete::preclaim reads. Erased trust lines and MPTokens need no
+    // special handling here: the `if (after)` branch below already records them.
+    if (isDelete && before && before->getType() == ltLOAN_BROKER)
+    {
+        if (deletedBroker_)
+        {
+            multipleBrokerDeletions_ = true;
+        }
+        else
+        {
+            deletedBroker_ = before;
+        }
+    }
     if (after)
     {
         if (after->getType() == ltLOAN_BROKER)
@@ -99,6 +122,64 @@ ValidLoanBroker::finalize(
     // Loan Brokers will not exist on ledger if the Lending Protocol amendment
     // is not enabled, so there's no need to check it.
 
+    // Deletion invariants (featureLendingProtocolV1_1). At most one
+    // LoanBroker may be removed per transaction, and only by
+    // ttLOAN_BROKER_DELETE, and only when its pre-state OwnerCount is zero and
+    // its pre-state DebtTotal is zero to the precision of the vault asset. The
+    // DebtTotal check complements ValidLoan's
+    // LoanBrokerDelete-must-not-touch-any-loan rule: even a broker that has
+    // finished paying off every loan may still hold non-zero exposure until
+    // its LoanBrokerCoverWithdraw settles, and neither state is safe to
+    // delete.
+    if (view.rules().enabled(featureLendingProtocolV1_1))
+    {
+        if (multipleBrokerDeletions_)
+        {
+            JLOG(j.fatal())
+                << "Invariant failed: more than one Loan Broker deleted in a single transaction";
+            return false;
+        }
+        if (deletedBroker_)
+        {
+            if (tx.getTxnType() != ttLOAN_BROKER_DELETE)
+            {
+                JLOG(j.fatal()) << "Invariant failed: " <<  //
+                    "Loan Broker deleted by a transaction other than LoanBrokerDelete";
+                return false;
+            }
+            // Mirror LoanBrokerDelete::preclaim, which accepts a DebtTotal
+            // that rounds to zero at the vault's AssetsTotal scale rather than
+            // requiring an exact zero. Requiring more here would turn a
+            // transaction the transactor deliberately permits into an
+            // invariant failure.
+            if (auto const debtTotal = deletedBroker_->at(sfDebtTotal); debtTotal != beast::kZero)
+            {
+                // The erased broker is also collected in brokers_, and that
+                // loop reports a missing vault, so no separate diagnostic is
+                // needed here. Without a vault there is no scale to round at,
+                // so the residue cannot be excused as dust.
+                auto const vault = view.read(keylet::vault(deletedBroker_->at(sfVaultID)));
+                if (!vault ||
+                    roundToAsset(
+                        Asset{vault->at(sfAsset)},
+                        debtTotal,
+                        getAssetsTotalScale(vault),
+                        Number::RoundingMode::TowardsZero) != beast::kZero)
+                {
+                    JLOG(j.fatal())
+                        << "Invariant failed: Loan Broker deleted with non-zero debt total";
+                    return false;
+                }
+            }
+            if (deletedBroker_->at(sfOwnerCount) != 0)
+            {
+                JLOG(j.fatal())
+                    << "Invariant failed: Loan Broker deleted with non-zero owner count";
+                return false;
+            }
+        }
+    }
+
     for (auto const& line : lines_)
     {
         for (auto const& field : {&sfLowLimit, &sfHighLimit})
@@ -142,7 +223,6 @@ ValidLoanBroker::finalize(
 
         auto const& before = broker.brokerBefore;
 
-        // https://github.com/Tapanito/XRPL-Standards/blob/xls-66-lending-protocol/XLS-0066d-lending-protocol/README.md#3123-invariants
         // If `LoanBroker.OwnerCount = 0` the `DirectoryNode` will have at most
         // one node (the root), which will only hold entries for `RippleState`
         // or `MPToken` objects.
diff --git a/src/libxrpl/tx/invariants/LoanInvariant.cpp b/src/libxrpl/tx/invariants/LoanInvariant.cpp
index 7b96790570..b34d7088be 100644
--- a/src/libxrpl/tx/invariants/LoanInvariant.cpp
+++ b/src/libxrpl/tx/invariants/LoanInvariant.cpp
@@ -1,10 +1,13 @@
 #include <xrpl/tx/invariants/LoanInvariant.h>
 
 #include <xrpl/basics/Log.h>
+#include <xrpl/basics/Number.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <xrpl/ledger/ReadView.h>
 #include <xrpl/ledger/helpers/VaultHelpers.h>
+#include <xrpl/protocol/Asset.h>
+#include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/LedgerFormats.h>
 #include <xrpl/protocol/Protocol.h>
@@ -13,6 +16,7 @@
 #include <xrpl/protocol/STNumber.h>  // IWYU pragma: keep
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/TER.h>
+#include <xrpl/protocol/TxFormats.h>
 #include <xrpl/protocol/XRPAmount.h>
 
 #include <cstdint>
@@ -22,7 +26,14 @@ namespace xrpl {
 void
 ValidLoan::visitEntry(bool isDelete, SLE::const_ref before, SLE::const_ref after)
 {
-    if (after && after->getType() == ltLOAN)
+    // Classify here, but leave the decision about which checks apply to
+    // finalize(), which is the only place that can see the Rules.
+    if (isDelete)
+    {
+        if (before && before->getType() == ltLOAN)
+            deletedLoans_.emplace_back(before, after);
+    }
+    else if (after && after->getType() == ltLOAN)
     {
         loans_.emplace_back(before, after);
     }
@@ -39,12 +50,23 @@ ValidLoan::finalize(
     // Loans will not exist on ledger if the Lending Protocol amendment
     // is not enabled, so there's no need to check it.
 
+    auto const txType = tx.getTxnType();
+    bool const lpV11Enabled = view.rules().enabled(featureLendingProtocolV1_1);
+
+    // Without featureLendingProtocolV1_1 an erased Loan is subject to the same
+    // per-entry checks as any modified Loan. From V1_1 onward it is only subject
+    // to the ttLOAN_DELETE check below.
+    if (!lpV11Enabled)
+        loans_.insert(loans_.end(), deletedLoans_.begin(), deletedLoans_.end());
+
+    // Ledger entry validation checks.
     for (auto const& [before, after] : loans_)
     {
-        // A closed-ended vault must not accept a loan whose final scheduled payment falls on or
-        // after the vault's RedemptionDate. This mirrors the LoanSet::preclaim gate and only fires
-        // on loan creation; once the loan exists, its StartDate / PaymentInterval are immutable and
-        // PaymentRemaining only decreases, so the bound is preserved.
+        // A closed-ended vault must not accept a loan whose final scheduled payment falls fewer
+        // than kLoanRedemptionBuffer seconds before the vault's RedemptionDate. This mirrors the
+        // LoanSet::preclaim gate and only fires on loan creation; once the loan exists, its
+        // StartDate / PaymentInterval are immutable and PaymentRemaining only decreases, so the
+        // bound is preserved.
         if (!before && isTesSuccess(result))
         {
             auto const broker = view.read(keylet::loanBroker(after->at(sfLoanBrokerID)));
@@ -59,11 +81,13 @@ ValidLoan::finalize(
                     std::uint32_t const interval = after->at(sfPaymentInterval);
                     std::uint32_t const remaining = after->at(sfPaymentRemaining);
                     std::uint32_t const redemption = vault->at(sfRedemptionDate);
-                    if (std::uint64_t{startDate} + (std::uint64_t{interval} * remaining) >=
+                    if (std::uint64_t{startDate} + (std::uint64_t{interval} * remaining) +
+                            kLoanRedemptionBuffer >
                         redemption)
                     {
                         JLOG(j.fatal()) << "Invariant failed: closed-ended loan final payment "
-                                           "must precede RedemptionDate";
+                                           "must precede RedemptionDate by at least "
+                                           "kLoanRedemptionBuffer";
                         return false;
                     }
                 }
@@ -91,7 +115,11 @@ ValidLoan::finalize(
             JLOG(j.fatal()) << "Invariant failed: Fully paid off Loan still has payments remaining";
             return false;
         }
-        if (before && (before->isFlag(lsfLoanOverpayment) != after->isFlag(lsfLoanOverpayment)))
+
+        // From featureLendingProtocolV1_1 onwards this flag is immutable by way of
+        // NoModifiedUnmodifiableFields.
+        if (!lpV11Enabled && before &&
+            (before->isFlag(lsfLoanOverpayment) != after->isFlag(lsfLoanOverpayment)))
         {
             JLOG(j.fatal()) << "Invariant failed: Loan Overpayment flag changed";
             return false;
@@ -123,6 +151,125 @@ ValidLoan::finalize(
                 return false;
             }
         }
+        if (lpV11Enabled)
+        {
+            // Only LoanSet may create a loan.
+            if (!before && txType != ttLOAN_SET)
+            {
+                JLOG(j.fatal()) << "Invariant failed: Loan created by a transaction "
+                                   "other than LoanSet";
+                return false;
+            }
+
+            if (after->at(sfPaymentRemaining) == 0 &&
+                after->at(~sfNextPaymentDueDate).value_or(0) != 0)
+            {
+                JLOG(j.fatal()) << "Invariant failed: Loan with zero payments must have zero next "
+                                   "payment due date";
+                return false;
+            }
+
+            if (before)
+            {
+                bool const wasImpaired = before->isFlag(lsfLoanImpaired);
+                bool const isImpaired = after->isFlag(lsfLoanImpaired);
+                bool const wasDefaulted = before->isFlag(lsfLoanDefault);
+                bool const isDefaulted = after->isFlag(lsfLoanDefault);
+
+                if (wasImpaired != isImpaired && txType != ttLOAN_MANAGE && txType != ttLOAN_PAY)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: lsfLoanImpaired changed "
+                                       "outside LoanManage or LoanPay";
+                    return false;
+                }
+                if (wasDefaulted != isDefaulted && txType != ttLOAN_MANAGE)
+                {
+                    JLOG(j.fatal()) << "Invariant failed: lsfLoanDefault changed "
+                                       "outside LoanManage";
+                    return false;
+                }
+            }
+
+            // A loan must reference a live loan broker, and that broker must
+            // reference a live vault; otherwise the loan is orphaned and its
+            // balances have no counterparty on the ledger.
+            auto const brokerSle = view.read(keylet::loanBroker(after->at(sfLoanBrokerID)));
+            if (!brokerSle)
+            {
+                JLOG(j.fatal()) << "Invariant failed: Loan broker does not exist";
+                return false;
+            }
+            auto const vaultSle = view.read(keylet::vault(brokerSle->at(sfVaultID)));
+            if (!vaultSle)
+            {
+                JLOG(j.fatal()) << "Invariant failed: Loan broker vault does not exist";
+                return false;
+            }
+
+            // Interest due (the total value owed less principal and management fee)
+            // must never be negative. TotalValueOutstanding, PrincipalOutstanding and
+            // ManagementFeeOutstanding are each independently rounded to sfLoanScale
+            // by the accounting code, so their difference can carry one unit of
+            // quantization noise even when the underlying flow is correct. Absorb
+            // one unit at that scale, matching the pattern used in ValidVault.
+            auto const interestDue = after->at(sfTotalValueOutstanding) -
+                after->at(sfPrincipalOutstanding) - after->at(sfManagementFeeOutstanding);
+
+            // Only IOU amounts can accumulate STAmount quantization noise. For integral-domain
+            // assets (XRP/MPT) enforce the boundary strictly.
+            bool const integral = Asset{vaultSle->at(sfAsset)}.integral();
+
+            Number const tolerance = integral ? Number{} : Number{-1, after->at(sfLoanScale)};
+            if (interestDue < tolerance)
+            {
+                JLOG(j.fatal()) << "Invariant failed: Loan interest due is negative";
+                return false;
+            }
+
+            // Transaction success post-conditions. A successful loan pay makes at least
+            // one scheduled payment, so a loan left with payments still outstanding
+            // must show that payment in its balance and schedule. A payment that clears
+            // the loan outright instead drives PaymentRemaining to zero, which the
+            // fully-paid-off and zero due-date checks above pin.
+            if (isTesSuccess(result) && txType == ttLOAN_PAY)
+            {
+                if (before && after->at(sfPaymentRemaining) != 0)
+                {
+                    if (!(after->at(sfPrincipalOutstanding) < before->at(sfPrincipalOutstanding)))
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: loan pay must strictly decrease "
+                                           "PrincipalOutstanding on a non-full-repayment";
+                        return false;
+                    }
+                    if (!(after->at(sfPaymentRemaining) < before->at(sfPaymentRemaining)))
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: loan pay must decrease "
+                                           "PaymentRemaining on a non-full-repayment";
+                        return false;
+                    }
+
+                    std::uint32_t const beforeDue = before->at(~sfNextPaymentDueDate).value_or(0);
+                    std::uint32_t const afterDue = after->at(~sfNextPaymentDueDate).value_or(0);
+                    std::uint32_t const interval = after->at(sfPaymentInterval);
+                    if (afterDue <= beforeDue || interval == 0 ||
+                        (afterDue - beforeDue) % interval != 0)
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: loan pay must advance "
+                                           "NextPaymentDueDate by a positive multiple of "
+                                           "PaymentInterval on a non-full-repayment";
+                        return false;
+                    }
+                }
+            }
+        }
+    }
+
+    // Only LoanDelete may delete a loan.
+    if (lpV11Enabled && txType != ttLOAN_DELETE && !deletedLoans_.empty())
+    {
+        JLOG(j.fatal()) << "Invariant failed: Loan deleted by a transaction "
+                           "other than LoanDelete";
+        return false;
     }
     return true;
 }
diff --git a/src/libxrpl/tx/invariants/MPTInvariant.cpp b/src/libxrpl/tx/invariants/MPTInvariant.cpp
index 2cfd069420..e38e8f2b93 100644
--- a/src/libxrpl/tx/invariants/MPTInvariant.cpp
+++ b/src/libxrpl/tx/invariants/MPTInvariant.cpp
@@ -234,14 +234,6 @@ ValidMPTIssuance::finalize(
 
         if (hasPrivilege(tx, Privilege::DestroyMptIssuance))
         {
-            // A VaultDelete that is still cleaning up credentials pinned to its
-            // pseudo-account returns tecINCOMPLETE and has not yet reached the
-            // share issuance. Don't require the issuance to be removed until
-            // the deletion completes (a later transaction).
-            if (rules.enabled(fixCleanup3_4_0) && txnType == ttVAULT_DELETE &&
-                result == tecINCOMPLETE)
-                return mptIssuancesDeleted_ == 0 && mptIssuancesCreated_ == 0;
-
             if (mptIssuancesDeleted_ == 0)
             {
                 JLOG(j.fatal()) << "Invariant failed: MPT issuance deletion "
@@ -832,6 +824,14 @@ ValidMPTTransfer::visitEntry(
 
     if (after)
         update(*after, false);
+
+    // Record whether every touched AccountRoot was a pseudo-account BEFORE
+    // the transaction applied (true and false). A transaction that erases a
+    // pseudo-account (and moves MPT out of it) in the same transaction leaves
+    // no trace of its pseudo-account status in the post-transaction view
+    // isAuthorized() sees at finalize() time.
+    if (before && before->getType() == ltACCOUNT_ROOT)
+        pseudoAccountsBefore_[before->at(sfAccount)] = isPseudoAccount(before);
 }
 
 bool
@@ -844,10 +844,19 @@ ValidMPTTransfer::isAuthorized(
     // Pseudo-accounts (Vault, LoanBroker, AMM) hold assets on behalf of their
     // participants and are implicitly authorized for any MPT they hold,
     // including vault shares whose underlying asset would otherwise require
-    // auth.  Exempt them here rather than relying on requireAuth: the recursive
+    // auth. Exempt them here rather than relying on requireAuth: the recursive
     // share -> underlying descent in requireAuth fails for a pseudo-account
     // that holds the share but not the underlying.
-    if (isPseudoAccount(view, holder, {&sfVaultID, &sfLoanBrokerID, &sfAMMID}))
+    //
+    // Use the pre-transaction classification for any account this
+    // transaction touched (pseudoAccountsBefore_): the post-transaction view
+    // is wrong for an account this same transaction erased. Untouched
+    // accounts aren't in the map, so fall back to the current view, which is
+    // still accurate for them since nothing changed.
+    auto const pseudoIt = pseudoAccountsBefore_.find(holder);
+    bool const isPseudo =
+        pseudoIt != pseudoAccountsBefore_.end() ? pseudoIt->second : isPseudoAccount(view, holder);
+    if (isPseudo)
         return true;
 
     auto const key = keylet::mptoken(mptid, holder);
diff --git a/src/libxrpl/tx/invariants/VaultInvariant.cpp b/src/libxrpl/tx/invariants/VaultInvariant.cpp
index 1bfb9d3d43..69c3ce92e0 100644
--- a/src/libxrpl/tx/invariants/VaultInvariant.cpp
+++ b/src/libxrpl/tx/invariants/VaultInvariant.cpp
@@ -21,6 +21,7 @@
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFormats.h>
 #include <xrpl/protocol/XRPAmount.h>
+#include <xrpl/tx/Transactor.h>
 #include <xrpl/tx/invariants/InvariantCheckPrivilege.h>
 
 #include <algorithm>
@@ -235,21 +236,57 @@ ValidVault::deltaAssets(AccountID const& id) const
         vaultAsset.value());
 }
 
+std::optional<AccountID>
+ValidVault::feePayerAccountRoot(ReadView const& view, STTx const& tx)
+{
+    auto const feePayer = Transactor::getFeePayer(view, tx);
+    if (feePayer.type == FeePayerType::SponsorPreFunded)
+        return std::nullopt;
+    return feePayer.id;
+}
+
 std::optional<ValidVault::DeltaInfo>
-ValidVault::deltaAssetsTxAccount(STTx const& tx, XRPAmount fee) const
+ValidVault::deltaAssetsForParty(
+    ReadView const& view,
+    AccountID const& id,
+    STTx const& tx,
+    XRPAmount fee,
+    bool fix340Enabled) const
 {
     auto const& vaultAsset = afterVault_[0].asset;
-    auto ret = deltaAssets(tx[sfAccount]);
+    auto ret = deltaAssets(id);
     if (!ret.has_value() || !vaultAsset.native())
         return ret;
 
-    // Only add the fee back if tx[sfAccount] actually paid it. When the fee is
-    // paid by someone else (a delegate or a fee sponsor), the
-    // account's XRP balance moved only by the vault amount.
-    if (tx.getFeePayerID() != tx[sfAccount])
-        return ret;
+    if (!fix340Enabled)
+    {
+        // Legacy behaviour: only tx[sfAccount] was ever considered for a fee
+        // correction, and only when STTx::getFeePayerID identified it as the
+        // fee payer (which is never true for a sponsor, since
+        // self-sponsorship is disallowed). After that sender-only correction
+        // a zero delta is collapsed to absence; if the correction does not
+        // apply, a present-zero is returned as-is.
+        if (id != tx[sfAccount] || tx.getFeePayerID() != id)
+            return ret;
 
-    ret->delta += fee.drops();
+        ret->delta += fee.drops();
+        if (ret->delta == kZero)
+            return std::nullopt;
+
+        return ret;
+    }
+
+    // Add the fee back only onto the AccountRoot that actually paid it: an
+    // ordinary sender, a delegate, or a co-signed fee sponsor -- but never a
+    // pre-funded sponsorship, whose fee is drawn from the ltSponsorship
+    // object rather than the sponsor's own XRP balance.
+    if (auto const payer = feePayerAccountRoot(view, tx); payer && *payer == id)
+        ret->delta += fee.drops();
+
+    // Normalize an economically zero delta to absence regardless of who (if
+    // anyone) paid the fee, so a touched-but-unchanged AccountRoot (e.g. the
+    // sender in a third-party withdrawal, touched only for sequence/ticket
+    // processing) is never misread as a second payout recipient.
     if (ret->delta == kZero)
         return std::nullopt;
 
@@ -380,7 +417,7 @@ ValidVault::finalize(
     beast::Journal const& j)
 {
     bool const enforce = view.rules().enabled(featureSingleAssetVault);
-    bool const fixEnabled = view.rules().enabled(fixCleanup3_4_0);
+    bool const fix340Enabled = view.rules().enabled(fixCleanup3_4_0);
 
     if (!isTesSuccess(ret))
         return true;  // Do not perform checks
@@ -515,7 +552,8 @@ ValidVault::finalize(
     bool result = true;
 
     // Universal transaction checks
-    if (!beforeVault_.empty())
+    // From LendingProtocolV1_1 onwards, vault immutability check is moved to InvariantCheck.cpp
+    if (!beforeVault_.empty() && !view.rules().enabled(featureLendingProtocolV1_1))
     {
         auto const& beforeVault = beforeVault_[0];
         if (afterVault.asset != beforeVault.asset || afterVault.pseudoId != beforeVault.pseudoId ||
@@ -571,7 +609,7 @@ ValidVault::finalize(
     else
     {
         bool const gapExceeded = [&] {
-            if (!fixEnabled)
+            if (!fix340Enabled)
             {
                 return afterVault.lossUnrealized >
                     afterVault.assetsTotal - afterVault.assetsAvailable;
@@ -593,7 +631,7 @@ ValidVault::finalize(
         }
     }
 
-    if (fixEnabled && afterVault.lossUnrealized < kZero)
+    if (fix340Enabled && afterVault.lossUnrealized < kZero)
     {
         JLOG(j.fatal()) << "Invariant failed: loss unrealized must not be negative";
         result = false;
@@ -764,8 +802,13 @@ ValidVault::finalize(
                     result = false;
                 }
 
+                // AssetsTotal may exceed AssetsMaximum when the excess is interest. After
+                // fixCleanup3_4_0, only reject a VaultSet that supplies sfAssetsMaximum or
+                // otherwise changes the cap to a nonzero value still below AssetsTotal.
                 if (afterVault.assetsMaximum > kZero &&
-                    afterVault.assetsTotal > afterVault.assetsMaximum)
+                    afterVault.assetsTotal > afterVault.assetsMaximum &&
+                    (!fix340Enabled || tx.isFieldPresent(sfAssetsMaximum) ||
+                     beforeVault.assetsMaximum != afterVault.assetsMaximum))
                 {
                     JLOG(j.fatal()) <<  //
                         "Invariant failed: set assets outstanding must not "
@@ -854,7 +897,8 @@ ValidVault::finalize(
 
                 if (!issuerDeposit)
                 {
-                    auto const maybeAccDeltaAssets = deltaAssetsTxAccount(tx, fee);
+                    auto const maybeAccDeltaAssets =
+                        deltaAssetsForParty(view, tx[sfAccount], tx, fee, fix340Enabled);
                     if (!maybeAccDeltaAssets)
                     {
                         JLOG(j.fatal())
@@ -879,7 +923,7 @@ ValidVault::finalize(
                         result = false;
                     }
 
-                    bool const acctVaultAddsUp = fixEnabled
+                    bool const acctVaultAddsUp = fix340Enabled
                         ? agreesWithinOneUnit(
                               localVaultDeltaAssets * -1,
                               accountDeltaAssets,
@@ -934,7 +978,7 @@ ValidVault::finalize(
 
                 auto const assetTotalDelta = roundToAsset(
                     vaultAsset, afterVault.assetsTotal - beforeVault.assetsTotal, minScale);
-                bool const totalAddsUp = fixEnabled
+                bool const totalAddsUp = fix340Enabled
                     ? agreesWithinOneUnit(assetTotalDelta, vaultDeltaAssets, vaultAsset, minScale)
                     : assetTotalDelta == vaultDeltaAssets;
                 if (!totalAddsUp)
@@ -946,7 +990,7 @@ ValidVault::finalize(
 
                 auto const assetAvailableDelta = roundToAsset(
                     vaultAsset, afterVault.assetsAvailable - beforeVault.assetsAvailable, minScale);
-                bool const availableAddsUp = fixEnabled
+                bool const availableAddsUp = fix340Enabled
                     ? agreesWithinOneUnit(
                           assetAvailableDelta, vaultDeltaAssets, vaultAsset, minScale)
                     : assetAvailableDelta == vaultDeltaAssets;
@@ -992,7 +1036,7 @@ ValidVault::finalize(
                 // value merely rounds down to zero, so a missing delta while
                 // the pool still held positive effective value indicates a
                 // real accounting bug, not this exception.
-                bool const zeroDeltaIsLegitimate = fixEnabled && !maybeVaultDeltaAssets &&
+                bool const zeroDeltaIsLegitimate = fix340Enabled && !maybeVaultDeltaAssets &&
                     beforeVault.assetsTotal == beforeVault.lossUnrealized;
 
                 if (!maybeVaultDeltaAssets && !zeroDeltaIsLegitimate)
@@ -1027,21 +1071,39 @@ ValidVault::finalize(
 
                 if (!issuerWithdrawal)
                 {
-                    auto const maybeAccDelta = deltaAssetsTxAccount(tx, fee);
-                    auto const maybeOtherAccDelta = [&]() -> std::optional<DeltaInfo> {
-                        if (auto const destination = tx[~sfDestination];
-                            destination && *destination != tx[sfAccount])
-                            return deltaAssets(*destination);
-                        return std::nullopt;
-                    }();
+                    // Identify the intended recipient explicitly from
+                    // sfDestination (falling back to sfAccount for a
+                    // self-withdrawal), rather than inferring it from which
+                    // side happens to show a delta. When a distinct
+                    // destination is named, the sending account must not
+                    // also show a real economic delta -- that would mean two
+                    // accounts were paid, which is always a bug, regardless
+                    // of what (if anything) the named destination received.
+                    auto const destinationField = tx[~sfDestination];
+                    AccountID const recipient = destinationField.value_or(tx[sfAccount]);
+                    bool const distinctDestination =
+                        destinationField.has_value() && *destinationField != tx[sfAccount];
 
-                    if (maybeAccDelta.has_value() == maybeOtherAccDelta.has_value())
+                    // Intentionally ungated: `fix340Enabled &&` here would let the
+                    // pre-amendment sponsored case succeed and change consensus.
+                    if (distinctDestination &&
+                        deltaAssetsForParty(view, tx[sfAccount], tx, fee, fix340Enabled)
+                            .has_value())
                     {
-                        // Both changed is always a bug. Neither changed is
-                        // consistent only with a legitimate zero-value
-                        // withdrawal, which moves nothing on either side —
-                        // there is nothing left to cross-check.
-                        if (!zeroDeltaIsLegitimate || maybeAccDelta.has_value())
+                        JLOG(j.fatal()) <<  //
+                            "Invariant failed: withdrawal must change one destination balance";
+                        return false;
+                    }
+
+                    auto const maybeRecipientDelta =
+                        deltaAssetsForParty(view, recipient, tx, fee, fix340Enabled);
+
+                    if (!maybeRecipientDelta.has_value())
+                    {
+                        // A legitimate zero-value withdrawal moves nothing to
+                        // the recipient either; there is nothing left to
+                        // cross-check.
+                        if (!zeroDeltaIsLegitimate)
                         {
                             JLOG(j.fatal()) <<  //
                                 "Invariant failed: withdrawal must change one destination balance";
@@ -1053,8 +1115,7 @@ ValidVault::finalize(
                         // A one-sided change is cross-checked even for a
                         // legitimate zero vault delta: the destination must
                         // then have moved by (rounded) zero as well.
-                        auto const destinationDelta =
-                            *maybeAccDelta.or_else([&] { return maybeOtherAccDelta; });
+                        auto const destinationDelta = *maybeRecipientDelta;
 
                         // the scale of destinationDelta can be coarser than
                         // minScale, so we take that into account when rounding
@@ -1068,9 +1129,7 @@ ValidVault::finalize(
                         // only. If the receiver's trust line sits at a coarser scale, the inflow
                         // may safely round down to zero.
                         //
-                        // XRP and MPT remain strict. Because they are integer-exact, a zero
-                        // destination delta indicates a true accounting bug, not a rounding
-                        // artifact.
+                        // XRP and MPT remain strict for rounding artifacts.
                         bool const tolerateZeroDelta =
                             view.rules().enabled(fixCleanup3_2_0) && !vaultAsset.integral();
                         auto const invalidBalanceChange = tolerateZeroDelta
@@ -1099,7 +1158,7 @@ ValidVault::finalize(
                                 vaultDeltaAssets.delta * -1 - destinationDelta.delta,
                                 destinationScale,
                                 Number::RoundingMode::Downward) == kZero;
-                        bool const withdrawAddsUp = fixEnabled
+                        bool const withdrawAddsUp = fix340Enabled
                             ? agreesWithinOneUnit(
                                   localPseudoDeltaAssets * -1,
                                   roundedDestinationDelta,
@@ -1149,7 +1208,7 @@ ValidVault::finalize(
                 auto const assetTotalDelta = roundToAsset(
                     vaultAsset, afterVault.assetsTotal - beforeVault.assetsTotal, minScale);
                 // Note, vaultBalance is negative (see check above)
-                bool const totalAddsUp = fixEnabled
+                bool const totalAddsUp = fix340Enabled
                     ? agreesWithinOneUnit(
                           assetTotalDelta, vaultPseudoDeltaAssets, vaultAsset, minScale)
                     : assetTotalDelta == vaultPseudoDeltaAssets;
@@ -1163,7 +1222,7 @@ ValidVault::finalize(
                 auto const assetAvailableDelta = roundToAsset(
                     vaultAsset, afterVault.assetsAvailable - beforeVault.assetsAvailable, minScale);
 
-                bool const availableAddsUp = fixEnabled
+                bool const availableAddsUp = fix340Enabled
                     ? agreesWithinOneUnit(
                           assetAvailableDelta, vaultPseudoDeltaAssets, vaultAsset, minScale)
                     : assetAvailableDelta == vaultPseudoDeltaAssets;
@@ -1212,7 +1271,7 @@ ValidVault::finalize(
 
                     auto const assetsTotalDelta = roundToAsset(
                         vaultAsset, afterVault.assetsTotal - beforeVault.assetsTotal, minScale);
-                    bool const totalAddsUp = fixEnabled
+                    bool const totalAddsUp = fix340Enabled
                         ? agreesWithinOneUnit(
                               assetsTotalDelta, vaultDeltaAssets, vaultAsset, minScale)
                         : assetsTotalDelta == vaultDeltaAssets;
@@ -1227,7 +1286,7 @@ ValidVault::finalize(
                         vaultAsset,
                         afterVault.assetsAvailable - beforeVault.assetsAvailable,
                         minScale);
-                    bool const availableAddsUp = fixEnabled
+                    bool const availableAddsUp = fix340Enabled
                         ? agreesWithinOneUnit(
                               assetAvailableDelta, vaultDeltaAssets, vaultAsset, minScale)
                         : assetAvailableDelta == vaultDeltaAssets;
diff --git a/src/libxrpl/tx/paths/BookStep.cpp b/src/libxrpl/tx/paths/BookStep.cpp
index 2823627108..ae218a4cff 100644
--- a/src/libxrpl/tx/paths/BookStep.cpp
+++ b/src/libxrpl/tx/paths/BookStep.cpp
@@ -1500,6 +1500,13 @@ template <class TIn, class TOut, class TDerived>
 bool
 BookStep<TIn, TOut, TDerived>::checkMPTDEX(ReadView const& view, AccountID const& owner) const
 {
+    // Offer-owner locks on book_.in and book_.out are handled by the
+    // liquidity sources before an offer reaches this point. OfferStream
+    // filters CLOB offers through the assetIn deep-freeze check and the
+    // assetOut owner-funds check using FreezeHandling::ZeroIfFrozen, while
+    // AMMLiquidity gets pool balances through ammAccountHolds(), which zeroes
+    // locked holdings. This method only enforces MPT trade and transfer
+    // permissions.
     if (!isTesSuccess(canTrade(view, book_.in)) || !isTesSuccess(canTrade(view, book_.out)))
         return false;
 
@@ -1513,14 +1520,8 @@ BookStep<TIn, TOut, TDerived>::checkMPTDEX(ReadView const& view, AccountID const
             // Offer's owner is an issuer
             if (asset.getIssuer() == owner)
                 return true;
-            // The previous step could be MPTEndpointStep with non issuer account or
-            // BookStep. Fail both if in asset is locked. In the former case it is holder
-            // to locked holder transfer. In the latter case it is not possible to tell if
-            // it is issuer to holder or holder to holder transfer.
-            if (isFrozen(view, owner, book_.in.get<MPTIssue>()))
-                return false;
-            // Previous step is BookStep. BookStep only sends if CanTransfer is
-            // set and not locked or the offer is owned by an issuer
+            // Previous BookStep already enforced transferability for the asset
+            // it sends to this offer.
             if (prevStep_->bookStepBook())
                 return true;
             // Previous step is MPTEndpointStep and offer's owner is not an
diff --git a/src/libxrpl/tx/paths/MPTEndpointStep.cpp b/src/libxrpl/tx/paths/MPTEndpointStep.cpp
index a47cfa15a5..8fd69d3106 100644
--- a/src/libxrpl/tx/paths/MPTEndpointStep.cpp
+++ b/src/libxrpl/tx/paths/MPTEndpointStep.cpp
@@ -13,6 +13,7 @@
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/MPTAmount.h>
 #include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/Quality.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/TER.h>
@@ -89,6 +90,13 @@ protected:
     void
     resetCache(DebtDirection dir);
 
+    [[nodiscard]] TER
+    sendWithMPTCreate(
+        ApplyView& view,
+        AccountID const& src,
+        AccountID const& dst,
+        MPTAmount const& amount);
+
 private:
     MPTEndpointStep(
         StrandContext const& ctx,
@@ -274,7 +282,7 @@ public:
 
     // Not applicable for payment
     static TER
-    checkCreateMPT(ApplyView&, DebtDirection)
+    checkCreateMPT(ApplyView&)
     {
         return tesSUCCESS;
     }
@@ -322,7 +330,7 @@ public:
 
     // Can be created in rev or fwd (if limiting step) direction.
     TER
-    checkCreateMPT(ApplyView& view, DebtDirection srcDebtDir);
+    checkCreateMPT(ApplyView& view);
 };
 
 //------------------------------------------------------------------------------
@@ -401,7 +409,7 @@ MPTEndpointOfferCrossingStep::check(StrandContext const& ctx, SLE::const_ref)
 }
 
 TER
-MPTEndpointOfferCrossingStep::checkCreateMPT(ApplyView& view, xrpl::DebtDirection srcDebtDir)
+MPTEndpointOfferCrossingStep::checkCreateMPT(ApplyView& view)
 {
     // TakerPays is the last step if offer crossing
     if (isLast_)
@@ -412,9 +420,14 @@ MPTEndpointOfferCrossingStep::checkCreateMPT(ApplyView& view, xrpl::DebtDirectio
         // crossed. See CreateOffer::applyGuts() for reserve check.
         if (auto const err = xrpl::checkCreateMPT(view, mptIssue_, dst_, j_); !isTesSuccess(err))
         {
+            // Unreachable: offer-crossing checks reject an offer whose owner
+            // could fail to create the MPToken.
+            // LCOV_EXCL_START
+            UNREACHABLE(
+                "xrpl::MPTEndpointOfferCrossingStep::checkCreateMPT : create MPToken failed");
             JLOG(j_.trace()) << "MPTEndpointStep::checkCreateMPT: failed create MPT";
-            resetCache(srcDebtDir);
             return err;
+            // LCOV_EXCL_STOP
         }
     }
     return tesSUCCESS;
@@ -422,6 +435,30 @@ MPTEndpointOfferCrossingStep::checkCreateMPT(ApplyView& view, xrpl::DebtDirectio
 
 //------------------------------------------------------------------------------
 
+template <class TDerived>
+TER
+MPTEndpointStep<TDerived>::sendWithMPTCreate(
+    ApplyView& view,
+    AccountID const& src,
+    AccountID const& dst,
+    MPTAmount const& amount)
+{
+    // Only offer crossing can fail here (payment checkCreateMPT is a no-op),
+    // via the unreachable path excluded in checkCreateMPT() above.
+    if (auto const err = static_cast<TDerived*>(this)->checkCreateMPT(view); !isTesSuccess(err))
+        return err;  // LCOV_EXCL_LINE
+
+    return directSendNoFee(
+        view,
+        src,
+        dst,
+        toSTAmount(amount, mptIssue_),
+        /*checkIssuer*/ false,
+        j_);
+}
+
+//------------------------------------------------------------------------------
+
 template <class TDerived>
 std::pair<MPTAmount, DebtDirection>
 MPTEndpointStep<TDerived>::maxPaymentFlow(ReadView const& sb) const
@@ -478,8 +515,6 @@ MPTEndpointStep<TDerived>::revImp(
     auto const [srcQOut, dstQIn] = qualities(sb, srcDebtDir, StrandDirection::Reverse);
     (void)dstQIn;
 
-    MPTIssue const srcToDstIss(mptIssue_);
-
     JLOG(j_.trace()) << "MPTEndpointStep::rev"
                      << " srcRedeems: " << redeems(srcDebtDir) << " outReq: " << to_string(out)
                      << " maxSrcToDst: " << to_string(maxSrcToDst) << " srcQOut: " << srcQOut
@@ -492,59 +527,41 @@ MPTEndpointStep<TDerived>::revImp(
         return {beast::kZero, beast::kZero};
     }
 
-    if (auto const err = static_cast<TDerived*>(this)->checkCreateMPT(sb, srcDebtDir);
-        !isTesSuccess(err))
-        return {beast::kZero, beast::kZero};
+    // When a previous step feeds this issuing step, srcQOut is the issuer's
+    // transfer rate and maxPaymentFlow() returns the issuance maximum rather
+    // than a real limit, so srcToDst * srcQOut need not be representable. Cap
+    // srcToDst at the largest amount whose input is; the previous step then
+    // limits the flow to what the source actually holds.
+    MPTAmount const maxRepresentable =
+        mulRatio(MPTAmount(kMaxMpTokenAmount), QUALITY_ONE, srcQOut, /*roundUp*/ false);
 
     // Don't have to factor in dstQIn since it is always QUALITY_ONE
-    MPTAmount const srcToDst = out;
+    MPTAmount const srcToDst = std::min({out, maxSrcToDst, maxRepresentable});
 
-    if (srcToDst <= maxSrcToDst)
-    {
-        MPTAmount const in = mulRatio(srcToDst, srcQOut, QUALITY_ONE, /*roundUp*/ true);
-        cache_.emplace(in, srcToDst, srcToDst, srcDebtDir);
-        auto const ter = directSendNoFee(
-            sb,
-            src_,
-            dst_,
-            toSTAmount(srcToDst, srcToDstIss),
-            /*checkIssuer*/ false,
-            j_);
-        if (!isTesSuccess(ter))
-        {
-            JLOG(j_.trace()) << "MPTEndpointStep::rev: error " << ter;
-            resetCache(srcDebtDir);
-            return {beast::kZero, beast::kZero};
-        }
-        JLOG(j_.trace()) << "MPTEndpointStep::rev: Non-limiting"
-                         << " srcRedeems: " << redeems(srcDebtDir) << " in: " << to_string(in)
-                         << " srcToDst: " << to_string(srcToDst) << " out: " << to_string(out);
-        return {in, out};
-    }
+    // Can't overflow: srcToDst <= kMaxMpTokenAmount * QUALITY_ONE / srcQOut,
+    // so the rounded up product is at most kMaxMpTokenAmount.
+    MPTAmount const in = mulRatio(srcToDst, srcQOut, QUALITY_ONE, /*roundUp*/ true);
 
-    // limiting node
-    MPTAmount const in = mulRatio(maxSrcToDst, srcQOut, QUALITY_ONE, /*roundUp*/ true);
-    // Don't have to factor in dsqQIn since it's always QUALITY_ONE
-    MPTAmount const actualOut = maxSrcToDst;
-    cache_.emplace(in, maxSrcToDst, actualOut, srcDebtDir);
+    cache_.emplace(in, srcToDst, srcToDst, srcDebtDir);
 
-    auto const ter = directSendNoFee(
-        sb,
-        src_,
-        dst_,
-        toSTAmount(maxSrcToDst, srcToDstIss),
-        /*checkIssuer*/ false,
-        j_);
+    auto const ter = sendWithMPTCreate(sb, src_, dst_, srcToDst);
     if (!isTesSuccess(ter))
     {
+        // Unreachable: send fails only on funds/auth/overflow, precluded by
+        // maxPaymentFlow, check() requireAuth, and 2*kMaxMpTokenAmount < 2^64.
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::MPTEndpointStep::revImp : send failed");
         JLOG(j_.trace()) << "MPTEndpointStep::rev: error " << ter;
         resetCache(srcDebtDir);
         return {beast::kZero, beast::kZero};
+        // LCOV_EXCL_STOP
     }
-    JLOG(j_.trace()) << "MPTEndpointStep::rev: Limiting"
+
+    JLOG(j_.trace()) << "MPTEndpointStep::rev: " << (srcToDst < out ? "Limiting" : "Non-limiting")
                      << " srcRedeems: " << redeems(srcDebtDir) << " in: " << to_string(in)
-                     << " srcToDst: " << to_string(maxSrcToDst) << " out: " << to_string(out);
-    return {in, actualOut};
+                     << " srcToDst: " << to_string(srcToDst) << " out: " << to_string(out);
+
+    return {in, srcToDst};
 }
 
 // The forward pass should never have more liquidity than the reverse
@@ -609,8 +626,6 @@ MPTEndpointStep<TDerived>::fwdImp(
     auto const [srcQOut, dstQIn] = qualities(sb, srcDebtDir, StrandDirection::Forward);
     (void)dstQIn;
 
-    MPTIssue const srcToDstIss(mptIssue_);
-
     JLOG(j_.trace()) << "MPTEndpointStep::fwd"
                      << " srcRedeems: " << redeems(srcDebtDir) << " inReq: " << to_string(in)
                      << " maxSrcToDst: " << to_string(maxSrcToDst) << " srcQOut: " << srcQOut
@@ -618,63 +633,81 @@ MPTEndpointStep<TDerived>::fwdImp(
 
     if (maxSrcToDst.signum() <= 0)
     {
+        // Unreachable: the reverse pass owns dry detection; every path that
+        // reaches fwdImp (see StrandFlow::flow) has a funded source.
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::MPTEndpointStep::fwdImp : dry source");
         JLOG(j_.trace()) << "MPTEndpointStep::fwd: dry";
         resetCache(srcDebtDir);
         return {beast::kZero, beast::kZero};
+        // LCOV_EXCL_STOP
     }
 
-    if (auto const err = static_cast<TDerived*>(this)->checkCreateMPT(sb, srcDebtDir);
-        !isTesSuccess(err))
+    auto const maybeSrcToDst = tryMulRatio(in, QUALITY_ONE, srcQOut, /*roundUp*/ false);
+    if (!maybeSrcToDst)
+    {
+        // Unreachable: divides by srcQOut >= QUALITY_ONE, so result <= in <=
+        // maxMPTAmount and can never overflow int64.
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::MPTEndpointStep::fwdImp : source to destination overflow");
+        JLOG(j_.trace()) << "MPTEndpointStep::fwd: overflow";
+        resetCache(srcDebtDir);
         return {beast::kZero, beast::kZero};
+        // LCOV_EXCL_STOP
+    }
 
-    MPTAmount const srcToDst = mulRatio(in, QUALITY_ONE, srcQOut, /*roundUp*/ false);
+    MPTAmount const srcToDst = *maybeSrcToDst;
 
     if (srcToDst <= maxSrcToDst)
     {
         // Don't have to factor in dstQIn since it's always QUALITY_ONE
         MPTAmount const out = srcToDst;
         setCacheLimiting(in, srcToDst, out, srcDebtDir);
-        auto const ter = directSendNoFee(
-            sb,
-            src_,
-            dst_,
-            toSTAmount(cache_->srcToDst, srcToDstIss),
-            /*checkIssuer*/ false,
-            j_);
-        if (!isTesSuccess(ter))
-        {
-            JLOG(j_.trace()) << "MPTEndpointStep::fwd: error " << ter;
-            resetCache(srcDebtDir);
-            return {beast::kZero, beast::kZero};
-        }
+
         JLOG(j_.trace()) << "MPTEndpointStep::fwd: Non-limiting"
                          << " srcRedeems: " << redeems(srcDebtDir) << " in: " << to_string(in)
                          << " srcToDst: " << to_string(srcToDst) << " out: " << to_string(out);
     }
     else
     {
+        // Unreachable: the reverse pass owns all limiting; the forward driver
+        // (StrandFlow::flow) never re-finds a limit, so srcToDst <= maxSrcToDst.
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::MPTEndpointStep::fwdImp : forward pass limiting");
         // limiting node
-        MPTAmount const actualIn = mulRatio(maxSrcToDst, srcQOut, QUALITY_ONE, /*roundUp*/ true);
-        // Don't have to factor in dstQIn since it's always QUALITY_ONE
-        MPTAmount const out = maxSrcToDst;
-        setCacheLimiting(actualIn, maxSrcToDst, out, srcDebtDir);
-        auto const ter = directSendNoFee(
-            sb,
-            src_,
-            dst_,
-            toSTAmount(cache_->srcToDst, srcToDstIss),
-            /*checkIssuer*/ false,
-            j_);
-        if (!isTesSuccess(ter))
+        auto const maybeActualIn = tryMulRatio(maxSrcToDst, srcQOut, QUALITY_ONE, /*roundUp*/ true);
+        if (!maybeActualIn)
         {
-            JLOG(j_.trace()) << "MPTEndpointStep::fwd: error " << ter;
+            JLOG(j_.trace()) << "MPTEndpointStep::fwd: overflow";
             resetCache(srcDebtDir);
             return {beast::kZero, beast::kZero};
         }
+
+        MPTAmount const actualIn = *maybeActualIn;
+
+        // Don't have to factor in dstQIn since it's always QUALITY_ONE
+        MPTAmount const out = maxSrcToDst;
+        setCacheLimiting(actualIn, maxSrcToDst, out, srcDebtDir);
+
         JLOG(j_.trace()) << "MPTEndpointStep::fwd: Limiting"
                          << " srcRedeems: " << redeems(srcDebtDir) << " in: " << to_string(actualIn)
                          << " srcToDst: " << to_string(srcToDst) << " out: " << to_string(out);
+        // LCOV_EXCL_STOP
     }
+
+    auto const ter = sendWithMPTCreate(sb, src_, dst_, cache_->srcToDst);
+    if (!isTesSuccess(ter))
+    {
+        // Unreachable: send fails only on funds/auth/overflow, precluded by
+        // maxPaymentFlow, check() requireAuth, and 2*kMaxMpTokenAmount < 2^64.
+        // LCOV_EXCL_START
+        UNREACHABLE("xrpl::MPTEndpointStep::fwdImp : send failed");
+        JLOG(j_.trace()) << "MPTEndpointStep::fwd: error " << ter;
+        resetCache(srcDebtDir);
+        return {beast::kZero, beast::kZero};
+        // LCOV_EXCL_STOP
+    }
+
     return {cache_->in, cache_->out};
     // NOLINTEND(bugprone-unchecked-optional-access)
 }
diff --git a/src/libxrpl/tx/transactors/dex/AMMClawback.cpp b/src/libxrpl/tx/transactors/dex/AMMClawback.cpp
index b25c90069c..f95f257ab6 100644
--- a/src/libxrpl/tx/transactors/dex/AMMClawback.cpp
+++ b/src/libxrpl/tx/transactors/dex/AMMClawback.cpp
@@ -237,6 +237,7 @@ AMMClawback::applyGuts(Sandbox& sb)
                 0,
                 FreezeHandling::IgnoreFreeze,
                 AuthHandling::IgnoreAuth,
+                ReserveHandling::IgnoreReserve,
                 WithdrawAll::Yes,
                 preFeeBalance_,
                 ctx_.journal);
@@ -345,6 +346,7 @@ AMMClawback::equalWithdrawMatchingOneAmount(
             0,
             FreezeHandling::IgnoreFreeze,
             AuthHandling::IgnoreAuth,
+            ReserveHandling::IgnoreReserve,
             WithdrawAll::Yes,
             preFeeBalance_,
             ctx_.journal);
@@ -385,6 +387,7 @@ AMMClawback::equalWithdrawMatchingOneAmount(
             0,
             FreezeHandling::IgnoreFreeze,
             AuthHandling::IgnoreAuth,
+            ReserveHandling::IgnoreReserve,
             WithdrawAll::No,
             preFeeBalance_,
             ctx_.journal);
@@ -406,6 +409,7 @@ AMMClawback::equalWithdrawMatchingOneAmount(
         0,
         FreezeHandling::IgnoreFreeze,
         AuthHandling::IgnoreAuth,
+        ReserveHandling::IgnoreReserve,
         WithdrawAll::No,
         preFeeBalance_,
         ctx_.journal);
diff --git a/src/libxrpl/tx/transactors/dex/AMMWithdraw.cpp b/src/libxrpl/tx/transactors/dex/AMMWithdraw.cpp
index edd2cc2037..77b9071cf8 100644
--- a/src/libxrpl/tx/transactors/dex/AMMWithdraw.cpp
+++ b/src/libxrpl/tx/transactors/dex/AMMWithdraw.cpp
@@ -527,6 +527,7 @@ AMMWithdraw::withdraw(
         tfee,
         issuerFreezeHandling(),
         AuthHandling::ZeroIfUnauthorized,
+        ReserveHandling::EnforceReserve,
         isWithdrawAll(ctx_.tx),
         preFeeBalance_,
         j_);
@@ -548,6 +549,7 @@ AMMWithdraw::withdraw(
     std::uint16_t tfee,
     FreezeHandling freezeHandling,
     AuthHandling authHandling,
+    ReserveHandling reserveHandling,
     WithdrawAll withdrawAll,
     XRPAmount const& priorBalance,
     beast::Journal const& journal)
@@ -669,19 +671,26 @@ AMMWithdraw::withdraw(
         mptokenKey = std::nullopt;
         if (!enabledFixAmMv12 || isXRP(asset))
             return tesSUCCESS;
-        bool const isIssue = asset.holds<Issue>();
-        bool const assetNotExists = [&] {
-            if (isIssue)
-                return !view.exists(keylet::trustLine(account, asset.get<Issue>()));
-            auto const issuanceKey = keylet::mptokenIssuance(asset.get<MPTIssue>());
-            mptokenKey = keylet::mptoken(issuanceKey.key, account);
-            if (!view.exists(*mptokenKey))
-                return true;
-            mptokenKey = std::nullopt;
-            return false;
-        }();
+        bool const assetNotExists = asset.visit(
+            [&](Issue const& issue) { return !view.exists(keylet::trustLine(account, issue)); },
+            [&](MPTIssue const& issue) {
+                auto const issuanceKey = keylet::mptokenIssuance(issue);
+                mptokenKey = keylet::mptoken(issuanceKey.key, account);
+                if (!view.exists(*mptokenKey))
+                    return true;
+                mptokenKey = std::nullopt;
+                return false;
+            });
         if (assetNotExists)
         {
+            // Intentionally ignore the reserve check for AMMClawback, so the
+            // holder can not avoid clawback by deleting the trustline/MPToken
+            // and keeping a low spendable balance. AMMClawback has a higher
+            // priority than the reserve check.
+            if (view.rules().enabled(fixCleanup3_4_0) &&
+                reserveHandling == ReserveHandling::IgnoreReserve)
+                return tesSUCCESS;
+
             auto sleAccount = view.peek(keylet::account(account));
             if (!sleAccount)
                 return tecINTERNAL;  // LCOV_EXCL_LINE
@@ -693,7 +702,7 @@ AMMWithdraw::withdraw(
                     ? XRPAmount(beast::kZero)
                     : accountReserve(view, sleAccount, journal, {.ownerCountDelta = 1}));
 
-            auto const balanceAdj = isIssue ? std::max(priorBalance, balance) : priorBalance;
+            auto const balanceAdj = std::max(priorBalance, balance);
             if (balanceAdj < reserve)
                 return tecINSUFFICIENT_RESERVE;
         }
@@ -851,6 +860,7 @@ AMMWithdraw::equalWithdrawTokens(
         tfee,
         issuerFreezeHandling(),
         AuthHandling::ZeroIfUnauthorized,
+        ReserveHandling::EnforceReserve,
         isWithdrawAll(ctx_.tx),
         preFeeBalance_,
         ctx_.journal);
@@ -904,6 +914,7 @@ AMMWithdraw::equalWithdrawTokens(
     std::uint16_t tfee,
     FreezeHandling freezeHandling,
     AuthHandling authHandling,
+    ReserveHandling reserveHandling,
     WithdrawAll withdrawAll,
     XRPAmount const& priorBalance,
     beast::Journal const& journal)
@@ -927,6 +938,7 @@ AMMWithdraw::equalWithdrawTokens(
                 tfee,
                 freezeHandling,
                 authHandling,
+                reserveHandling,
                 WithdrawAll::Yes,
                 priorBalance,
                 journal);
@@ -963,6 +975,7 @@ AMMWithdraw::equalWithdrawTokens(
             tfee,
             freezeHandling,
             authHandling,
+            reserveHandling,
             withdrawAll,
             priorBalance,
             journal);
diff --git a/src/libxrpl/tx/transactors/dex/OfferCreate.cpp b/src/libxrpl/tx/transactors/dex/OfferCreate.cpp
index 0492f9c062..57ba6eff0d 100644
--- a/src/libxrpl/tx/transactors/dex/OfferCreate.cpp
+++ b/src/libxrpl/tx/transactors/dex/OfferCreate.cpp
@@ -11,6 +11,7 @@
 #include <xrpl/ledger/Sandbox.h>
 #include <xrpl/ledger/View.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
+#include <xrpl/ledger/helpers/CredentialHelpers.h>
 #include <xrpl/ledger/helpers/DirectoryHelpers.h>
 #include <xrpl/ledger/helpers/MPTokenHelpers.h>
 #include <xrpl/ledger/helpers/OfferHelpers.h>
@@ -242,8 +243,31 @@ OfferCreate::preclaim(PreclaimContext const& ctx)
     // is part of the domain
     if (ctx.tx.isFieldPresent(sfDomainID))
     {
-        if (!permissioned_dex::accountInDomain(ctx.view, id, ctx.tx[sfDomainID]))
-            return tecNO_PERMISSION;
+        if (ctx.view.rules().enabled(fixCleanup3_4_0))
+        {
+            auto const domainID = ctx.tx[sfDomainID];
+            auto const sleDomain = ctx.view.read(keylet::permissionedDomain(domainID));
+            if (!sleDomain)
+                return tecNO_PERMISSION;
+
+            // Domain owner is always considered in the domain, no credential check
+            // needed. For all other accounts, use validDomain which detects expired
+            // credentials. Suppress tecEXPIRED here so doApply can run and delete
+            // the expired credential SLEs from the ledger.
+            if (sleDomain->getAccountID(sfOwner) != id)
+            {
+                // validDomain returns tecNO_AUTH when no matching credential is
+                // found. Map it to tecNO_PERMISSION to preserve existing behavior.
+                if (auto const err = credentials::validDomain(ctx.view, domainID, id);
+                    !isTesSuccess(err) && err != tecEXPIRED)
+                    return tecNO_PERMISSION;
+            }
+        }
+        else
+        {
+            if (!permissioned_dex::accountInDomain(ctx.view, id, ctx.tx[sfDomainID]))
+                return tecNO_PERMISSION;
+        }
     }
 
     if (auto const ter = canTrade(ctx.view, saTakerPays.asset()); !isTesSuccess(ter))
@@ -672,6 +696,7 @@ OfferCreate::applyGuts(Sandbox& sb, Sandbox& sbCancel)
     }
 
     bool crossed = false;
+    bool const mptV2 = ctx_.view().rules().enabled(featureMPTokensV2);
 
     if (isTesSuccess(result))
     {
@@ -694,7 +719,12 @@ OfferCreate::applyGuts(Sandbox& sb, Sandbox& sbCancel)
             if (sle && sle->isFieldPresent(sfTickSize))
                 uTickSize = std::min(uTickSize, (*sle)[sfTickSize]);
         }
-        if (uTickSize < Quality::kMaxTickSize)
+        // Quality's ctor is the same getRate() call that produced uRate, and
+        // round() maps zero to zero, so an unrepresentable quality would make
+        // divide() below throw (tefEXCEPTION). Skip the rounding instead: the
+        // offer still crosses, and any residual is stopped before placement.
+        bool const unrepresentableRate = mptV2 && uRate == 0;
+        if (uTickSize < Quality::kMaxTickSize && !unrepresentableRate)
         {
             auto const rate = Quality{saTakerGets, saTakerPays}.round(uTickSize).rate();
 
@@ -841,6 +871,20 @@ OfferCreate::applyGuts(Sandbox& sb, Sandbox& sbCancel)
         return {tesSUCCESS, true};
     }
 
+    // The remainder rests at uRate, the original pre-crossing rate. A zero
+    // rate (quality not representable) puts it in the directory whose index
+    // equals getBookBase(book), and BookTip scans keys strictly greater, so it
+    // could never be crossed while holding the owner's reserve. Don't place
+    // it; anything that crossed is kept, and a fully crossed offer has already
+    // returned above. Gated to preserve pre-amendment behavior.
+    if (mptV2 && uRate == 0)
+    {
+        JLOG(j_.debug()) << "Unrepresentable quality: remainder not placed";
+        if (!crossed)
+            return {tecKILLED, false};
+        return {tesSUCCESS, true};
+    }
+
     auto const sleCreator = sb.peek(keylet::account(accountID_));
     if (!sleCreator)
         return {tefINTERNAL, false};
@@ -980,6 +1024,27 @@ OfferCreate::applyGuts(Sandbox& sb, Sandbox& sbCancel)
 TER
 OfferCreate::doApply()
 {
+    // If a DomainID is present, verify the account is still in the domain and
+    // delete any expired credential SLEs. This must happen before the Sandboxes
+    // are created: if we return a tec error, the engine applies sbCancel (not
+    // sb) to rawView, so deletions made inside sb would be lost. Deletions made
+    // directly to ctx_.view() here are preserved regardless of which branch
+    // applyGuts takes.
+    if (ctx_.tx.isFieldPresent(sfDomainID) && ctx_.view().rules().enabled(fixCleanup3_4_0))
+    {
+        auto const domainID = ctx_.tx[sfDomainID];
+        auto const sleDomain = ctx_.view().read(keylet::permissionedDomain(domainID));
+        if (!sleDomain)
+            return tecINTERNAL;  // LCOV_EXCL_LINE
+
+        if (sleDomain->getAccountID(sfOwner) != accountID_)
+        {
+            if (auto const err = verifyValidDomain(ctx_.view(), accountID_, domainID, j_);
+                !isTesSuccess(err))
+                return err;
+        }
+    }
+
     // This is the ledger view that we work against. Transactions are applied
     // as we go on processing transactions.
     Sandbox sb(&ctx_.view());
diff --git a/src/libxrpl/tx/transactors/escrow/EscrowCancel.cpp b/src/libxrpl/tx/transactors/escrow/EscrowCancel.cpp
index b1cfcb3df1..9128d0767f 100644
--- a/src/libxrpl/tx/transactors/escrow/EscrowCancel.cpp
+++ b/src/libxrpl/tx/transactors/escrow/EscrowCancel.cpp
@@ -169,6 +169,14 @@ EscrowCancel::doApply()
     auto const sle = ctx_.view().peek(keylet::account(account));
     STAmount const amount = slep->getFieldAmount(sfAmount);
 
+    auto const reserveToSubtract = calculateAdditionalReserve((*slep)[~sfBytecode]);
+
+    // The return can re-create a holding the owner deleted while the escrow
+    // was pending; the removed escrow must not be counted against its reserve.
+    bool const recycleReserve = ctx_.view().rules().enabled(fixCleanup3_4_0);
+    if (recycleReserve)
+        decreaseOwnerCountForObject(ctx_.view(), sle, slep, reserveToSubtract, ctx_.journal);
+
     // Transfer amount back to the owner
     if (isXRP(amount))
     {
@@ -212,8 +220,8 @@ EscrowCancel::doApply()
         }
     }
 
-    auto const reserveToSubtract = calculateAdditionalReserve((*slep)[~sfBytecode]);
-    decreaseOwnerCountForObject(ctx_.view(), sle, slep, reserveToSubtract, ctx_.journal);
+    if (!recycleReserve)
+        decreaseOwnerCountForObject(ctx_.view(), sle, slep, reserveToSubtract, ctx_.journal);
 
     // Remove escrow from ledger
     ctx_.view().erase(slep);
diff --git a/src/libxrpl/tx/transactors/escrow/EscrowFinish.cpp b/src/libxrpl/tx/transactors/escrow/EscrowFinish.cpp
index 9a947e1d9b..796241708b 100644
--- a/src/libxrpl/tx/transactors/escrow/EscrowFinish.cpp
+++ b/src/libxrpl/tx/transactors/escrow/EscrowFinish.cpp
@@ -492,14 +492,12 @@ EscrowFinish::doApply()
 
     auto const reserveToSubtract = calculateAdditionalReserve((*slep)[~sfBytecode]);
 
-    // With the Sponsor amendment, release the escrow reserve before delivery.
-    // Token delivery can auto-create a destination holding, and the same
-    // sponsor (or the same account, for a self-escrow) may cover both the
-    // escrow being removed and the holding being created. Without the
-    // amendment, keep the legacy order: releasing early changes the reserve
-    // arithmetic for self-escrows and would break consensus if not gated.
-    bool const sponsorEnabled = ctx_.view().rules().enabled(featureSponsor);
-    if (sponsorEnabled)
+    // Delivery can auto-create the destination's holding; the removed escrow
+    // must not be counted against its reserve. The two share a reserve payer
+    // for a self-escrow, or when one sponsor covers both.
+    bool const recycleReserve =
+        ctx_.view().rules().enabled(featureSponsor) || ctx_.view().rules().enabled(fixCleanup3_4_0);
+    if (recycleReserve)
         decreaseOwnerCountForObject(ctx_.view(), account, slep, reserveToSubtract, ctx_.journal);
 
     STAmount const amount = slep->getFieldAmount(sfAmount);
@@ -551,8 +549,7 @@ EscrowFinish::doApply()
 
     ctx_.view().update(sled);
 
-    // Adjust source owner count (legacy position, pre-Sponsor)
-    if (!sponsorEnabled)
+    if (!recycleReserve)
         decreaseOwnerCountForObject(ctx_.view(), account, slep, reserveToSubtract, ctx_.journal);
 
     // Remove escrow from ledger
diff --git a/src/libxrpl/tx/transactors/lending/LoanBrokerCoverWithdraw.cpp b/src/libxrpl/tx/transactors/lending/LoanBrokerCoverWithdraw.cpp
index e914596599..88b6f8c38b 100644
--- a/src/libxrpl/tx/transactors/lending/LoanBrokerCoverWithdraw.cpp
+++ b/src/libxrpl/tx/transactors/lending/LoanBrokerCoverWithdraw.cpp
@@ -65,6 +65,7 @@ LoanBrokerCoverWithdraw::preclaim(PreclaimContext const& ctx)
 {
     auto const fix320Enabled = ctx.view.rules().enabled(fixCleanup3_2_0);
     auto const fix330Enabled = ctx.view.rules().enabled(fixCleanup3_3_0);
+    auto const fix340Enabled = ctx.view.rules().enabled(fixCleanup3_4_0);
     auto const& tx = ctx.tx;
 
     auto const account = tx[sfAccount];
@@ -140,6 +141,12 @@ LoanBrokerCoverWithdraw::preclaim(PreclaimContext const& ctx)
     if (auto const ter = requireAuth(ctx.view, vaultAsset, dstAcct, authType))
         return ter;
 
+    if (fix340Enabled && account == dstAcct && !holdingExists(ctx.view, dstAcct, vaultAsset))
+    {
+        if (auto const ter = canAddHolding(ctx.view, vaultAsset); !isTesSuccess(ter))
+            return ter;
+    }
+
     if (fix330Enabled)
     {
         if (auto const ret =
diff --git a/src/libxrpl/tx/transactors/lending/LoanBrokerDelete.cpp b/src/libxrpl/tx/transactors/lending/LoanBrokerDelete.cpp
index 06907ce366..433d77806a 100644
--- a/src/libxrpl/tx/transactors/lending/LoanBrokerDelete.cpp
+++ b/src/libxrpl/tx/transactors/lending/LoanBrokerDelete.cpp
@@ -4,13 +4,11 @@
 #include <xrpl/basics/Number.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
-#include <xrpl/ledger/helpers/CredentialHelpers.h>
 #include <xrpl/ledger/helpers/LendingHelpers.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
-#include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STLedgerEntry.h>
@@ -142,19 +140,6 @@ LoanBrokerDelete::doApply()
 
     auto const brokerPseudoID = broker->at(sfAccount);
 
-    // Remove any credentials pinned to the broker pseudo-account before anything
-    // else. They would otherwise keep its owner directory alive and block
-    // deletion with tecHAS_OBLIGATIONS. Doing it first means a bounded,
-    // tecINCOMPLETE cleanup can be resumed by a later transaction without having
-    // already torn down the broker.
-    if (view().rules().enabled(fixCleanup3_4_0))
-    {
-        if (auto const ter = credentials::deletePseudoAccountCredentials(
-                view(), brokerPseudoID, kMaxDeletablePseudoAccountCredentials, j_);
-            !isTesSuccess(ter))
-            return ter;
-    }
-
     if (!view().dirRemove(
             keylet::ownerDir(accountID_), broker->at(sfOwnerNode), broker->key(), false))
     {
diff --git a/src/libxrpl/tx/transactors/lending/LoanSet.cpp b/src/libxrpl/tx/transactors/lending/LoanSet.cpp
index 2def3d2eb2..f7b97dfedf 100644
--- a/src/libxrpl/tx/transactors/lending/LoanSet.cpp
+++ b/src/libxrpl/tx/transactors/lending/LoanSet.cpp
@@ -40,6 +40,12 @@
 
 namespace xrpl {
 
+// StartDate is strictly after SubscriptionDate. A min-gap vault must still
+// fit a minimum-interval loan plus kLoanRedemptionBuffer. The interval and
+// buffer constants are independent; only their sum (plus the +1 for a
+// strictly-later StartDate) is required to fit in kMinInvestmentPeriod.
+static_assert(kMinInvestmentPeriod >= LoanSet::kMinPaymentInterval + kLoanRedemptionBuffer + 1);
+
 bool
 LoanSet::checkExtraFeatures(PreflightContext const& ctx)
 {
@@ -327,16 +333,22 @@ LoanSet::preclaim(PreclaimContext const& ctx)
         {
             auto const finalPayment =
                 std::uint64_t{getStartDate(ctx.view)} + (std::uint64_t{interval} * total);
-            if (finalPayment >= vault->at(sfRedemptionDate))
+            if (finalPayment + kLoanRedemptionBuffer > vault->at(sfRedemptionDate))
             {
-                JLOG(ctx.j.warn()) << "Final loan payment date is on or after "
-                                      "the vault's redemption date.";
+                JLOG(ctx.j.warn())
+                    << "Final loan payment date is fewer than " << kLoanRedemptionBuffer
+                    << " seconds before the vault's redemption date.";
                 return tecNO_PERMISSION;
             }
         }
     }
 
-    if (vault->at(sfAssetsMaximum) != 0 && vault->at(sfAssetsTotal) >= vault->at(sfAssetsMaximum))
+    // Accrual origination credits interestDue into AssetsTotal, so a vault
+    // already at AssetsMaximum cannot take another loan. Cash-basis origination
+    // does not change AssetsTotal (see cash_basis::loanOriginationDeltas), so
+    // this leftover accrual gate must not apply there.
+    if (getVaultVersion(vault) != VaultVersion::CashBasis && vault->at(sfAssetsMaximum) != 0 &&
+        vault->at(sfAssetsTotal) >= vault->at(sfAssetsMaximum))
     {
         JLOG(ctx.j.warn()) << "Vault at maximum assets limit. Can't add another loan.";
         return tecLIMIT_EXCEEDED;
@@ -360,8 +372,24 @@ LoanSet::preclaim(PreclaimContext const& ctx)
         }
     }
 
-    if (auto const ter = canAddHolding(ctx.view, asset))
-        return ter;
+    // canAddHolding is an issuer-level check (DefaultRipple for IOU,
+    // lsfMPTCanTransfer for MPT); neither overload looks at the
+    // destination, so the holdingExists() clauses only decide whether a
+    // create path is reachable at all. It always runs before
+    // fixCleanup3_4_0: IOU addEmptyHolding checks DefaultRipple ahead of
+    // the existing-line case, so only preclaim can turn an existing line
+    // under a cleared DefaultRipple into terNO_RIPPLE rather than
+    // tecINTERNAL. After the amendment an existing line short-circuits to
+    // tecDUPLICATE, which doApply ignores, so run the check only when the
+    // borrower lacks a holding, or the origination fee is nonzero and the
+    // broker owner lacks one.
+    auto const originationFee = tx[~sfLoanOriginationFee].value_or(Number{});
+    if (!ctx.view.rules().enabled(fixCleanup3_4_0) || !holdingExists(ctx.view, borrower, asset) ||
+        (originationFee != beast::kZero && !holdingExists(ctx.view, brokerOwner, asset)))
+    {
+        if (auto const ter = canAddHolding(ctx.view, asset))
+            return ter;
+    }
 
     // vaultPseudo is going to send funds, so it can't be frozen.
     if (auto const ret = checkFrozen(ctx.view, vaultPseudo, asset))
@@ -467,9 +495,11 @@ LoanSet::doApply()
         properties.loanState.managementFeeDue);
 
     XRPL_ASSERT_PARTS(
-        *vaultSle->at(sfAssetsMaximum) == 0 || *vaultSle->at(sfAssetsMaximum) > *vaultTotalProxy,
+        *vaultSle->at(sfAssetsMaximum) == 0 ||
+            getVaultVersion(vaultSle) == VaultVersion::CashBasis ||
+            *vaultSle->at(sfAssetsMaximum) > *vaultTotalProxy,
         "xrpl::LoanSet::doApply",
-        "Vault is below maximum limit");
+        "accrual vault is below maximum limit");
 
     if (loanOriginationExceedsVaultMaximum(vaultSle, vaultTotalProxy, state.interestDue))
     {
diff --git a/src/libxrpl/tx/transactors/payment/Payment.cpp b/src/libxrpl/tx/transactors/payment/Payment.cpp
index c8b00f0193..c4c2f9227b 100644
--- a/src/libxrpl/tx/transactors/payment/Payment.cpp
+++ b/src/libxrpl/tx/transactors/payment/Payment.cpp
@@ -458,11 +458,41 @@ Payment::preclaim(PreclaimContext const& ctx)
 
     if (ctx.tx.isFieldPresent(sfDomainID))
     {
-        if (!permissioned_dex::accountInDomain(ctx.view, ctx.tx[sfAccount], ctx.tx[sfDomainID]))
-            return tecNO_PERMISSION;
+        if (ctx.view.rules().enabled(fixCleanup3_4_0))
+        {
+            auto const domainID = ctx.tx[sfDomainID];
+            auto const sleDomain = ctx.view.read(keylet::permissionedDomain(domainID));
+            if (!sleDomain)
+                return tecNO_PERMISSION;
 
-        if (!permissioned_dex::accountInDomain(ctx.view, ctx.tx[sfDestination], ctx.tx[sfDomainID]))
-            return tecNO_PERMISSION;
+            // Domain owner is always considered in the domain. For other accounts,
+            // suppress tecEXPIRED so doApply can run and delete expired credential
+            // SLEs from the ledger.
+            auto const checkAccount = [&](AccountID const& acct) -> TER {
+                if (sleDomain->getAccountID(sfOwner) == acct)
+                    return tesSUCCESS;
+                // validDomain returns tecNO_AUTH when no matching credential is
+                // found. Map it to tecNO_PERMISSION to preserve existing behavior.
+                if (auto const err = credentials::validDomain(ctx.view, domainID, acct);
+                    !isTesSuccess(err) && err != tecEXPIRED)
+                    return tecNO_PERMISSION;
+                return tesSUCCESS;
+            };
+
+            if (auto const err = checkAccount(ctx.tx[sfAccount]); !isTesSuccess(err))
+                return err;
+            if (auto const err = checkAccount(ctx.tx[sfDestination]); !isTesSuccess(err))
+                return err;
+        }
+        else
+        {
+            if (!permissioned_dex::accountInDomain(ctx.view, ctx.tx[sfAccount], ctx.tx[sfDomainID]))
+                return tecNO_PERMISSION;
+
+            if (!permissioned_dex::accountInDomain(
+                    ctx.view, ctx.tx[sfDestination], ctx.tx[sfDomainID]))
+                return tecNO_PERMISSION;
+        }
     }
 
     return tesSUCCESS;
@@ -471,6 +501,31 @@ Payment::preclaim(PreclaimContext const& ctx)
 TER
 Payment::doApply()
 {
+    // If a DomainID is present, verify both sender and destination are still in
+    // the domain and delete any expired credential SLEs from the ledger.
+    if (ctx_.tx.isFieldPresent(sfDomainID) && ctx_.view().rules().enabled(fixCleanup3_4_0))
+    {
+        auto const domainID = ctx_.tx[sfDomainID];
+        auto const sleDomain = ctx_.view().read(keylet::permissionedDomain(domainID));
+        if (!sleDomain)
+            return tecINTERNAL;  // LCOV_EXCL_LINE
+
+        auto const cleanupFor = [&](AccountID const& acct) -> TER {
+            if (sleDomain->getAccountID(sfOwner) == acct)
+                return tesSUCCESS;
+            return verifyValidDomain(ctx_.view(), acct, domainID, j_);
+        };
+
+        auto const destination = ctx_.tx[sfDestination];
+        auto const senderErr = cleanupFor(accountID_);
+        auto const destinationErr = accountID_ == destination ? senderErr : cleanupFor(destination);
+
+        if (!isTesSuccess(senderErr))
+            return senderErr;
+        if (!isTesSuccess(destinationErr))
+            return destinationErr;
+    }
+
     auto const deliverMin = ctx_.tx[~sfDeliverMin];
 
     // Ripple if source or destination is non-native or if there are paths.
diff --git a/src/libxrpl/tx/transactors/token/MPTokenAuthorize.cpp b/src/libxrpl/tx/transactors/token/MPTokenAuthorize.cpp
index c19b8f64d7..60b5c6d3af 100644
--- a/src/libxrpl/tx/transactors/token/MPTokenAuthorize.cpp
+++ b/src/libxrpl/tx/transactors/token/MPTokenAuthorize.cpp
@@ -150,7 +150,7 @@ MPTokenAuthorize::preclaim(PreclaimContext const& ctx)
     // always authorized. No need to amendment gate since Vault and LoanBroker
     // can only be created if the Vault amendment is enabled; AMM with MPToken asset
     // can only be created if MPTokensV2 is enabled.
-    if (isPseudoAccount(ctx.view, *holderID, {&sfVaultID, &sfLoanBrokerID, &sfAMMID}))
+    if (isPseudoAccount(ctx.view, *holderID))
         return tecNO_PERMISSION;
 
     return tesSUCCESS;
diff --git a/src/libxrpl/tx/transactors/token/MPTokenIssuanceSet.cpp b/src/libxrpl/tx/transactors/token/MPTokenIssuanceSet.cpp
index e8fd2e22b6..6bd7140631 100644
--- a/src/libxrpl/tx/transactors/token/MPTokenIssuanceSet.cpp
+++ b/src/libxrpl/tx/transactors/token/MPTokenIssuanceSet.cpp
@@ -119,7 +119,15 @@ MPTokenIssuanceSet::preflight(PreflightContext const& ctx)
     if (hasHolder && (hasIssuerElGamalKey || hasAuditorElGamalKey))
         return temMALFORMED;
 
-    if (hasAuditorElGamalKey && !hasIssuerElGamalKey)
+    // Pre-ConfidentialMPTKeyRotation amendment, the auditor key could not be
+    // registered independently of the issuer key. The issuer could either:
+    // - Register only the issuer key (in which case an auditor key could not be added later), or
+    // - Register both the issuer and auditor keys simultaneously.
+    //
+    // Post-ConfidentialMPTKeyRotation amendment, the auditor key can be
+    // registered after the issuer key has already been registered.
+    if (hasAuditorElGamalKey && !hasIssuerElGamalKey &&
+        !ctx.rules.enabled(featureConfidentialMPTKeyRotation))
         return temMALFORMED;
 
     if (hasIssuerElGamalKey && !isValidCompressedECPoint(ctx.tx[sfIssuerEncryptionKey]))
@@ -219,18 +227,57 @@ MPTokenIssuanceSet::preclaim(PreclaimContext const& ctx)
             return tecNO_PERMISSION;
     }
 
-    // cannot update issuer public key
-    if (ctx.tx.isFieldPresent(sfIssuerEncryptionKey) &&
-        sleMptIssuance->isFieldPresent(sfIssuerEncryptionKey))
-    {
-        return tecNO_PERMISSION;
-    }
+    // Updating an existing encryption key requires the
+    // ConfidentialMPTKeyRotation amendment.
+    bool const canRotateKey = ctx.view.rules().enabled(featureConfidentialMPTKeyRotation);
 
-    // cannot update auditor public key
-    if (ctx.tx.isFieldPresent(sfAuditorEncryptionKey) &&
-        sleMptIssuance->isFieldPresent(sfAuditorEncryptionKey))
+    bool const txHasIssuerKey = ctx.tx.isFieldPresent(sfIssuerEncryptionKey);
+    bool const txHasAuditorKey = ctx.tx.isFieldPresent(sfAuditorEncryptionKey);
+    bool const sleHasIssuerKey = sleMptIssuance->isFieldPresent(sfIssuerEncryptionKey);
+    bool const sleHasAuditorKey = sleMptIssuance->isFieldPresent(sfAuditorEncryptionKey);
+
+    if (canRotateKey)
     {
-        return tecNO_PERMISSION;  // LCOV_EXCL_LINE
+        // Post-ConfidentialMPTKeyRotation amendment, the encryption keys can be updated.
+        // A first-time auditor key registration requires an issuer key,
+        // either already on the issuance or set by the same transaction.
+        bool const registersAuditorKey = txHasAuditorKey && !sleHasAuditorKey;
+        bool const issuerKeyExists = sleHasIssuerKey || txHasIssuerKey;
+        if (registersAuditorKey && !issuerKeyExists)
+            return tecNO_PERMISSION;
+
+        // Rotating a key to its current value is not permitted: a key epoch
+        // increment must always correspond to an actual key change.
+        if (txHasIssuerKey && sleHasIssuerKey &&
+            ctx.tx[sfIssuerEncryptionKey] == (*sleMptIssuance)[sfIssuerEncryptionKey])
+            return tecDUPLICATE;
+
+        if (txHasAuditorKey && sleHasAuditorKey &&
+            ctx.tx[sfAuditorEncryptionKey] == (*sleMptIssuance)[sfAuditorEncryptionKey])
+            return tecDUPLICATE;
+
+        // Key epochs must never wrap. Epoch 0 serves as the sentinel for "never
+        // rotated." Holders' mirror epochs are checked against it for equality,
+        // so a wrap would cause stale mirror ciphertexts to appear valid instead
+        // of failing loudly.
+        if (txHasIssuerKey && sleHasIssuerKey &&
+            (*sleMptIssuance)[~sfIssuerKeyEpoch].value_or(0) == kMaxKeyEpoch)
+            return tecNO_PERMISSION;
+
+        if (txHasAuditorKey && sleHasAuditorKey &&
+            (*sleMptIssuance)[~sfAuditorKeyEpoch].value_or(0) == kMaxKeyEpoch)
+            return tecNO_PERMISSION;
+    }
+    else
+    {
+        // Pre-ConfidentialMPTKeyRotation amendment, the encryption keys can not be updated.
+        // cannot update issuer public key
+        if (txHasIssuerKey && sleHasIssuerKey)
+            return tecNO_PERMISSION;
+
+        // cannot update auditor public key
+        if (txHasAuditorKey && sleHasAuditorKey)
+            return tecNO_PERMISSION;  // LCOV_EXCL_LINE
     }
 
     auto const enablesConfidentialBalance =
@@ -241,25 +288,30 @@ MPTokenIssuanceSet::preclaim(PreclaimContext const& ctx)
 
     // Encryption keys can only be set if confidential amounts are already
     // enabled on the issuance OR if the transaction is enabling it
-    if (ctx.tx.isFieldPresent(sfIssuerEncryptionKey) &&
-        !sleMptIssuance->isFlag(lsfMPTCanHoldConfidentialBalance) && !enablesConfidentialBalance)
+    if (txHasIssuerKey && !sleMptIssuance->isFlag(lsfMPTCanHoldConfidentialBalance) &&
+        !enablesConfidentialBalance)
     {
         return tecNO_PERMISSION;
     }
 
-    if (ctx.tx.isFieldPresent(sfAuditorEncryptionKey) &&
-        !sleMptIssuance->isFlag(lsfMPTCanHoldConfidentialBalance) && !enablesConfidentialBalance)
+    if (txHasAuditorKey && !sleMptIssuance->isFlag(lsfMPTCanHoldConfidentialBalance) &&
+        !enablesConfidentialBalance)
     {
         return tecNO_PERMISSION;
     }
 
-    // cannot upload key if there's circulating supply of COA
-    if ((ctx.tx.isFieldPresent(sfIssuerEncryptionKey) ||
-         ctx.tx.isFieldPresent(sfAuditorEncryptionKey) || enablesConfidentialBalance) &&
-        (*sleMptIssuance)[~sfConfidentialOutstandingAmount].value_or(0) > 0)
-    {
+    bool const hasConfidentialOA =
+        (*sleMptIssuance)[~sfConfidentialOutstandingAmount].value_or(0) > 0;
+
+    // Pre-ConfidentialMPTKeyRotation amendment, keys cannot be uploaded while
+    // COA > 0. Post-amendment they can be uploaded even if COA > 0.
+    if (!canRotateKey && (txHasIssuerKey || txHasAuditorKey) && hasConfidentialOA)
         return tecNO_PERMISSION;  // LCOV_EXCL_LINE
-    }
+
+    // Enabling confidential balances when COA > 0 is not permitted, regardless of
+    // ConfidentialMPTKeyRotation.
+    if (enablesConfidentialBalance && hasConfidentialOA)
+        return tecNO_PERMISSION;
 
     return tesSUCCESS;
 }
@@ -377,25 +429,69 @@ MPTokenIssuanceSet::doApply()
         }
     }
 
-    if (auto const pubKey = ctx_.tx[~sfIssuerEncryptionKey])
-    {
-        // This is enforced in preflight.
+    // Sets an encryption key on the issuance. Overwriting an existing key
+    // (a rotation) increments the corresponding key epoch; a first-time
+    // registration leaves the epoch absent (epoch 0), matching issuances
+    // whose keys were registered before the ConfidentialMPTKeyRotation
+    // amendment.
+    bool const canRotateKey = view().rules().enabled(featureConfidentialMPTKeyRotation);
+    auto const setEncryptionKey = [&](SF_VL const& keyField, SF_UINT32 const& epochField) -> TER {
+        auto const pubKey = ctx_.tx[~keyField];
+        if (!pubKey)
+            return tesSUCCESS;
+
+        // This is enforced in preflight, which rejects a transaction carrying
+        // both sfHolder and an encryption key.
         XRPL_ASSERT(
             sle->getType() == ltMPTOKEN_ISSUANCE,
             "MPTokenIssuanceSet::doApply : modifying MPTokenIssuance");
 
-        sle->setFieldVL(sfIssuerEncryptionKey, *pubKey);
-    }
+        // Add sanity check under the amendment ConfidentialMPTKeyRotation.
+        // Pre-confidentialMPTKeyRotation did not return tecINTERNAL so
+        // this should be under the amendment guard.
+        if (canRotateKey && sle->getType() != ltMPTOKEN_ISSUANCE)
+            return tecINTERNAL;  // LCOV_EXCL_LINE
 
-    if (auto const pubKey = ctx_.tx[~sfAuditorEncryptionKey])
-    {
-        // This is enforced in preflight.
-        XRPL_ASSERT(
-            sle->getType() == ltMPTOKEN_ISSUANCE,
-            "MPTokenIssuanceSet::doApply : modifying MPTokenIssuance");
+        // NOTE: presence must be checked before the key is overwritten below.
+        bool const isRotation = sle->isFieldPresent(keyField);
+        sle->setFieldVL(keyField, *pubKey);
 
-        sle->setFieldVL(sfAuditorEncryptionKey, *pubKey);
-    }
+        if (isRotation)
+        {
+            // Preclaim rejects overwriting an existing key unless the amendment is
+            // enabled.
+            if (!canRotateKey)
+            {
+                // LCOV_EXCL_START
+                UNREACHABLE("xrpl::MPTokenIssuanceSet::doApply : rotation without amendment");
+                return tecINTERNAL;
+                // LCOV_EXCL_STOP
+            }
+
+            auto const epoch = (*sle)[~epochField].valueOr(0);
+
+            // Preclaim rejects a rotation that would wrap the epoch. So this should never happen.
+            if (epoch >= kMaxKeyEpoch)
+            {
+                // LCOV_EXCL_START
+                UNREACHABLE("xrpl::MPTokenIssuanceSet::doApply : key epoch overflow");
+                return tecINTERNAL;
+                // LCOV_EXCL_STOP
+            }
+
+            (*sle)[epochField] = epoch + 1;
+        }
+
+        return tesSUCCESS;
+    };
+
+    if (auto const ter = setEncryptionKey(sfIssuerEncryptionKey, sfIssuerKeyEpoch);
+        !isTesSuccess(ter))
+        return ter;  // LCOV_EXCL_LINE
+
+    if (auto const ter = setEncryptionKey(sfAuditorEncryptionKey, sfAuditorKeyEpoch);
+        !isTesSuccess(ter))
+        return ter;  // LCOV_EXCL_LINE
 
     view().update(sle);
 
diff --git a/src/libxrpl/tx/transactors/vault/VaultClawback.cpp b/src/libxrpl/tx/transactors/vault/VaultClawback.cpp
index c2c099f14e..059da7cc0f 100644
--- a/src/libxrpl/tx/transactors/vault/VaultClawback.cpp
+++ b/src/libxrpl/tx/transactors/vault/VaultClawback.cpp
@@ -237,6 +237,7 @@ VaultClawback::assetsToClawback(
     AccountID const& holder,
     STAmount const& clawbackAmount)
 {
+    bool const fix340Enabled = ctx_.view().rules().enabled(fixCleanup3_4_0);
     if (clawbackAmount.asset() != vault->at(sfAsset))
     {
         // preclaim should have blocked this , now it's an internal error
@@ -268,14 +269,35 @@ VaultClawback::assetsToClawback(
     STAmount sharesDestroyed;
     STAmount assetsRecovered;
 
+    // Number arithmetic can throw overflow_error when Scale and totals are large. Caught below.
     try
     {
+        // Do not discount a sole holder's shares: clawing back AssetsAvailable
+        // at the discounted rate can burn every share while loan assets remain.
+        auto const waiveUnrealizedLoss =
+            fix340Enabled && isSoleShareholder(view(), holder, sleShareIssuance)
+            ? WaiveUnrealizedLoss::Yes
+            : WaiveUnrealizedLoss::No;
+
         if (clawbackAmount == beast::kZero)
         {
-            sharesDestroyed = accountHolds(
-                view(), holder, share, FreezeHandling::IgnoreFreeze, AuthHandling::IgnoreAuth, j_);
-            auto const maybeAssets =
-                sharesToAssetsWithdraw(vault, sleShareIssuance, sharesDestroyed);
+            // Zero amount means clawback all shares the holder has; derive the corresponding asset
+            // amount from the share balance.
+            // isSoleShareholder already established that the holder owns the
+            // entire outstanding share supply whenever the waiver applies, so
+            // sfOutstandingAmount gives sharesDestroyed directly, avoiding a
+            // redundant MPToken read via accountHolds.
+            sharesDestroyed = waiveUnrealizedLoss == WaiveUnrealizedLoss::Yes
+                ? STAmount{share, sleShareIssuance->at(sfOutstandingAmount)}
+                : accountHolds(
+                      view(),
+                      holder,
+                      share,
+                      FreezeHandling::IgnoreFreeze,
+                      AuthHandling::IgnoreAuth,
+                      j_);
+            auto const maybeAssets = sharesToAssetsWithdraw(
+                vault, sleShareIssuance, sharesDestroyed, waiveUnrealizedLoss);
             if (!maybeAssets)
                 return std::unexpected(tecINTERNAL);  // LCOV_EXCL_LINE
 
@@ -288,40 +310,43 @@ VaultClawback::assetsToClawback(
             // Post-amendment: truncate shares so assetsRecovered <=
             // clawbackAmount by construction (matches the clamp branch
             // below).
-            auto const truncate = ctx_.view().rules().enabled(fixCleanup3_4_0) ? TruncateShares::Yes
-                                                                               : TruncateShares::No;
-            auto const maybeShares =
-                assetsToSharesWithdraw(vault, sleShareIssuance, clawbackAmount, truncate);
+            auto const truncate = fix340Enabled ? TruncateShares::Yes : TruncateShares::No;
+            auto const maybeShares = assetsToSharesWithdraw(
+                vault, sleShareIssuance, clawbackAmount, truncate, waiveUnrealizedLoss);
             if (!maybeShares)
                 return std::unexpected(tecINTERNAL);  // LCOV_EXCL_LINE
             sharesDestroyed = *maybeShares;
 
-            auto const maybeAssets =
-                sharesToAssetsWithdraw(vault, sleShareIssuance, sharesDestroyed);
+            auto const maybeAssets = sharesToAssetsWithdraw(
+                vault, sleShareIssuance, sharesDestroyed, waiveUnrealizedLoss);
             if (!maybeAssets)
                 return std::unexpected(tecINTERNAL);  // LCOV_EXCL_LINE
             assetsRecovered = *maybeAssets;
         }
-        // Clamp to maximum.
+        // Clamp assetsRecovered to sfAssetsAvailable, then re-derive shares and assets so the pair
+        // stays consistent.
         if (assetsRecovered > *assetsAvailable)
         {
             assetsRecovered = *assetsAvailable;
-            // Note, it is important to truncate the number of shares,
-            // otherwise the corresponding assets might breach the
-            // AssetsAvailable
             {
                 auto const maybeShares = assetsToSharesWithdraw(
-                    vault, sleShareIssuance, assetsRecovered, TruncateShares::Yes);
+                    vault,
+                    sleShareIssuance,
+                    assetsRecovered,
+                    TruncateShares::Yes,
+                    waiveUnrealizedLoss);
                 if (!maybeShares)
                     return std::unexpected(tecINTERNAL);  // LCOV_EXCL_LINE
                 sharesDestroyed = *maybeShares;
             }
 
-            auto const maybeAssets =
-                sharesToAssetsWithdraw(vault, sleShareIssuance, sharesDestroyed);
+            auto const maybeAssets = sharesToAssetsWithdraw(
+                vault, sleShareIssuance, sharesDestroyed, waiveUnrealizedLoss);
             if (!maybeAssets)
                 return std::unexpected(tecINTERNAL);  // LCOV_EXCL_LINE
             assetsRecovered = *maybeAssets;
+            // Truncation should guarantee the invariant holds. If it does not, a conversion
+            // helper is broken; refuse rather than over-recover.
             if (assetsRecovered > *assetsAvailable)
             {
                 // LCOV_EXCL_START
@@ -330,6 +355,18 @@ VaultClawback::assetsToClawback(
                 // LCOV_EXCL_STOP
             }
         }
+
+        // Post-fixCleanup3_4_0: round the recovery down at the posterior sfAssetsTotal scale so all
+        // rails change by the same representable delta. sharesDestroyed is intentionally NOT
+        // re-derived here: the holder's shares are burned for their pre-clamp value, so any
+        // sub-ULP trimmed off stays in the vault for the remaining shareholders.
+        if (ctx_.view().rules().enabled(fixCleanup3_4_0) && assetsRecovered > beast::kZero)
+        {
+            auto const maybeClamped = clampToAssetsTotalScale(vault, -assetsRecovered);
+            if (!maybeClamped)
+                return std::unexpected(maybeClamped.error());
+            assetsRecovered = *maybeClamped;
+        }
     }
     catch (std::overflow_error const&)
     {
@@ -341,6 +378,8 @@ VaultClawback::assetsToClawback(
             << ", assetsTotal=" << vault->at(sfAssetsTotal).value()
             << ", sharesTotal=" << sleShareIssuance->at(sfOutstandingAmount)
             << ", amount=" << clawbackAmount.value();
+        // Overflow means this transaction cannot apply, but ledger state is still consistent.
+        // Return tecPATH_DRY rather than a hard internal error.
         return std::unexpected(tecPATH_DRY);
     }
 
@@ -394,21 +433,44 @@ VaultClawback::doApply()
         sharesDestroyed = clawbackParts->second;
     }
 
+    // The holder has no shares (or the recovery clamped to zero). Nothing to burn; refuse rather
+    // than modifying vault state.
     if (sharesDestroyed == beast::kZero)
         return tecPRECISION_LOSS;
 
-    // A recovered amount can be genuinely non-zero yet still be dust relative to a
-    // sfAssetsTotal/sfAssetsAvailable large enough to exceed STAmount's significant-digit
-    // precision: subtracting it below rounds the stored total right back to where it started.
-    // The shares still move, so ValidVault would fail after the fact with "clawback must
-    // decrease vault balance" instead of a clean upfront rejection.
-    if (view().rules().enabled(fixCleanup3_4_0) &&
-        (debitIsNonZeroDust(vaultAsset, assetsTotal, assetsRecovered) ||
-         debitIsNonZeroDust(vaultAsset, assetsAvailable, assetsRecovered)))
+    // Number arithmetic can throw overflow_error when Scale and totals are large.
+    if (view().rules().enabled(fixCleanup3_4_0))
     {
-        JLOG(j_.debug()) << "VaultClawback: clawback amount too small to change stored vault"
-                            " balance";
-        return tecPRECISION_LOSS;
+        try
+        {
+            // A non-zero recovery can be too small to change the stored sfAssetsTotal at
+            // STAmount's precision. Shares would still be burned, reject it instead.
+            if (debitIsNonZeroDust(vaultAsset, assetsTotal, assetsRecovered))
+            {
+                // LCOV_EXCL_START
+                JLOG(j_.debug())
+                    << "VaultClawback: clawback amount too small to change stored vault"
+                       " balance";
+                return tecPRECISION_LOSS;
+                // LCOV_EXCL_STOP
+            }
+        }
+        // LCOV_EXCL_START
+        catch (std::overflow_error const&)
+        {
+            // It's easy to hit this exception from Number with large enough Scale
+            // so we avoid spamming the log and only use debug here.
+            JLOG(j_.debug())  //
+                << "VaultClawback: overflow error with"
+                << " scale=" << (int)vault->at(sfScale).value()  //
+                << ", assetsTotal=" << vault->at(sfAssetsTotal).value()
+                << ", sharesTotal=" << sleIssuance->at(sfOutstandingAmount)
+                << ", amount=" << amount.value();
+            // Overflow means this transaction cannot apply, but ledger state is still
+            // consistent. Return tecPATH_DRY rather than a hard internal error.
+            return tecPATH_DRY;
+        }
+        // LCOV_EXCL_STOP
     }
 
     assetsTotal -= assetsRecovered;
diff --git a/src/libxrpl/tx/transactors/vault/VaultDelete.cpp b/src/libxrpl/tx/transactors/vault/VaultDelete.cpp
index 35bf80c29f..9c6c41654b 100644
--- a/src/libxrpl/tx/transactors/vault/VaultDelete.cpp
+++ b/src/libxrpl/tx/transactors/vault/VaultDelete.cpp
@@ -4,7 +4,6 @@
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
-#include <xrpl/ledger/helpers/CredentialHelpers.h>
 #include <xrpl/ledger/helpers/MPTokenHelpers.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/AccountID.h>
@@ -102,19 +101,6 @@ VaultDelete::doApply()
     if (!vault)
         return tefINTERNAL;  // LCOV_EXCL_LINE
 
-    // Remove any credentials pinned to the vault pseudo-account before anything
-    // else. They would otherwise keep its owner directory alive and block
-    // deletion with tecHAS_OBLIGATIONS. Doing it first means a bounded,
-    // tecINCOMPLETE cleanup can be resumed by a later transaction without having
-    // already torn down the vault.
-    if (view().rules().enabled(fixCleanup3_4_0))
-    {
-        if (auto const ter = credentials::deletePseudoAccountCredentials(
-                view(), vault->at(sfAccount), kMaxDeletablePseudoAccountCredentials, j_);
-            !isTesSuccess(ter))
-            return ter;
-    }
-
     // Destroy the asset holding.
     auto asset = vault->at(sfAsset);
 
diff --git a/src/libxrpl/tx/transactors/vault/VaultDeposit.cpp b/src/libxrpl/tx/transactors/vault/VaultDeposit.cpp
index 27e590338c..fc72159444 100644
--- a/src/libxrpl/tx/transactors/vault/VaultDeposit.cpp
+++ b/src/libxrpl/tx/transactors/vault/VaultDeposit.cpp
@@ -307,6 +307,8 @@ VaultDeposit::doApply()
     }
 
     STAmount sharesCreated = {vault->at(sfShareMPTID)}, assetsDeposited;
+
+    // Number arithmetic can throw overflow_error when Scale and totals are large. Caught below.
     try
     {
         // Compute exchange before transferring any amounts.
@@ -316,14 +318,20 @@ VaultDeposit::doApply()
                 return tecINTERNAL;  // LCOV_EXCL_LINE
             sharesCreated = *maybeShares;
         }
+
         if (sharesCreated == beast::kZero)
             return tecPRECISION_LOSS;
 
+        // Convert shares back to assets so the depositor is debited for the amount actually minted.
+        // The truncated share count is worth <= amount; without this the difference would be
+        // credited to the vault for free.
         auto const maybeAssets = sharesToAssetsDeposit(vault, sleIssuance, sharesCreated);
         if (!maybeAssets)
         {
             return tecINTERNAL;  // LCOV_EXCL_LINE
         }
+        // The round-trip must never return more than the original amount. If it does, a conversion
+        // helper is broken. Reject rather than overcharge the depositor.
         if (*maybeAssets > amount)
         {
             // LCOV_EXCL_START
@@ -331,13 +339,28 @@ VaultDeposit::doApply()
             return tecINTERNAL;
             // LCOV_EXCL_STOP
         }
-        // What a deposit transfers is not the requested amount but that amount truncated to a
-        // whole number of shares and converted back, which can be smaller. Only here is that
-        // value known rather than recomputed, so this is where it can be checked against the
-        // depositor's balance before anything moves.
-        if (fix340Enabled && roundsToZeroForDepositor(view(), accountID_, *maybeAssets, j_))
-            return tecPRECISION_LOSS;
         assetsDeposited = *maybeAssets;
+
+        // Post-fixCleanup3_4_0: round the deposit to the sfAssetsTotal scale so all accounting
+        // fields (trust line / MPT, sfAssetsAvailable, sfAssetsTotal) change by the same
+        // representable delta.
+        if (fix340Enabled)
+        {
+            // Round down at the posterior sfAssetsTotal scale so the vault is credited by no more
+            // than the depositor paid. Keep the share count from the first round trip: the clamp
+            // only drops a last digit of the new total. Converting the clamped amount back to
+            // shares would mint fewer shares while still charging the N-share debit.
+            auto const maybeClamped = clampToAssetsTotalScale(vault, assetsDeposited);
+            if (!maybeClamped)
+                return maybeClamped.error();
+            assetsDeposited = *maybeClamped;
+
+            // The actual deposit amount is truncated to whole shares, converted back to assets,
+            // and clamped to the sfAssetsTotal scale (post-fixCleanup3_4_0). Check the depositor's
+            // balance here—after clamping—before making any state changes.
+            if (roundsToZeroForDepositor(view(), accountID_, assetsDeposited, j_))
+                return tecPRECISION_LOSS;
+        }
     }
     catch (std::overflow_error const&)
     {
diff --git a/src/libxrpl/tx/transactors/vault/VaultWithdraw.cpp b/src/libxrpl/tx/transactors/vault/VaultWithdraw.cpp
index 9e066304ed..4dc5b95c89 100644
--- a/src/libxrpl/tx/transactors/vault/VaultWithdraw.cpp
+++ b/src/libxrpl/tx/transactors/vault/VaultWithdraw.cpp
@@ -1,6 +1,7 @@
 #include <xrpl/tx/transactors/vault/VaultWithdraw.h>
 
 #include <xrpl/basics/Log.h>
+#include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <xrpl/beast/utility/instrumentation.h>
@@ -204,6 +205,15 @@ VaultWithdraw::preclaim(PreclaimContext const& ctx)
     if (auto const ter = requireAuth(ctx.view, vaultAsset, dstAcct, authType); !isTesSuccess(ter))
         return ter;
 
+    // Fail early when self-destination would have to create a holding.
+    // Skip when a holding already exists: canAddHolding does not look at that,
+    // and would block a no-op create (the DefaultRipple-cleared self-withdraw).
+    if (fix340Enabled && account == dstAcct && !holdingExists(ctx.view, dstAcct, vaultAsset))
+    {
+        if (auto const ter = canAddHolding(ctx.view, vaultAsset); !isTesSuccess(ter))
+            return ter;
+    }
+
     // The checks above only establish that an account may hold the asset. A
     // private vault additionally restricts who may take part in it, so paying
     // its asset out to a third party requires both ends of that payout to be
@@ -267,6 +277,7 @@ VaultWithdraw::preclaim(PreclaimContext const& ctx)
 TER
 VaultWithdraw::doApply()
 {
+    bool const fix340Enabled = view().rules().enabled(fixCleanup3_4_0);
     auto const vault = view().peek(keylet::vault(ctx_.tx[sfVaultID]));
     auto applyViewContext = ctx_.getApplyViewContext();
     if (!vault)
@@ -300,6 +311,7 @@ VaultWithdraw::doApply()
     // We waive the unrealized-loss subtraction in this case to avoid user withdrawing all of their
     // shares but keeping future value in the vault.
     auto const waiveUnrealizedLoss = shouldWaiveWithdrawal(view(), accountID_, sleIssuance);
+    // Number arithmetic can throw overflow_error when Scale and totals are large. Caught below.
     try
     {
         if (amount.asset() == vaultAsset)
@@ -324,8 +336,12 @@ VaultWithdraw::doApply()
                 sharesRedeemed = *maybeShares;
             }
 
+            // Shares are MPT (integer). Small requested amounts truncate to zero; refuse rather
+            // than burn nothing while paying out assets.
             if (sharesRedeemed == beast::kZero)
                 return tecPRECISION_LOSS;
+            // Convert shares back to assets so the payout matches the shares actually burned, not
+            // the requested amount. The extra would otherwise be paid from the vault for free.
             auto const maybeAssets =
                 sharesToAssetsWithdraw(vault, sleIssuance, sharesRedeemed, waiveUnrealizedLoss);
             if (!maybeAssets)
@@ -334,7 +350,8 @@ VaultWithdraw::doApply()
         }
         else if (amount.asset() == share)
         {
-            // Fixed shares, variable assets.
+            // Fixed shares, variable assets. No round-trip: the share count is exactly what the
+            // caller specified; only the payout amount is derived.
             sharesRedeemed = amount;
             auto const maybeAssets =
                 sharesToAssetsWithdraw(vault, sleIssuance, sharesRedeemed, waiveUnrealizedLoss);
@@ -357,6 +374,8 @@ VaultWithdraw::doApply()
             << ", assetsTotal=" << vault->at(sfAssetsTotal).value()
             << ", sharesTotal=" << sleIssuance->at(sfOutstandingAmount)
             << ", amount=" << amount.value();
+        // Overflow means this transaction cannot apply, but ledger state is still consistent.
+        // Return tecPATH_DRY rather than a hard internal error.
         return tecPATH_DRY;
     }
 
@@ -369,12 +388,11 @@ VaultWithdraw::doApply()
     auto assetsTotal = vault->at(sfAssetsTotal);
     auto const lossUnrealized = vault->at(sfLossUnrealized);
 
-    if (view().rules().enabled(fixCleanup3_4_0) && !isFinalWithdrawal)
+    if (fix340Enabled && !isFinalWithdrawal)
     {
-        // A withdrawal for a fixed share amount (variable assets) has no requested-asset
-        // amount to check for rounding, unlike the fixed-assets branch above: a small enough
-        // share amount can round down to an exact zero even though the vault still holds
-        // positive effective value backing outstanding shares.
+        // Fixed-shares path: a small share count can round to zero assets even though the vault has
+        // backing value. Reject rather than burn shares for a zero payout. The fixed-assets branch
+        // above has already rejected zero via the sharesRedeemed check.
         if (amount.asset() == share && assetsWithdrawn == beast::kZero &&
             assetsTotalForWithdrawal(vault, waiveUnrealizedLoss) != beast::kZero)
         {
@@ -382,17 +400,34 @@ VaultWithdraw::doApply()
             return tecPRECISION_LOSS;
         }
 
-        // assetsWithdrawn can also be genuinely non-zero and still too small to move
-        // sfAssetsTotal or sfAssetsAvailable once canonicalized to STAmount's precision. Either
-        // way the shares still move, so ValidVault would otherwise fail after the fact instead
-        // of a clean upfront rejection.
-        if (debitIsNonZeroDust(vaultAsset, assetsTotal, assetsWithdrawn) ||
-            debitIsNonZeroDust(vaultAsset, assetsAvailable, assetsWithdrawn))
+        // Number arithmetic can throw overflow_error when Scale and totals are large.
+        try
         {
-            JLOG(j_.debug()) << "VaultWithdraw: withdrawal amount too small to change stored"
-                                " vault balance";
-            return tecPRECISION_LOSS;
+            // A non-zero payout can be too small to change the stored sfAssetsTotal at
+            // STAmount's precision. Shares would still be burned, reject it instead.
+            if (debitIsNonZeroDust(vaultAsset, assetsTotal, assetsWithdrawn))
+            {
+                JLOG(j_.debug()) << "VaultWithdraw: withdrawal amount too small to change stored"
+                                    " vault balance";
+                return tecPRECISION_LOSS;
+            }
         }
+        // LCOV_EXCL_START
+        catch (std::overflow_error const&)
+        {
+            // It's easy to hit this exception from Number with large enough Scale
+            // so we avoid spamming the log and only use debug here.
+            JLOG(j_.debug())  //
+                << "VaultWithdraw: overflow error with"
+                << " scale=" << (int)vault->at(sfScale).value()  //
+                << ", assetsTotal=" << vault->at(sfAssetsTotal).value()
+                << ", sharesTotal=" << sleIssuance->at(sfOutstandingAmount)
+                << ", amount=" << amount.value();
+            // Overflow means this transaction cannot apply, but ledger state is still consistent.
+            // Return tecPATH_DRY rather than a hard internal error.
+            return tecPATH_DRY;
+        }
+        // LCOV_EXCL_STOP
     }
 
     // Post-fixCleanup3_3_0: preclaim already validated all freeze conditions
@@ -409,6 +444,54 @@ VaultWithdraw::doApply()
         return tecINSUFFICIENT_FUNDS;
     }
 
+    // Post-fixCleanup3_4_0: round the payout to the sfAssetsTotal scale so all three rails
+    // (trust line / MPT, sfAssetsAvailable, sfAssetsTotal) change by the same representable delta.
+    // Skip when assetsWithdrawn is already zero: the earlier fix340 guard above deliberately
+    // permits fixed-share zero-asset withdrawals in a fully-impaired vault (where
+    // assetsTotalForWithdrawal == 0), and clamping-then-rejecting would undo that. Also skip on
+    // the final-withdrawal path, which overwrites assetsWithdrawn with sfAssetsAvailable below.
+    if (fix340Enabled && !isFinalWithdrawal && assetsWithdrawn > beast::kZero)
+    {
+        // Check availability against the unclamped amount first, so a withdrawal that is both
+        // over the vault's available balance and sub-ULP at the posterior sfAssetsTotal scale
+        // reports tecINSUFFICIENT_FUNDS rather than tecPRECISION_LOSS. The clamp below only ever
+        // shrinks assetsWithdrawn, so this check stays valid; the post-clamp check further down
+        // remains in place to catch the (now smaller) clamped value too.
+        if (*assetsAvailable < assetsWithdrawn)
+        {
+            JLOG(j_.debug()) << "VaultWithdraw: vault doesn't hold enough assets";
+            return tecINSUFFICIENT_FUNDS;
+        }
+
+        // Number arithmetic can throw overflow_error when Scale and totals are large.
+        try
+        {
+            // Round down at the posterior sfAssetsTotal scale so the payout never exceeds the
+            // value represented by the redeemed shares. sharesRedeemed is intentionally not
+            // re-derived: any trimmed residue stays with remaining shareholders.
+            auto const maybeClamped = clampToAssetsTotalScale(vault, -assetsWithdrawn);
+            if (!maybeClamped)
+                return maybeClamped.error();  // LCOV_EXCL_LINE
+            assetsWithdrawn = *maybeClamped;
+        }
+        // LCOV_EXCL_START
+        catch (std::overflow_error const&)
+        {
+            // It's easy to hit this exception from Number with large enough Scale
+            // so we avoid spamming the log and only use debug here.
+            JLOG(j_.debug())  //
+                << "VaultWithdraw: overflow error with"
+                << " scale=" << (int)vault->at(sfScale).value()  //
+                << ", assetsTotal=" << vault->at(sfAssetsTotal).value()
+                << ", sharesTotal=" << sleIssuance->at(sfOutstandingAmount)
+                << ", amount=" << amount.value();
+            // Overflow means this transaction cannot apply, but ledger state is still consistent.
+            // Return tecPATH_DRY rather than a hard internal error.
+            return tecPATH_DRY;
+        }
+        // LCOV_EXCL_STOP
+    }
+
     // The vault must have enough assets on hand.
     if (*assetsAvailable < assetsWithdrawn)
     {
@@ -416,14 +499,12 @@ VaultWithdraw::doApply()
         return tecINSUFFICIENT_FUNDS;
     }
 
-    // Post-fixCleanup3_2_0 "final withdrawal" rule:
-    // a transaction that would burn every outstanding share is only permitted when the vault is in
-    // a clean state — no outstanding receivables and no unrealized loss. Otherwise the resulting
-    // (shares == 0, assetsTotal > 0) state would violate the zero-sized-vault invariant.
+    // Post-fixCleanup3_2_0: burning every outstanding share is only allowed when the vault has no
+    // unrealized loss. Otherwise the resulting (shares == 0, assetsTotal > 0) state would violate
+    // the zero-sized-vault invariant.
     //
-    // When the rule applies, the payout is the remaining sfAssetsAvailable; in a clean vault
-    // the helper result should already equal that value, and any mismatch is a rounding artifact
-    // worth logging.
+    // The payout is set to the remaining sfAssetsAvailable. The helper result should already
+    // equal that value in a clean vault; any mismatch is a rounding artifact and is logged.
     if (view().rules().enabled(fixCleanup3_2_0) && isFinalWithdrawal)
     {
         // Unreachable: a final withdrawal with lossUnrealized > 0 has
@@ -457,6 +538,8 @@ VaultWithdraw::doApply()
     }
     else
     {
+        // Debit both rails by the same delta so sfAssetsTotal and sfAssetsAvailable stay in step,
+        // as required by the ValidVault invariant.
         assetsTotal -= assetsWithdrawn;
         assetsAvailable -= assetsWithdrawn;
     }
diff --git a/src/test/app/AMMClawbackMPT_test.cpp b/src/test/app/AMMClawbackMPT_test.cpp
index 1d75c4db22..44eb61395a 100644
--- a/src/test/app/AMMClawbackMPT_test.cpp
+++ b/src/test/app/AMMClawbackMPT_test.cpp
@@ -2198,6 +2198,89 @@ class AMMClawbackMPT_test : public beast::unit_test::Suite
         BEAST_EXPECT(amm.ammExists());
     }
 
+    void
+    testClawbackBypassesReserve(FeatureBitset features)
+    {
+        // Same as the IOU case, but the paired asset is an MPT alice does not
+        // hold yet. The reserve check is skipped on the clawback path while
+        // createMPToken() still runs, so alice's MPToken is created even though
+        // neither she nor the low-XRP issuer can cover the owner reserve.
+        testcase("test clawback bypasses recipient reserve (MPT)");
+        using namespace jtx;
+
+        Env env(*this, features);
+        Account const gw{"gateway"};    // IOU issuer + claw authority, low XRP
+        Account const gw2{"gateway2"};  // MPT issuer of the paired asset
+        Account const carol{"carol"};
+        Account const alice{"alice"};
+
+        auto const usd = gw["USD"];
+        auto const baseFee = env.current()->fees().base;
+
+        env.fund(XRP(1'000'000), gw2, carol);
+        // Low XRP so the legacy issuer-balance check cannot pass.
+        env.fund(env.current()->fees().accountReserve(0, 1) + baseFee * 10, gw);
+        // Reserve for the USD trustline and LP token trustline.
+        env.fund(env.current()->fees().accountReserve(2, 1) + baseFee * 5, alice);
+        env.close();
+
+        env(fset(gw, asfAllowTrustLineClawback));
+        env.close();
+
+        // The paired MPT: transferable so an AMM can hold it, and no
+        // RequireAuth so createMPToken()'s WeakAuth check passes.
+        MPT const btc = MPTTester(
+            {.env = env,
+             .issuer = gw2,
+             .holders = {carol},
+             .pay = 1'000'000,
+             .flags = kMptDexFlags});
+
+        env.trust(usd(1'000'000), carol);
+        env(pay(gw, carol, usd(100'000)));
+        env.close();
+        AMM amm(env, carol, usd(1'000), btc(1'000), Ter(tesSUCCESS));
+        env.close();
+
+        // alice holds a USD trustline and LP tokens, but no BTC MPToken.
+        env.trust(usd(100'000), alice);
+        env(pay(gw, alice, usd(1'000)));
+        env.close();
+        amm.deposit(alice, usd(100));
+
+        BEAST_EXPECT(env.ownerCount(alice) == 2);
+        BEAST_EXPECT(!env.le(keylet::mptoken(btc.issuanceID, alice.id())));
+
+        // AMMWithdraw still enforces the reserve check.
+        amm.withdrawAll(alice, std::nullopt, Ter(tecINSUFFICIENT_RESERVE));
+        BEAST_EXPECT(!env.le(keylet::mptoken(btc.issuanceID, alice.id())));
+        BEAST_EXPECT(env.ownerCount(alice) == 2);
+        // alice cannot afford a third owner object.
+        BEAST_EXPECT(env.balance(alice) < STAmount(env.current()->fees().accountReserve(3, 1)));
+
+        if (features[fixCleanup3_4_0])
+        {
+            // Reserve check skipped; the paired BTC returns to alice on a
+            // newly created MPToken.
+            env(amm::ammClawback(gw, alice, usd, btc, usd(10)), Ter(tesSUCCESS));
+            env.close();
+
+            BEAST_EXPECT(env.le(keylet::mptoken(btc.issuanceID, alice.id())));
+            BEAST_EXPECT(env.balance(alice, btc) > btc(0));
+            BEAST_EXPECT(env.ownerCount(alice) == 3);
+        }
+        else
+        {
+            // Legacy path: the check runs against max(issuer, holder) XRP,
+            // neither of which covers a third owner object.
+            env(amm::ammClawback(gw, alice, usd, btc, usd(10)), Ter(tecINSUFFICIENT_RESERVE));
+            env.close();
+
+            BEAST_EXPECT(!env.le(keylet::mptoken(btc.issuanceID, alice.id())));
+            BEAST_EXPECT(env.ownerCount(alice) == 2);
+        }
+    }
+
     void
     run() override
     {
@@ -2225,6 +2308,8 @@ class AMMClawbackMPT_test : public beast::unit_test::Suite
             featureLendingProtocol);
         testLastHolderLPTokenBalance(all - fixAMMClawbackRounding);
         testClawAssetCheck(all);
+        testClawbackBypassesReserve(all);
+        testClawbackBypassesReserve(all - fixCleanup3_4_0);
     }
 };
 
diff --git a/src/test/app/AMMClawback_test.cpp b/src/test/app/AMMClawback_test.cpp
index 230d148ff9..4f025f08eb 100644
--- a/src/test/app/AMMClawback_test.cpp
+++ b/src/test/app/AMMClawback_test.cpp
@@ -15,6 +15,7 @@
 #include <xrpl/ledger/helpers/AMMHelpers.h>
 #include <xrpl/protocol/AmountConversions.h>
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFlags.h>
@@ -2715,6 +2716,81 @@ class AMMClawback_test : public beast::unit_test::Suite
         }
     }
 
+    void
+    testClawbackBypassesReserve(FeatureBitset features)
+    {
+        // Clawback must not fail the holder-side reserve check: a holder could
+        // otherwise veto it by omitting the paired trustline. AMMWithdraw still
+        // enforces the check. Pre-fixCleanup3_4_0 the holder's reserve was
+        // compared against max(issuer pre-fee, holder current) XRP, so the
+        // clawback was blocked when neither balance covered it.
+        testcase("test clawback bypasses recipient reserve");
+        using namespace jtx;
+
+        Env env(*this, features);
+        Account const gw{"gateway"};
+        Account const carol{"carol"};
+        Account const alice{"alice"};
+
+        auto const usd = gw["USD"];
+        auto const eur = gw["EUR"];
+        auto const baseFee = env.current()->fees().base;
+
+        env.fund(XRP(1'000'000), carol);
+        // Low XRP so the legacy issuer-balance check cannot pass.
+        env.fund(env.current()->fees().accountReserve(0, 1) + baseFee * 10, gw);
+        // Reserve for the USD trustline and LP token trustline.
+        env.fund(env.current()->fees().accountReserve(2, 1) + baseFee * 5, alice);
+        env.close();
+
+        env(fset(gw, asfAllowTrustLineClawback));
+        env.close();
+
+        env.trust(usd(1'000'000), carol);
+        env.trust(eur(1'000'000), carol);
+        env(pay(gw, carol, usd(100'000)));
+        env(pay(gw, carol, eur(100'000)));
+        env.close();
+        AMM amm(env, carol, usd(1'000), eur(1'000), Ter(tesSUCCESS));
+        env.close();
+
+        // alice holds a USD trustline and LP tokens, but no EUR trustline.
+        env.trust(usd(100'000), alice);
+        env(pay(gw, alice, usd(1'000)));
+        env.close();
+        amm.deposit(alice, usd(100));
+
+        BEAST_EXPECT(env.ownerCount(alice) == 2);
+        // alice cannot afford a third owner object.
+        BEAST_EXPECT(env.balance(alice) < STAmount(env.current()->fees().accountReserve(3, 1)));
+
+        // AMMWithdraw still enforces the reserve check.
+        amm.withdraw(
+            WithdrawArg{
+                .account = alice, .asset1Out = eur(1), .err = Ter(tecINSUFFICIENT_RESERVE)});
+        BEAST_EXPECT(env.ownerCount(alice) == 2);
+
+        if (features[fixCleanup3_4_0])
+        {
+            // Reserve check skipped; the paired EUR returns to alice on a
+            // newly created EUR trustline.
+            env(amm::ammClawback(gw, alice, usd, eur, usd(10)), Ter(tesSUCCESS));
+            env.close();
+
+            BEAST_EXPECT(env.le(keylet::trustLine(alice.id(), eur.issue())));
+            BEAST_EXPECT(env.balance(alice, eur) > eur(0));
+            BEAST_EXPECT(env.ownerCount(alice) == 3);
+        }
+        else
+        {
+            // Legacy path: the check runs against max(issuer, holder) XRP,
+            // neither of which covers a third owner object.
+            env(amm::ammClawback(gw, alice, usd, eur, usd(10)), Ter(tecINSUFFICIENT_RESERVE));
+            env.close();
+            BEAST_EXPECT(env.ownerCount(alice) == 2);
+        }
+    }
+
     void
     testExactLPTokenEquality(FeatureBitset features)
     {
@@ -2809,6 +2885,7 @@ class AMMClawback_test : public beast::unit_test::Suite
             testAssetFrozen(features);
             testSingleDepositAndClawback(features);
             testLastHolderLPTokenBalance(features);
+            testClawbackBypassesReserve(features);
             testExactLPTokenEquality(features);
         }
     }
diff --git a/src/test/app/AMMMPT_test.cpp b/src/test/app/AMMMPT_test.cpp
index ac9728ede1..37e0ed585d 100644
--- a/src/test/app/AMMMPT_test.cpp
+++ b/src/test/app/AMMMPT_test.cpp
@@ -15,6 +15,7 @@
 #include <test/jtx/rate.h>
 #include <test/jtx/sendmax.h>
 #include <test/jtx/seq.h>
+#include <test/jtx/tags.h>
 #include <test/jtx/ter.h>
 #include <test/jtx/trust.h>
 #include <test/jtx/txflags.h>
@@ -3318,6 +3319,65 @@ private:
         }
     }
 
+    void
+    testWithdrawReserveUsesLiveBalance()
+    {
+        testcase("Withdraw reserve check uses live balance");
+
+        using namespace jtx;
+
+        auto const test = [&](auto&& makeToken) {
+            Env env(*this);
+            env.fund(XRP(30'000), gw_, alice_, bob_);
+            env.close();
+
+            auto const token = makeToken(env);
+            AMM amm(env, gw_, XRP(100), token(100));
+
+            // The EUR trustline is an unrelated owner object. The XRP-only
+            // AMM deposit adds the LP token trustline, so Alice has 2 owners.
+            env.trust(gw_["EUR"](1), alice_);
+            amm.deposit(DepositArg{.account = alice_, .asset1In = XRP(10)});
+            BEAST_EXPECT(env.ownerCount(alice_) == 2);
+            env.require(Balance(alice_, token(kNone)));
+
+            // Drain Alice to one drop below the reserve for a third owner
+            // object, accounting for the fee on the drain payment.
+            auto const reserveForToken = reserve(env, 3);
+            auto const targetBalance = reserveForToken - XRPAmount{1};
+            auto const baseFee = env.current()->fees().base;
+            auto const currentBalance = env.balance(alice_).value().xrp();
+            auto const drainAmount = currentBalance - targetBalance - baseFee;
+            BEAST_EXPECT(drainAmount > XRPAmount{0});
+            env(pay(alice_, bob_, drops(drainAmount)));
+            env.close();
+
+            // AMMWithdraw captures priorBalance before the fee, then the XRP
+            // leg raises the live sandbox balance before the token leg.
+            // XRP(2) keeps the integral MPT side positive after rounding.
+            auto const xrpOut = XRP(2);
+            auto const tokenOut = token(2);
+            auto const priorBalance = env.balance(alice_).value().xrp();
+            auto const liveBalanceAfterXrpLeg = priorBalance - baseFee + xrpOut.value().xrp();
+            BEAST_EXPECT(priorBalance < reserveForToken);
+            BEAST_EXPECT(liveBalanceAfterXrpLeg > priorBalance);
+            BEAST_EXPECT(liveBalanceAfterXrpLeg >= reserveForToken);
+
+            // The XRP leg runs first, so the missing IOU trustline or MPToken
+            // is reserved against the updated sandbox balance.
+            amm.withdraw(
+                WithdrawArg{.account = alice_, .asset1Out = xrpOut, .asset2Out = tokenOut});
+
+            // The withdrawal succeeds only if the missing token holding can be
+            // reserved from the live balance after the XRP leg.
+            BEAST_EXPECT(env.ownerCount(alice_) == 3);
+            BEAST_EXPECT(env.balance(alice_, token).value().signum() > 0);
+        };
+
+        test([&](Env&) -> PrettyAsset { return gw_["USD"]; });
+        test([&](Env& env) -> PrettyAsset { return MPTTester({.env = env, .issuer = gw_}); });
+    }
+
     void
     testInvalidFeeVote()
     {
@@ -7491,6 +7551,7 @@ private:
         testDeposit();
         testInvalidWithdraw();
         testWithdraw();
+        testWithdrawReserveUsesLiveBalance();
         testInvalidFeeVote();
         testFeeVote();
         testInvalidBid();
diff --git a/src/test/app/AMM_test.cpp b/src/test/app/AMM_test.cpp
index f541f61bff..58d41c40b7 100644
--- a/src/test/app/AMM_test.cpp
+++ b/src/test/app/AMM_test.cpp
@@ -4,7 +4,6 @@
 #include <test/jtx/Env.h>
 #include <test/jtx/TestHelpers.h>
 #include <test/jtx/amount.h>
-#include <test/jtx/credentials.h>
 #include <test/jtx/envconfig.h>
 #include <test/jtx/escrow.h>
 #include <test/jtx/fee.h>
@@ -5193,51 +5192,6 @@ private:
             {features});
     }
 
-    void
-    testCredentialPinsPseudoAccount()
-    {
-        testcase("Credential pins AMM pseudo-account");
-
-        using namespace jtx;
-        FeatureBitset const all{testableAmendments()};
-
-        // A credential issued to an AMM pseudo-account can't be accepted or
-        // deleted by it. A pin created before the cure activates stays pinned
-        // in the pseudo-account's owner directory and makes AMM deletion fail
-        // with tecINTERNAL (deleteAMMTrustLines rejects the unexpected
-        // directory entry).
-        Account const attacker{"attacker"};
-        char const credType[] = "FN36";
-
-        Env env(*this, all - fixCleanup3_3_0 - fixCleanup3_4_0);
-        fund(env, gw_, {alice_}, XRP(20'000), {USD(10'000)});
-        env.fund(XRP(1'000), attacker);
-        env.close();
-
-        AMM amm(env, alice_, XRP(10'000), USD(10'000));
-        Account const ammAcct{"amm pseudo-account", amm.ammAccount()};
-        env.memoize(ammAcct);
-
-        env(credentials::create(ammAcct, attacker, credType));
-        env.close();
-        auto const credKey = credentials::keylet(ammAcct, attacker, credType);
-        BEAST_EXPECT(env.le(credKey));
-
-        // Emptying the AMM would auto-delete it, but the pinned credential makes
-        // deleteAMMAccount fail; the withdraw is rolled back and the AMM stays.
-        amm.withdrawAll(alice_, std::nullopt, Ter(tecINTERNAL));
-        BEAST_EXPECT(amm.ammExists());
-
-        env.enableFeature(fixCleanup3_4_0);
-        env.close();
-
-        // The pre-existing pin is cleaned up and the AMM deletes.
-        amm.withdrawAll(alice_);
-        BEAST_EXPECT(!amm.ammExists());
-        BEAST_EXPECT(!env.le(credKey));
-        BEAST_EXPECT(!env.le(keylet::ownerDir(amm.ammAccount())));
-    }
-
     void
     testAutoDelete()
     {
@@ -7505,7 +7459,6 @@ private:
         FeatureBitset const all{testableAmendments()};
         testInvalidInstance();
         testInstanceCreate();
-        testCredentialPinsPseudoAccount();
         for (auto const& f : amendmentCombinations({fixCleanup3_3_0, featureAMMClawback}))
             testInvalidDeposit(f);
         testDeposit();
diff --git a/src/test/app/AccountDelete_test.cpp b/src/test/app/AccountDelete_test.cpp
index 15668d4d71..aa7fe898e3 100644
--- a/src/test/app/AccountDelete_test.cpp
+++ b/src/test/app/AccountDelete_test.cpp
@@ -29,6 +29,8 @@
 #include <xrpl/basics/chrono.h>
 #include <xrpl/basics/strHex.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/json/json_value.h>
+#include <xrpl/json/to_string.h>
 #include <xrpl/ledger/ReadView.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
@@ -67,7 +69,8 @@ private:
         // We can't use env.meta() here, because meta() doesn't include
         // delivered_amount.
         env.close();
-        json::Value const meta = env.rpc("tx", txHash)[jss::result][jss::meta];
+        json::Value const txResult = env.rpc("tx", txHash)[jss::result];
+        json::Value const meta = txResult[jss::meta];
 
         // Expect there to be a DeliveredAmount field.
         if (!BEAST_EXPECT(meta.isMember(sfDeliveredAmount.jsonName)))
@@ -78,6 +81,21 @@ private:
         json::Value const jsonExpect{amount.getJson(JsonOptions::Values::None)};
         BEAST_EXPECT(meta[sfDeliveredAmount.jsonName] == jsonExpect);
         BEAST_EXPECT(meta[jss::delivered_amount] == jsonExpect);
+
+        // The `ledger` RPC (with expanded transactions) should also report
+        // delivered_amount for this transaction, matching the `tx` RPC.
+        json::Value ledgerParams;
+        ledgerParams[jss::ledger_index] = txResult[jss::ledger_index].asUInt();
+        ledgerParams[jss::transactions] = true;
+        ledgerParams[jss::expand] = true;
+
+        auto const ledgerResult = env.rpc("json", "ledger", to_string(ledgerParams));
+        auto const& ledgerTx = ledgerResult[jss::result][jss::ledger][jss::transactions][0u];
+        BEAST_EXPECT(ledgerTx[jss::hash].asString() == txHash);
+
+        json::Value const& ledgerMeta = ledgerTx[jss::metaData];
+        BEAST_EXPECT(ledgerMeta[sfDeliveredAmount.jsonName] == jsonExpect);
+        BEAST_EXPECT(ledgerMeta[jss::delivered_amount] == jsonExpect);
     }
 
     // Helper function to create a payment channel.
diff --git a/src/test/app/ConfidentialMPTKeyRotation_test.cpp b/src/test/app/ConfidentialMPTKeyRotation_test.cpp
new file mode 100644
index 0000000000..c4e8e607da
--- /dev/null
+++ b/src/test/app/ConfidentialMPTKeyRotation_test.cpp
@@ -0,0 +1,634 @@
+#include <test/jtx/Account.h>
+#include <test/jtx/ConfidentialTransfer.h>
+#include <test/jtx/Env.h>
+#include <test/jtx/mpt.h>
+
+#include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/ledger/OpenView.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/Protocol.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STLedgerEntry.h>
+#include <xrpl/protocol/TER.h>
+#include <xrpl/protocol/TxFlags.h>
+
+#include <cstdint>
+#include <memory>
+#include <optional>
+
+namespace xrpl {
+
+class ConfidentialMPTKeyRotation_test : public ConfidentialTransferTestBase
+{
+    void
+    testMPTokenIssuanceSetRotateIssuerKey(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet rotate issuer key");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const bob("bob");
+        MPTTester mptAlice(env, alice, {.holders = {bob}});
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(bob);
+
+        // First-time registration.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+        });
+
+        // Verify that no epochs are set when registering for the first time.
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+
+        // Rotating the issuer key requires the key rotation amendment
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(bob),
+            .err = rotationEnabled ? TER(tesSUCCESS) : TER(tecNO_PERMISSION),
+        });
+
+        // A rotation replaces the issuer key and bumps its epoch. The auditor
+        // key was never registered, so it and its epoch stay absent.
+        if (rotationEnabled)
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(bob, std::nullopt));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(1u, std::nullopt));
+        }
+        else
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, std::nullopt));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+        }
+
+        if (rotationEnabled)
+        {
+            // A second rotation increments the epoch again
+            mptAlice.set({
+                .account = alice,
+                .issuerPubKey = mptAlice.getPubKey(alice),
+            });
+
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(2u, std::nullopt));
+        }
+    }
+
+    void
+    testMPTokenIssuanceSetRotateBothKeys(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet rotate both issuer and auditor keys");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const bob("bob");
+        Account const auditor("auditor");
+        MPTTester mptAlice(env, alice, {.holders = {bob}});
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(bob);
+        mptAlice.generateKeyPair(auditor);
+
+        // Register both keys together.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+            .auditorPubKey = mptAlice.getPubKey(auditor),
+        });
+
+        // Verify that no epochs are set when registering for the first time.
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+
+        // Rotating both keys requires the amendment
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(bob),
+            .auditorPubKey = mptAlice.getPubKey(alice),
+            .err = rotationEnabled ? TER(tesSUCCESS) : TER(tecNO_PERMISSION),
+        });
+
+        if (rotationEnabled)
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(bob, alice));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(1u, 1u));
+        }
+        else
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, auditor));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+        }
+
+        if (rotationEnabled)
+        {
+            // Rotating the issuer key to its current value fails.
+            // Current issuer key is bob, duplicate.
+            mptAlice.set({
+                .account = alice,
+                .issuerPubKey = mptAlice.getPubKey(bob),
+                .err = tecDUPLICATE,
+            });
+
+            // Rotating the auditor key to its current value fails.
+            // Current auditor key is alice, duplicate.
+            mptAlice.set({
+                .account = alice,
+                .auditorPubKey = mptAlice.getPubKey(alice),
+                .err = tecDUPLICATE,
+            });
+
+            // The whole transaction fails when one key is unchanged, even if
+            // the other key is rotated to a new value.
+            // Current issuer key is bob, duplicate.
+            mptAlice.set({
+                .account = alice,
+                .issuerPubKey = mptAlice.getPubKey(bob),
+                .auditorPubKey = mptAlice.getPubKey(auditor),
+                .err = tecDUPLICATE,
+            });
+
+            // Current auditor key is alice, duplicate.
+            mptAlice.set({
+                .account = alice,
+                .issuerPubKey = mptAlice.getPubKey(auditor),
+                .auditorPubKey = mptAlice.getPubKey(alice),
+                .err = tecDUPLICATE,
+            });
+
+            // Nothing changed: keys and epochs are untouched
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(1u, 1u));
+
+            // A second rotation increments both epochs again
+            mptAlice.set({
+                .account = alice,
+                .issuerPubKey = mptAlice.getPubKey(alice),
+                .auditorPubKey = mptAlice.getPubKey(auditor),
+            });
+
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(2u, 2u));
+        }
+    }
+
+    void
+    testMPTokenIssuanceSetRotateAuditorKeyOnly(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet rotate auditor key only");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const bob("bob");
+        Account const auditor("auditor");
+        MPTTester mptAlice(env, alice, {.holders = {bob}});
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(bob);
+        mptAlice.generateKeyPair(auditor);
+
+        // Register both keys together.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+            .auditorPubKey = mptAlice.getPubKey(auditor),
+        });
+
+        // A transaction carrying only the auditor key fails preflight
+        // pre-ConfidentialMPTKeyRotation; post-ConfidentialMPTKeyRotation it rotates the auditor
+        // key
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(bob),
+            .err = rotationEnabled ? TER(tesSUCCESS) : TER(temMALFORMED),
+        });
+
+        // The issuer key keeps unchanged, and rotating only the auditor key
+        // bumps only its epoch.
+        if (rotationEnabled)
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, bob));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, 1u));
+        }
+        else
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, auditor));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+        }
+
+        if (rotationEnabled)
+        {
+            // A second rotation increments the epoch again
+            mptAlice.set({
+                .account = alice,
+                .auditorPubKey = mptAlice.getPubKey(auditor),
+            });
+
+            // The issuer key epoch is still untouched.
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, 2u));
+        }
+    }
+
+    void
+    testMPTokenIssuanceSetRegisterAuditorKeyLater(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet register auditor key after issuer key");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const auditor("auditor");
+        MPTTester mptAlice(env, alice);
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(auditor);
+
+        // Register the issuer key first. We'll register the auditor key in a separate transaction.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+        });
+
+        // Register the auditor key separately.
+        // pre-ConfidentialMPTKeyRotation it fails preflight; post-ConfidentialMPTKeyRotation it
+        // succeeds without touching any epoch because it's a first-time registration.
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(auditor),
+            .err = rotationEnabled ? TER(tesSUCCESS) : TER(temMALFORMED),
+        });
+
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(
+            alice, rotationEnabled ? std::optional<Account>(auditor) : std::nullopt));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+    }
+
+    void
+    testMPTokenIssuanceSetRegisterAuditorKeyLaterWithCOA(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet register auditor key later with circulating supply");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const bob("bob");
+        Account const auditor("auditor");
+        MPTTester mptAlice(env, alice, {.holders = {bob}});
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.authorize({.account = bob});
+        mptAlice.pay(alice, bob, 100);
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(bob);
+        mptAlice.generateKeyPair(auditor);
+
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+        });
+
+        // Convert some of bob's balance so that COA > 0
+        mptAlice.convert({
+            .account = bob,
+            .amt = 50,
+            .holderPubKey = mptAlice.getPubKey(bob),
+        });
+
+        auto const sleIssuanceBefore = env.le(keylet::mptokenIssuance(mptAlice.issuanceID()));
+        if (!BEAST_EXPECT(sleIssuanceBefore))
+            return;
+        auto const coaBefore = (*sleIssuanceBefore)[~sfConfidentialOutstandingAmount].value_or(0);
+        BEAST_EXPECT(coaBefore > 0);
+
+        // Registering the auditor key for the first time while confidential
+        // supply is circulating: pre-ConfidentialMPTKeyRotation an auditor-only
+        // transaction fails preflight; post-ConfidentialMPTKeyRotation it
+        // succeeds as a first-time late-registration even COA > 0.
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(auditor),
+            .err = rotationEnabled ? TER(tesSUCCESS) : TER(temMALFORMED),
+        });
+
+        auto const sleIssuance = env.le(keylet::mptokenIssuance(mptAlice.issuanceID()));
+        if (!BEAST_EXPECT(sleIssuance))
+            return;
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(
+            alice, rotationEnabled ? std::optional<Account>(auditor) : std::nullopt));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+
+        // The circulating supply itself is not affected.
+        BEAST_EXPECT((*sleIssuance)[~sfConfidentialOutstandingAmount].value_or(0) == coaBefore);
+    }
+
+    void
+    testMPTokenIssuanceSetAuditorKeyWithoutIssuerKey(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet auditor key requires issuer key");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const auditor("auditor");
+        MPTTester mptAlice(env, alice);
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.generateKeyPair(auditor);
+        // The issuer key was never registered. pre-ConfidentialMPTKeyRotation an auditor-only
+        // transaction fails preflight; post-ConfidentialMPTKeyRotation it passes preflight
+        // but preclaim rejects registering an auditor key on an issuance
+        // without an issuer key.
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(auditor),
+            .err = rotationEnabled ? TER(tecNO_PERMISSION) : TER(temMALFORMED),
+        });
+
+        // The rejected transaction leaves the issuance without either key.
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(std::nullopt, std::nullopt));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+    }
+
+    void
+    testMPTokenIssuanceSetRotateWithCOA(FeatureBitset features)
+    {
+        testcase("MPTokenIssuanceSet rotate with circulating confidential supply");
+        using namespace test::jtx;
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const bob("bob");
+        Account const carol("carol");
+        MPTTester mptAlice(env, alice, {.holders = {bob}});
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.authorize({.account = bob});
+        mptAlice.pay(alice, bob, 100);
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(bob);
+        mptAlice.generateKeyPair(carol);
+
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+        });
+
+        // Convert some of bob's balance to confidential spending, so that the
+        // issuance has confidential supply. COA > 0.
+        mptAlice.convert({
+            .account = bob,
+            .amt = 50,
+            .holderPubKey = mptAlice.getPubKey(bob),
+        });
+
+        auto const sleIssuanceBeforeRotation =
+            env.le(keylet::mptokenIssuance(mptAlice.issuanceID()));
+        if (!BEAST_EXPECT(sleIssuanceBeforeRotation))
+            return;
+        auto const coaBeforeRotation =
+            (*sleIssuanceBeforeRotation)[~sfConfidentialOutstandingAmount].value_or(0);
+        BEAST_EXPECT(coaBeforeRotation > 0);
+
+        // Rotating key requires the
+        // amendment.
+        bool const rotationEnabled = features[featureConfidentialMPTKeyRotation];
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(carol),
+            .err = rotationEnabled ? TER(tesSUCCESS) : TER(tecNO_PERMISSION),
+        });
+
+        auto const sleIssuance = env.le(keylet::mptokenIssuance(mptAlice.issuanceID()));
+        if (!BEAST_EXPECT(sleIssuance))
+            return;
+        if (rotationEnabled)
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(carol, std::nullopt));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(1u, std::nullopt));
+        }
+        else
+        {
+            BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, std::nullopt));
+            BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+        }
+
+        // The confidential outstanding amount is not affected by the rotation
+        BEAST_EXPECT(
+            (*sleIssuance)[~sfConfidentialOutstandingAmount].value_or(0) == coaBeforeRotation);
+
+        // Re-enabling confidential balances while supply is circulating is
+        // rejected regardless of the ConfidentialMPTKeyRotation amendment.
+        mptAlice.set({
+            .account = alice,
+            .flags = tfMPTSetCanHoldConfidentialBalance,
+            .err = tecNO_PERMISSION,
+        });
+    }
+
+    void
+    testMPTokenIssuanceSetKeyEpochAtMax(FeatureBitset features)
+    {
+        using namespace test::jtx;
+        if (!features[featureConfidentialMPTKeyRotation])
+            return;
+
+        testcase("MPTokenIssuanceSet key epoch cannot wrap");
+
+        Env env{*this, features};
+        Account const alice("alice");
+        Account const bob("bob");
+        Account const carol("carol");
+        Account const auditor("auditor");
+
+        // Keep the ledger open so that we can write the key epochs directly into it.
+        MPTTester mptAlice(env, alice, {.holders = {bob}, .close = false});
+
+        mptAlice.create({
+            .ownerCount = 1,
+            .flags = tfMPTCanTransfer | tfMPTCanHoldConfidentialBalance,
+        });
+
+        mptAlice.generateKeyPair(alice);
+        mptAlice.generateKeyPair(bob);
+        mptAlice.generateKeyPair(carol);
+        mptAlice.generateKeyPair(auditor);
+
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+            .auditorPubKey = mptAlice.getPubKey(auditor),
+        });
+
+        auto const issuanceKeylet = keylet::mptokenIssuance(mptAlice.issuanceID());
+
+        // Writes the supplied key epochs straight into the open ledger so that
+        // the maximum epoch is reachable without submitting four billion
+        // rotations.
+        auto setEpochs = [&](std::optional<std::uint32_t> const& issuerKeyEpoch,
+                             std::optional<std::uint32_t> const& auditorKeyEpoch) {
+            env.app().getOpenLedger().modify([&](OpenView& view, beast::Journal) {
+                auto const sle = view.read(issuanceKeylet);
+                if (!sle)
+                    return false;  // LCOV_EXCL_LINE
+
+                auto replacement = std::make_shared<SLE>(*sle);
+                if (issuerKeyEpoch)
+                    (*replacement)[sfIssuerKeyEpoch] = *issuerKeyEpoch;
+                if (auditorKeyEpoch)
+                    (*replacement)[sfAuditorKeyEpoch] = *auditorKeyEpoch;
+                view.rawReplace(replacement);
+                return true;
+            });
+        };
+
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, auditor));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, std::nullopt));
+
+        // Increment the auditor epoch to kMaxKeyEpoch - 1, leaving the issuer epoch absent.
+        setEpochs(std::nullopt, kMaxKeyEpoch - 1);
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, auditor));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, kMaxKeyEpoch - 1));
+
+        // Rotating the auditor key to kMaxKeyEpoch succeeds.
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(carol),
+        });
+
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, carol));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, kMaxKeyEpoch));
+
+        // A further auditor rotation is rejected because the epoch is exhausted.
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(bob),
+            .err = tecNO_PERMISSION,
+        });
+
+        // Rotating both keys at once is rejected as a whole because the auditor
+        // epoch is exhausted.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(auditor),
+            .auditorPubKey = mptAlice.getPubKey(bob),
+            .err = tecNO_PERMISSION,
+        });
+
+        // Both rejections leave every key and epoch as it was.
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(alice, carol));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(std::nullopt, kMaxKeyEpoch));
+
+        // The issuer key is unaffected by the exhausted auditor epoch.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(bob),
+        });
+
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(bob, carol));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(1u, kMaxKeyEpoch));
+
+        // Increment the issuer epoch to kMaxKeyEpoch - 1.
+        setEpochs(kMaxKeyEpoch - 1, std::nullopt);
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(bob, carol));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(kMaxKeyEpoch - 1, kMaxKeyEpoch));
+
+        // Rotating the issuer key to kMaxKeyEpoch succeeds.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(auditor),
+        });
+
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(auditor, carol));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(kMaxKeyEpoch, kMaxKeyEpoch));
+
+        // With both epochs exhausted neither key can be rotated again.
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+            .err = tecNO_PERMISSION,
+        });
+        mptAlice.set({
+            .account = alice,
+            .auditorPubKey = mptAlice.getPubKey(bob),
+            .err = tecNO_PERMISSION,
+        });
+        mptAlice.set({
+            .account = alice,
+            .issuerPubKey = mptAlice.getPubKey(alice),
+            .auditorPubKey = mptAlice.getPubKey(bob),
+            .err = tecNO_PERMISSION,
+        });
+
+        BEAST_EXPECT(mptAlice.checkEncryptionKeys(auditor, carol));
+        BEAST_EXPECT(mptAlice.checkKeyEpochs(kMaxKeyEpoch, kMaxKeyEpoch));
+    }
+
+    void
+    testMPTokenIssuanceSetWithFeats(FeatureBitset features)
+    {
+        testMPTokenIssuanceSetRotateIssuerKey(features);
+        testMPTokenIssuanceSetRotateBothKeys(features);
+        testMPTokenIssuanceSetRotateAuditorKeyOnly(features);
+        testMPTokenIssuanceSetRegisterAuditorKeyLater(features);
+        testMPTokenIssuanceSetRegisterAuditorKeyLaterWithCOA(features);
+        testMPTokenIssuanceSetAuditorKeyWithoutIssuerKey(features);
+        testMPTokenIssuanceSetRotateWithCOA(features);
+        testMPTokenIssuanceSetKeyEpochAtMax(features);
+    }
+
+public:
+    void
+    run() override
+    {
+        using namespace test::jtx;
+        FeatureBitset const all{testableAmendments()};
+
+        testMPTokenIssuanceSetWithFeats(all);
+        testMPTokenIssuanceSetWithFeats(all - featureConfidentialMPTKeyRotation);
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(ConfidentialMPTKeyRotation, app, xrpl);
+
+}  // namespace xrpl
diff --git a/src/test/app/ConfidentialTransfer_test.cpp b/src/test/app/ConfidentialTransfer_test.cpp
index 6450ceeb61..a964193c1a 100644
--- a/src/test/app/ConfidentialTransfer_test.cpp
+++ b/src/test/app/ConfidentialTransfer_test.cpp
@@ -736,12 +736,8 @@ class ConfidentialTransfer_test : public ConfidentialTransferTestBase
                 .err = temMALFORMED,
             });
 
-            // Cannot set auditor key without issuer key
-            mptAlice.set({
-                .account = alice,
-                .auditorPubKey = mptAlice.getPubKey(alice),
-                .err = temMALFORMED,
-            });
+            // Note: "auditor key without issuer key" (temMALFORMED before
+            // ConfidentialMPTKeyRotation) is covered in ConfidentialMPTKeyRotation_test
 
             // Cannot set Holder and issuer Keys in the same transaction
             mptAlice.set({
@@ -787,9 +783,9 @@ class ConfidentialTransfer_test : public ConfidentialTransferTestBase
             });
         }
 
-        // Cannot update issuer public key once set
+        // Cannot update issuer public key once set (pre-ConfidentialMPTKeyRotation behavior)
         {
-            Env env{*this, features};
+            Env env{*this, features - featureConfidentialMPTKeyRotation};
             Account const alice("alice");
             Account const bob("bob");
             MPTTester mptAlice(env, alice, {.holders = {bob}});
@@ -819,8 +815,9 @@ class ConfidentialTransfer_test : public ConfidentialTransferTestBase
         // Cannot update issuer and auditor public keys once set
         // Note: trying to set only auditor key fails in preflight (temMALFORMED)
         // so we must provide both keys, which fails on issuer key check first
+        // (pre-ConfidentialMPTKeyRotation behavior)
         {
-            Env env{*this, features};
+            Env env{*this, features - featureConfidentialMPTKeyRotation};
             Account const alice("alice");
             Account const bob("bob");
             Account const auditor("auditor");
@@ -900,8 +897,9 @@ class ConfidentialTransfer_test : public ConfidentialTransferTestBase
         }
 
         // Set issuer key first, then auditor key in a separate tx
+        // (pre-ConfidentialMPTKeyRotation behavior)
         {
-            Env env{*this, features};
+            Env env{*this, features - featureConfidentialMPTKeyRotation};
             Account const alice("alice");
             Account const auditor("auditor");
             MPTTester mptAlice(env, alice, {.holders = {}, .auditor = auditor});
diff --git a/src/test/app/EscrowToken_test.cpp b/src/test/app/EscrowToken_test.cpp
index 72db63bd3f..3a2bc14183 100644
--- a/src/test/app/EscrowToken_test.cpp
+++ b/src/test/app/EscrowToken_test.cpp
@@ -951,6 +951,99 @@ struct EscrowToken_test : public beast::unit_test::Suite
         }
     }
 
+    void
+    testIOUCancelReserveRecycle(FeatureBitset features)
+    {
+        testcase("IOU Cancel Reserve Recycle");
+        using namespace jtx;
+        using namespace std::literals;
+
+        // Escrowing the whole IOU balance lets the owner delete the now-zero
+        // trust line, so cancelling has to re-create it: one object destroyed,
+        // one created, and the reserve requirement unchanged.
+        Env env{*this, features};
+        bool const fixEnabled = env.current()->rules().enabled(fixCleanup3_4_0);
+
+        auto const baseFee = env.current()->fees().base;
+        auto const alice = Account("alice");
+        auto const bob = Account("bob");
+        auto const gw = Account("gw");
+        auto const usd = gw["USD"];
+
+        env.fund(XRP(10'000), alice, bob, gw);
+        env.close();
+
+        env(fset(gw, asfAllowTrustLineLocking));
+        env.close();
+
+        env.trust(usd(10'000), alice);
+        env.close();
+
+        env(pay(gw, alice, usd(10'000)));
+        env.close();
+        BEAST_EXPECT(env.ownerCount(alice) == 1);
+
+        auto const cancelAfter = env.now() + 100s;
+        auto const seq = env.seq(alice);
+        env(escrow::create(alice, bob, usd(10'000)),
+            escrow::kFinishTime(env.now() + 1s),
+            escrow::kCancelTime(cancelAfter),
+            Fee(baseFee));
+        env.close();
+        BEAST_EXPECT(env.ownerCount(alice) == 2);
+
+        auto const trustLineKey = keylet::trustLine(alice.id(), gw.id(), usd.currency);
+        env(trust(alice, usd(0)));
+        env.close();
+        BEAST_EXPECT(!env.current()->exists(trustLineKey));
+        BEAST_EXPECT(env.ownerCount(alice) == 1);
+
+        // Leave alice holding the reserve for exactly one owned object. That
+        // is the escrow now and the re-created trust line after the cancel.
+        auto const oneObject = env.current()->fees().accountReserve(1, 1);
+        auto const twoObjects = env.current()->fees().accountReserve(2, 1);
+        auto const balance = env.balance(alice).value().xrp();
+        auto const feeCushion = baseFee.drops() * 20;
+        env(pay(alice, bob, drops(balance.drops() - oneObject.drops() - feeCushion)));
+        env.close();
+        BEAST_EXPECT(env.balance(alice).value().xrp() >= oneObject);
+        BEAST_EXPECT(env.balance(alice).value().xrp() < twoObjects);
+
+        for (; env.now() < cancelAfter; env.close())
+        {
+        }
+        env.close();
+        env.close();
+
+        auto const expectedResult = fixEnabled ? Ter(tesSUCCESS) : Ter(tecNO_LINE_INSUF_RESERVE);
+        env(escrow::cancel(alice, alice, seq), Fee(baseFee), expectedResult);
+        env.close();
+
+        auto const escrowKey = keylet::escrow(alice.id(), SeqProxy::rawSequence(seq));
+        if (fixEnabled)
+        {
+            BEAST_EXPECT(!env.le(escrowKey));
+            BEAST_EXPECT(env.current()->exists(trustLineKey));
+            BEAST_EXPECT(env.balance(alice, usd) == usd(10'000));
+            BEAST_EXPECT(env.ownerCount(alice) == 1);
+        }
+        else
+        {
+            // The tec keeps the escrow, so one more owner reserve lets the
+            // retry through.
+            BEAST_EXPECT(env.le(escrowKey) != nullptr);
+            BEAST_EXPECT(!env.current()->exists(trustLineKey));
+            BEAST_EXPECT(env.ownerCount(alice) == 1);
+
+            env(pay(bob, alice, drops(twoObjects.drops() - oneObject.drops())));
+            env.close();
+            env(escrow::cancel(alice, alice, seq), Fee(baseFee), Ter(tesSUCCESS));
+            env.close();
+            BEAST_EXPECT(!env.le(escrowKey));
+            BEAST_EXPECT(env.balance(alice, usd) == usd(10'000));
+        }
+    }
+
     void
     testIOUBalances(FeatureBitset features)
     {
@@ -4250,6 +4343,8 @@ public:
         }
         testMPTSplitEscrowTransferFee(all - fixCleanup3_4_0);
         testMPTSplitEscrowTransferFee(all);
+        testIOUCancelReserveRecycle(all - fixCleanup3_4_0);
+        testIOUCancelReserveRecycle(all);
     }
 };
 
diff --git a/src/test/app/FlowMPT_test.cpp b/src/test/app/FlowMPT_test.cpp
index 49e3f9be94..0f88814d4f 100644
--- a/src/test/app/FlowMPT_test.cpp
+++ b/src/test/app/FlowMPT_test.cpp
@@ -29,6 +29,7 @@
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Keylet.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STPathSet.h>
@@ -638,6 +639,149 @@ struct FlowMPT_test : public beast::unit_test::Suite
         }
     }
 
+    void
+    testMPTEndpointTransferRateOverflow(FeatureBitset features)
+    {
+        testcase("MPT Endpoint transfer rate overflow");
+
+        using namespace jtx;
+
+        Account const iouGW("iou_gateway");
+        Account const mptGW("mpt_gateway");
+        Account const alice("alice");
+        Account const bob("bob");
+
+        {
+            // Control: the same issuer-owned offer path works when the
+            // transfer-fee-adjusted input amount remains representable.
+            Env env(*this, features);
+
+            std::int64_t constexpr deliverAmount = 1'000'000'000'000'000'000LL;
+            std::int64_t constexpr offerAmount = deliverAmount + (deliverAmount / 2);
+
+            env.fund(XRP(10'000), iouGW, mptGW, alice, bob);
+            env.close();
+
+            auto const usd = iouGW["USD"];
+            env.trust(usd(offerAmount), alice);
+            env.trust(usd(offerAmount), mptGW);
+            env(pay(iouGW, alice, usd(offerAmount)));
+
+            MPTTester const mpt(
+                {.env = env, .issuer = mptGW, .holders = {bob}, .transferFee = kMaxTransferFee});
+
+            env(offer(mptGW, usd(offerAmount), mpt(offerAmount)));
+
+            env(pay(alice, bob, mpt(deliverAmount)),
+                Path(~mpt),
+                Sendmax(usd(offerAmount)),
+                Txflags(tfNoRippleDirect | tfPartialPayment));
+
+            env.require(Balance(alice, usd(0)), Balance(bob, mpt(deliverAmount)));
+            BEAST_EXPECT(!isOffer(env, mptGW, usd(offerAmount), mpt(offerAmount)));
+        }
+        {
+            // Regression: an extreme transfer-fee-adjusted MPT amount used to
+            // throw from MPTAmount::mulRatio during the endpoint reverse pass.
+            // The reverse pass now caps srcToDst at the largest amount whose
+            // transfer-fee-adjusted input is representable, so the offer limits
+            // the strand and a partial payment goes through.
+            Env env(*this, features);
+
+            std::int64_t constexpr overflowAmount = 7'000'000'000'000'000'000LL;
+            // The offer caps the input at overflowAmount, which the maximum
+            // transfer rate of 1.5 scales down to 7e18 * 2 / 3, rounded down
+            std::int64_t constexpr deliveredAmount = 4'666'666'666'666'666'666LL;
+
+            env.fund(XRP(10'000), iouGW, mptGW, alice, bob);
+            env.close();
+
+            auto const usd = iouGW["USD"];
+            env.trust(usd(overflowAmount), alice);
+            env.trust(usd(overflowAmount), mptGW);
+            env(pay(iouGW, alice, usd(overflowAmount)));
+
+            MPTTester const mpt(
+                {.env = env, .issuer = mptGW, .holders = {bob}, .transferFee = kMaxTransferFee});
+
+            env(offer(mptGW, usd(overflowAmount), mpt(overflowAmount)));
+
+            env(pay(alice, bob, mpt(overflowAmount)),
+                Path(~mpt),
+                Sendmax(usd(overflowAmount)),
+                Txflags(tfNoRippleDirect | tfPartialPayment));
+
+            env.require(Balance(alice, usd(0)), Balance(bob, mpt(deliveredAmount)));
+            BEAST_EXPECT(!isOffer(env, mptGW, usd(overflowAmount), mpt(overflowAmount)));
+        }
+    }
+
+    void
+    testMPTEndpointRipplingInputOverflow(FeatureBitset features)
+    {
+        // A payment between the holders of an MPT with a transfer fee ripples
+        // through the issuer, and the issuing step has to charge the transfer
+        // rate on the amount it receives. maxPaymentFlow() returns the issuance
+        // maximum for that step, so srcToDst * transferRate is not necessarily
+        // representable as an MPT amount. The reverse pass must cap the flow at
+        // the largest representable input instead of declaring the strand dry,
+        // otherwise a deliverable partial payment fails with tecPATH_DRY.
+        //
+        // Same defect as the case above, reached without an offer: holder ->
+        // issuer -> holder, one case per branch of the pre-fix revImp.
+        testcase("MPT Endpoint rippling input overflow");
+
+        using namespace jtx;
+
+        Account const gw("gateway");
+        Account const alice("alice");
+        Account const bob("bob");
+
+        // The maximum transfer fee gives a transfer rate of 1.5, so an input of
+        // kMaxMpTokenAmount covers at most kMaxMpTokenAmount * 2 / 3 of output.
+        std::int64_t constexpr maxRepresentable = 6'148'914'691'236'517'204LL;
+        std::int64_t constexpr aliceBalance = 1'000;
+        // The forward pass rounds the delivered amount down: 1000 / 1.5
+        std::int64_t constexpr bobBalance = 666;
+
+        auto const test =
+            [&](std::uint64_t maxAmt, std::int64_t deliver, std::string const& label) {
+                Env env(*this, features);
+                env.fund(XRP(10'000), gw, alice, bob);
+                env.close();
+
+                auto mpt = MPTTester(
+                    {.env = env,
+                     .issuer = gw,
+                     .holders = {alice, bob},
+                     .transferFee = kMaxTransferFee,
+                     .maxAmt = maxAmt});
+
+                env(pay(gw, alice, mpt(aliceBalance)));
+                env.close();
+
+                // alice asks to deliver more than the transfer rate can scale,
+                // so the issuing step caps the flow and her balance limits it
+                // further
+                env(pay(alice, bob, mpt(deliver)),
+                    Sendmax(mpt(kMaxMpTokenAmount)),
+                    Txflags(tfPartialPayment));
+                BEAST_EXPECTS(env.ter() == tesSUCCESS, label);
+                BEAST_EXPECTS(env.balance(alice, mpt) == mpt(0), label);
+                BEAST_EXPECTS(env.balance(bob, mpt) == mpt(bobBalance), label);
+                BEAST_EXPECTS(mpt.checkMPTokenOutstandingAmount(bobBalance), label);
+            };
+
+        // The requested amount is below MaximumAmount, so the reverse pass
+        // takes the non-limiting branch and overflows on the requested amount
+        test(kMaxMpTokenAmount, maxRepresentable + 1, "non-limiting");
+
+        // MaximumAmount is below the requested amount but still large enough
+        // that scaling it by the transfer rate is not representable, so the
+        // reverse pass takes the limiting branch and overflows on the maximum
+        test(maxRepresentable + 1, kMaxMpTokenAmount, "limiting");
+    }
+
     void
     testFalseDry(FeatureBitset features)
     {
@@ -2271,6 +2415,103 @@ struct FlowMPT_test : public beast::unit_test::Suite
         }
     }
 
+    void
+    testLockedMidPathHolder(FeatureBitset features)
+    {
+        // Regression: a cross-currency strand whose second book step
+        // consumes the offer of a holder that is locked on the step's
+        // in-asset (an MPT). The strand is XRP -> [book1: XRP/USD] ->
+        // USD -> [book2: USD/EUR] -> EUR, so book2 has book_.in == USD
+        // (an MPT) and its previous step is another BookStep. That is
+        // exactly the checkMPTDEX() branch that trusts the preceding
+        // BookStep and no longer re-checks isFrozen(owner, book_.in).
+        //
+        // The bypass the branch might appear to open does not exist:
+        // for MPT, isDeepFrozen() == isFrozen() (frozen MPTs can neither
+        // send nor receive), and OfferStream gates every offer through
+        // isDeepFrozen(owner, assetIn) before it can reach checkMPTDEX().
+        // So a locked mid-path holder's offer is removed by the liquidity
+        // source and the strand simply finds no liquidity at book2.
+        testcase("Locked mid-path holder behind a BookStep");
+
+        using namespace jtx;
+
+        Account const gw("gw");
+        Account const alice("alice");  // book1 (XRP/USD) offer owner
+        Account const mid("mid");      // book2 (USD/EUR) offer owner
+        Account const sam("sam");      // source
+        Account const bill("bill");    // destination
+
+        auto const test = [&](bool lock) {
+            Env env(*this, features);
+            env.fund(XRP(1'000), gw, alice, mid, sam, bill);
+            env.close();
+
+            auto usd = MPTTester(
+                {.env = env,
+                 .issuer = gw,
+                 .holders = {alice, mid},
+                 .flags = kMptDexFlags | tfMPTCanLock,
+                 .maxAmt = 1'000});
+            auto const eur = gw["EUR"];
+
+            // alice funds book1 (sells USD for XRP); mid funds book2
+            // (sells EUR for USD, i.e. receives the mid-path USD).
+            env(pay(gw, alice, usd(100)));
+            env(trust(mid, eur(100)));
+            env(pay(gw, mid, eur(100)));
+            env(trust(bill, eur(100)));
+            env.close();
+
+            env(offer(alice, XRP(100), usd(100)));  // XRP/USD, sells USD
+            env.close();
+            env(offer(mid, usd(100), eur(100)));  // USD/EUR, sells EUR
+            env.close();
+            BEAST_EXPECT(expectOffers(env, alice, 1));
+            BEAST_EXPECT(expectOffers(env, mid, 1));
+
+            // Lock mid on USD *after* its offer is already on the book:
+            // the reviewer's "frozen holder's offer sits behind a
+            // BookStep" scenario.
+            if (lock)
+            {
+                usd.set({.holder = mid, .flags = tfMPTLock});
+                env.close();
+            }
+
+            env(pay(sam, bill, eur(100)),
+                Sendmax(XRP(100)),
+                Path(~usd, ~eur),
+                Txflags(tfNoRippleDirect),
+                // book1 (XRP/USD) still has liquidity, so the strand is
+                // not fully dry; it just cannot cross book2 once mid's
+                // offer is removed, hence PARTIAL rather than DRY.
+                Ter(lock ? TER(tecPATH_PARTIAL) : TER(tesSUCCESS)));
+            env.close();
+
+            if (lock)
+            {
+                // No liquidity reached book2: mid neither received USD
+                // nor delivered EUR, so bill received nothing.
+                BEAST_EXPECT(env.balance(bill, eur) == eur(0));
+                BEAST_EXPECT(env.balance(mid, usd) == usd(0));
+            }
+            else
+            {
+                // The strand crosses both books: mid receives the
+                // mid-path USD and bill receives EUR.
+                BEAST_EXPECT(env.balance(bill, eur) == eur(100));
+                BEAST_EXPECT(env.balance(mid, usd) == usd(100));
+                BEAST_EXPECT(env.balance(alice, usd) == usd(0));
+                BEAST_EXPECT(expectOffers(env, alice, 0));
+                BEAST_EXPECT(expectOffers(env, mid, 0));
+            }
+        };
+
+        test(false);  // baseline: unlocked strand succeeds
+        test(true);   // locked mid-path holder: strand finds no liquidity
+    }
+
     void
     testWithFeats(FeatureBitset features)
     {
@@ -2282,6 +2523,8 @@ struct FlowMPT_test : public beast::unit_test::Suite
         testBookStep(features);
         testOfferOwnerMPTCreation(features);
         testTransferRate(features);
+        testMPTEndpointTransferRateOverflow(features);
+        testMPTEndpointRipplingInputOverflow(features);
         testSelfPayment1(features);
         testSelfPayment2(features);
         testSelfFundedXRPEndpoint(false, features);
@@ -2289,6 +2532,7 @@ struct FlowMPT_test : public beast::unit_test::Suite
         testUnfundedOffer(features);
         testReExecuteDirectStep(features);
         testSelfPayLowQualityOffer(features);
+        testLockedMidPathHolder(features);
     }
 
     void
diff --git a/src/test/app/LedgerMaster_test.cpp b/src/test/app/LedgerMaster_test.cpp
index ece25356fd..2f2f81bb8a 100644
--- a/src/test/app/LedgerMaster_test.cpp
+++ b/src/test/app/LedgerMaster_test.cpp
@@ -11,14 +11,18 @@
 #include <xrpl/basics/ToString.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/core/JobQueue.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STObject.h>
 #include <xrpl/protocol/STTx.h>
 
+#include <chrono>
 #include <cstdint>
 #include <memory>
+#include <optional>
+#include <ostream>
 #include <sstream>
 #include <vector>
 
@@ -115,6 +119,96 @@ class LedgerMaster_test : public beast::unit_test::Suite
         }
     }
 
+    // Wait until the SHAMapStore has finished processing the ledger that the
+    // preceding env.close() produced.
+    //
+    // env.close() returns as soon as the ledger_accept RPC returns, but the
+    // validated ledger path -- LedgerMaster::setValidLedger() ->
+    // SHAMapStore::onLedgerClosed() -- runs on a job queue thread. Without
+    // draining the job queue first, the store may not have been handed the
+    // ledger at all, in which case rendezvous() observes working_ == false and
+    // returns immediately, before any work has been done.
+    [[nodiscard]] static bool
+    syncStore(jtx::Env& env)
+    {
+        // Drain the job queue first, so that onLedgerClosed() has run and
+        // working_ is set. Then use the store's timeout overload, so a store
+        // that never finishes fails this test instead of blocking on it.
+        //
+        // Only the second wait is bounded: JobQueue::rendezvous() has no
+        // timeout overload, so a job that never completes hangs here. That is
+        // pre-existing -- ~AppBundle waits on it the same way for every jtx
+        // test -- but it does mean this helper is not hang-proof end to end.
+        env.app().getJobQueue().rendezvous();
+        return env.app().getSHAMapStore().rendezvous(std::chrono::seconds{60});
+    }
+
+    // Bring the SHAMapStore to the point where it has been handed a validated
+    // ledger and initialized lastRotated, and report how many extra ledgers had
+    // to be closed to get it there (normally none). Returns std::nullopt if
+    // syncStore() itself failed.
+    //
+    // syncStore() alone does not guarantee that, because
+    // SHAMapStoreImp::run()'s loop does not use the notification and the
+    // working_ flag safely:
+    //
+    //   * onLedgerClosed() notifies cond_ whether or not run()'s thread is
+    //     parked on it, and run() waits on cond_ without a predicate, so a
+    //     notification that lands while the thread is still starting up --
+    //     before it first reaches that wait -- is lost.
+    //   * run() clears working_ at the top of its loop without checking
+    //     whether newLedger_ is still set, so rendezvous() can report the
+    //     store idle with a validated ledger queued.
+    //
+    // Either way the store ends up parked with work pending, and only another
+    // notification gets it moving again. In a standalone test nothing else
+    // closes ledgers, so that has to come from here: this closes a ledger
+    // rather than polling getLastRotated(), because polling would just time
+    // out. onLedgerClosed() keeps only the most recent ledger in newLedger_,
+    // so the ledger the store picks up -- and therefore lastRotated -- is a
+    // timing detail, which is why the caller derives its expectations from the
+    // value it observes instead of assuming one.
+    //
+    // run() is deliberately left as it is. In production the only effect is
+    // latency: the trigger is validatedSeq >= lastRotated + deleteInterval, so
+    // a lost notification delays rotation to the next validated ledger and
+    // nothing is skipped or accumulated -- starting at 513 instead of 512 does
+    // not matter. Two consequences do follow from leaving it in place, and both
+    // hold today: nothing in production decides anything from working_ or
+    // rendezvous() (rendezvous() has no production callers at all), and a node
+    // whose ledgers only advance on demand -- standalone, driven by
+    // ledger_accept -- can sit on a queued ledger until something closes the
+    // next one, which is exactly the situation this helper is working around.
+    //
+    // So this helper is permanent rather than a stopgap. Working around the
+    // race must not make it invisible, so every extra close is logged. That
+    // keeps how often it is actually hit observable in the unit test output --
+    // which is the only signal left once this testcase stops flaking on it.
+    [[nodiscard]] std::optional<int>
+    initializeStore(jtx::Env& env, int const maxExtraCloses = 3)
+    {
+        auto& store = env.app().getSHAMapStore();
+
+        for (int extraCloses = 0;; ++extraCloses)
+        {
+            if (!syncStore(env))
+                return std::nullopt;
+            if (store.getLastRotated() != 0 || extraCloses == maxExtraCloses)
+            {
+                if (extraCloses != 0)
+                {
+                    log << "initializeStore: the store needed " << extraCloses
+                        << " extra ledger close(s) to pick up a validated ledger. "
+                           "SHAMapStoreImp::run() dropped the notification for the "
+                           "first one; see the comment on initializeStore()."
+                        << std::endl;
+                }
+                return extraCloses;
+            }
+            env.close();
+        }
+    }
+
     void
     testCompleteLedgerRange(FeatureBitset features)
     {
@@ -136,15 +230,42 @@ class LedgerMaster_test : public beast::unit_test::Suite
 
         auto& lm = env.app().getLedgerMaster();
         LedgerIndex minSeq = 2;
-        LedgerIndex maxSeq = env.closed()->header().seq;
         auto& store = env.app().getSHAMapStore();
-        BEAST_EXPECT(store.rendezvous());
+        // Which of the existing complete ledgers the store initializes
+        // lastRotated from is a timing detail; all this test needs is that it is
+        // one of them. Everything below derives from the observed value rather
+        // than assuming a particular one.
+        //
+        // The range check and the initializeStore() one both end the testcase
+        // rather than merely reporting, because lastRotated is the only value
+        // from the store that enters minSeq. A lastRotated of 0 -- the value
+        // getLastRotated() reports until the store has been handed a
+        // validated ledger -- makes minSeq 0 below, and the minSeq - 1 and
+        // minSeq - 2 ranges then underflow to first > last, which aborts a
+        // Debug build inside missingFromCompleteLedgerRange().
+        auto const extraCloses = initializeStore(env);
+        if (!BEAST_EXPECT(extraCloses.has_value()))
+            return;
+        LedgerIndex maxSeq = env.closed()->header().seq;
         LedgerIndex lastRotated = store.getLastRotated();
-        BEAST_EXPECTS(maxSeq == 3, to_string(maxSeq));
-        BEAST_EXPECTS(lm.getCompleteLedgers() == "2-3", lm.getCompleteLedgers());
-        BEAST_EXPECTS(lastRotated == 3, to_string(lastRotated));
+        if (!BEAST_EXPECTS(lastRotated >= minSeq && lastRotated <= maxSeq, to_string(lastRotated)))
+            return;
+        // The BEAST_EXPECT above already returned if this is nullopt, but that
+        // is invisible to clang-tidy's optional model.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        BEAST_EXPECTS(maxSeq == 3 + *extraCloses, to_string(maxSeq));
+        std::stringstream initialRange;
+        initialRange << minSeq << "-" << maxSeq;
+        BEAST_EXPECTS(lm.getCompleteLedgers() == initialRange.str(), lm.getCompleteLedgers());
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq, maxSeq) == 0);
-        BEAST_EXPECT(minSeq + 1 > maxSeq - 1);
+        // The inner range is empty unless initializeStore() had to close extra
+        // ledgers, and missingFromCompleteLedgerRange() treats first > last as a
+        // precondition violation that aborts a Debug build via UNREACHABLE, so
+        // only check it when it is well formed.
+        if (minSeq + 1 <= maxSeq - 1)
+        {
+            BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 1, maxSeq - 1) == 0);
+        }
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq - 1, maxSeq + 1) == 2);
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq - 2, maxSeq - 2) == 2);
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 2, maxSeq + 2) == 2);
@@ -157,7 +278,7 @@ class LedgerMaster_test : public beast::unit_test::Suite
                 env(noop(alice));
             }
             env.close();
-            BEAST_EXPECT(store.rendezvous());
+            BEAST_EXPECT(syncStore(env));
 
             ++maxSeq;
 
@@ -173,7 +294,19 @@ class LedgerMaster_test : public beast::unit_test::Suite
             expectedRange << minSeq << "-" << maxSeq;
             BEAST_EXPECTS(lm.getCompleteLedgers() == expectedRange.str(), lm.getCompleteLedgers());
             BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq, maxSeq) == 0);
-            BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 1, maxSeq - 1) == 0);
+            // missingFromCompleteLedgerRange() treats first > last as a
+            // precondition violation and aborts a Debug build via UNREACHABLE.
+            // The range can only collapse if this test's model of minSeq /
+            // maxSeq has desynced from the store, so report that as a failure
+            // instead of taking down the whole unit test job.
+            if (minSeq + 1 <= maxSeq - 1)
+            {
+                BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 1, maxSeq - 1) == 0);
+            }
+            else
+            {
+                BEAST_EXPECTS(false, to_string(minSeq) + "-" + to_string(maxSeq));
+            }
             BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq - 1, maxSeq + 1) == 2);
             BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq - 2, maxSeq - 2) == 2);
             BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 2, maxSeq + 2) == 2);
diff --git a/src/test/app/NFToken_test.cpp b/src/test/app/NFToken_test.cpp
index 08c12e94d1..89c14fbfc5 100644
--- a/src/test/app/NFToken_test.cpp
+++ b/src/test/app/NFToken_test.cpp
@@ -29,6 +29,7 @@
 #include <xrpl/json/json_value.h>
 #include <xrpl/json/to_string.h>
 #include <xrpl/ledger/OpenView.h>
+#include <xrpl/protocol/ApiVersion.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Protocol.h>
@@ -6326,84 +6327,162 @@ class NFTokenBaseUtil_test : public beast::unit_test::Suite
         env.fund(XRP(10000), alice, bob, broker);
         env.close();
 
-        // Verify `nftoken_id` value equals to the NFTokenID that was
-        // changed in the most recent NFTokenMint or NFTokenAcceptOffer
-        // transaction
-        auto verifyNFTokenID = [&](uint256 const& actualNftID) {
+        // Transaction metadata is not always reported under the same field
+        // name: the `ledger` RPC uses `metaData`, the others use `meta`.
+        auto const getMeta = [](json::Value const& tx) -> json::Value const* {
+            if (tx.isMember(jss::meta))
+                return &tx[jss::meta];
+            if (tx.isMember(jss::metaData))
+                return &tx[jss::metaData];
+            return nullptr;
+        };
+
+        // Neither is the transaction hash: api_version 1 nests the
+        // transaction under `tx`, later versions use `tx_json`, and some
+        // responses put the hash on the entry itself.
+        auto const getHash = [](json::Value const& entry) -> std::string {
+            if (entry.isMember(jss::tx) && entry[jss::tx].isMember(jss::hash))
+                return entry[jss::tx][jss::hash].asString();
+            if (entry.isMember(jss::tx_json) && entry[jss::tx_json].isMember(jss::hash))
+                return entry[jss::tx_json][jss::hash].asString();
+            return entry[jss::hash].asString();
+        };
+
+        // Run `verifyMeta` against the metadata of the most recent
+        // transaction as reported by the `tx`, `ledger` and `account_tx`
+        // RPCs, so that the synthetic fields are checked in every response
+        // that carries them. Runs under both api_version 1 (`tx`/`meta`)
+        // and the latest api_version (`tx_json`/synthetic fields alongside
+        // it), since the two versions place fields differently.
+        auto verifyMetaInAllResponses = [&](auto verifyMeta) {
             // Get the hash for the most recent transaction.
             std::string const txHash{
                 env.tx()->getJson(JsonOptions::Values::None)[jss::hash].asString()};
 
             env.close();
-            json::Value const meta = env.rpc("tx", txHash)[jss::result][jss::meta];
 
-            // Expect nftokens_id field
-            if (!BEAST_EXPECT(meta.isMember(jss::nftoken_id)))
-                return;
+            for (unsigned const apiVersion :
+                 {unsigned{rpc::kApiMinimumSupportedVersion},
+                  unsigned{rpc::kApiMaximumSupportedVersion}})
+            {
+                // Test 1: Check tx RPC response
+                json::Value const txResult = env.rpc(apiVersion, "tx", txHash)[jss::result];
+                verifyMeta(txResult[jss::meta]);
 
-            // Check the value of NFT ID in the meta with the
-            // actual value
-            uint256 nftID;
-            BEAST_EXPECT(nftID.parseHex(meta[jss::nftoken_id].asString()));
-            BEAST_EXPECT(nftID == actualNftID);
+                // Test 2: Check ledger RPC response with expanded
+                // transactions
+                json::Value ledgerParams;
+                ledgerParams[jss::ledger_index] = txResult[jss::ledger_index].asUInt();
+                ledgerParams[jss::transactions] = true;
+                ledgerParams[jss::expand] = true;
+
+                auto const ledgerResult =
+                    env.rpc(apiVersion, "json", "ledger", to_string(ledgerParams));
+                auto const& ledgerTx =
+                    ledgerResult[jss::result][jss::ledger][jss::transactions][0u];
+
+                // Verify transaction hash matches
+                BEAST_EXPECT(getHash(ledgerTx) == txHash);
+
+                if (auto const* meta = getMeta(ledgerTx); BEAST_EXPECT(meta != nullptr))
+                    verifyMeta(*meta);
+
+                // Test 3: Check account_tx RPC response
+                // The transaction is not necessarily alice's, so query
+                // account_tx for the account that actually submitted it.
+                json::Value accountTxParams;
+                accountTxParams[jss::account] = txResult.isMember(jss::tx_json)
+                    ? txResult[jss::tx_json][jss::Account].asString()
+                    : txResult[jss::Account].asString();
+
+                auto const accountTxResult =
+                    env.rpc(apiVersion, "json", "account_tx", to_string(accountTxParams));
+
+                // account_tx ordering is not guaranteed, so find our
+                // transaction by hash rather than assuming it is the most
+                // recent one.
+                json::Value const* accountTx = nullptr;
+                for (auto const& entry : accountTxResult[jss::result][jss::transactions])
+                {
+                    if (getHash(entry) == txHash)
+                    {
+                        accountTx = &entry;
+                        break;
+                    }
+                }
+
+                if (!BEAST_EXPECT(accountTx != nullptr))
+                    continue;
+
+                if (auto const* meta = getMeta(*accountTx); BEAST_EXPECT(meta != nullptr))
+                    verifyMeta(*meta);
+            }
+        };
+
+        // Verify `nftoken_id` value equals to the NFTokenID that was
+        // changed in the most recent NFTokenMint or NFTokenAcceptOffer
+        // transaction
+        auto verifyNFTokenID = [&](uint256 const& actualNftID) {
+            verifyMetaInAllResponses([&](json::Value const& meta) {
+                // Expect nftoken_id field
+                if (!BEAST_EXPECT(meta.isMember(jss::nftoken_id)))
+                    return;
+
+                // Check the value of NFT ID matches
+                uint256 nftID;
+                BEAST_EXPECT(nftID.parseHex(meta[jss::nftoken_id].asString()));
+                BEAST_EXPECT(nftID == actualNftID);
+            });
         };
 
         // Verify `nftoken_ids` value equals to the NFTokenIDs that were
         // changed in the most recent NFTokenCancelOffer transaction
         auto verifyNFTokenIDsInCancelOffer = [&](std::vector<uint256> actualNftIDs) {
-            // Get the hash for the most recent transaction.
-            std::string const txHash{
-                env.tx()->getJson(JsonOptions::Values::None)[jss::hash].asString()};
-
-            env.close();
-            json::Value const meta = env.rpc("tx", txHash)[jss::result][jss::meta];
-
-            // Expect nftokens_ids field and verify the values
-            if (!BEAST_EXPECT(meta.isMember(jss::nftoken_ids)))
-                return;
-
-            // Convert NFT IDs from json::Value to uint256
-            std::vector<uint256> metaIDs;
-            std::transform(
-                meta[jss::nftoken_ids].begin(),
-                meta[jss::nftoken_ids].end(),
-                std::back_inserter(metaIDs),
-                [this](json::Value id) {
-                    uint256 nftID;
-                    BEAST_EXPECT(nftID.parseHex(id.asString()));
-                    return nftID;
-                });
-
-            // Sort both array to prepare for comparison
-            std::ranges::sort(metaIDs);
+            // Sort to prepare for comparison
             std::ranges::sort(actualNftIDs);
 
-            // Make sure the expect number of NFTs is correct
-            BEAST_EXPECT(metaIDs.size() == actualNftIDs.size());
+            verifyMetaInAllResponses([&](json::Value const& meta) {
+                // Expect nftoken_ids field and verify the values
+                if (!BEAST_EXPECT(meta.isMember(jss::nftoken_ids)))
+                    return;
 
-            // Check the value of NFT ID in the meta with the
-            // actual values
-            for (size_t i = 0; i < metaIDs.size(); ++i)
-                BEAST_EXPECT(metaIDs[i] == actualNftIDs[i]);
+                // Convert NFT IDs from json::Value to uint256
+                std::vector<uint256> metaIDs;
+                std::transform(
+                    meta[jss::nftoken_ids].begin(),
+                    meta[jss::nftoken_ids].end(),
+                    std::back_inserter(metaIDs),
+                    [this](json::Value id) {
+                        uint256 nftID;
+                        BEAST_EXPECT(nftID.parseHex(id.asString()));
+                        return nftID;
+                    });
+
+                std::ranges::sort(metaIDs);
+
+                // Make sure the expect number of NFTs is correct
+                if (!BEAST_EXPECT(metaIDs.size() == actualNftIDs.size()))
+                    return;
+
+                // Check the value of NFT ID in the meta with the
+                // actual values
+                for (size_t i = 0; i < metaIDs.size(); ++i)
+                    BEAST_EXPECT(metaIDs[i] == actualNftIDs[i]);
+            });
         };
 
         // Verify `offer_id` value equals to the offerID that was
         // changed in the most recent NFTokenCreateOffer tx
         auto verifyNFTokenOfferID = [&](uint256 const& offerID) {
-            // Get the hash for the most recent transaction.
-            std::string const txHash{
-                env.tx()->getJson(JsonOptions::Values::None)[jss::hash].asString()};
+            verifyMetaInAllResponses([&](json::Value const& meta) {
+                // Expect offer_id field and verify the value
+                if (!BEAST_EXPECT(meta.isMember(jss::offer_id)))
+                    return;
 
-            env.close();
-            json::Value const meta = env.rpc("tx", txHash)[jss::result][jss::meta];
-
-            // Expect offer_id field and verify the value
-            if (!BEAST_EXPECT(meta.isMember(jss::offer_id)))
-                return;
-
-            uint256 metaOfferID;
-            BEAST_EXPECT(metaOfferID.parseHex(meta[jss::offer_id].asString()));
-            BEAST_EXPECT(metaOfferID == offerID);
+                uint256 metaOfferID;
+                BEAST_EXPECT(metaOfferID.parseHex(meta[jss::offer_id].asString()));
+                BEAST_EXPECT(metaOfferID == offerID);
+            });
         };
 
         // Check new fields in tx meta when for all NFTtransactions
diff --git a/src/test/app/OfferMPT_test.cpp b/src/test/app/OfferMPT_test.cpp
index e262954fdf..80541480e8 100644
--- a/src/test/app/OfferMPT_test.cpp
+++ b/src/test/app/OfferMPT_test.cpp
@@ -24,12 +24,14 @@
 #include <test/jtx/trust.h>
 #include <test/jtx/txflags.h>
 
+#include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/core/ServiceRegistry.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/ledger/helpers/DirectoryHelpers.h>
 #include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/Book.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Issue.h>
@@ -3679,6 +3681,26 @@ public:
         }
 
         {
+            // Companion to the transfer-rate overflow cases above. The taker
+            // sells TakerPays=MPT(~1.84e18) for TakerGets=XRP(1) against a
+            // same-magnitude poison offer, forcing BookStep::revImp()'s
+            // limitStepOut() to strictly reduce and overflow.
+            //
+            // The taker's own quality is also unrepresentable here
+            // (getRate(TakerGets, TakerPays) == 0: a large MPT numerator over
+            // a small XRP denominator overflows the rate mantissa), but that
+            // no longer short-circuits the transaction -- crossing is
+            // attempted, and only a residual that would REST is stopped. So
+            // this exercises the deeper safety net:
+            // BookStep::forEachOffer's catch(std::overflow_error), which under
+            // featureMPTokensV2 removes the offending offer rather than
+            // propagating.
+            //
+            // Net effect: the poison offer is consumed off the book instead of
+            // being left to poison the next taker, nothing crosses, and the
+            // taker's own offer is not placed because its rate is
+            // unrepresentable -- so tecKILLED, which charges a fee and
+            // advances the sequence.
             Env env{*this, features};
             env.fund(XRP(10'000), issuer, taker);
             env.close();
@@ -3686,18 +3708,9 @@ public:
             MPTTester const token{
                 {.env = env, .issuer = issuer, .holders = {taker}, .maxAmt = kMaxMpTokenAmount}};
 
-            // Give the taker exactly one MPT. If the old rounding overflow
-            // collapsed the required input to the minimum positive amount, the
-            // taker could afford the bad fill and the balance checks below
-            // would catch the economic gain.
             env(pay(issuer, taker, token(1)));
             env.close();
 
-            // Covers BookStep::revImp() output reduction. The issuer's offer
-            // is fully funded and has no transfer fee, so offer preparation
-            // succeeds. The taker asks for slightly less output, forcing
-            // limitStepOut() to reduce the offer; that strict reduction used
-            // to overflow and leave the poison offer on the book.
             auto const funded = 1'844'674'407'370'955'162LL;
             auto const offerOut = funded + 1;
 
@@ -3711,21 +3724,23 @@ public:
             auto const issuerXRPBefore = env.balance(issuer, XRP);
             auto const takerXRPBefore = env.balance(taker, XRP);
             auto const takerMPTBefore = env.balance(taker, token);
-            auto const fee = env.current()->fees().base;
+            auto const takerSeqBefore = env.seq(taker);
 
-            auto const takerSeq = env.seq(taker);
-            env(offer(taker, token(funded), XRP(1)));
+            auto const takerSeq = takerSeqBefore;
+            auto const fee = env.current()->fees().base;
+            env(offer(taker, token(funded), XRP(1)), Ter(tecKILLED));
             env.close();
 
-            // The former overflow point must not turn into a near-free fill:
-            // the unusable offer is removed, the taker's offer remains, and no
-            // value changes hands beyond the taker's transaction fee.
+            // The overflowing poison offer is removed by BookStep. Nothing
+            // crossed, so no asset changes hands and the taker's offer is not
+            // placed; the fee is burned and the sequence advances.
             BEAST_EXPECT(env.le(poisonKeylet) == nullptr);
             BEAST_EXPECT(
-                env.le(keylet::offer(taker.id(), SeqProxy::rawSequence(takerSeq))) != nullptr);
+                env.le(keylet::offer(taker.id(), SeqProxy::rawSequence(takerSeq))) == nullptr);
             BEAST_EXPECT(env.balance(issuer, XRP) == issuerXRPBefore);
             BEAST_EXPECT(env.balance(taker, XRP) == takerXRPBefore - fee);
             BEAST_EXPECT(env.balance(taker, token) == takerMPTBefore);
+            BEAST_EXPECT(env.seq(taker) == takerSeqBefore + 1);
         }
 
         {
@@ -5494,6 +5509,215 @@ public:
         }
     }
 
+    void
+    testMPTOfferZeroRate(FeatureBitset features)
+    {
+        // An MPT offer whose quality is not representable must not REST -- on
+        // both the buy and sell sides, with or without a TickSize on the IOU
+        // issuer. Here nothing crosses it, so the whole offer is the remainder
+        // and the result is tecKILLED with nothing placed.
+        //
+        // getRate(TakerGets, TakerPays) returns 0 when the rate overflows: a
+        // large MPT TakerPays (XLS-0082 allows up to 2^63-1) over a small IOU
+        // TakerGets. Such an offer would otherwise (a) rest in the quality-0
+        // book directory, whose index equals getBookBase(), which BookTip's
+        // strict successor scan never returns -- so it can never be crossed yet
+        // still consumes the owner's reserve; and (b) on a TickSize market,
+        // drive the tick-rounding path in applyGuts to divide by a zero rate,
+        // throwing and surfacing as tefEXCEPTION. A normally-priced offer in the
+        // same market is unaffected.
+        //
+        // See testMPTOfferZeroRateCrossable for the other half of the
+        // behavior: an unrepresentable quality that CROSSES is not rejected.
+        testcase("MPT Offer Zero Rate");
+
+        using namespace jtx;
+
+        // Mantissa well above the ~1.84e17 overflow threshold (with an IOU
+        // denominator mantissa of 1e15); still within the XLS-0082 range.
+        auto const kBigMpt = 5'000'000'000'000'000'000LL;
+
+        auto runScenario = [&](bool withTickSize) {
+            Env env{*this, features};
+            auto const gw = Account{"gateway"};
+            auto const alice = Account{"alice"};
+            env.fund(XRP(10'000), gw, alice);
+            env.close();
+
+            auto const usd = gw["USD"];
+            env(trust(alice, usd(1'000)));
+            env(pay(gw, alice, usd(100)));
+            env.close();
+
+            if (withTickSize)
+            {
+                auto txn = noop(gw);
+                txn[sfTickSize.fieldName] = 5;
+                env(txn);
+                env.close();
+                BEAST_EXPECT((*env.le(gw))[sfTickSize] == 5);
+            }
+
+            // gw issues a DEX-tradable MPT (CanTrade | CanTransfer by default)
+            // and authorizes alice to hold it.
+            MPT const mpt = MPTTester(
+                {.env = env, .issuer = gw, .holders = {alice}, .maxAmt = kMaxMpTokenAmount});
+
+            // Buy side: TakerPays = large MPT, TakerGets = small IOU.
+            // getRate() overflows to 0 and nothing crosses -> killed, no
+            // offer placed and no reserve consumed.
+            BEAST_EXPECT(getRate(usd(1), mpt(kBigMpt)) == 0);
+            env(offer(alice, mpt(kBigMpt), usd(1)), Ter(tecKILLED));
+            env.close();
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+
+            // Sell side (tfSell): killed regardless of the flag, since the
+            // rate is computed from the raw amounts either way.
+            BEAST_EXPECT(getRate(usd(1), mpt(kBigMpt)) == 0);
+            env(offer(alice, mpt(kBigMpt), usd(1), tfSell), Ter(tecKILLED));
+            env.close();
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+
+            // Control: a normally-priced offer in the same market still
+            // places (and the tick-size rounding path still works when
+            // withTickSize is set).
+            env(offer(alice, mpt(10'000'000), usd(30)), Ter(tesSUCCESS));
+            env.close();
+            BEAST_EXPECT(offersOnAccount(env, alice).size() == 1);
+        };
+
+        // Without a TickSize: previously placed as a dead, never-crossable
+        // quality-0 entry that still consumed reserve.
+        runScenario(/*withTickSize=*/false);
+        // With a TickSize: previously threw and surfaced as tefEXCEPTION. The
+        // rounding is now skipped when the rate is unrepresentable.
+        runScenario(/*withTickSize=*/true);
+    }
+
+    void
+    testZeroRateXrpIouOffer(FeatureBitset features)
+    {
+        // A rate-0 offer is reachable without MPT: for XRP/IOU the "too
+        // good" underflow path makes getRate() return 0 when a tiny IOU
+        // TakerPays is divided by an XRP TakerGets.
+        //
+        // Without featureMPTokensV2 the offer is accepted and placed, but
+        // rests in the quality-0 book directory (whose index == getBookBase),
+        // which BookTip's strict successor scan never returns -- so it can
+        // never be crossed, even by a willing, better-priced counterparty.
+        // With featureMPTokensV2 the same offer crosses nothing and is not
+        // placed, so it is killed.
+        testcase("Zero Rate XRP/IOU Offer");
+
+        using namespace jtx;
+
+        auto const gw = Account{"gateway"};
+        auto const alice = Account{"alice"};
+        auto const bob = Account{"bob"};
+        auto const usd = gw["USD"];
+
+        // Smallest-magnitude IOU: mantissa kMinValue, exponent kMinOffset
+        // (= 1e-81). divide(tinyUsd, XRP(1000)) underflows below kMinOffset
+        // and canonicalizes to 0, so getRate() returns 0.
+        auto const tinyUsd = STAmount{usd, UINT64_C(1'000'000'000'000'000), -96};
+
+        auto setup = [&](Env& env) {
+            env.fund(XRP(100'000), gw, alice, bob);
+            env.close();
+            env(trust(alice, usd(1'000)));
+            env(trust(bob, usd(1'000)));
+            env(pay(gw, bob, usd(100)));
+            env.close();
+        };
+
+        // featureMPTokensV2 disabled: legacy behavior -- placed but inert.
+        {
+            Env env{*this, features - featureMPTokensV2};
+            setup(env);
+
+            // TakerPays = tiny IOU, TakerGets = XRP -> rate 0.
+            BEAST_EXPECT(getRate(XRP(1'000), tinyUsd) == 0);
+            env(offer(alice, tinyUsd, XRP(1'000)), Ter(tesSUCCESS));
+            env.close();
+
+            auto const aliceOffers = offersOnAccount(env, alice);
+            BEAST_EXPECT(aliceOffers.size() == 1);
+            // Placed in the quality-0 book directory.
+            BEAST_EXPECT(getQuality((*aliceOffers.front())[sfBookDirectory]) == 0);
+
+            // A complementary offer that would cross a usable offer at this
+            // (astronomically good) price does NOT cross it, because the
+            // quality-0 directory is never visited: both offers rest.
+            env(offer(bob, XRP(1'000), usd(10)), Ter(tesSUCCESS));
+            env.close();
+            BEAST_EXPECT(offersOnAccount(env, alice).size() == 1);
+            BEAST_EXPECT(offersOnAccount(env, bob).size() == 1);
+        }
+
+        // featureMPTokensV2 disabled, with a TickSize on the IOU issuer: the
+        // tick-rounding path divides by the zero rate and throws, surfacing as
+        // tefEXCEPTION. Legacy behavior, and it must stay that way -- the
+        // guard that skips the rounding is gated on the amendment, since
+        // changing this without a gate would fork a pre-amendment ledger.
+        {
+            Env env{*this, features - featureMPTokensV2};
+            setup(env);
+
+            auto txn = noop(gw);
+            txn[sfTickSize.fieldName] = 5;
+            env(txn);
+            env.close();
+            BEAST_EXPECT((*env.le(gw))[sfTickSize] == 5);
+
+            BEAST_EXPECT(getRate(XRP(1'000), tinyUsd) == 0);
+            env(offer(alice, tinyUsd, XRP(1'000)), Ter(tefEXCEPTION));
+            env.close();
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+        }
+
+        // featureMPTokensV2 enabled: nothing crosses, so the remainder is the
+        // whole offer and it is killed rather than placed.
+        {
+            Env env{*this, features};
+            setup(env);
+
+            BEAST_EXPECT(getRate(XRP(1000), tinyUsd) == 0);
+            env(offer(alice, tinyUsd, XRP(1000)), Ter(tecKILLED));
+            env.close();
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+        }
+
+        // featureMPTokensV2 enabled, with a counterparty already on the book:
+        // the same unrepresentable quality now CROSSES. This is the reviewer's
+        // objection with no MPT anywhere in it -- the old preflight check
+        // rejected this outright even though it fills completely and rests
+        // nothing.
+        {
+            Env env{*this, features};
+            setup(env);
+
+            // Bob rests first: he gives usd(10) to receive XRP(1'000).
+            auto const bobSeq = env.seq(bob);
+            env(offer(bob, XRP(1'000), usd(10)), Ter(tesSUCCESS));
+            env.close();
+            BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) != nullptr);
+
+            // Alice offers up to XRP(1'000) for a dust amount of USD -- rate
+            // 0, at a price bob's offer improves on enormously.
+            BEAST_EXPECT(getRate(XRP(1'000), tinyUsd) == 0);
+            env(offer(alice, tinyUsd, XRP(1'000)), Ter(tesSUCCESS));
+            env.close();
+
+            // Alice asked for dust and got exactly that, so her offer is
+            // fully satisfied and never reaches the book. Bob's offer is
+            // barely touched and stays. The old preflight check rejected this
+            // transaction outright, with no MPT involved anywhere.
+            BEAST_EXPECT(env.balance(alice, usd).value() == tinyUsd);
+            BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) != nullptr);
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+        }
+    }
+
     void
     testAutoCreateReserve(FeatureBitset features)
     {
@@ -5589,6 +5813,642 @@ public:
         }
     }
 
+    void
+    testBookOffersMPTFunding(FeatureBitset features)
+    {
+        testcase("book_offers uses MPT issuer capacity, transfer fees, and locks");
+
+        using namespace jtx;
+
+        Account const issuer{"issuer"};
+        Account const maker{"maker"};
+        Account const buyer{"buyer"};
+
+        // Issuer-owned MPT offers are funded only by remaining issuance
+        // capacity. Once ordinary issuance consumes the cap, book_offers must
+        // report the stale issuer offer as zero-funded.
+        {
+            Env env{*this, features};
+
+            env.fund(XRP(10'000), issuer, maker, buyer);
+            env.close();
+
+            MPTTester musd(
+                {.env = env, .issuer = issuer, .holders = {maker, buyer}, .maxAmt = 100});
+            MPT const usd = musd;
+
+            auto const issuerOfferSeq = env.seq(issuer);
+            env(offer(issuer, XRP(100), usd(100)));
+
+            musd.pay(issuer, maker, 100);
+
+            auto const issuance = env.le(keylet::mptokenIssuance(usd.mpt()));
+            if (!BEAST_EXPECT(issuance))
+                return;
+            BEAST_EXPECT(issuance->getFieldU64(sfOutstandingAmount) == 100);
+            BEAST_EXPECT(issuance->getFieldU64(sfMaximumAmount) == 100);
+
+            env(offer(maker, XRP(200), usd(100)));
+
+            json::Value const jrr = getBookOffers(env, XRP, usd);
+            json::Value const& bookOffers = jrr[jss::offers];
+            BEAST_EXPECT(bookOffers.isArray());
+            if (!BEAST_EXPECT(bookOffers.size() >= 2))
+                return;
+
+            json::Value const& issuerOffer = bookOffers[0u];
+            BEAST_EXPECT(issuerOffer[sfAccount.jsonName] == issuer.human());
+            BEAST_EXPECT(issuerOffer[sfSequence.jsonName] == issuerOfferSeq);
+            BEAST_EXPECT(issuerOffer[jss::owner_funds] == "0");
+            BEAST_EXPECT(issuerOffer.isMember(jss::taker_gets_funded));
+            BEAST_EXPECT(issuerOffer[jss::taker_gets_funded][jss::value] == "0");
+            BEAST_EXPECT(issuerOffer.isMember(jss::taker_pays_funded));
+            BEAST_EXPECT(issuerOffer[jss::taker_pays_funded] == "0");
+        }
+
+        // Multiple issuer-owned MPT offers share the same bounded self-issue
+        // capacity. The second offer exercises the cached running balance path
+        // after the first offer has consumed part of the issuer's capacity.
+        {
+            Env env{*this, features};
+
+            env.fund(XRP(10'000), issuer, buyer);
+            env.close();
+
+            MPTTester const musd({.env = env, .issuer = issuer, .holders = {buyer}, .maxAmt = 150});
+            MPT const usd = musd;
+
+            auto const firstIssuerOfferSeq = env.seq(issuer);
+            env(offer(issuer, XRP(100), usd(100)));
+            auto const secondIssuerOfferSeq = env.seq(issuer);
+            env(offer(issuer, XRP(100), usd(100)));
+
+            json::Value const jrr = getBookOffers(env, XRP, usd);
+            json::Value const& bookOffers = jrr[jss::offers];
+            BEAST_EXPECT(bookOffers.isArray());
+            if (!BEAST_EXPECT(bookOffers.size() >= 2))
+                return;
+
+            json::Value const& firstOffer = bookOffers[0u];
+            BEAST_EXPECT(firstOffer[sfAccount.jsonName] == issuer.human());
+            BEAST_EXPECT(firstOffer[sfSequence.jsonName] == firstIssuerOfferSeq);
+            BEAST_EXPECT(firstOffer[jss::owner_funds] == "150");
+            BEAST_EXPECT(!firstOffer.isMember(jss::taker_gets_funded));
+            BEAST_EXPECT(!firstOffer.isMember(jss::taker_pays_funded));
+
+            json::Value const& secondOffer = bookOffers[1u];
+            BEAST_EXPECT(secondOffer[sfAccount.jsonName] == issuer.human());
+            BEAST_EXPECT(secondOffer[sfSequence.jsonName] == secondIssuerOfferSeq);
+            BEAST_EXPECT(!secondOffer.isMember(jss::owner_funds));
+            BEAST_EXPECT(secondOffer.isMember(jss::taker_gets_funded));
+            BEAST_EXPECT(secondOffer[jss::taker_gets_funded][jss::value] == "50");
+            BEAST_EXPECT(secondOffer.isMember(jss::taker_pays_funded));
+            BEAST_EXPECT(secondOffer[jss::taker_pays_funded] == "50000000");
+        }
+
+        auto checkTransferFeeBookOffers = [&](std::uint16_t transferFee, auto&& checkOffers) {
+            Env env{*this, features};
+
+            env.fund(XRP(10'000), issuer, maker, buyer);
+            env.close();
+
+            MPTTester const musd(
+                {.env = env,
+                 .issuer = issuer,
+                 .holders = {maker, buyer},
+                 .transferFee = transferFee,
+                 .pay = 3'000});
+            MPT const usd = musd;
+            if (transferFee != 0)
+                BEAST_EXPECT(musd.checkTransferFee(transferFee));
+
+            auto const firstOfferSeq = env.seq(maker);
+            env(offer(maker, XRP(1'500), usd(1'500)));
+            auto const secondOfferSeq = env.seq(maker);
+            env(offer(maker, XRP(1'500), usd(1'500)));
+
+            json::Value const jrr = getBookOffers(env, XRP, usd);
+            json::Value const& bookOffers = jrr[jss::offers];
+            BEAST_EXPECT(bookOffers.isArray());
+            if (!BEAST_EXPECT(bookOffers.size() == 2))
+                return;
+
+            checkOffers(bookOffers, firstOfferSeq, secondOfferSeq);
+        };
+
+        // With no MPT transfer fee, two identical maker offers backed by 3000
+        // owner funds are both fully funded for 1500 MPT.
+        checkTransferFeeBookOffers(
+            0,
+            [&](json::Value const& bookOffers,
+                std::uint32_t firstOfferSeq,
+                std::uint32_t secondOfferSeq) {
+                for (auto const i : {0u, 1u})
+                {
+                    json::Value const& offer = bookOffers[i];
+                    BEAST_EXPECT(offer[sfAccount.jsonName] == maker.human());
+                    BEAST_EXPECT(
+                        offer[sfSequence.jsonName] == (i == 0u ? firstOfferSeq : secondOfferSeq));
+                    BEAST_EXPECT(!offer.isMember(jss::taker_gets_funded));
+                    BEAST_EXPECT(!offer.isMember(jss::taker_pays_funded));
+                }
+                BEAST_EXPECT(bookOffers[0u][jss::owner_funds] == "3000");
+            });
+
+        // With a 50% MPT transfer fee, the first identical maker offer consumes
+        // 2250 owner funds, so the second offer can deliver only 500 MPT.
+        checkTransferFeeBookOffers(
+            50'000,
+            [&](json::Value const& bookOffers,
+                std::uint32_t firstOfferSeq,
+                std::uint32_t secondOfferSeq) {
+                json::Value const& firstOffer = bookOffers[0u];
+                BEAST_EXPECT(firstOffer[sfAccount.jsonName] == maker.human());
+                BEAST_EXPECT(firstOffer[sfSequence.jsonName] == firstOfferSeq);
+                BEAST_EXPECT(firstOffer[jss::owner_funds] == "3000");
+                BEAST_EXPECT(!firstOffer.isMember(jss::taker_gets_funded));
+                BEAST_EXPECT(!firstOffer.isMember(jss::taker_pays_funded));
+
+                json::Value const& secondOffer = bookOffers[1u];
+                BEAST_EXPECT(secondOffer[sfAccount.jsonName] == maker.human());
+                BEAST_EXPECT(secondOffer[sfSequence.jsonName] == secondOfferSeq);
+                // A 50% MPT transfer fee leaves only 750 owner funds after
+                // the first offer. That can fund 500 MPT delivered to the
+                // taker on the same second offer that was fully funded without
+                // the transfer fee.
+                BEAST_EXPECT(secondOffer.isMember(jss::taker_gets_funded));
+                BEAST_EXPECT(secondOffer[jss::taker_gets_funded][jss::value] == "500");
+                BEAST_EXPECT(secondOffer.isMember(jss::taker_pays_funded));
+                BEAST_EXPECT(secondOffer[jss::taker_pays_funded] == "500000000");
+            });
+
+        // A large MPT balance used to overflow the fee adjustment. divide()
+        // assumes an IOU mantissa, always normalized into [1e15, 1e16), and
+        // scales the numerator by 1e17. An MPT mantissa is the raw int64
+        // balance, so past ~1.8e17 the scaled quotient leaves uint64 range and
+        // throws -- failing the whole RPC with "internal", so one offer owner
+        // blanked the entire book for every caller.
+        //
+        // The quotient itself always fits, because the branch only runs when
+        // the rate exceeds parity. The cases below pin that at the edges of
+        // the domain rather than leaving it to inspection.
+        auto checkLargeOwnerFunds =
+            [&](std::uint16_t transferFee, std::int64_t funds, char const* expectedFunded) {
+                Env env{*this, features};
+                env.fund(XRP(10'000), issuer, maker, buyer);
+                env.close();
+
+                MPT const usd = MPTTester(
+                    {.env = env,
+                     .issuer = issuer,
+                     .holders = {maker, buyer},
+                     .transferFee = transferFee,
+                     .maxAmt = kMaxMpTokenAmount});
+                env(pay(issuer, maker, usd(funds)));
+                env.close();
+
+                auto const offerSeq = env.seq(maker);
+                env(offer(maker, XRP(100), usd(funds)));
+                env.close();
+
+                json::Value const jrr = getBookOffers(env, XRP, usd);
+                BEAST_EXPECT(!jrr.isMember(jss::error));
+                json::Value const& bookOffers = jrr[jss::offers];
+                BEAST_EXPECT(bookOffers.isArray());
+                if (!BEAST_EXPECT(bookOffers.size() == 1))
+                    return;
+
+                json::Value const& offer = bookOffers[0u];
+                BEAST_EXPECT(offer[sfAccount.jsonName] == maker.human());
+                BEAST_EXPECT(offer[sfSequence.jsonName] == offerSeq);
+                BEAST_EXPECT(offer[jss::owner_funds] == std::to_string(funds));
+                BEAST_EXPECT(offer[jss::taker_gets_funded][jss::value] == expectedFunded);
+            };
+
+        // Above the ~2.77e17 boundary at the maximum transfer rate of 1.5:
+        // 3e17 of owner funds covers 2e17 delivered.
+        checkLargeOwnerFunds(kMaxTransferFee, 300'000'000'000'000'000LL, "200000000000000000");
+        // Large balance at the maximum rate. Kept at 6e18 so that 6e18 * 1.5
+        // stays representable: offer crossing's rate-preservation path
+        // overflows above that, which is a separate defect from this one.
+        checkLargeOwnerFunds(kMaxTransferFee, 6'000'000'000'000'000'000LL, "4000000000000000000");
+        // Near-maximum balance at the smallest rate above parity. This is the
+        // largest quotient the branch can produce, and the case the old code
+        // failed earliest on -- its overflow boundary is lowest, ~1.8e17, when
+        // the rate is closest to parity.
+        checkLargeOwnerFunds(1, 9'000'000'000'000'000'000LL, "8999910000899991000");
+
+        // An MPT global lock makes book_offers report the locked MPT book
+        // liquidity as zero-funded instead of funded.
+        {
+            Env env{*this, features};
+
+            env.fund(XRP(10'000), issuer, maker, buyer);
+            env.close();
+
+            MPTTester musd(
+                {.env = env,
+                 .issuer = issuer,
+                 .holders = {maker, buyer},
+                 .pay = 100,
+                 .flags = kMptDexFlags | tfMPTCanLock});
+            MPT const usd = musd;
+
+            auto const offerSeq = env.seq(maker);
+            env(offer(maker, XRP(100), usd(100)));
+            env.close();
+
+            {
+                json::Value const jrr = getBookOffers(env, XRP, usd);
+                json::Value const& bookOffers = jrr[jss::offers];
+                BEAST_EXPECT(bookOffers.isArray());
+                if (!BEAST_EXPECT(bookOffers.size() == 1))
+                    return;
+
+                json::Value const& offer = bookOffers[0u];
+                BEAST_EXPECT(offer[sfAccount.jsonName] == maker.human());
+                BEAST_EXPECT(offer[sfSequence.jsonName] == offerSeq);
+                BEAST_EXPECT(offer[jss::owner_funds] == "100");
+                BEAST_EXPECT(!offer.isMember(jss::taker_gets_funded));
+                BEAST_EXPECT(!offer.isMember(jss::taker_pays_funded));
+            }
+
+            musd.set({.flags = tfMPTLock});
+
+            {
+                // The lock does not remove the offer from the ledger;
+                // book_offers must report it as zero-funded liquidity.
+                auto const bookOffers = getBookOffers(env, XRP, usd)[jss::offers];
+                BEAST_EXPECT(bookOffers.isArray() && bookOffers.size() == 1);
+
+                json::Value const& offer = bookOffers[0u];
+                BEAST_EXPECT(offer[sfAccount] == maker.human());
+                BEAST_EXPECT(offer[sfSequence] == offerSeq);
+                BEAST_EXPECT(offer[jss::owner_funds] == "0");
+                BEAST_EXPECT(offer.isMember(jss::taker_gets_funded));
+                BEAST_EXPECT(offer[jss::taker_gets_funded][jss::value] == "0");
+                BEAST_EXPECT(offer.isMember(jss::taker_pays_funded));
+                BEAST_EXPECT(offer[jss::taker_pays_funded] == "0");
+            }
+        }
+    }
+
+    // getBookBase hashes raw concatenations of fixed-width fields, so the
+    // (Issue,MPT) preimage `currency(20)||mptID(24)||account(20)` and the
+    // (MPT,Issue) preimage `mptID(24)||currency(20)||account(20)` are both
+    // 64 bytes and collide when the bytes align. An attacker picks the IOU
+    // currency, reuses an IOU issuer, and grinds an MPT issuer / sequence;
+    // the per-branch discriminator in getBookBase blocks this.
+    void
+    testBookBaseMixedAssetCollision(FeatureBitset /*features*/)
+    {
+        testcase("getBookBase: (Issue,MPT) vs (MPT,Issue) preimage collision");
+
+        // Construction recipe:
+        //   issuerB last 4 bytes == seq_A; mptID_B = BE(5) || issuerB
+        //   currencyA            == mptID_B[0..19] = BE(5) || issuerB[0..15]
+        //   issuerA              == currencyB (both 20-byte all-0xBB)
+        //   sharedIOUIssuer      == acct_A == acct_B
+        AccountID issuerB;
+        AccountID issuerA;
+        Currency currencyB;
+        Currency currencyA;
+        AccountID sharedIOUIssuer;
+        BEAST_EXPECT(issuerB.parseHex("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA00000007"));
+        BEAST_EXPECT(issuerA.parseHex("BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"));
+        BEAST_EXPECT(currencyB.parseHex("BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"));
+        BEAST_EXPECT(currencyA.parseHex("00000005AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"));
+        BEAST_EXPECT(sharedIOUIssuer.parseHex("CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC"));
+
+        Book const bookA{
+            Asset{Issue{currencyA, sharedIOUIssuer}},
+            Asset{MPTIssue{0x00000007u, issuerA}},
+            std::nullopt};
+        Book const bookB{
+            Asset{MPTIssue{0x00000005u, issuerB}},
+            Asset{Issue{currencyB, sharedIOUIssuer}},
+            std::nullopt};
+
+        BEAST_EXPECT(bookA != bookB);
+        BEAST_EXPECT(getBookBase(bookA) != getBookBase(bookB));
+    }
+
+    // (MPT,MPT) bodies are 48 bytes and can't length-match the 64-byte
+    // mixed branches, but tag them too for symmetry/future-proofing; this
+    // test also pins the directional asymmetry of an (MPT,MPT) book.
+    void
+    testBookBaseMptMptDistinct(FeatureBitset /*features*/)
+    {
+        testcase("getBookBase: (MPT,MPT) distinguishes from mixed branches");
+
+        AccountID issuerX;
+        AccountID issuerY;
+        Currency currency;
+        AccountID iouIssuer;
+        BEAST_EXPECT(issuerX.parseHex("1111111111111111111111111111111111111111"));
+        BEAST_EXPECT(issuerY.parseHex("2222222222222222222222222222222222222222"));
+        BEAST_EXPECT(currency.parseHex("3333333333333333333333333333333333333333"));
+        BEAST_EXPECT(iouIssuer.parseHex("4444444444444444444444444444444444444444"));
+
+        Asset const mptX{MPTIssue{1u, issuerX}};
+        Asset const mptY{MPTIssue{2u, issuerY}};
+        Book const mptBook{mptX, mptY, std::nullopt};
+        Book const mixedBook{mptX, Asset{Issue{currency, iouIssuer}}, std::nullopt};
+        Book const reversedMptBook{mptY, mptX, std::nullopt};
+
+        BEAST_EXPECT(getBookBase(mptBook) != getBookBase(mixedBook));
+        BEAST_EXPECT(getBookBase(mptBook) != getBookBase(reversedMptBook));
+    }
+
+    void
+    testBookBaseDomainMptDistinct(FeatureBitset /*features*/)
+    {
+        testcase("getBookBase: domain does not reopen MPT preimage collisions");
+
+        // The type tag is a front prefix and the domain is a 32-byte suffix, so a
+        // domain'd book must (a) stay distinct from its public counterpart and
+        // (b) preserve the mixed-branch tag distinction that the public case has.
+        AccountID issuerX, issuerY, iouIssuer;
+        Currency currency;
+        BEAST_EXPECT(issuerX.parseHex("1111111111111111111111111111111111111111"));
+        BEAST_EXPECT(issuerY.parseHex("2222222222222222222222222222222222222222"));
+        BEAST_EXPECT(currency.parseHex("3333333333333333333333333333333333333333"));
+        BEAST_EXPECT(iouIssuer.parseHex("4444444444444444444444444444444444444444"));
+
+        uint256 const domainA = uint256::fromVoid(
+            "\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD"
+            "\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD\xDD");
+
+        Asset const mptX{MPTIssue{1u, issuerX}};
+        Asset const iou{Issue{currency, iouIssuer}};
+
+        // (a) same pair, public vs domain'd -> distinct directories.
+        Book const publicBook{mptX, iou, std::nullopt};
+        Book const domainBook{mptX, iou, domainA};
+        BEAST_EXPECT(getBookBase(publicBook) != getBookBase(domainBook));
+
+        // (b) mixed-branch tag distinction still holds *with* a domain set:
+        //     (MPT,Issue) vs (Issue,MPT), both domain'd, must not collide.
+        Book const mi{mptX, iou, domainA};
+        Book const im{iou, mptX, domainA};
+        BEAST_EXPECT(mi != im);
+        BEAST_EXPECT(getBookBase(mi) != getBookBase(im));
+    }
+
+    void
+    testMPTOfferZeroRateCrossable(FeatureBitset features)
+    {
+        // An unrepresentable quality does not imply an offer that cannot
+        // function. "Can never be crossed" describes an offer that RESTS:
+        // crossing happens in applyGuts, before any residual is placed in the
+        // book, so an offer whose rate is unrepresentable can still consume a
+        // resting offer in full and never reach the quality-0 directory.
+        //
+        // The two sides of one trade do not have the same rate
+        // representability: getRate(TakerGets, TakerPays) overflows to 0 for
+        // the side paying a large MPT, but not for the side paying XRP. So a
+        // preflight rejection keyed on getRate() == 0 admits the resting half
+        // of a trade and rejects the crossing half.
+        testcase("MPT Offer Zero Rate - crossable quality");
+
+        using namespace jtx;
+
+        // Above the rate-overflow threshold: divide() scales the XRP
+        // denominator up to a 1e15 mantissa and then evaluates
+        // muldiv(mptMantissa, 1e17, denMantissa), which exceeds 2^64 -- so
+        // getRate() takes its catch-all and returns 0.
+        auto const kBigMpt = 200'000'000'000'000'000LL;
+
+        // Both scenarios are the same trade against the same resting offer,
+        // and both execute identically (at bob's price). They differ only in
+        // the price alice quotes, and therefore only in whether the rate on
+        // HER side of the book is representable.
+        auto runScenario = [&](STAmount const& aliceQuote, bool rateRepresentable) {
+            Env env{*this, features};
+            auto const gw = Account{"gateway"};
+            auto const alice = Account{"alice"};
+            auto const bob = Account{"bob"};
+            env.fund(XRP(10'000), gw, alice, bob);
+            env.close();
+
+            MPT const mpt = MPTTester(
+                {.env = env, .issuer = gw, .holders = {alice, bob}, .maxAmt = kMaxMpTokenAmount});
+
+            env(pay(gw, bob, mpt(kBigMpt)));
+            env.close();
+
+            // Bob rests the sell side: TakerPays = XRP(1), TakerGets =
+            // kBigMpt. getRate(TakerGets, TakerPays) is representable in this
+            // direction, so preflight admits it and it rests at a normal
+            // quality.
+            BEAST_EXPECT(getRate(mpt(kBigMpt), XRP(1)) != 0);
+            auto const bobSeq = env.seq(bob);
+            env(offer(bob, XRP(1), mpt(kBigMpt)), Ter(tesSUCCESS));
+            env.close();
+            BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) != nullptr);
+
+            // Alice takes it from the other side: TakerPays = kBigMpt,
+            // TakerGets = her quote.
+            BEAST_EXPECT((getRate(aliceQuote, mpt(kBigMpt)) != 0) == rateRepresentable);
+
+            auto const bobXrpBefore = env.balance(bob).value().xrp();
+            env(offer(alice, mpt(kBigMpt), aliceQuote), Ter(tesSUCCESS));
+            env.close();
+
+            // Alice's offer crosses bob's in full, so it never rests: nothing
+            // ends up in the quality-0 directory, no reserve is stranded, and
+            // the tick-rounding divide is never reached with a zero rate.
+            BEAST_EXPECT(env.balance(alice, mpt) == mpt(kBigMpt));
+            BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) == nullptr);
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+            // And it executes at bob's 1 XRP, whatever alice quoted.
+            BEAST_EXPECT(env.balance(bob).value().xrp() == bobXrpBefore + XRP(1).value().xrp());
+        };
+
+        // Alice quotes bob's exact price. getRate() overflows to 0 on her
+        // side, yet the offer crosses in full and never rests.
+        runScenario(XRP(1), /*rateRepresentable=*/false);
+        // Alice quotes a price worse for herself, which halves the rate into
+        // representable range. Same execution as above: she pays 1 XRP for
+        // kBigMpt. The two cases are therefore numerically, not economically,
+        // different.
+        runScenario(XRP(2), /*rateRepresentable=*/true);
+    }
+
+    void
+    testMPTOfferZeroRatePartialCross(FeatureBitset features)
+    {
+        // The case between the two extremes: an unrepresentable quality that
+        // crosses PARTIALLY. The crossed portion must execute -- it never
+        // touches the book -- while the residual must not be placed, since it
+        // would rest in the quality-0 directory holding a reserve it could
+        // never earn back by being crossed.
+        testcase("MPT Offer Zero Rate - partial cross");
+
+        using namespace jtx;
+
+        auto const kBigMpt = 200'000'000'000'000'000LL;
+
+        Env env{*this, features};
+        auto const gw = Account{"gateway"};
+        auto const alice = Account{"alice"};
+        auto const bob = Account{"bob"};
+        env.fund(XRP(10'000), gw, alice, bob);
+        env.close();
+
+        MPT const mpt = MPTTester(
+            {.env = env, .issuer = gw, .holders = {alice, bob}, .maxAmt = kMaxMpTokenAmount});
+
+        env(pay(gw, bob, mpt(kBigMpt)));
+        env.close();
+
+        // Bob rests a sell of kBigMpt for XRP(1) -- representable on his side.
+        auto const bobSeq = env.seq(bob);
+        env(offer(bob, XRP(1), mpt(kBigMpt)), Ter(tesSUCCESS));
+        env.close();
+        BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) != nullptr);
+
+        // Alice asks for twice what bob has, at the same price. Her rate is
+        // unrepresentable: mantissa ratio 4e17 / 2e15 = 200 > ~184.47.
+        BEAST_EXPECT(getRate(XRP(2), mpt(2 * kBigMpt)) == 0);
+
+        auto const aliceXrpBefore = env.balance(alice).value().xrp();
+        auto const fee = env.current()->fees().base;
+
+        env(offer(alice, mpt(2 * kBigMpt), XRP(2)), Ter(tesSUCCESS));
+        env.close();
+
+        // The half that crossed executed at bob's price...
+        BEAST_EXPECT(env.balance(alice, mpt) == mpt(kBigMpt));
+        BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) == nullptr);
+        BEAST_EXPECT(
+            env.balance(alice).value().xrp() == aliceXrpBefore - XRP(1).value().xrp() - fee);
+        // ...and the half that did not is dropped rather than placed, so no
+        // offer rests and no reserve is consumed.
+        BEAST_EXPECT(offersOnAccount(env, alice).empty());
+        BEAST_EXPECT((*env.le(alice))[sfOwnerCount] == 1);  // the MPToken only
+    }
+
+    void
+    testMPTOfferZeroRateTickSizeCross(FeatureBitset features)
+    {
+        // TickSize plus an unrepresentable quality plus a counterparty on the
+        // book. The tick-rounding path is skipped for a zero rate, since it
+        // would divide by that rate and throw, so the offer crosses at its raw
+        // price. Every other TickSize case here faces an empty book, making
+        // this the only coverage that the skip leaves crossing intact --
+        // without it this transaction is tefEXCEPTION.
+        testcase("MPT Offer Zero Rate - tick size with crossing");
+
+        using namespace jtx;
+
+        auto const kBigMpt = 5'000'000'000'000'000'000LL;
+
+        Env env{*this, features};
+        auto const gw = Account{"gateway"};
+        auto const alice = Account{"alice"};
+        auto const bob = Account{"bob"};
+        env.fund(XRP(10'000), gw, alice, bob);
+        env.close();
+
+        auto const usd = gw["USD"];
+        env(trust(alice, usd(1'000)));
+        env(pay(gw, alice, usd(100)));
+        env.close();
+
+        auto txn = noop(gw);
+        txn[sfTickSize.fieldName] = 5;
+        env(txn);
+        env.close();
+        BEAST_EXPECT((*env.le(gw))[sfTickSize] == 5);
+
+        MPT const mpt = MPTTester(
+            {.env = env, .issuer = gw, .holders = {alice, bob}, .maxAmt = kMaxMpTokenAmount});
+        env(pay(gw, bob, mpt(kBigMpt)));
+        env.close();
+
+        // Bob rests the sell side; representable in that direction.
+        BEAST_EXPECT(getRate(mpt(kBigMpt), usd(1)) != 0);
+        auto const bobSeq = env.seq(bob);
+        env(offer(bob, usd(1), mpt(kBigMpt)), Ter(tesSUCCESS));
+        env.close();
+        BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) != nullptr);
+
+        // Alice takes it from the unrepresentable side, with the tick size in
+        // force on her TakerGets.
+        BEAST_EXPECT(getRate(usd(1), mpt(kBigMpt)) == 0);
+        env(offer(alice, mpt(kBigMpt), usd(1)), Ter(tesSUCCESS));
+        env.close();
+
+        BEAST_EXPECT(env.balance(alice, mpt) == mpt(kBigMpt));
+        BEAST_EXPECT(env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) == nullptr);
+        BEAST_EXPECT(offersOnAccount(env, alice).empty());
+    }
+
+    void
+    testMPTOfferZeroRateFlags(FeatureBitset features)
+    {
+        // A zero rate must not change what tfFillOrKill and tfImmediateOrCancel
+        // do. Both are handled above the unrepresentable-quality guard, but the
+        // ordering is not observable and no test can pin it: the guard returns
+        // the same pair either flag would. Immediate-or-cancel matches it by
+        // construction, and fill-or-kill disables partial payment
+        // (OfferCreate.cpp: flowCross is passed !tfFillOrKill), so a
+        // not-fully-fillable offer leaves crossed == false and both paths give
+        // {tecKILLED, false}. What this does cover is flags combined with an
+        // unrepresentable quality, which nothing else exercises.
+        testcase("MPT Offer Zero Rate - IOC and FoK");
+
+        using namespace jtx;
+
+        auto const kBigMpt = 200'000'000'000'000'000LL;
+
+        auto const runScenario = [&](std::uint32_t flags, TER expected) {
+            Env env{*this, features};
+            auto const gw = Account{"gateway"};
+            auto const alice = Account{"alice"};
+            auto const bob = Account{"bob"};
+            env.fund(XRP(10'000), gw, alice, bob);
+            env.close();
+
+            MPT const mpt = MPTTester(
+                {.env = env, .issuer = gw, .holders = {alice, bob}, .maxAmt = kMaxMpTokenAmount});
+            env(pay(gw, bob, mpt(kBigMpt)));
+            env.close();
+
+            auto const bobSeq = env.seq(bob);
+            env(offer(bob, XRP(1), mpt(kBigMpt)), Ter(tesSUCCESS));
+            env.close();
+
+            // Asking for twice what bob has forces a partial cross, so the
+            // flag handling -- not the fully-crossed early return -- decides.
+            BEAST_EXPECT(getRate(XRP(2), mpt(2 * kBigMpt)) == 0);
+            env(offer(alice, mpt(2 * kBigMpt), XRP(2), flags), Ter(expected));
+            env.close();
+
+            auto const bobOfferLive =
+                env.le(keylet::offer(bob.id(), SeqProxy::rawSequence(bobSeq))) != nullptr;
+            if (isTesSuccess(expected))
+            {
+                // Immediate-or-cancel: the crossed part is kept, the rest is
+                // cancelled -- the same shape the guard would produce.
+                BEAST_EXPECT(env.balance(alice, mpt) == mpt(kBigMpt));
+                BEAST_EXPECT(!bobOfferLive);
+            }
+            else
+            {
+                // Fill-or-kill: the offer is not fully fillable, so nothing
+                // crosses at all and bob's offer survives untouched.
+                BEAST_EXPECT(env.balance(alice, mpt) == mpt(0));
+                BEAST_EXPECT(bobOfferLive);
+            }
+            BEAST_EXPECT(offersOnAccount(env, alice).empty());
+        };
+
+        runScenario(tfImmediateOrCancel, tesSUCCESS);
+        runScenario(tfFillOrKill, tecKILLED);
+    }
+
     void
     testAll(FeatureBitset features)
     {
@@ -5649,7 +6509,17 @@ public:
         testPartiallyFundedMPTInputOfferZeroInput(features);
         testFillOrKill(features);
         testTickSize(features);
+        testMPTOfferZeroRate(features);
+        testMPTOfferZeroRateCrossable(features);
+        testMPTOfferZeroRatePartialCross(features);
+        testMPTOfferZeroRateTickSizeCross(features);
+        testMPTOfferZeroRateFlags(features);
+        testZeroRateXrpIouOffer(features);
+        testBookOffersMPTFunding(features);
         testAutoCreateReserve(features);
+        testBookBaseMixedAssetCollision(features);
+        testBookBaseMptMptDistinct(features);
+        testBookBaseDomainMptDistinct(features);
     }
 
     void
diff --git a/src/test/app/PathMPT_test.cpp b/src/test/app/PathMPT_test.cpp
index ff4a024cb8..87da13087f 100644
--- a/src/test/app/PathMPT_test.cpp
+++ b/src/test/app/PathMPT_test.cpp
@@ -14,6 +14,8 @@
 #include <xrpld/rpc/Context.h>
 #include <xrpld/rpc/RPCHandler.h>
 #include <xrpld/rpc/Role.h>
+#include <xrpld/rpc/detail/AccountAssets.h>
+#include <xrpld/rpc/detail/AssetCache.h>
 #include <xrpld/rpc/detail/RPCHelpers.h>
 #include <xrpld/rpc/detail/Tuning.h>
 
@@ -25,6 +27,8 @@
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/ApiVersion.h>
 #include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/PathAsset.h>
+#include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STPathSet.h>
 #include <xrpl/protocol/UintTypes.h>
@@ -33,6 +37,7 @@
 #include <xrpl/resource/Consumer.h>
 #include <xrpl/resource/Fees.h>
 
+#include <algorithm>
 #include <cstdint>
 #include <memory>
 #include <optional>
@@ -231,6 +236,102 @@ public:
         env.require(Balance("bob", usd(24)));
     }
 
+    void
+    sourceCurrencyWithSendMax()
+    {
+        testcase("source currency with send_max");
+        using namespace jtx;
+
+        Env env = pathTestEnv();
+        auto const alice = Account("alice");
+        auto const bob = Account("bob");
+        auto const gw = Account("gateway");
+        env.fund(XRP(10'000), alice, bob, gw);
+
+        MPT const usd = MPTTester({.env = env, .issuer = gw, .holders = {alice, bob}});
+        env(pay(gw, alice, usd(25)));
+        env.close();
+
+        // MPT source_currencies entries do not carry an issuer. A matching
+        // send_max identifies the same issuance, so the request should not run
+        // the IOU issuer reconciliation path.
+        auto const result = findPathsRequest(
+            env,
+            alice,
+            bob,
+            usd(-1),
+            std::optional<STAmount>(usd(10).value()),
+            std::optional<PathAsset>(usd.mpt()));
+        BEAST_EXPECTS(!result.isMember(jss::error), result.toStyledString());
+
+        auto const& alternatives = result[jss::alternatives];
+        if (BEAST_EXPECT(alternatives.size() == 1))
+        {
+            auto const sa = amountFromJson(sfGeneric, alternatives[0u][jss::source_amount]);
+            auto const da = amountFromJson(sfGeneric, alternatives[0u][jss::destination_amount]);
+            BEAST_EXPECTS(equal(sa, usd(10)), sa.getFullText());
+            BEAST_EXPECTS(equal(da, usd(10)), da.getFullText());
+        }
+    }
+
+    void
+    maxedOutMPTPathfinding()
+    {
+        testcase("maxed-out MPT pathfinding");
+        using namespace jtx;
+
+        auto hasMPT = [](auto const& assets, MPT const& mpt) {
+            return std::ranges::any_of(assets, [&](auto const& asset) {
+                return asset.template holds<MPTID>() && asset.template get<MPTID>() == mpt.mpt();
+            });
+        };
+
+        Env env = pathTestEnv();
+        auto const gw = Account("gateway");
+        auto const alice = Account("alice");
+        auto const bob = Account("bob");
+        auto const carol = Account("carol");
+
+        env.fund(XRP(10'000), gw, alice, bob, carol);
+        env.close();
+
+        MPT const usd =
+            MPTTester({.env = env, .issuer = gw, .holders = {alice, bob, carol}, .maxAmt = 100});
+        env(pay(gw, alice, usd(90)));
+        env(pay(gw, bob, usd(10)));
+        env.close();
+
+        auto const cache =
+            std::make_shared<AssetCache>(env.current(), env.app().getJournal("AssetCache"));
+
+        BEAST_EXPECT(hasMPT(accountSourceAssets(alice.id(), cache, false), usd));
+        BEAST_EXPECT(hasMPT(accountDestAssets(bob.id(), cache, false), usd));
+        BEAST_EXPECT(hasMPT(accountDestAssets(carol.id(), cache, false), usd));
+
+        // A fully minted issuance should not be advertised as issuer-side
+        // mintable source liquidity.
+        BEAST_EXPECT(!hasMPT(accountSourceAssets(gw.id(), cache, false), usd));
+
+        auto [st, sa, da] = findPaths(env, alice, bob, usd(5));
+        BEAST_EXPECT(st.empty());
+        BEAST_EXPECT(equal(sa, usd(5)));
+        BEAST_EXPECT(equal(da, usd(5)));
+
+        env(offer(carol, usd(5), XRP(5)));
+        env.close();
+
+        std::tie(st, sa, da) = findPaths(env, alice, bob, drops(-1), usd(100).value());
+        BEAST_EXPECT(sa == usd(5));
+        BEAST_EXPECT(equal(da, XRP(5)));
+        if (BEAST_EXPECT(st.size() == 1 && st[0].size() == 1))
+        {
+            auto const& pathElem = st[0][0];
+            BEAST_EXPECT(
+                pathElem.isOffer() && pathElem.getIssuerID() == xrpAccount() &&
+                pathElem.getCurrency() == xrpCurrency());
+        }
+    }
+
     void
     pathFind(bool const domainEnabled)
     {
@@ -441,6 +542,124 @@ public:
         }
     }
 
+    // Regression test: the Pathfinder constructor must honor the
+    // caller-supplied srcAmount (= the user's send_max from PathRequest)
+    // when ranking candidate paths in convert_all mode.
+    //
+    // Background. The MPT-DEX refactor of `Pathfinder::Pathfinder`
+    // (src/xrpld/rpc/detail/Pathfinder.cpp) replaced the original
+    // `mSrcAmount(srcAmount.value_or(...))` initializer with an
+    // unconditional `amountFromPathAsset(...)` call. The latter always
+    // returns the negative "no limit" STAmount sentinel, so the
+    // `srcAmount` constructor parameter became dead code:
+    // `getPathLiquidity` and `computePathRanks` ran `rippleCalculate`
+    // with `saMaxAmountReq` = sentinel and recorded each path's
+    // saturated capacity instead of the capacity reachable inside
+    // send_max.
+    //
+    // In convert_all_ mode (the only mode that allows send_max),
+    // `Pathfinder::rankPaths` ignores quality and orders purely by
+    // liquidity, then `Pathfinder::getBestPaths` only fills the last
+    // (kMaxPaths-th = 4th) slot when `pathRank.liquidity >= remaining`.
+    // For convert_all_ `remaining = largestAmount(dstAmount_)`, so the
+    // last slot effectively never fills and the cut keeps the top 3
+    // ranked paths. With the wrong (unbounded-budget) ranking, a
+    // low-capacity / high-rate path that would actually deliver the
+    // most under the user's send_max can be excluded entirely.
+    //
+    // Topology. Four candidate paths from alice's XRP to bob's USD-MPT,
+    // each via a distinct IOU intermediary issued by a different market
+    // maker:
+    //
+    //   charlie: XRP(1000) -> AUD(1000) -> USD(500)    cap 1000 XRP, rate 0.5
+    //   dave:    XRP(1000) -> EUR(1000) -> USD(500)    cap 1000 XRP, rate 0.5
+    //   eve:     XRP(1000) -> GBP(1000) -> USD(500)    cap 1000 XRP, rate 0.5
+    //   frank:   XRP(50)   -> JPY(50)   -> USD(75)     cap   50 XRP, rate 1.5
+    //
+    // Alice queries findPaths with destination = USD-MPT(-1) (convert_all)
+    // and send_max = XRP(100).
+    //
+    // Bug-free ranking (post-fix), with srcAmount = XRP(100):
+    //   charlie/dave/eve liquidity = min(100, 1000) * 0.5 = 50 USD each
+    //   frank   liquidity         = min(100, 50)   * 1.5 = 75 USD
+    // -> frank ranks first; the flow uses frank's 50 XRP at 1.5 (=75 USD)
+    //    plus 50 XRP via a 0.5-rate path (=25 USD), delivering USD(100).
+    //
+    // Pre-fix ranking, with srcAmount silently replaced by the sentinel:
+    //   charlie/dave/eve liquidity = 1000 * 0.5 = 500 USD each
+    //   frank   liquidity         =   50 * 1.5 = 75 USD
+    // -> frank ranks 4th; the last-slot rule excludes it from the
+    //    surviving path set, the cut keeps the three 0.5-rate paths,
+    //    and the flow delivers only 100 * 0.5 = USD(50).
+    //
+    // This test asserts the post-fix outcome (USD(100)). On the pre-fix
+    // tree the assertion fails with USD(50).
+    void
+    convertAllSendMaxRanking()
+    {
+        testcase("convert_all + send_max: srcAmount governs path ranking");
+        using namespace jtx;
+
+        Env env = pathTestEnv();
+        auto const alice = Account("alice");
+        auto const bob = Account("bob");
+        auto const gw = Account("gateway");
+        auto const charlie = Account("charlie");
+        auto const dave = Account("dave");
+        auto const eve = Account("eve");
+        auto const frank = Account("frank");
+
+        env.fund(XRP(10'000), alice, bob, gw, charlie, dave, eve, frank);
+        env.close();
+
+        // USD MPT issued by gw; the four market makers and bob are holders.
+        // alice is not a holder because she only pays XRP; USD only ever
+        // flows from gw / market-maker offers to bob.
+        MPT const usd =
+            MPTTester({.env = env, .issuer = gw, .holders = {charlie, dave, eve, frank, bob}});
+
+        // Capitalize each market maker with the USD-MPT they will sell.
+        env(pay(gw, charlie, usd(500)));
+        env(pay(gw, dave, usd(500)));
+        env(pay(gw, eve, usd(500)));
+        env(pay(gw, frank, usd(75)));
+        env.close();
+
+        // Each market maker issues their own intermediate IOU.
+        auto const aud = charlie["AUD"];
+        auto const eur = dave["EUR"];
+        auto const gbp = eve["GBP"];
+        auto const jpy = frank["JPY"];
+
+        // Three high-capacity, low-rate paths (1 XRP -> 0.5 USD-MPT,
+        // capacity 1000 XRP each).
+        env(offer(charlie, XRP(1'000), aud(1'000)));
+        env(offer(charlie, aud(1'000), usd(500)));
+        env(offer(dave, XRP(1'000), eur(1'000)));
+        env(offer(dave, eur(1'000), usd(500)));
+        env(offer(eve, XRP(1'000), gbp(1'000)));
+        env(offer(eve, gbp(1'000), usd(500)));
+
+        // One low-capacity, high-rate path (1 XRP -> 1.5 USD-MPT,
+        // capacity 50 XRP).
+        env(offer(frank, XRP(50), jpy(50)));
+        env(offer(frank, jpy(50), usd(75)));
+        env.close();
+
+        // ripple_path_find with convert_all (USD(-1)) and send_max XRP(100).
+        STPathSet st;
+        STAmount sa;
+        STAmount da;
+        std::tie(st, sa, da) =
+            findPaths(env, alice, bob, usd(-1), std::optional<STAmount>(XRP(100).value()));
+
+        // Post-fix: frank's high-rate path is included in the surviving
+        // path set, so the flow uses 50 XRP at 1.5 plus 50 XRP at 0.5,
+        // delivering exactly USD(100) on alice's 100-XRP budget.
+        BEAST_EXPECT(sa == XRP(100));
+        BEAST_EXPECT(equal(da, usd(100)));
+    }
+
     void
     run() override
     {
@@ -448,6 +667,9 @@ public:
         noDirectPathNoIntermediaryNoAlternatives();
         directPathNoIntermediary();
         paymentAutoPathFind();
+        sourceCurrencyWithSendMax();
+        maxedOutMPTPathfinding();
+        convertAllSendMaxRanking();
         for (auto const domainEnabled : {false, true})
         {
             pathFind(domainEnabled);
diff --git a/src/test/app/Path_test.cpp b/src/test/app/Path_test.cpp
index 29b4a5b048..cd61668b03 100644
--- a/src/test/app/Path_test.cpp
+++ b/src/test/app/Path_test.cpp
@@ -147,7 +147,8 @@ public:
         STAmount const& saDstAmount,
         std::optional<STAmount> const& saSendMax = std::nullopt,
         std::optional<Currency> const& saSrcCurrency = std::nullopt,
-        std::optional<uint256> const& domain = std::nullopt)
+        std::optional<uint256> const& domain = std::nullopt,
+        std::optional<AccountID> const& saSrcIssuer = std::nullopt)
     {
         using namespace jtx;
 
@@ -181,6 +182,10 @@ public:
             auto& sc = params[jss::source_currencies] = json::ValueType::Array;
             json::Value j = json::ValueType::Object;
             j[jss::currency] = to_string(saSrcCurrency.value());
+            // Optional issuer for tests that need to exercise
+            // source_currencies entries more precisely than currency alone.
+            if (saSrcIssuer)
+                j[jss::issuer] = toBase58(*saSrcIssuer);
             sc.append(j);
         }
         if (domain)
@@ -209,10 +214,11 @@ public:
         STAmount const& saDstAmount,
         std::optional<STAmount> const& saSendMax = std::nullopt,
         std::optional<Currency> const& saSrcCurrency = std::nullopt,
-        std::optional<uint256> const& domain = std::nullopt)
+        std::optional<uint256> const& domain = std::nullopt,
+        std::optional<AccountID> const& saSrcIssuer = std::nullopt)
     {
-        json::Value result =
-            findPathsRequest(env, src, dst, saDstAmount, saSendMax, saSrcCurrency, domain);
+        json::Value result = findPathsRequest(
+            env, src, dst, saDstAmount, saSendMax, saSrcCurrency, domain, saSrcIssuer);
         BEAST_EXPECT(!result.isMember(jss::error));
 
         STAmount da;
@@ -325,6 +331,53 @@ public:
         BEAST_EXPECT(result.isMember(jss::error));
     }
 
+    void
+    sourceCurrencyIssuerSelection()
+    {
+        testcase("source currency issuer selection");
+        using namespace jtx;
+
+        Env env = pathTestEnv();
+        auto const alice = Account("alice");
+        auto const bob = Account("bob");
+        auto const gateway = Account("gateway");
+
+        env.fund(XRP(10000), alice, bob, gateway);
+        env.close();
+
+        auto const usd = gateway["USD"];
+        env.trust(usd(600), alice);
+        env.trust(usd(700), bob);
+        env.trust(alice["USD"](700), bob);
+        env(pay(gateway, alice, usd(70)));
+        env(pay(gateway, bob, usd(50)));
+        env.close();
+
+        // Ask for USD from an explicit source issuer while send_max is
+        // Alice-issued USD. The parser should choose gateway-issued USD
+        // because gateway is the issuer in source_currencies.
+        //
+        // The Alice/Bob trust line is intentional: if Alice-issued USD is also
+        // considered as a source asset, pathfinding can produce an additional
+        // alternative. The single expected alternative below verifies that only
+        // the explicit issuer is selected.
+        auto const result = findPathsRequest(
+            env,
+            alice,
+            bob,
+            bob["USD"](-1),
+            alice["USD"](100).value(),
+            usd.currency,
+            std::nullopt,
+            gateway.id());
+        auto const& alternatives = result[jss::alternatives];
+        BEAST_EXPECT(alternatives.size() == 1);
+        auto const sa = amountFromJson(sfGeneric, alternatives[0u][jss::source_amount]);
+        auto const da = amountFromJson(sfGeneric, alternatives[0u][jss::destination_amount]);
+        BEAST_EXPECTS(equal(sa, usd(100)), sa.getFullText());
+        BEAST_EXPECTS(equal(da, bob["USD"](100)), da.getFullText());
+    }
+
     void
     noDirectPathNoIntermediaryNoAlternatives()
     {
@@ -1968,6 +2021,7 @@ public:
     run() override
     {
         sourceCurrenciesLimit();
+        sourceCurrencyIssuerSelection();
         noDirectPathNoIntermediaryNoAlternatives();
         directPathNoIntermediary();
         paymentAutoPathFind();
diff --git a/src/test/app/PermissionedDEX_test.cpp b/src/test/app/PermissionedDEX_test.cpp
index ddb56a1480..fbe942948d 100644
--- a/src/test/app/PermissionedDEX_test.cpp
+++ b/src/test/app/PermissionedDEX_test.cpp
@@ -21,6 +21,7 @@
 #include <test/jtx/trust.h>
 #include <test/jtx/txflags.h>
 
+#include <xrpl/basics/Slice.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/beast/utility/Journal.h>
@@ -179,7 +180,10 @@ class PermissionedDEX_test : public beast::unit_test::Suite
     void
     testOfferCreate(FeatureBitset features)
     {
-        testcase("OfferCreate");
+        bool const fixEnabled = features[fixCleanup3_4_0];
+
+        testcase << "OfferCreate"
+                 << (fixEnabled ? " (Cleanup3_4_0 enabled)" : " (Cleanup3_4_0 disabled)");
 
         // test preflight
         {
@@ -273,8 +277,10 @@ class PermissionedDEX_test : public beast::unit_test::Suite
             // time advance
             env.close(std::chrono::seconds(20));
 
-            // devin cannot create offer with expired cred
-            env(offer(devin, XRP(10), USD(10)), Domain(domainID), Ter(tecNO_PERMISSION));
+            // Devin cannot create offer with expired cred. After fixCleanup3_4_0,
+            // doApply deletes the expired credential SLE and returns tecEXPIRED.
+            TER const expectedExpiredCredTer = fixEnabled ? tecEXPIRED : tecNO_PERMISSION;
+            env(offer(devin, XRP(10), USD(10)), Domain(domainID), Ter(expectedExpiredCredTer));
             env.close();
         }
 
@@ -1510,7 +1516,9 @@ class PermissionedDEX_test : public beast::unit_test::Suite
         env.close(std::chrono::seconds(100));
 
         // Confirm devin can no longer create domain offers.
-        env(offer(devin, XRP(1), USD(1)), Domain(domainID), Ter(tecNO_PERMISSION));
+        // After fixCleanup3_4_0, OfferCreate deletes the expired credential and
+        // returns tecEXPIRED (covered in depth by testExpiredCredentialCleanup).
+        env(offer(devin, XRP(1), USD(1)), Domain(domainID), Ter(tecEXPIRED));
         env.close();
 
         // The hybrid offer must still exist in the open book after expiry.
@@ -1635,6 +1643,202 @@ class PermissionedDEX_test : public beast::unit_test::Suite
         BEAST_EXPECT(!offerExists(env, bob, carolOfferSeq));
     }
 
+    void
+    testExpiredCredentialCleanup(FeatureBitset features)
+    {
+        bool const fixEnabled = features[fixCleanup3_4_0];
+
+        testcase << "Expired credential cleanup"
+                 << (fixEnabled ? " (Cleanup3_4_0 enabled)" : " (Cleanup3_4_0 disabled)");
+
+        TER const expectedExpiredCredTer = fixEnabled ? tecEXPIRED : tecNO_PERMISSION;
+
+        auto const fundAccount =
+            [](Env& env, Account const& account, Account const& gw, IOU const& usd) {
+                env.fund(XRP(1000), account);
+                env.close();
+                env.trust(usd(1000), account);
+                env.close();
+                env(pay(gw, account, usd(100)));
+                env.close();
+            };
+
+        auto const fundDevin = [&](Env& env, Account const& gw, IOU const& usd) {
+            Account const devin("devin");
+            fundAccount(env, devin, gw, usd);
+            return devin;
+        };
+
+        auto const createExpiringCredential = [](Env& env,
+                                                 Account const& subject,
+                                                 Account const& issuer,
+                                                 std::string const& credType) {
+            auto jv = credentials::create(subject, issuer, credType);
+            uint32_t const t = env.current()->header().parentCloseTime.time_since_epoch().count();
+            jv[sfExpiration.jsonName] = t + 20;
+            env(jv);
+            env(credentials::accept(subject, issuer, credType));
+            env.close();
+
+            return keylet::credential(subject.id(), issuer.id(), makeSlice(credType));
+        };
+
+        auto const expectExpiredCredentialState = [&](Env const& env, Keylet const& credKey) {
+            if (fixEnabled)
+            {
+                BEAST_EXPECT(!env.le(credKey));
+            }
+            else
+            {
+                BEAST_EXPECT(env.le(credKey));
+            }
+        };
+
+        // A payment referencing a non-existent domain is rejected in preclaim.
+        {
+            Env env(*this, features);
+            auto const& [gw, domainOwner, alice, bob, carol, USD, domainID, credType] =
+                PermissionedDEX(env);
+
+            uint256 const badDomain{
+                "F10D0CC9A0F9A3CBF585B80BE09A186483668FDBDD39AA7E3370F3649CE134"
+                "E5"};
+
+            env(offer(bob, XRP(10), USD(10)), Domain(domainID));
+            env.close();
+
+            env(pay(alice, bob, USD(10)),
+                Path(~USD),
+                Sendmax(XRP(10)),
+                Domain(badDomain),
+                Ter(tecNO_PERMISSION));
+            env.close();
+        }
+
+        // OfferCreate with an expired credential.
+        {
+            Env env(*this, features);
+            auto const& [gw, domainOwner, alice, bob, carol, USD, domainID, credType] =
+                PermissionedDEX(env);
+
+            Account const devin = fundDevin(env, gw, USD);
+            auto const credKey = createExpiringCredential(env, devin, domainOwner, credType);
+            BEAST_EXPECT(env.le(credKey));  // credential exists before expiry
+
+            env.close(std::chrono::seconds(20));
+
+            env(offer(devin, XRP(10), USD(10)), Domain(domainID), Ter(expectedExpiredCredTer));
+            env.close();
+
+            expectExpiredCredentialState(env, credKey);
+        }
+
+        // Payment where the sender's credential is expired.
+        {
+            Env env(*this, features);
+            auto const& [gw, domainOwner, alice, bob, carol, USD, domainID, credType] =
+                PermissionedDEX(env);
+
+            Account const devin = fundDevin(env, gw, USD);
+            auto const credKey = createExpiringCredential(env, devin, domainOwner, credType);
+
+            auto const bobOfferSeq{env.seq(bob)};
+            auto const bobCredKey =
+                keylet::credential(bob.id(), domainOwner.id(), makeSlice(credType));
+            env(offer(bob, XRP(10), USD(10)), Domain(domainID));
+            env.close();
+
+            BEAST_EXPECT(env.le(credKey));
+            BEAST_EXPECT(env.le(bobCredKey));
+            BEAST_EXPECT(offerExists(env, bob, bobOfferSeq));
+
+            env.close(std::chrono::seconds(20));
+
+            env(pay(devin, alice, USD(10)),
+                Path(~USD),
+                Sendmax(XRP(10)),
+                Domain(domainID),
+                Ter(expectedExpiredCredTer));
+            env.close();
+
+            expectExpiredCredentialState(env, credKey);
+            BEAST_EXPECT(env.le(bobCredKey));
+            BEAST_EXPECT(offerExists(env, bob, bobOfferSeq));
+        }
+
+        // Payment where the destination's credential is expired.
+        {
+            Env env(*this, features);
+            auto const& [gw, domainOwner, alice, bob, carol, USD, domainID, credType] =
+                PermissionedDEX(env);
+
+            Account const devin = fundDevin(env, gw, USD);
+            auto const credKey = createExpiringCredential(env, devin, domainOwner, credType);
+
+            auto const bobOfferSeq{env.seq(bob)};
+            auto const bobCredKey =
+                keylet::credential(bob.id(), domainOwner.id(), makeSlice(credType));
+            env(offer(bob, XRP(10), USD(10)), Domain(domainID));
+            env.close();
+
+            BEAST_EXPECT(env.le(credKey));
+            BEAST_EXPECT(env.le(bobCredKey));
+            BEAST_EXPECT(offerExists(env, bob, bobOfferSeq));
+
+            env.close(std::chrono::seconds(20));
+
+            env(pay(alice, devin, USD(10)),
+                Path(~USD),
+                Sendmax(XRP(10)),
+                Domain(domainID),
+                Ter(expectedExpiredCredTer));
+            env.close();
+
+            expectExpiredCredentialState(env, credKey);
+            BEAST_EXPECT(env.le(bobCredKey));
+            BEAST_EXPECT(offerExists(env, bob, bobOfferSeq));
+        }
+
+        // Payment where both sender and destination credentials are expired.
+        {
+            Env env(*this, features);
+            auto const& [gw, domainOwner, alice, bob, carol, USD, domainID, credType] =
+                PermissionedDEX(env);
+
+            Account const devin = fundDevin(env, gw, USD);
+            Account const erin("erin");
+            fundAccount(env, erin, gw, USD);
+
+            auto const devinCredKey = createExpiringCredential(env, devin, domainOwner, credType);
+            auto const erinCredKey = createExpiringCredential(env, erin, domainOwner, credType);
+
+            auto const bobOfferSeq{env.seq(bob)};
+            auto const bobCredKey =
+                keylet::credential(bob.id(), domainOwner.id(), makeSlice(credType));
+            env(offer(bob, XRP(10), USD(10)), Domain(domainID));
+            env.close();
+
+            BEAST_EXPECT(env.le(devinCredKey));
+            BEAST_EXPECT(env.le(erinCredKey));
+            BEAST_EXPECT(env.le(bobCredKey));
+            BEAST_EXPECT(offerExists(env, bob, bobOfferSeq));
+
+            env.close(std::chrono::seconds(20));
+
+            env(pay(devin, erin, USD(10)),
+                Path(~USD),
+                Sendmax(XRP(10)),
+                Domain(domainID),
+                Ter(expectedExpiredCredTer));
+            env.close();
+
+            expectExpiredCredentialState(env, devinCredKey);
+            expectExpiredCredentialState(env, erinCredKey);
+            BEAST_EXPECT(env.le(bobCredKey));
+            BEAST_EXPECT(offerExists(env, bob, bobOfferSeq));
+        }
+    }
+
     void
     testHybridMalformedOffer(FeatureBitset features)
     {
@@ -2209,6 +2413,7 @@ public:
         // Test domain offer (w/o hybrid)
         testOfferCreate(all);
         testOfferCreate(all - fixCleanup3_2_0);
+        testOfferCreate(all - fixCleanup3_4_0);
         testPayment(all);
         testPayment(all - fixCleanup3_2_0);
         testBookStep(all);
@@ -2219,6 +2424,8 @@ public:
         testAmmQualityNotLeaked(all);
         testAmmQualityNotLeaked(all - fixCleanup3_3_0);
         testAutoBridge(all);
+        testExpiredCredentialCleanup(all);
+        testExpiredCredentialCleanup(all - fixCleanup3_4_0);
 
         // Test hybrid offers
         testHybridOfferCreate(all);
diff --git a/src/test/app/SHAMapStore_test.cpp b/src/test/app/SHAMapStore_test.cpp
index 0a8c51c56a..4a69ac17f9 100644
--- a/src/test/app/SHAMapStore_test.cpp
+++ b/src/test/app/SHAMapStore_test.cpp
@@ -1,3 +1,4 @@
+#include <test/jtx/Account.h>
 #include <test/jtx/Env.h>
 #include <test/jtx/amount.h>
 #include <test/jtx/envconfig.h>
@@ -11,10 +12,13 @@
 #include <xrpld/core/Config.h>
 
 #include <xrpl/basics/ByteUtilities.h>
+#include <xrpl/basics/Log.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/beast/utility/Journal.h>
 #include <xrpl/config/BasicConfig.h>
 #include <xrpl/config/Constants.h>
+#include <xrpl/core/JobQueue.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/nodestore/Backend.h>
 #include <xrpl/nodestore/Manager.h>
@@ -26,14 +30,21 @@
 #include <xrpl/protocol/jss.h>
 #include <xrpl/server/NetworkOPs.h>
 
+#include <algorithm>
 #include <atomic>
+#include <chrono>
+#include <condition_variable>
 #include <cstddef>
 #include <cstdint>
+#include <exception>
 #include <filesystem>
+#include <functional>
 #include <limits>
 #include <map>
 #include <memory>
+#include <mutex>
 #include <optional>
+#include <ostream>
 #include <sstream>
 #include <string>
 #include <thread>
@@ -44,7 +55,170 @@ namespace xrpl::test {
 
 class SHAMapStore_test : public beast::unit_test::Suite
 {
-    static auto const kDeleteInterval = 8;
+    static constexpr int kDeleteInterval = 8;
+
+    // Mirrors SHAMapStoreImp::kMinimumDeletionIntervalSa, the floor that
+    // online_delete is held to in standalone mode. Note that the
+    // max_waiting_ledgers floor is derived from this minimum rather than from
+    // the configured interval -- SHAMapStoreImp.cpp computes it as
+    // minInterval / 4 -- so both constants below stay put if kDeleteInterval is
+    // ever raised.
+    static constexpr int kMinDeleteInterval = 8;
+    static constexpr int kMinWaitingLedgers = kMinDeleteInterval / 4;
+    static_assert(kDeleteInterval >= kMinDeleteInterval);
+
+    // The two wait durations healthWait() can choose from, spelled as they
+    // appear in its log message. onlineDelete() below sets
+    // recovery_wait_seconds to 1, so the full wait is 1000ms and the shortened
+    // wait is a tenth of that. Note that "Waiting 1000ms" does not contain
+    // "Waiting 100ms", so the two are distinguishable by substring.
+    static constexpr char const* kFullWait = "Waiting 1000ms for node to stabilize";
+    static constexpr char const* kShortWait = "Waiting 100ms for node to stabilize";
+
+    // Distinctive fragments of the other messages the tests below key off. Each
+    // is unique among everything SHAMapStoreImp logs, so a substring match
+    // identifies the message unambiguously.
+    //
+    // kRotating is logged once run() has committed to a rotation, immediately
+    // after the health check that gates it, and kFinished once a rotation has
+    // run to completion. kExpired is logged by healthWait() when the circuit
+    // breaker trips.
+    static constexpr char const* kRotating = "rotating";
+    static constexpr char const* kFinished = "finished rotation";
+    static constexpr char const* kExpired = "unable to make progress";
+
+    // A Logs implementation that records every message the store's own
+    // partition emits, keeping each message's severity alongside its text, and
+    // lets a test block until a given message has appeared.
+    //
+    // Severity is recorded because healthWait() picks the severity and the wait
+    // duration together, so the pair identifies which of its three logging
+    // branches ran: warn at the full wait when the server is unhealthy for a
+    // reason that is not expected to resolve on its own, trace at a tenth of
+    // the wait when the only missing ledger is the one currently being built,
+    // and info at the full wait otherwise. Matching on the pair is what lets
+    // the tests below assert which branch was taken instead of merely that some
+    // wait happened.
+    //
+    // waitFor() exists because run() logs on entry to a rotation, which is the
+    // only signal a test has that the store has passed the health check gating
+    // the rotation and is now inside it. Several of the branches under test are
+    // only reachable from there, and no other handle on the store exposes it.
+    class StoreLogs : public Logs
+    {
+        mutable std::mutex mutex_;
+        std::condition_variable cond_;
+        std::vector<std::pair<beast::Severity, std::string>> messages_;
+
+        class Sink : public beast::Journal::Sink
+        {
+            StoreLogs& owner_;
+
+        public:
+            Sink(beast::Severity threshold, StoreLogs& owner)
+                : beast::Journal::Sink(threshold, false), owner_(owner)
+            {
+            }
+
+            // Env::AppBundle calls Logs::threshold() after the Application is
+            // built, which would otherwise raise this sink above Trace and
+            // discard the messages the buildingIndex branch logs.
+            void
+            threshold(beast::Severity) override
+            {
+            }
+
+            void
+            write(beast::Severity level, std::string const& text) override
+            {
+                {
+                    std::scoped_lock const lock(owner_.mutex_);
+                    owner_.messages_.emplace_back(level, text);
+                }
+                owner_.cond_.notify_all();
+            }
+
+            void
+            writeAlways(beast::Severity level, std::string const& text) override
+            {
+                write(level, text);
+            }
+        };
+
+        // Caller must hold mutex_. A nullopt severity matches any severity.
+        [[nodiscard]] std::size_t
+        countLocked(std::optional<beast::Severity> severity, std::string const& text) const
+        {
+            return std::count_if(messages_.begin(), messages_.end(), [&](auto const& message) {
+                return (!severity || message.first == *severity) &&
+                    message.second.find(text) != std::string::npos;
+            });
+        }
+
+    public:
+        StoreLogs() : Logs(beast::Severity::Trace)
+        {
+        }
+
+        // Only the store's own partition is logged at Trace; everything else
+        // is silenced, so that enabling trace for this one branch does not pay
+        // for formatting every trace message in the server.
+        std::unique_ptr<beast::Journal::Sink>
+        makeSink(std::string const& partition, beast::Severity) override
+        {
+            return std::make_unique<Sink>(
+                partition == "SHAMapStore" ? beast::Severity::Trace : beast::Severity::Disabled,
+                *this);
+        }
+
+        // How many recorded messages were logged at `severity` and contain
+        // `text`.
+        [[nodiscard]] std::size_t
+        count(beast::Severity severity, std::string const& text) const
+        {
+            std::scoped_lock const lock(mutex_);
+            return countLocked(severity, text);
+        }
+
+        // How many recorded messages contain `text`, at any severity.
+        [[nodiscard]] std::size_t
+        count(std::string const& text) const
+        {
+            std::scoped_lock const lock(mutex_);
+            return countLocked(std::nullopt, text);
+        }
+
+        // Blocks until `text` has been logged at least `expected` times at
+        // `severity` -- or at any severity, if that is nullopt -- or until the
+        // timeout expires. Returns whether it got there.
+        //
+        // Waiting rather than sleeping-then-counting matters for the branches
+        // that are only reached after a rotation has started: the store gets
+        // there when it gets there, so a fixed sleep has to be sized for the
+        // slowest plausible machine, whereas this returns as soon as the
+        // message appears.
+        [[nodiscard]] bool
+        waitFor(
+            std::optional<beast::Severity> severity,
+            std::string const& text,
+            std::chrono::milliseconds timeout,
+            std::size_t expected = 1)
+        {
+            std::unique_lock lock(mutex_);
+            return cond_.wait_for(
+                lock, timeout, [&] { return countLocked(severity, text) >= expected; });
+        }
+
+        // As above, at any severity.
+        [[nodiscard]] bool
+        waitFor(
+            std::string const& text,
+            std::chrono::milliseconds timeout,
+            std::size_t expected = 1)
+        {
+            return waitFor(std::nullopt, text, timeout, expected);
+        }
+    };
 
     static auto
     onlineDelete(std::unique_ptr<Config> cfg)
@@ -54,6 +228,32 @@ class SHAMapStore_test : public beast::unit_test::Suite
         return cfg;
     }
 
+    // online delete tuned so that a rotation, once it has started, spends a
+    // long time in clearPrior() before reaching the first health check inside
+    // the rotation body.
+    //
+    // clearSql() sleeps back_off_milliseconds at the top of every iteration and
+    // advances by delete_batch rows per iteration, so a delete_batch of 1 costs
+    // one sleep per ledger removed, for each of the three tables it is called
+    // on. That is what gives parkMidRotation() below a window measured in
+    // seconds rather than in microseconds. delete_batch is therefore the actual
+    // lever; back_off_milliseconds is set to the value SHAMapStoreImp already
+    // defaults to, and is spelled out only so the arithmetic above can be
+    // checked against the config rather than against the implementation.
+    //
+    // max_waiting_ledgers is pinned to its floor so that tripping the circuit
+    // breaker takes the fewest possible ledger closes.
+    static auto
+    slowOnlineDelete(std::unique_ptr<Config> cfg)
+    {
+        cfg = onlineDelete(std::move(cfg));
+        auto& section = cfg->section(Sections::kNodeDatabase);
+        section.set(Keys::kDeleteBatch, "1");
+        section.set(Keys::kBackOffMilliseconds, "100");
+        section.set(Keys::kMaxWaitingLedgers, std::to_string(kMinWaitingLedgers));
+        return cfg;
+    }
+
     static auto
     advisoryDelete(std::unique_ptr<Config> cfg)
     {
@@ -141,6 +341,96 @@ class SHAMapStore_test : public beast::unit_test::Suite
         BEAST_EXPECT(env.app().getRelationalDatabase().getAccountTransactionCount() == rows);
     }
 
+    // Wait until the SHAMapStore has finished processing the ledger that the
+    // preceding env.close() produced.
+    //
+    // env.close() returns as soon as the ledger_accept RPC returns, but the
+    // validated ledger path -- LedgerMaster::setValidLedger() ->
+    // SHAMapStore::onLedgerClosed() -- runs on a job queue thread. Without
+    // draining the job queue first, the store may not have been handed the
+    // ledger at all, in which case rendezvous() observes working_ == false and
+    // returns immediately, before any work has been done.
+    [[nodiscard]] static bool
+    syncStore(jtx::Env& env)
+    {
+        // Drain the job queue first, so that onLedgerClosed() has run and
+        // working_ is set. Then use the store's timeout overload, so a store
+        // that never finishes fails this test instead of blocking on it.
+        //
+        // Only the second wait is bounded: JobQueue::rendezvous() has no
+        // timeout overload, so a job that never completes hangs here. That is
+        // pre-existing -- ~AppBundle waits on it the same way for every jtx
+        // test -- but it does mean this helper is not hang-proof end to end.
+        env.app().getJobQueue().rendezvous();
+        return env.app().getSHAMapStore().rendezvous(std::chrono::seconds{60});
+    }
+
+    // Bring the SHAMapStore to the point where it has been handed a validated
+    // ledger and initialized lastRotated, and report how many extra ledgers had
+    // to be closed to get it there (normally none). Returns std::nullopt if
+    // syncStore() itself failed.
+    //
+    // syncStore() alone does not guarantee that, because
+    // SHAMapStoreImp::run()'s loop does not use the notification and the
+    // working_ flag safely:
+    //
+    //   * onLedgerClosed() notifies cond_ whether or not run()'s thread is
+    //     parked on it, and run() waits on cond_ without a predicate, so a
+    //     notification that lands while the thread is still starting up --
+    //     before it first reaches that wait -- is lost.
+    //   * run() clears working_ at the top of its loop without checking
+    //     whether newLedger_ is still set, so rendezvous() can report the
+    //     store idle with a validated ledger queued.
+    //
+    // Either way the store ends up parked with work pending, and only another
+    // notification gets it moving again. In a standalone test nothing else
+    // closes ledgers, so that has to come from here: this closes a ledger
+    // rather than polling getLastRotated(), because polling would just time
+    // out. onLedgerClosed() keeps only the most recent ledger in newLedger_,
+    // so the ledger the store picks up -- and therefore lastRotated -- is a
+    // timing detail, which is why the callers derive their expectations from
+    // the value they observe instead of assuming one.
+    //
+    // run() is deliberately left as it is. In production the only effect is
+    // latency: the trigger is validatedSeq >= lastRotated + deleteInterval, so
+    // a lost notification delays rotation to the next validated ledger and
+    // nothing is skipped or accumulated -- starting at 513 instead of 512 does
+    // not matter. Two consequences do follow from leaving it in place, and both
+    // hold today: nothing in production decides anything from working_ or
+    // rendezvous() (rendezvous() has no production callers at all), and a node
+    // whose ledgers only advance on demand -- standalone, driven by
+    // ledger_accept -- can sit on a queued ledger until something closes the
+    // next one, which is exactly the situation this helper is working around.
+    //
+    // So this helper is permanent rather than a stopgap. Working around the
+    // race must not make it invisible, so every extra close is logged. That
+    // keeps how often it is actually hit observable in the unit test output --
+    // which is the only signal left once these testcases stop flaking on it.
+    [[nodiscard]] std::optional<int>
+    initializeStore(jtx::Env& env, int const maxExtraCloses = 3)
+    {
+        auto& store = env.app().getSHAMapStore();
+
+        for (int extraCloses = 0;; ++extraCloses)
+        {
+            if (!syncStore(env))
+                return std::nullopt;
+            if (store.getLastRotated() != 0 || extraCloses == maxExtraCloses)
+            {
+                if (extraCloses != 0)
+                {
+                    log << "initializeStore: the store needed " << extraCloses
+                        << " extra ledger close(s) to pick up a validated ledger. "
+                           "SHAMapStoreImp::run() dropped the notification for the "
+                           "first one; see the comment on initializeStore()."
+                        << std::endl;
+                }
+                return extraCloses;
+            }
+            env.close();
+        }
+    }
+
     int
     waitForReady(jtx::Env& env)
     {
@@ -149,11 +439,11 @@ class SHAMapStore_test : public beast::unit_test::Suite
         auto& store = env.app().getSHAMapStore();
 
         int ledgerSeq = 3;
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
         BEAST_EXPECT(!store.getLastRotated());
 
         env.close();
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         auto ledger = env.rpc("ledger", "validated");
         BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq++)));
@@ -162,7 +452,417 @@ class SHAMapStore_test : public beast::unit_test::Suite
         return ledgerSeq;
     }
 
+    // Construct an Env whose config has online_delete enabled and is then
+    // mutated by `tweak`, and report how SHAMapStoreImp's constructor judged
+    // it: the message of the exception it threw, or std::nullopt if the Env was
+    // constructed successfully.
+    //
+    // SHAMapStoreImp is built from ApplicationImp's member initializer list, so
+    // a configuration it rejects surfaces as an exception thrown out of the Env
+    // constructor rather than as a failure at some later point.
+    //
+    // Note that ~AppBundle does not run when the Env constructor throws, so the
+    // global debug log sink it installed -- which holds a reference to this
+    // suite -- would outlive the suite. The catch below clears it, so callers
+    // are free to end on a configuration that is rejected.
+    std::optional<std::string>
+    storeConfigResult(std::function<void(Config&)> const& tweak)
+    {
+        using namespace test::jtx;
+
+        try
+        {
+            Env const env{
+                *this,
+                envconfig([&tweak](std::unique_ptr<Config> cfg) {
+                    cfg = onlineDelete(std::move(cfg));
+                    tweak(*cfg);
+                    return cfg;
+                }),
+                nullptr,
+                beast::Severity::Disabled};
+            return std::nullopt;
+        }
+        // Deliberately broader than the std::runtime_error that
+        // SHAMapStoreImp throws: an unexpected exception type then shows up as
+        // a message mismatch naming the actual failure, rather than escaping
+        // this testcase.
+        catch (std::exception const& e)
+        {
+            // ~AppBundle did not run, so drop the sink it installed by hand
+            // rather than leaving a reference to this suite live in a global.
+            setDebugLogSink(nullptr);
+            return std::string{e.what()};
+        }
+    }
+
+    void
+    expectConfigRejected(std::string const& expected, std::function<void(Config&)> const& tweak)
+    {
+        auto const result = storeConfigResult(tweak);
+        BEAST_EXPECTS(result == expected, result.value_or("<accepted>"));
+    }
+
+    void
+    expectConfigAccepted(std::function<void(Config&)> const& tweak)
+    {
+        auto const result = storeConfigResult(tweak);
+        BEAST_EXPECTS(!result, result.value_or(""));
+    }
+
+    // The state parkInHealthWait() leaves behind.
+    struct Parked
+    {
+        // Value of getLastRotated() before the rotation attempt began. The
+        // store must still report this for as long as it stays parked.
+        LedgerIndex lastRotated = 0;
+        // The validated ledger the store is waiting on, and the sequence
+        // getLastRotated() will report once the rotation finally completes.
+        LedgerIndex validated = 0;
+        // Sequence removed from LedgerMaster to create the gap, or 0 if
+        // `createGap` was false.
+        LedgerIndex gap = 0;
+    };
+
+    // Drive the store to the point where it is parked inside healthWait(),
+    // unable to proceed with a rotation: close ledgers until one more close
+    // would make the store due to rotate, optionally remove the newest ledger
+    // from LedgerMaster so that the attempt sees a gap in the range, close the
+    // triggering ledger, and then set the operating mode to `modeAfterClose`.
+    //
+    // Once parked, the store stays parked indefinitely. Its wait loop reruns
+    // every recovery_wait_seconds and exits only when the server looks healthy,
+    // when it is stopped, or when the validated ledger index reaches the
+    // circuit breaker -- and that index only advances when this test closes
+    // another ledger. So a caller can establish any server state it likes,
+    // hold it, and be sure the store observes it. That is what makes the tests
+    // below state machines rather than races.
+    //
+    // Returns std::nullopt if the setup did not reach a parked store, having
+    // already reported the failure.
+    std::optional<Parked>
+    parkInHealthWait(jtx::Env& env, bool createGap, OperatingMode modeAfterClose)
+    {
+        using namespace std::chrono_literals;
+        using namespace test::jtx;
+
+        auto& lm = env.app().getLedgerMaster();
+        auto& store = env.app().getSHAMapStore();
+        auto& netOPs = env.app().getOPs();
+
+        env.fund(XRP(1000), Account("alice"));
+        env.close();
+        if (!BEAST_EXPECT(initializeStore(env).has_value()))
+            return std::nullopt;
+
+        Parked parked;
+        // The store adopts the first validated ledger it sees as lastRotated,
+        // and which one that is depends on timing, so read it rather than
+        // assuming a value.
+        parked.lastRotated = store.getLastRotated();
+        if (!BEAST_EXPECT(parked.lastRotated))
+            return std::nullopt;
+
+        // Close ledgers until the next close is the one that makes
+        // validatedSeq reach lastRotated + deleteInterval.
+        LedgerIndex maxSeq = env.closed()->header().seq;
+        while (maxSeq + 1 < parked.lastRotated + kDeleteInterval)
+        {
+            env.close();
+            ++maxSeq;
+            if (!BEAST_EXPECT(syncStore(env)))
+                return std::nullopt;
+            if (!BEAST_EXPECTS(
+                    store.getLastRotated() == parked.lastRotated,
+                    std::to_string(store.getLastRotated())))
+                return std::nullopt;
+        }
+
+        // Drop out of FULL before touching LedgerMaster's internals, matching
+        // testLedgerGaps. This also keeps the store from rotating on the
+        // triggering close before the caller has set the state it wants
+        // observed.
+        netOPs.setMode(OperatingMode::CONNECTED);
+
+        // The gap goes one below the sequence that the close further down makes
+        // validated, never at that sequence itself: healthWait() derives
+        // buildingIndex from numMissing == 1 && !haveLedger(index), so a gap at
+        // the validated index reads as "that ledger is about to be built" and
+        // takes the short trace wait, whereas a gap below it reads as a
+        // genuinely incomplete range and takes the full wait. Nothing refills
+        // the gap, so the wait loop ends only when the circuit breaker trips or
+        // stop() intervenes.
+        if (createGap)
+        {
+            std::size_t iterations = 30;
+            while (!lm.haveLedger(maxSeq) && --iterations > 0)
+            {
+                std::this_thread::sleep_for(10ms);
+            }
+            if (!BEAST_EXPECTS(lm.haveLedger(maxSeq), std::to_string(maxSeq)))
+                return std::nullopt;
+
+            // Give the server a moment to finish any internal work on the
+            // ledger about to be removed, as testLedgerGaps does.
+            std::this_thread::sleep_for(250ms);
+
+            lm.clearLedger(maxSeq);
+            if (!BEAST_EXPECT(!lm.haveLedger(maxSeq)))
+                return std::nullopt;
+            parked.gap = maxSeq;
+        }
+
+        // This close makes the store due to rotate.
+        env.close();
+        ++maxSeq;
+        parked.validated = maxSeq;
+        netOPs.setMode(modeAfterClose);
+
+        // Drain the job queue so that onLedgerClosed() has handed the ledger to
+        // the store. Without this, working_ may still be false from the
+        // previous cycle and rendezvous() would report "done" before the store
+        // has even looked at this ledger.
+        env.app().getJobQueue().rendezvous();
+
+        if (!BEAST_EXPECT(!store.rendezvous(1s)))
+            return std::nullopt;
+        if (!BEAST_EXPECTS(
+                store.getLastRotated() == parked.lastRotated,
+                std::to_string(store.getLastRotated())))
+            return std::nullopt;
+
+        return parked;
+    }
+
+    // Drive the store to the point where it has passed the health check that
+    // gates a rotation and is inside the rotation body, then make the server
+    // unhealthy so that the next health check in there parks it.
+    //
+    // The gap cannot be created up front the way parkInHealthWait() does it,
+    // because the gating check would see it and refuse to start the rotation at
+    // all -- which is what testLedgerGaps() exercises. So this waits for the
+    // message run() logs immediately after that check, which is the store
+    // publishing that it is committed to the rotation, and creates the gap then.
+    //
+    // The margin that makes that safe is clearPrior(), which runs between the
+    // log and the first health check inside the rotation. Under
+    // slowOnlineDelete() it works through three tables one sequence at a time,
+    // sleeping back_off_milliseconds before each, and checks health after every
+    // one of those sleeps. So the store spends on the order of a second per
+    // table repeatedly asking whether it is healthy, against the microseconds
+    // this function needs to clear a ledger once waitFor() has returned.
+    //
+    // The gap has to be the validated ledger itself. healthWait() counts missing
+    // ledgers over the range from lastGoodValidatedLedger_ to the validated
+    // index, and run() sets the former to the latter just before starting the
+    // rotation, so for the duration of the rotation that range begins as a
+    // single sequence and grows only as the caller closes more ledgers.
+    //
+    // Which health check inside the rotation ends up observing the gap is not
+    // pinned down, and does not need to be: whichever one it is returns the same
+    // answer, clearPrior() gives up, and run() reaches its first switch on
+    // healthWait() with the condition still in force. Every assertion below
+    // holds for any of them.
+    //
+    // Returns std::nullopt if the setup did not reach a parked store, having
+    // already reported the failure.
+    std::optional<Parked>
+    parkMidRotation(jtx::Env& env, StoreLogs& log)
+    {
+        using namespace std::chrono_literals;
+        using namespace test::jtx;
+
+        auto& lm = env.app().getLedgerMaster();
+        auto& store = env.app().getSHAMapStore();
+
+        auto const alice = Account("alice");
+        env.fund(XRP(1000), alice);
+        env.close();
+        if (!BEAST_EXPECT(initializeStore(env).has_value()))
+            return std::nullopt;
+
+        LedgerIndex maxSeq = env.closed()->header().seq;
+        // Close one ledger, carrying a transaction so that the sequence has rows
+        // in all three of the tables clearSql() works through.
+        auto closeOne = [&]() -> bool {
+            env(noop(alice));
+            env.close();
+            ++maxSeq;
+            return BEAST_EXPECT(syncStore(env));
+        };
+
+        // Let one rotation complete before setting up the one to be parked. The
+        // window this helper depends on only exists once the tables hold a full
+        // delete interval of rows: on the very first rotation there is at most
+        // one sequence to remove, so clearSql() sleeps once or not at all.
+        LedgerIndex const firstRotated = store.getLastRotated();
+        if (!BEAST_EXPECT(firstRotated))
+            return std::nullopt;
+        while (store.getLastRotated() == firstRotated)
+        {
+            if (!closeOne())
+                return std::nullopt;
+            // The rotation is due once maxSeq reaches firstRotated +
+            // kDeleteInterval. Allow one close beyond that before giving up,
+            // rather than closing ledgers forever.
+            if (!BEAST_EXPECTS(maxSeq <= firstRotated + kDeleteInterval, std::to_string(maxSeq)))
+                return std::nullopt;
+        }
+
+        Parked parked;
+        parked.lastRotated = store.getLastRotated();
+
+        // Close ledgers until the next close is the one that makes the store due
+        // to rotate again.
+        while (maxSeq + 1 < parked.lastRotated + kDeleteInterval)
+        {
+            if (!closeOne())
+                return std::nullopt;
+            if (!BEAST_EXPECTS(
+                    store.getLastRotated() == parked.lastRotated,
+                    std::to_string(store.getLastRotated())))
+                return std::nullopt;
+        }
+
+        // One rotation has already been logged, so wait for the next one rather
+        // than for the first.
+        auto const rotationsBefore = log.count(kRotating);
+
+        // This close makes the store due to rotate. Deliberately do not drain
+        // the store here: the point is to interrupt it partway through.
+        env(noop(alice));
+        env.close();
+        ++maxSeq;
+        parked.validated = maxSeq;
+
+        // Draining the job queue, on the other hand, is required. In standalone
+        // mode switchLCL() inserts the closed ledger into LedgerMaster's
+        // complete range and then posts an advance job, and publishing the
+        // ledger from that job inserts it a second time. Clearing the ledger
+        // between those two inserts does not leave a lasting gap: publication
+        // puts it straight back, the rotation's health checks see a healthy
+        // node, and the rotation runs to completion. Waiting for the queue to
+        // drain closes that window, because publication is what advances
+        // pubLedger_ -- once it has happened, the ledger is never published, and
+        // so never inserted, again.
+        //
+        // This waits only for the job queue, not for the store, whose thread is
+        // its own and is the thing being interrupted here.
+        env.app().getJobQueue().rendezvous();
+
+        // Publishing the ledger is what advances pubLedger_, so this is the
+        // observable confirmation that the window above has closed. Asserting it
+        // here means that if anything ever reopens it, this setup step says so
+        // directly instead of the tests below failing for reasons that look
+        // nothing like the cause.
+        auto const published = lm.getPublishedLedger();
+        if (!BEAST_EXPECTS(
+                published && published->header().seq >= parked.validated,
+                std::to_string(published ? published->header().seq : 0)))
+            return std::nullopt;
+
+        if (!BEAST_EXPECT(log.waitFor(kRotating, 10s, rotationsBefore + 1)))
+            return std::nullopt;
+
+        // The store is now inside clearPrior(). Remove the validated ledger so
+        // that every health check from here on reports a gap.
+        if (!BEAST_EXPECTS(lm.haveLedger(parked.validated), std::to_string(parked.validated)))
+            return std::nullopt;
+        lm.clearLedger(parked.validated);
+        parked.gap = parked.validated;
+        if (!BEAST_EXPECT(!lm.haveLedger(parked.gap)))
+            return std::nullopt;
+
+        // The rotation must now be stuck. Wait longer than
+        // recovery_wait_seconds, so that this is a settled state rather than a
+        // store that has yet to reach its next health check.
+        if (!BEAST_EXPECT(!store.rendezvous(1500ms)))
+            return std::nullopt;
+        if (!BEAST_EXPECTS(
+                store.getLastRotated() == parked.lastRotated,
+                std::to_string(store.getLastRotated())))
+            return std::nullopt;
+        // The rotation started, has not finished, and has not yet given up.
+        if (!BEAST_EXPECTS(
+                log.count(kRotating) == rotationsBefore + 1, std::to_string(log.count(kRotating))))
+            return std::nullopt;
+        if (!BEAST_EXPECTS(log.count(kFinished) == 1, std::to_string(log.count(kFinished))))
+            return std::nullopt;
+        if (!BEAST_EXPECTS(log.count(kExpired) == 0, std::to_string(log.count(kExpired))))
+            return std::nullopt;
+
+        return parked;
+    }
+
 public:
+    // Cover the [node_db] validation that SHAMapStoreImp performs when it is
+    // constructed. The rejected cases stop inside SHAMapStoreImp's constructor,
+    // so they cost only a partial Application construction; the accepted ones
+    // start a full node and immediately tear it down.
+    void
+    testConfig()
+    {
+        testcase("config validation");
+
+        // online_delete below the standalone minimum. ledger_history is still
+        // kDeleteInterval here, so it is too large for this online_delete as
+        // well; the assertion pins which of the two errors wins.
+        expectConfigRejected(
+            "online_delete must be at least " + std::to_string(kMinDeleteInterval),
+            [](Config& cfg) {
+                cfg.section(Sections::kNodeDatabase)
+                    .set(Keys::kOnlineDelete, std::to_string(kMinDeleteInterval - 1));
+            });
+
+        // ledger_history above online_delete asks the node to retain more
+        // history than online delete is allowed to keep.
+        expectConfigRejected(
+            "online_delete must not be less than ledger_history (currently " +
+                std::to_string(kDeleteInterval + 1) + ")",
+            [](Config& cfg) { cfg.ledgerHistory = kDeleteInterval + 1; });
+
+        // recovery_wait_seconds is the interval at which online delete rechecks
+        // the node's health while it waits for missing ledgers to arrive, so a
+        // zero wait would turn that into a spin.
+        expectConfigRejected("recovery_wait_seconds must be at least 1 second", [](Config& cfg) {
+            cfg.section(Sections::kNodeDatabase).set(Keys::kRecoveryWaitSeconds, "0");
+        });
+
+        // max_waiting_ledgers is the circuit breaker that eventually lets
+        // online delete stop waiting, so it has a floor rather than being
+        // free-form.
+        auto const tooFewWaiting =
+            "max_waiting_ledgers must be at least " + std::to_string(kMinWaitingLedgers);
+        expectConfigRejected(tooFewWaiting, [](Config& cfg) {
+            cfg.section(Sections::kNodeDatabase)
+                .set(Keys::kMaxWaitingLedgers, std::to_string(kMinWaitingLedgers - 1));
+        });
+        // 0 is not a magic "never give up" value, just a value below the floor.
+        expectConfigRejected(tooFewWaiting, [](Config& cfg) {
+            cfg.section(Sections::kNodeDatabase).set(Keys::kMaxWaitingLedgers, "0");
+        });
+
+        // The floor itself is accepted, and so is a value far above
+        // online_delete: there is no upper bound.
+        expectConfigAccepted([](Config& cfg) {
+            cfg.section(Sections::kNodeDatabase)
+                .set(Keys::kMaxWaitingLedgers, std::to_string(kMinWaitingLedgers));
+        });
+        expectConfigAccepted([](Config& cfg) {
+            cfg.section(Sections::kNodeDatabase)
+                .set(Keys::kMaxWaitingLedgers, std::to_string(kDeleteInterval * 100));
+        });
+
+        // All of the above is gated on online_delete being enabled. With it
+        // turned off, the same values are ignored rather than rejected.
+        expectConfigAccepted([](Config& cfg) {
+            auto& section = cfg.section(Sections::kNodeDatabase);
+            section.set(Keys::kOnlineDelete, "0");
+            section.set(Keys::kMaxWaitingLedgers, "0");
+            section.set(Keys::kRecoveryWaitSeconds, "0");
+        });
+    }
+
     void
     testClear()
     {
@@ -233,7 +933,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(kDeleteInterval + 4)));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         BEAST_EXPECT(store.getLastRotated() == kDeleteInterval + 3);
         lastRotated = store.getLastRotated();
@@ -260,7 +960,7 @@ public:
                 !getHash(ledgers[i]).empty());
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         BEAST_EXPECT(store.getLastRotated() == kDeleteInterval + lastRotated);
 
@@ -298,7 +998,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         // The database will always have back to ledger 2,
         // regardless of lastRotated.
@@ -313,7 +1013,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq++), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - lastRotated, lastRotated);
         BEAST_EXPECT(lastRotated != store.getLastRotated());
@@ -329,7 +1029,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, kDeleteInterval + 1, lastRotated);
         BEAST_EXPECT(lastRotated != store.getLastRotated());
@@ -368,7 +1068,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - 2, 2);
         BEAST_EXPECT(lastRotated == store.getLastRotated());
@@ -378,7 +1078,7 @@ public:
         BEAST_EXPECT(!rpc::containsError(canDelete[jss::result]));
         BEAST_EXPECT(canDelete[jss::result][jss::can_delete] == ledgerSeq + (kDeleteInterval / 2));
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - 2, 2);
         BEAST_EXPECT(store.getLastRotated() == lastRotated);
@@ -391,7 +1091,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq++), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - lastRotated, lastRotated);
 
@@ -407,7 +1107,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         BEAST_EXPECT(store.getLastRotated() == lastRotated);
 
@@ -419,7 +1119,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq++), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - firstBatch, firstBatch);
 
@@ -441,7 +1141,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         BEAST_EXPECT(store.getLastRotated() == lastRotated);
 
@@ -453,7 +1153,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq++), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - lastRotated, lastRotated);
 
@@ -474,7 +1174,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         BEAST_EXPECT(store.getLastRotated() == lastRotated);
 
@@ -486,7 +1186,7 @@ public:
             BEAST_EXPECT(goodLedger(env, ledger, std::to_string(ledgerSeq++), true));
         }
 
-        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECT(syncStore(env));
 
         ledgerCheck(env, ledgerSeq - lastRotated, lastRotated);
 
@@ -634,19 +1334,45 @@ public:
 
         auto& lm = env.app().getLedgerMaster();
         LedgerIndex minSeq = 2;
-        LedgerIndex maxSeq = env.closed()->header().seq;
         auto& store = env.app().getSHAMapStore();
-        LedgerIndex lastRotated = store.getLastRotated();
         auto& netOPs = env.app().getOPs();
-        while (lastRotated != 3)
-        {
-            BEAST_EXPECT(store.rendezvous());
-            lastRotated = store.getLastRotated();
-        }
-        BEAST_EXPECTS(maxSeq == 3, std::to_string(maxSeq));
-        BEAST_EXPECTS(lm.getCompleteLedgers() == "2-3", lm.getCompleteLedgers());
+        // Which of the existing complete ledgers the store initializes
+        // lastRotated from is a timing detail, so everything below derives from
+        // the observed value rather than assuming a particular one. Spinning
+        // until it equals a hard-coded value never terminates when a different
+        // one legitimately wins.
+        //
+        // The range check and the initializeStore() one both end the testcase
+        // rather than merely reporting, because lastRotated is the only value
+        // from the store that enters minSeq. A lastRotated of 0 -- the value
+        // getLastRotated() reports until the store has been handed a validated
+        // ledger -- makes minSeq 0 below, and the minSeq - 1 and minSeq - 2
+        // ranges then underflow to first > last, which aborts a Debug build
+        // inside missingFromCompleteLedgerRange().
+        auto const extraCloses = initializeStore(env);
+        if (!BEAST_EXPECT(extraCloses.has_value()))
+            return;
+        LedgerIndex maxSeq = env.closed()->header().seq;
+        LedgerIndex lastRotated = store.getLastRotated();
+        if (!BEAST_EXPECTS(
+                lastRotated >= minSeq && lastRotated <= maxSeq, std::to_string(lastRotated)))
+            return;
+        // The BEAST_EXPECT above already returned if this is nullopt, but that
+        // is invisible to clang-tidy's optional model.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        BEAST_EXPECTS(maxSeq == 3 + *extraCloses, std::to_string(maxSeq));
+        std::stringstream initialRange;
+        initialRange << minSeq << "-" << maxSeq;
+        BEAST_EXPECTS(lm.getCompleteLedgers() == initialRange.str(), lm.getCompleteLedgers());
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq, maxSeq) == 0);
-        BEAST_EXPECT(minSeq + 1 > maxSeq - 1);
+        // The inner range is empty unless initializeStore() had to close extra
+        // ledgers, and missingFromCompleteLedgerRange() treats first > last as a
+        // precondition violation that aborts a Debug build via UNREACHABLE, so
+        // only check it when it is well formed.
+        if (minSeq + 1 <= maxSeq - 1)
+        {
+            BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 1, maxSeq - 1) == 0);
+        }
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq - 1, maxSeq + 1) == 2);
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq - 2, maxSeq - 2) == 2);
         BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq + 2, maxSeq + 2) == 2);
@@ -759,7 +1485,7 @@ public:
                 env(noop(alice));
             }
             env.close();
-            BEAST_EXPECT(store.rendezvous());
+            BEAST_EXPECT(syncStore(env));
 
             ++maxSeq;
 
@@ -825,7 +1551,7 @@ public:
                             lm.getCompleteLedgers()));
 
                     // The circuit breaker has been triggered.
-                    BEAST_EXPECT(store.rendezvous());
+                    BEAST_EXPECT(syncStore(env));
                 }
                 {
                     // Recover before the circuit breaker triggers, so the test can continue.
@@ -870,7 +1596,7 @@ public:
                     deleteSeqs.pop_back();
 
                     // Wait for the rotation to finish
-                    BEAST_EXPECT(store.rendezvous());
+                    BEAST_EXPECT(syncStore(env));
 
                     minSeq = lastRotated;
                     while (deleteSeqs.front() < minSeq)
@@ -894,8 +1620,20 @@ public:
                     failureMessage("CompleteLedgers", expected, lm.getCompleteLedgers()));
             }
             BEAST_EXPECT(lm.missingFromCompleteLedgerRange(minSeq, maxSeq) == deleteSeqs.size());
-            BEAST_EXPECT(
-                lm.missingFromCompleteLedgerRange(minSeq + 1, maxSeq - 1) == deleteSeqs.size());
+            // missingFromCompleteLedgerRange() treats first > last as a
+            // precondition violation and aborts a Debug build via UNREACHABLE.
+            // The range can only collapse if this test's model of minSeq /
+            // maxSeq has desynced from the store, so report that as a failure
+            // instead of taking down the whole unit test job.
+            if (minSeq + 1 <= maxSeq - 1)
+            {
+                BEAST_EXPECT(
+                    lm.missingFromCompleteLedgerRange(minSeq + 1, maxSeq - 1) == deleteSeqs.size());
+            }
+            else
+            {
+                BEAST_EXPECTS(false, failureMessage("range collapsed", minSeq, maxSeq));
+            }
             BEAST_EXPECT(
                 lm.missingFromCompleteLedgerRange(minSeq - 1, maxSeq + 1) == deleteSeqs.size() + 2);
             BEAST_EXPECT(
@@ -905,14 +1643,297 @@ public:
         }
     }
 
+    // Cover the branches of SHAMapStoreImp::healthWait() that decide whether
+    // the server is healthy enough to rotate, and how loudly to complain while
+    // it is not. testLedgerGaps() covers the case where a gap holds the
+    // rotation back until the circuit breaker trips; these cover the rest of
+    // the decision table.
+    void
+    testHealthWaitState()
+    {
+        testcase("healthWait server state");
+
+        using namespace std::chrono_literals;
+        using namespace test::jtx;
+
+        auto logs = std::make_unique<StoreLogs>();
+        // Not `auto const*`: waitFor() blocks, so it is not const.
+        auto* const log = logs.get();
+        Env env{*this, envconfig(onlineDelete), std::move(logs), beast::Severity::Trace};
+
+        auto& store = env.app().getSHAMapStore();
+        auto& netOPs = env.app().getOPs();
+
+        // No gap: the only thing holding the store back is the operating mode.
+        auto const parked = parkInHealthWait(env, false, OperatingMode::CONNECTED);
+        if (!parked)
+            return;
+
+        // Hold the non-FULL mode until the store has logged that it is waiting
+        // on it. With no gap, a fresh validated ledger and a mode that is not
+        // DISCONNECTED, the only check left that can report unhealthy is
+        // "mode != FULL", and a mode that is not FULL is not expected to fix
+        // itself, so the wait is logged at warn, for the full duration.
+        //
+        // Waiting for the message rather than sleeping past it is what keeps
+        // this from depending on how quickly the store gets around to sampling.
+        // The store cannot leave the wait loop while the mode stays put -- the
+        // validated ledger index does not advance, so the circuit breaker is
+        // never reached -- so the rendezvous() below is not racing it.
+        BEAST_EXPECT(log->waitFor(beast::Severity::Warning, kFullWait, 10s));
+        BEAST_EXPECT(!store.rendezvous(10ms));
+        BEAST_EXPECT(netOPs.getOperatingMode() != OperatingMode::FULL);
+        BEAST_EXPECT(netOPs.getOperatingMode() != OperatingMode::DISCONNECTED);
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+
+        // Now make the mode FULL but the validated ledger stale. Advancing the
+        // clock without closing a ledger ages the validated ledger past
+        // age_threshold_seconds, which defaults to 60. The mode check can no
+        // longer be the reason the store is unhealthy, so the age check is.
+        //
+        // This one does sleep: what is being asserted is that the store did not
+        // rotate, and 1500ms is long enough for it to have re-sampled the server
+        // at least once -- the full wait is 1000ms -- so the age check, not a
+        // stale sample of the old mode, is what held it back.
+        auto const closeTime = env.now();
+        env.timeKeeper().set(closeTime + 2min);
+        netOPs.setMode(OperatingMode::FULL);
+        BEAST_EXPECT(netOPs.getOperatingMode() == OperatingMode::FULL);
+        BEAST_EXPECT(!store.rendezvous(1500ms));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+
+        // Restore the clock. Nothing is wrong any more, so the rotation that
+        // has been waiting all along runs to completion.
+        env.timeKeeper().set(closeTime);
+        BEAST_EXPECT(syncStore(env));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->validated, std::to_string(store.getLastRotated()));
+    }
+
+    void
+    testHealthWaitGapLevels()
+    {
+        testcase("healthWait gap wait levels");
+
+        using namespace std::chrono_literals;
+        using namespace test::jtx;
+
+        auto logs = std::make_unique<StoreLogs>();
+        // Not `auto const*`: waitFor() blocks, so it is not const.
+        auto* const log = logs.get();
+        Env env{*this, envconfig(onlineDelete), std::move(logs), beast::Severity::Trace};
+
+        auto& lm = env.app().getLedgerMaster();
+        auto& store = env.app().getSHAMapStore();
+
+        auto const parked = parkInHealthWait(env, true, OperatingMode::FULL);
+        if (!parked)
+            return;
+
+        // The missing ledger is an older one; the validated ledger itself is
+        // present. The store has no reason to think the gap will close on its
+        // own, so it waits the full duration and says so at info -- not warn,
+        // because the server is otherwise healthy and has not been waiting long
+        // enough to have fallen behind.
+        BEAST_EXPECT(lm.haveLedger(parked->validated));
+        BEAST_EXPECT(!lm.haveLedger(parked->gap));
+        BEAST_EXPECT(log->waitFor(beast::Severity::Info, kFullWait, 10s));
+        // Nothing so far should have looked like a ledger being built.
+        BEAST_EXPECT(log->count(beast::Severity::Trace, kShortWait) == 0);
+        // Nothing fills the gap in, so the store is still in the wait loop.
+        BEAST_EXPECT(!store.rendezvous(10ms));
+
+        // Move the gap onto the validated ledger itself. That is the one case
+        // the store treats as transient -- the ledger is expected to be built
+        // shortly -- so it drops to trace and waits a tenth as long. Asserting
+        // that the shortened wait appears only after this swap is what pins the
+        // branch to the buildingIndex condition, rather than to anything
+        // incidental about a store that happens to be waiting.
+        lm.setLedgerRangePresent(parked->gap, parked->gap);
+        lm.clearLedger(parked->validated);
+        BEAST_EXPECT(lm.haveLedger(parked->gap));
+        BEAST_EXPECT(!lm.haveLedger(parked->validated));
+        BEAST_EXPECT(log->waitFor(beast::Severity::Trace, kShortWait, 10s));
+        BEAST_EXPECT(!store.rendezvous(10ms));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+
+        // Fill it in and the rotation completes.
+        lm.setLedgerRangePresent(parked->validated, parked->validated);
+        BEAST_EXPECT(syncStore(env));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->validated, std::to_string(store.getLastRotated()));
+    }
+
+    void
+    testHealthWaitDisconnected()
+    {
+        testcase("healthWait disconnected");
+
+        using namespace std::chrono_literals;
+        using namespace test::jtx;
+
+        Env env{*this, envconfig(onlineDelete)};
+
+        auto& lm = env.app().getLedgerMaster();
+        auto& store = env.app().getSHAMapStore();
+        auto& netOPs = env.app().getOPs();
+
+        auto const parked = parkInHealthWait(env, true, OperatingMode::FULL);
+        if (!parked)
+            return;
+
+        // While the server is FULL, the gap holds the rotation back.
+        BEAST_EXPECT(!store.rendezvous(1500ms));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+
+        // A disconnected server is not doing any ledger I/O, so the gap cannot
+        // have been caused by its own activity and will not close until it has
+        // peers again. The store deliberately takes advantage of that to get as
+        // much rotation done as possible: this is the one case where a gap does
+        // not hold online delete back at all.
+        netOPs.setMode(OperatingMode::DISCONNECTED);
+        BEAST_EXPECT(netOPs.getOperatingMode() == OperatingMode::DISCONNECTED);
+        BEAST_EXPECT(syncStore(env));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->validated, std::to_string(store.getLastRotated()));
+        // The rotation ran with the gap still present -- nothing filled it in.
+        BEAST_EXPECT(!lm.haveLedger(parked->gap));
+    }
+
+    void
+    testHealthWaitStop()
+    {
+        testcase("healthWait stop");
+
+        using namespace test::jtx;
+
+        Env env{*this, envconfig(onlineDelete)};
+
+        auto& store = env.app().getSHAMapStore();
+
+        auto const parked = parkInHealthWait(env, true, OperatingMode::FULL);
+        if (!parked)
+            return;
+
+        // Stopping the store has to break it out of the wait loop, which it
+        // would otherwise never leave: the gap is never filled in and the
+        // validated ledger index never advances to reach the circuit breaker.
+        //
+        // stop() joins the store's thread, so its return is the
+        // synchronisation point here. rendezvous() afterwards is only a
+        // cross-check, and cannot block: the store is parked in the health
+        // check that gates a rotation, so Stopping there merely leaves
+        // readyToRotate false, and run() falls through to the top of its loop,
+        // where it clears working_ and notifies before returning on stop_.
+        store.stop();
+        BEAST_EXPECT(store.rendezvous());
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+    }
+
+    // The two tests below cover the health check that run() performs between the
+    // stages of a rotation it has already committed to, which is a different
+    // decision from the one that gates the rotation in the first place: giving
+    // up here means abandoning work in progress. run() makes it at four points
+    // -- after clearing prior ledgers, after copying the validated ledger, after
+    // freshening the caches, and after clearing them -- with the same three-way
+    // switch each time, and parkMidRotation() parks the store at the first of
+    // them.
+    void
+    testHealthWaitExpiredMidRotation()
+    {
+        testcase("healthWait circuit breaker mid-rotation");
+
+        using namespace test::jtx;
+
+        auto logs = std::make_unique<StoreLogs>();
+        auto* const log = logs.get();
+        Env env{*this, envconfig(slowOnlineDelete), std::move(logs), beast::Severity::Trace};
+
+        auto& lm = env.app().getLedgerMaster();
+        auto& store = env.app().getSHAMapStore();
+
+        auto const parked = parkMidRotation(env, *log);
+        if (!parked)
+            return;
+
+        // Advance the validated ledger index past the circuit breaker. The store
+        // has had no successful health check since the gap appeared, so once the
+        // index has moved max_waiting_ledgers on from the last one that did
+        // succeed, it abandons the rotation instead of waiting for the gap
+        // forever. Nothing here fills the gap in.
+        for (int i = 0; i < kMinWaitingLedgers; ++i)
+        {
+            env.close();
+            BEAST_EXPECT(!lm.haveLedger(parked->gap));
+        }
+
+        // Abandoning the rotation returns the store to waiting for work, so it
+        // reports itself idle -- but with lastRotated left where it started,
+        // unlike the completed rotation parkMidRotation() drove first.
+        BEAST_EXPECT(syncStore(env));
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+        BEAST_EXPECT(log->count(kExpired) > 0);
+        BEAST_EXPECTS(log->count(kFinished) == 1, std::to_string(log->count(kFinished)));
+        BEAST_EXPECT(!lm.haveLedger(parked->gap));
+    }
+
+    void
+    testHealthWaitStopMidRotation()
+    {
+        testcase("healthWait stop mid-rotation");
+
+        using namespace test::jtx;
+
+        auto logs = std::make_unique<StoreLogs>();
+        auto* const log = logs.get();
+        Env env{*this, envconfig(slowOnlineDelete), std::move(logs), beast::Severity::Trace};
+
+        auto& store = env.app().getSHAMapStore();
+
+        auto const parked = parkMidRotation(env, *log);
+        if (!parked)
+            return;
+
+        // Stopping has to break the store out of the rotation, which it would
+        // otherwise never leave: the gap is never filled in and the validated
+        // ledger index never advances to reach the circuit breaker. Note that
+        // being stopped outranks being healthy -- the health check reports it
+        // even when nothing is wrong with the server -- so this does not depend
+        // on the store still being parked when stop() lands.
+        //
+        // stop() joins the store's thread, so its return is the synchronisation
+        // point. Deliberately do not call the untimed rendezvous() afterwards:
+        // run() returns without clearing working_, so it would block forever.
+        store.stop();
+        BEAST_EXPECTS(
+            store.getLastRotated() == parked->lastRotated, std::to_string(store.getLastRotated()));
+        // The rotation was abandoned rather than completed, and the circuit
+        // breaker was not what abandoned it.
+        BEAST_EXPECTS(log->count(kFinished) == 1, std::to_string(log->count(kFinished)));
+        BEAST_EXPECTS(log->count(kExpired) == 0, std::to_string(log->count(kExpired)));
+    }
+
     void
     run() override
     {
+        testConfig();
         testClear();
         testAutomatic();
         testCanDelete();
         testRotate();
         testLedgerGaps();
+        testHealthWaitState();
+        testHealthWaitGapLevels();
+        testHealthWaitDisconnected();
+        testHealthWaitStop();
+        testHealthWaitExpiredMidRotation();
+        testHealthWaitStopMidRotation();
     }
 };
 
diff --git a/src/test/app/Sponsor_test.cpp b/src/test/app/Sponsor_test.cpp
index e58d8c9f8f..71d968014f 100644
--- a/src/test/app/Sponsor_test.cpp
+++ b/src/test/app/Sponsor_test.cpp
@@ -376,11 +376,11 @@ public:
     }
 
     void
-    testSingleSigning()
+    testSingleSigning(FeatureBitset features)
     {
         testcase("Single signing");
         using namespace test::jtx;
-        Env env{*this, testableAmendments()};
+        Env env{*this, features};
         Account const alice("alice");
         Account const sponsor("sponsor");
         Account const invalid("invalid");
@@ -415,11 +415,11 @@ public:
     }
 
     void
-    testMultiSigning()
+    testMultiSigning(FeatureBitset features)
     {
         testcase("Multi signing");
         using namespace test::jtx;
-        Env env{*this, testableAmendments()};
+        Env env{*this, features};
         Account const alice("alice");
         Account const bob("bob");
         Account const sponsor("sponsor");
@@ -5467,13 +5467,12 @@ public:
         using namespace test::jtx;
         using namespace std::chrono_literals;
 
-        // Finishing a self-escrow (source == destination) whose trust line
-        // was deleted while the escrow was outstanding auto-creates the line,
-        // and the outcome of that reserve check depends on whether the escrow
-        // reserve is released before delivery (Sponsor) or after (legacy).
-        // With the source's balance in the one-increment window
-        // [reserve(1), reserve(2)), the legacy order requires reserve(2) and
-        // fails, while the Sponsor order requires reserve(1) and succeeds.
+        // Finishing a self-escrow (source == destination) whose trust line was
+        // deleted while the escrow was outstanding auto-creates the line. With
+        // the source's balance in the one-increment window
+        // [reserve(1), reserve(2)), the finish succeeds only when the escrow
+        // reserve is released before delivery, which either featureSponsor or
+        // fixCleanup3_4_0 does.
         auto runTest = [&](FeatureBitset features, TER expected) {
             Account const alice("alice");
             Account const gw("gw");
@@ -5538,11 +5537,9 @@ public:
             }
         };
 
-        // Pre-amendment: legacy order — the escrow still counts against the
-        // reserve while the auto-created line is checked.
-        runTest(testableAmendments() - featureSponsor, tecNO_LINE_INSUF_RESERVE);
-
-        // Post-amendment: the escrow reserve is recycled into the new line.
+        runTest(testableAmendments() - featureSponsor - fixCleanup3_4_0, tecNO_LINE_INSUF_RESERVE);
+        runTest(testableAmendments() - featureSponsor, tesSUCCESS);
+        runTest(testableAmendments() - fixCleanup3_4_0, tesSUCCESS);
         runTest(testableAmendments(), tesSUCCESS);
     }
 
@@ -5585,9 +5582,9 @@ public:
             Ter(tesSUCCESS));
         env.close();
 
-        // The same helper (deltaAssetsTxAccount) drives the withdraw path, so a
-        // fee-sponsored withdrawal back to the depositor's own account also
-        // passes on the destination side.
+        // The same fee-correction logic (ValidVault::deltaAssetsForParty)
+        // drives the withdraw path, so a fee-sponsored withdrawal back to
+        // the depositor's own account also passes on the destination side.
         env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = xrpAsset(50)}),
             Fee(XRP(1)),
             sponsor::As(sponsor, spfSponsorFee),
@@ -5678,8 +5675,12 @@ protected:
         testInvalidSponsorshipSet();
         testPseudoAccountSponsorship();
 
-        testSingleSigning();
-        testMultiSigning();
+        // The signing prefix of an alternate signature field changes with
+        // fixCleanup3_4_0, so sign and verify under both rule sets.
+        testSingleSigning(jtx::testableAmendments());
+        testSingleSigning(jtx::testableAmendments() - fixCleanup3_4_0);
+        testMultiSigning(jtx::testableAmendments());
+        testMultiSigning(jtx::testableAmendments() - fixCleanup3_4_0);
 
         testInvalidSponsorField();
 
diff --git a/src/test/app/invariants/InvariantsBase.cpp b/src/test/app/invariants/InvariantsBase.cpp
index a573cc45ea..650a21cb07 100644
--- a/src/test/app/invariants/InvariantsBase.cpp
+++ b/src/test/app/invariants/InvariantsBase.cpp
@@ -10,11 +10,13 @@
 #include <test/jtx/vault.h>
 #include <test/unit_test/SuiteJournal.h>
 
+#include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/ledger/ApplyView.h>
 #include <xrpl/ledger/OpenView.h>
+#include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Keylet.h>
@@ -31,6 +33,7 @@
 #include <xrpl/tx/applySteps.h>
 
 #include <chrono>
+#include <cstdint>
 #include <initializer_list>
 #include <memory>
 #include <source_location>
@@ -206,4 +209,33 @@ InvariantsBase::createLoanBroker(
     return loanBrokerKeylet;
 }
 
+SLE::pointer
+InvariantsBase::makeLoanSle(
+    uint256 const& loanBrokerID,
+    std::uint32_t loanSeq,
+    AccountID const& borrower)
+{
+    auto sleLoan =
+        std::make_shared<SLE>(keylet::loan(loanBrokerID, SeqProxy::rawSequence(loanSeq)));
+    // SoeRequired fields.
+    sleLoan->at(sfLoanBrokerID) = loanBrokerID;
+    sleLoan->at(sfLoanSequence) = loanSeq;
+    sleLoan->at(sfBorrower) = borrower;
+    sleLoan->at(sfStartDate) = 0u;
+    sleLoan->at(sfPaymentInterval) = 1u;
+    sleLoan->at(sfPeriodicPayment) = Number(1);
+    // SoeDefault fields, materialized so that an invariant reading them through
+    // at() does not throw on this hand-built entry.
+    sleLoan->at(sfLoanServiceFee) = Number(0);
+    sleLoan->at(sfLatePaymentFee) = Number(0);
+    sleLoan->at(sfClosePaymentFee) = Number(0);
+    sleLoan->at(sfPrincipalOutstanding) = Number(0);
+    sleLoan->at(sfTotalValueOutstanding) = Number(0);
+    sleLoan->at(sfManagementFeeOutstanding) = Number(0);
+    sleLoan->setFieldU32(sfPaymentRemaining, 0);
+    sleLoan->makeFieldPresent(sfOwnerNode);
+    sleLoan->makeFieldPresent(sfLoanBrokerNode);
+    return sleLoan;
+}
+
 }  // namespace xrpl::test
diff --git a/src/test/app/invariants/InvariantsBase.h b/src/test/app/invariants/InvariantsBase.h
index 73319d0ef8..6b4327eb78 100644
--- a/src/test/app/invariants/InvariantsBase.h
+++ b/src/test/app/invariants/InvariantsBase.h
@@ -4,7 +4,11 @@
 #include <test/jtx/Env.h>
 #include <test/jtx/amount.h>
 
+#include <xrpld/app/main/Application.h>
+
+#include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Keylet.h>
 #include <xrpl/protocol/STObject.h>
@@ -14,6 +18,7 @@
 #include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/tx/ApplyContext.h>
 
+#include <cstdint>
 #include <functional>
 #include <initializer_list>
 #include <memory>
@@ -117,6 +122,13 @@ protected:
 
     Keylet
     createLoanBroker(jtx::Account const& a, jtx::Env& env, jtx::PrettyAsset const& asset);
+
+    // Build an ltLOAN SLE with every SoeRequired field explicitly set and
+    // every SoeDefault field the invariants read via `at()` materialized, so
+    // rawInsert-based tests don't accidentally trip an unrelated invariant
+    // or throw from a missing SoeDefault field.
+    static SLE::pointer
+    makeLoanSle(uint256 const& loanBrokerID, std::uint32_t loanSeq, AccountID const& borrower);
 };
 
 }  // namespace xrpl::test
diff --git a/src/test/app/invariants/InvariantsMisc_test.cpp b/src/test/app/invariants/InvariantsMisc_test.cpp
index b0b6c02f5c..a0084ac530 100644
--- a/src/test/app/invariants/InvariantsMisc_test.cpp
+++ b/src/test/app/invariants/InvariantsMisc_test.cpp
@@ -4,10 +4,13 @@
 #include <test/jtx/Env.h>
 #include <test/jtx/TestHelpers.h>
 #include <test/jtx/amount.h>
+#include <test/jtx/pay.h>
 #include <test/jtx/token.h>
+#include <test/jtx/trust.h>
 #include <test/jtx/vault.h>
 #include <test/unit_test/SuiteJournal.h>
 
+#include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/beast/unit_test/suite.h>
@@ -43,6 +46,7 @@
 #include <xrpl/tx/invariants/InvariantRunner.h>
 
 #include <array>
+#include <cstdint>
 #include <functional>
 #include <initializer_list>
 #include <memory>
@@ -757,7 +761,255 @@ class InvariantsMisc_test : public InvariantsBase
             }
         }
 
-        // TODO: Loan Object
+        // Loan flag immutability lives in NoModifiedUnmodifiableFields's
+        // ltLOAN case: lsfLoanOverpayment must never toggle in either
+        // direction, and lsfLoanDefault (gated on featureLendingProtocolV1_1)
+        // may only transition from unset to set. Each case needs a loan that
+        // already exists in the base ledger, so that the apply-view modification
+        // is seen as a before/after change rather than an insertion.
+        {
+            struct Case
+            {
+                std::uint32_t before;
+                std::uint32_t after;
+                std::string expected;
+            };
+            auto const cases = std::to_array<Case>({
+                {.before = lsfLoanOverpayment,
+                 .after = 0,
+                 .expected = "lsfLoanOverpayment flag toggled on immutable ledger entry"},
+                {.before = 0,
+                 .after = lsfLoanOverpayment,
+                 .expected = "lsfLoanOverpayment flag toggled on immutable ledger entry"},
+                {.before = lsfLoanDefault,
+                 .after = 0,
+                 .expected = "lsfLoanDefault flag cleared on immutable ledger entry"},
+            });
+
+            for (auto const& c : cases)
+            {
+                Env env{*this, all_};
+                Account const a1{"A1"};
+                env.fund(XRP(1000), a1);
+                env.close();
+
+                OpenView ov{*env.current()};
+
+                auto const brokerKeylet =
+                    keylet::loanBroker(a1.id(), SeqProxy::rawSequence(ov.seq()));
+                auto const loanKeylet = keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+                {
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a1.id());
+                    sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(150);
+                    sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                    sleLoan->setFieldU32(sfFlags, c.before);
+                    ov.rawInsert(sleLoan);
+                }
+
+                STTx const tx{ttACCOUNT_SET, [](STObject&) {}};
+                test::StreamSink sink{beast::Severity::Warning};
+                beast::Journal const jlog{sink};
+                ApplyContext ac{
+                    env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+                CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+                auto sleLoan = ac.view().peek(loanKeylet);
+                if (!BEAST_EXPECT(sleLoan))
+                    continue;
+                sleLoan->setFieldU32(sfFlags, c.after);
+                ac.view().update(sleLoan);
+
+                auto transactor = makeTransactor(ac);
+                if (!BEAST_EXPECT(transactor))
+                    continue;
+                TER const result = transactor->checkInvariants(
+                    tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+                BEAST_EXPECT(result == tecINVARIANT_FAILED);
+                BEAST_EXPECT(sink.messages().str().contains(c.expected));
+            }
+        }
+
+        // Pre-featureLendingProtocolV1_1 sibling of the lsfLoanOverpayment
+        // cases above: the same set-once immutability was originally enforced
+        // by ValidLoan::finalize, so with V1_1 disabled toggling the flag
+        // must trip that legacy check instead. lsfLoanDefault immutability
+        // did not exist pre-V1_1 and is not tested here.
+        {
+            auto const cases = std::to_array<std::pair<std::uint32_t, std::uint32_t>>({
+                {lsfLoanOverpayment, 0},
+                {0, lsfLoanOverpayment},
+            });
+
+            for (auto const& [before, after] : cases)
+            {
+                Env env{*this, all_ - featureLendingProtocolV1_1};
+                Account const a1{"A1"};
+                env.fund(XRP(1000), a1);
+                env.close();
+
+                OpenView ov{*env.current()};
+
+                auto const brokerKeylet =
+                    keylet::loanBroker(a1.id(), SeqProxy::rawSequence(ov.seq()));
+                auto const loanKeylet = keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+                {
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a1.id());
+                    sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(150);
+                    sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                    sleLoan->setFieldU32(sfFlags, before);
+                    ov.rawInsert(sleLoan);
+                }
+
+                STTx const tx{ttACCOUNT_SET, [](STObject&) {}};
+                test::StreamSink sink{beast::Severity::Warning};
+                beast::Journal const jlog{sink};
+                ApplyContext ac{
+                    env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+                CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+                auto sleLoan = ac.view().peek(loanKeylet);
+                if (!BEAST_EXPECT(sleLoan))
+                    continue;
+                sleLoan->setFieldU32(sfFlags, after);
+                ac.view().update(sleLoan);
+
+                auto transactor = makeTransactor(ac);
+                if (!BEAST_EXPECT(transactor))
+                    continue;
+                TER const result = transactor->checkInvariants(
+                    tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+                BEAST_EXPECT(result == tecINVARIANT_FAILED);
+                BEAST_EXPECT(sink.messages().str().contains("Loan Overpayment flag changed"));
+            }
+        }
+
+        // Under featureLendingProtocolV1_1, ValidLoan::finalize requires
+        // interest due (total value minus principal and management fee) to be
+        // non-negative after each value is rounded to sfLoanScale. Test zero,
+        // each way to produce a one-unit deficit, and a two-unit deficit. At
+        // scale 0, an XRP-backed broker rejects any deficit, while an
+        // IOU-backed one permits one unit of rounding tolerance.
+        {
+            struct Case
+            {
+                Number totalValue;
+                Number principal;
+                Number managementFee;
+                bool expectFireIntegral;
+                bool expectFireTolerant;
+            };
+            // The first case sits exactly at the boundary, the middle three
+            // perturb one component so that interest due is -1, which is within
+            // the tolerance, and the last overshoots it at -2.
+            auto const cases = std::to_array<Case>({
+                {.totalValue = Number(100),
+                 .principal = Number(100),
+                 .managementFee = Number(0),
+                 .expectFireIntegral = false,
+                 .expectFireTolerant = false},
+                {.totalValue = Number(99),
+                 .principal = Number(100),
+                 .managementFee = Number(0),
+                 .expectFireIntegral = true,
+                 .expectFireTolerant = false},
+                {.totalValue = Number(100),
+                 .principal = Number(101),
+                 .managementFee = Number(0),
+                 .expectFireIntegral = true,
+                 .expectFireTolerant = false},
+                {.totalValue = Number(100),
+                 .principal = Number(100),
+                 .managementFee = Number(1),
+                 .expectFireIntegral = true,
+                 .expectFireTolerant = false},
+                {.totalValue = Number(98),
+                 .principal = Number(100),
+                 .managementFee = Number(0),
+                 .expectFireIntegral = true,
+                 .expectFireTolerant = true},
+            });
+
+            for (bool const integralAsset : {true, false})
+            {
+                for (auto const& c : cases)
+                {
+                    Env env{*this, all_};
+                    Account const a1{"A1"};
+                    Account const issuer{"issuer"};
+                    env.fund(XRP(1000), a1, issuer);
+                    env.close();
+
+                    // The check reads the broker's vault asset to decide
+                    // whether the rounding tolerance applies, so both
+                    // branches need a real broker over the relevant asset.
+                    auto const asset = [&]() -> PrettyAsset {
+                        if (integralAsset)
+                            return PrettyAsset{xrpIssue(), 1'000'000};
+                        PrettyAsset const iouAsset = issuer["IOU"];
+                        env(trust(a1, iouAsset(1000)));
+                        env(pay(issuer, a1, iouAsset(1000)));
+                        env.close();
+                        return iouAsset;
+                    }();
+
+                    auto const brokerKeylet = this->createLoanBroker(a1, env, asset);
+                    if (!BEAST_EXPECT(env.le(brokerKeylet)))
+                        continue;
+                    env.close();
+
+                    OpenView ov{*env.current()};
+
+                    auto const loanKeylet =
+                        keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+                    // Seed a loan whose interest due sits at the boundary. The
+                    // apply-view update below moves it.
+                    {
+                        auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a1.id());
+                        sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                        sleLoan->at(sfTotalValueOutstanding) = Number(100);
+                        sleLoan->at(sfManagementFeeOutstanding) = Number(0);
+                        sleLoan->at(sfLoanScale) = 0;
+                        sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                        ov.rawInsert(sleLoan);
+                    }
+
+                    STTx const tx{ttACCOUNT_SET, [](STObject&) {}};
+                    test::StreamSink sink{beast::Severity::Warning};
+                    beast::Journal const jlog{sink};
+                    ApplyContext ac{
+                        env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+                    CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+                    auto sleLoan = ac.view().peek(loanKeylet);
+                    if (!BEAST_EXPECT(sleLoan))
+                        continue;
+                    sleLoan->at(sfTotalValueOutstanding) = c.totalValue;
+                    sleLoan->at(sfPrincipalOutstanding) = c.principal;
+                    sleLoan->at(sfManagementFeeOutstanding) = c.managementFee;
+                    ac.view().update(sleLoan);
+
+                    auto transactor = makeTransactor(ac);
+                    if (!BEAST_EXPECT(transactor))
+                        continue;
+                    TER const result = transactor->checkInvariants(
+                        tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+                    auto const messages = sink.messages().str();
+                    if (integralAsset ? c.expectFireIntegral : c.expectFireTolerant)
+                    {
+                        BEAST_EXPECT(result == tecINVARIANT_FAILED);
+                        BEAST_EXPECT(messages.contains("Loan interest due is negative"));
+                    }
+                    else
+                    {
+                        // Other invariants may still fire on this raw-inserted
+                        // loan, so only assert the specific message is absent.
+                        BEAST_EXPECT(!messages.contains("Loan interest due is negative"));
+                    }
+                }
+            }
+        }
 
         // VaultKind, SubscriptionDate and RedemptionDate are immutable once set at creation.
         // Enforced by NoModifiedUnmodifiableFields on ltVAULT via kFieldChanged.
diff --git a/src/test/app/invariants/InvariantsPseudoAccount_test.cpp b/src/test/app/invariants/InvariantsPseudoAccount_test.cpp
index c43e73aca8..6c8a710bef 100644
--- a/src/test/app/invariants/InvariantsPseudoAccount_test.cpp
+++ b/src/test/app/invariants/InvariantsPseudoAccount_test.cpp
@@ -7,18 +7,23 @@
 #include <test/jtx/pay.h>
 #include <test/jtx/trust.h>
 #include <test/jtx/vault.h>
+#include <test/unit_test/SuiteJournal.h>
 
 #include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/beast/utility/Journal.h>
 #include <xrpl/ledger/ApplyView.h>
+#include <xrpl/ledger/OpenView.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
 #include <xrpl/ledger/helpers/DirectoryHelpers.h>
 #include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
 #include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/Keylet.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Rules.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STLedgerEntry.h>
 #include <xrpl/protocol/STObject.h>
@@ -28,6 +33,7 @@
 #include <xrpl/protocol/TxFormats.h>
 #include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/tx/ApplyContext.h>
+#include <xrpl/tx/Transactor.h>
 #include <xrpl/tx/applySteps.h>
 
 #include <array>
@@ -43,6 +49,8 @@ namespace xrpl::test {
 
 class InvariantsPseudoAccount_test : public InvariantsBase
 {
+    FeatureBitset const all_{test::jtx::testableAmendments()};
+
     void
     testValidPseudoAccounts()
     {
@@ -445,6 +453,281 @@ class InvariantsPseudoAccount_test : public InvariantsBase
                 STTx{ttLOAN_BROKER_SET, [](STObject& tx) {}},
                 {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
                 createLoanBroker);
+
+            // Deleting the IOU holding while leaving the broker unchanged must
+            // still expose CoverAvailable exceeding the now-zero balance: the
+            // broker is discovered through the deleted trust line. XRP has no
+            // holding SLE, while deleting an MPToken triggers other invariants,
+            // so IOU isolates this check. Verify that fixCleanup3_1_3 gates it
+            // by expecting failure only when the amendment is enabled.
+            if (assetType == Asset::IOU)
+            {
+                Keylet brokerKeylet = keylet::amendments();
+                Preclose const createBrokerWithCover =
+                    [&, this](Account const& alice, Account const& issuer, Env& env) {
+                        auto const asset = setupAsset(alice, issuer, env);
+                        brokerKeylet = this->createLoanBroker(alice, env, asset);
+                        if (!BEAST_EXPECT(env.le(brokerKeylet)))
+                            return false;
+                        env(loan_broker::coverDeposit(alice, brokerKeylet.key, asset(10)));
+                        env.close();
+                        return BEAST_EXPECT(env.le(brokerKeylet));
+                    };
+
+                Precheck const deleteHolding =
+                    [&](Account const&, Account const&, ApplyContext& ac) {
+                        if (brokerKeylet.type != ltLOAN_BROKER)
+                            return false;
+                        // Read (don't touch) the broker so it is only found via
+                        // the deleted holding, not as a modified entry.
+                        auto const sleBroker = ac.view().read(brokerKeylet);
+                        if (!BEAST_EXPECT(sleBroker))
+                            return false;
+                        auto const pseudoAccountID = sleBroker->at(sfAccount);
+
+                        // Erase every holding in the pseudo-account directory
+                        // and the directory root itself, mirroring a bug that
+                        // removed the cover holding without zeroing
+                        // CoverAvailable. Removing the root also keeps the
+                        // zero-OwnerCount directory check from firing first.
+                        auto sleDir = ac.view().peek(keylet::ownerDir(pseudoAccountID));
+                        if (!BEAST_EXPECT(sleDir))
+                            return false;
+                        for (auto const& index : sleDir->getFieldV256(sfIndexes))
+                        {
+                            if (auto holding = ac.view().peek(keylet::unchecked(index)))
+                            {
+                                ac.view().erase(holding);
+                            }
+                        }
+                        ac.view().erase(sleDir);
+                        return true;
+                    };
+
+                // With fixCleanup3_1_3: the invariant fires.
+                doInvariantCheck(
+                    makeEnv(all_),
+                    {{"Loan Broker cover available is greater than pseudo-account asset balance"}},
+                    deleteHolding,
+                    XRPAmount{},
+                    STTx{ttACCOUNT_SET, [](STObject&) {}},
+                    {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+                    createBrokerWithCover);
+
+                // Without fixCleanup3_1_3: the same state is silently accepted.
+                doInvariantCheck(
+                    makeEnv(all_ - fixCleanup3_1_3),
+                    {},
+                    deleteHolding,
+                    XRPAmount{},
+                    STTx{ttACCOUNT_SET, [](STObject&) {}},
+                    {tesSUCCESS, tesSUCCESS},
+                    createBrokerWithCover);
+            }
+
+            // A LoanBroker may only be removed by ttLOAN_BROKER_DELETE. Erase
+            // the broker in the apply view under a non-delete tx type and
+            // expect the deletion-tx invariant to fire.
+            doInvariantCheck(
+                {{"Loan Broker deleted by a transaction other than LoanBrokerDelete"}},
+                [&](Account const&, Account const&, ApplyContext& ac) {
+                    if (loanBrokerKeylet.type != ltLOAN_BROKER)
+                        return false;
+                    auto sleBroker = ac.view().peek(loanBrokerKeylet);
+                    if (!BEAST_EXPECT(sleBroker))
+                        return false;
+                    ac.view().erase(sleBroker);
+                    return true;
+                },
+                XRPAmount{},
+                STTx{ttACCOUNT_SET, [](STObject&) {}},
+                {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+                createLoanBroker);
+        }
+
+        // A LoanBrokerDelete must not remove a broker whose pre-transaction
+        // DebtTotal is non-zero. visitEntry captures `before` from the parent
+        // view, so the DebtTotal must be seeded in the OpenView before the
+        // ApplyContext is constructed; a Precheck modification would only
+        // land in the applyView (visible as `after`) and would leave `before`
+        // at the createLoanBroker-produced zero.
+        {
+            Env env{*this};
+            Account const a1{"A1"};
+            Account const a2{"A2"};
+            env.fund(XRP(1000), a1, a2);
+            env.close();
+
+            PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+            auto const brokerKeylet = createLoanBroker(a1, env, xrpAsset);
+            if (!BEAST_EXPECT(env.le(brokerKeylet)))
+                return;
+            env.close();
+
+            OpenView ov{*env.current()};
+
+            // Seed a non-zero DebtTotal in the base view so `before` at
+            // visitEntry time reports it.
+            {
+                auto const sleBrokerRead = ov.read(brokerKeylet);
+                if (!BEAST_EXPECT(sleBrokerRead))
+                    return;
+                auto sleBroker = std::make_shared<SLE>(*sleBrokerRead);
+                sleBroker->at(sfDebtTotal) = Number(1);
+                ov.rawReplace(sleBroker);
+            }
+
+            STTx const tx{ttLOAN_BROKER_DELETE, [](STObject&) {}};
+            test::StreamSink sink{beast::Severity::Warning};
+            beast::Journal const jlog{sink};
+            ApplyContext ac{
+                env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+            CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+            auto sleBroker = ac.view().peek(brokerKeylet);
+            if (!BEAST_EXPECT(sleBroker))
+                return;
+            ac.view().erase(sleBroker);
+
+            auto transactor = makeTransactor(ac);
+            if (!BEAST_EXPECT(transactor))
+                return;
+            TER const result = transactor->checkInvariants(
+                tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+            BEAST_EXPECT(result == tecINVARIANT_FAILED);
+            BEAST_EXPECT(
+                sink.messages().str().contains("Loan Broker deleted with non-zero debt total"));
+        }
+
+        // Residual DebtTotal dust that rounds to zero at the vault asset's
+        // scale must not trip the invariant: LoanBrokerDelete::preclaim
+        // deliberately permits it, so the invariant must not be stricter.
+        // Other invariants may still object to a hand-erased broker, so only
+        // the absence of the DebtTotal complaint is asserted.
+        {
+            Env env{*this};
+            Account const a1{"A1"};
+            Account const a2{"A2"};
+            env.fund(XRP(1000), a1, a2);
+            env.close();
+
+            PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+            auto const brokerKeylet = createLoanBroker(a1, env, xrpAsset);
+            if (!BEAST_EXPECT(env.le(brokerKeylet)))
+                return;
+            env.close();
+
+            OpenView ov{*env.current()};
+
+            // A thousandth of a drop: non-zero, but zero once quantized to XRP.
+            {
+                auto const sleBrokerRead = ov.read(brokerKeylet);
+                if (!BEAST_EXPECT(sleBrokerRead))
+                    return;
+                auto sleBroker = std::make_shared<SLE>(*sleBrokerRead);
+                sleBroker->at(sfDebtTotal) = Number(1, -3);
+                ov.rawReplace(sleBroker);
+            }
+
+            STTx const tx{ttLOAN_BROKER_DELETE, [](STObject&) {}};
+            test::StreamSink sink{beast::Severity::Warning};
+            beast::Journal const jlog{sink};
+            ApplyContext ac{
+                env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+            CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+            auto sleBroker = ac.view().peek(brokerKeylet);
+            if (!BEAST_EXPECT(sleBroker))
+                return;
+            ac.view().erase(sleBroker);
+
+            auto transactor = makeTransactor(ac);
+            if (!BEAST_EXPECT(transactor))
+                return;
+            [[maybe_unused]] TER const result = transactor->checkInvariants(
+                tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+            BEAST_EXPECT(
+                !sink.messages().str().contains("Loan Broker deleted with non-zero debt total"));
+        }
+
+        // A LoanBrokerDelete must not remove a broker whose pre-transaction
+        // OwnerCount is non-zero. DebtTotal is left at zero so the earlier
+        // check passes and the OwnerCount check is what fires.
+        {
+            Env env{*this};
+            Account const a1{"A1"};
+            Account const a2{"A2"};
+            env.fund(XRP(1000), a1, a2);
+            env.close();
+
+            PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+            auto const brokerKeylet = createLoanBroker(a1, env, xrpAsset);
+            if (!BEAST_EXPECT(env.le(brokerKeylet)))
+                return;
+            env.close();
+
+            OpenView ov{*env.current()};
+
+            {
+                auto const sleBrokerRead = ov.read(brokerKeylet);
+                if (!BEAST_EXPECT(sleBrokerRead))
+                    return;
+                auto sleBroker = std::make_shared<SLE>(*sleBrokerRead);
+                sleBroker->at(sfOwnerCount) = 1;
+                ov.rawReplace(sleBroker);
+            }
+
+            STTx const tx{ttLOAN_BROKER_DELETE, [](STObject&) {}};
+            test::StreamSink sink{beast::Severity::Warning};
+            beast::Journal const jlog{sink};
+            ApplyContext ac{
+                env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+            CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+            auto sleBroker = ac.view().peek(brokerKeylet);
+            if (!BEAST_EXPECT(sleBroker))
+                return;
+            ac.view().erase(sleBroker);
+
+            auto transactor = makeTransactor(ac);
+            if (!BEAST_EXPECT(transactor))
+                return;
+            TER const result = transactor->checkInvariants(
+                tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+            BEAST_EXPECT(result == tecINVARIANT_FAILED);
+            BEAST_EXPECT(
+                sink.messages().str().contains("Loan Broker deleted with non-zero owner count"));
+        }
+
+        // Only one LoanBroker may be deleted per transaction. Create two
+        // brokers under different owners, then erase both in the apply view
+        // and expect the multi-deletion invariant to fire.
+        {
+            Keylet loanBrokerKeylet1 = keylet::amendments();
+            Keylet loanBrokerKeylet2 = keylet::amendments();
+            Preclose const createTwoBrokers = [&, this](
+                                                  Account const& a1, Account const& a2, Env& env) {
+                PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+                loanBrokerKeylet1 = this->createLoanBroker(a1, env, xrpAsset);
+                loanBrokerKeylet2 = this->createLoanBroker(a2, env, xrpAsset);
+                return BEAST_EXPECT(env.le(loanBrokerKeylet1) && env.le(loanBrokerKeylet2));
+            };
+
+            doInvariantCheck(
+                {{"more than one Loan Broker deleted in a single transaction"}},
+                [&](Account const&, Account const&, ApplyContext& ac) {
+                    auto sle1 = ac.view().peek(loanBrokerKeylet1);
+                    auto sle2 = ac.view().peek(loanBrokerKeylet2);
+                    if (!BEAST_EXPECT(sle1 && sle2))
+                        return false;
+                    ac.view().erase(sle1);
+                    ac.view().erase(sle2);
+                    return true;
+                },
+                XRPAmount{},
+                STTx{ttLOAN_BROKER_DELETE, [](STObject&) {}},
+                {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+                createTwoBrokers);
         }
     }
 
diff --git a/src/test/app/invariants/InvariantsVault_test.cpp b/src/test/app/invariants/InvariantsVault_test.cpp
index 4b6002580b..dcf783a1b5 100644
--- a/src/test/app/invariants/InvariantsVault_test.cpp
+++ b/src/test/app/invariants/InvariantsVault_test.cpp
@@ -8,12 +8,16 @@
 #include <test/jtx/sig.h>
 #include <test/jtx/trust.h>
 #include <test/jtx/vault.h>
+#include <test/unit_test/SuiteJournal.h>
 
 #include <xrpl/basics/Number.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/beast/utility/Zero.h>
 #include <xrpl/ledger/ApplyView.h>
+#include <xrpl/ledger/OpenView.h>
 #include <xrpl/ledger/helpers/AccountRootHelpers.h>
 #include <xrpl/ledger/helpers/DirectoryHelpers.h>
 #include <xrpl/protocol/AccountID.h>
@@ -38,10 +42,12 @@
 #include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/protocol/jss.h>
 #include <xrpl/tx/ApplyContext.h>
+#include <xrpl/tx/Transactor.h>
 #include <xrpl/tx/applySteps.h>
 #include <xrpl/tx/invariants/VaultInvariant.h>
 
 #include <array>
+#include <chrono>
 #include <cstdint>
 #include <functional>
 #include <initializer_list>
@@ -68,6 +74,19 @@ class InvariantsVault_test : public InvariantsBase
             AccountID account;
             int amount;
         };
+        // Parameters for a synthetic loan object created alongside a vault
+        // adjustment. The interest due booked to the vault is
+        // totalValueOutstanding - principalOutstanding - managementFeeOutstanding.
+        struct LoanParams
+        {
+            int principalOutstanding = 0;
+            int totalValueOutstanding = 0;
+            int managementFeeOutstanding = 0;
+            AccountID borrower = beast::kZero;
+            // Broker the created loan references. Left unset when the test does
+            // not depend on the broker resolving to a real ledger entry.
+            uint256 brokerKey = beast::kZero;
+        };
         struct Adjustments
         {
             // NOLINTBEGIN(readability-redundant-member-init)
@@ -79,6 +98,10 @@ class InvariantsVault_test : public InvariantsBase
             std::optional<int> vaultAssets = std::nullopt;
             std::optional<AccountAmount> accountAssets = std::nullopt;
             std::optional<AccountAmount> accountShares = std::nullopt;
+            std::optional<LoanParams> createLoan = std::nullopt;
+            // Number of loan objects to create (only used when createLoan is
+            // set); a valid loan set creates exactly one.
+            int loanCount = 1;
             // NOLINTEND(readability-redundant-member-init)
         };
         constexpr auto kAdjust = [&](ApplyView& ac, xrpl::Keylet keylet, Adjustments args) {
@@ -186,6 +209,26 @@ class InvariantsVault_test : public InvariantsBase
                 (*sleMPToken)[sfMPTAmount] = addSigned(*(*sleMPToken)[sfMPTAmount], pair.amount);
                 ac.update(sleMPToken);
             }
+
+            if (args.createLoan)
+            {
+                auto const& lp = *args.createLoan;
+                bool const anyOutstanding = lp.principalOutstanding != 0 ||
+                    lp.totalValueOutstanding != 0 || lp.managementFeeOutstanding != 0;
+                // The vault key stands in for an unset broker: it keeps the loan
+                // keylet distinct per vault while resolving to no broker.
+                uint256 const brokerKey = lp.brokerKey != beast::kZero ? lp.brokerKey : keylet.key;
+                for (std::uint32_t seq = 1; seq <= static_cast<std::uint32_t>(args.loanCount);
+                     ++seq)
+                {
+                    auto sleLoan = makeLoanSle(brokerKey, seq, lp.borrower);
+                    sleLoan->at(sfPrincipalOutstanding) = Number(lp.principalOutstanding);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(lp.totalValueOutstanding);
+                    sleLoan->at(sfManagementFeeOutstanding) = Number(lp.managementFeeOutstanding);
+                    sleLoan->setFieldU32(sfPaymentRemaining, anyOutstanding ? 1 : 0);
+                    ac.insert(sleLoan);
+                }
+            }
             return true;
         };
 
@@ -206,7 +249,10 @@ class InvariantsVault_test : public InvariantsBase
 
         Account const a3{"A3"};
         Account const a4{"A4"};
-        auto const precloseXrp = [&](Account const& a1, Account const& a2, Env& env) -> bool {
+        auto const precloseXrp = [&](Account const& a1,
+                                     Account const& a2,
+                                     Env& env,
+                                     VaultVersion version = VaultVersion::CashBasis) -> bool {
             env.fund(XRP(1000), a3, a4);
             Vault const vault{env};
             auto [tx, keylet] = vault.create({.owner = a1, .asset = xrpIssue()});
@@ -217,6 +263,18 @@ class InvariantsVault_test : public InvariantsBase
             return true;
         };
 
+        auto const createClosedXrpBroker =
+            [&](Account const& owner, Env& env) -> std::optional<std::pair<Keylet, Keylet>> {
+            PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+            auto const brokerKeylet = createLoanBroker(owner, env, xrpAsset);
+            auto const sleBroker = env.le(brokerKeylet);
+            if (!BEAST_EXPECT(sleBroker))
+                return std::nullopt;
+            auto const vaultKeylet = keylet::vault(sleBroker->at(sfVaultID));
+            env.close(std::chrono::seconds{61});
+            return std::pair{vaultKeylet, brokerKeylet};
+        };
+
         testcase << "Vault general checks";
         doInvariantCheck(
             {"vault deletion succeeded without deleting a vault"},
@@ -598,7 +656,81 @@ class InvariantsVault_test : public InvariantsBase
             precloseXrp,
             TxAccount::A2);
 
+        // Under featureLendingProtocolV1_1 the immutability of sfAsset, sfAccount,
+        // sfShareMPTID and sfLEVersion is enforced by NoModifiedUnmodifiableFields.
         doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                sleVault->setFieldIssue(sfAsset, STIssue{sfAsset, MPTIssue(MPTID(42))});
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                sleVault->setAccountID(sfAccount, a2.id());
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                (*sleVault)[sfShareMPTID] = MPTID(42);
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                (*sleVault)[sfLEVersion] = std::to_underlying(VaultVersion::Legacy);
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            [&precloseXrp](Account const& a1, Account const& a2, Env& env) {
+                return precloseXrp(a1, a2, env, VaultVersion::CashBasis);
+            });
+
+        // Pre-featureLendingProtocolV1_1 sfAsset, sfAccount and sfShareMPTID are
+        // guarded by ValidVault instead, so both paths need coverage. ValidVault
+        // returns early once the result is already tec, hence no escalation to
+        // tef on the second pass.
+        auto const preLendingV11Amendments = all_ - featureLendingProtocolV1_1;
+        doInvariantCheck(
+            makeEnv(preLendingV11Amendments),
             {"violation of vault immutable data"},
             [&](Account const& a1, Account const& a2, ApplyContext& ac) {
                 auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
@@ -615,6 +747,7 @@ class InvariantsVault_test : public InvariantsBase
             precloseXrp);
 
         doInvariantCheck(
+            makeEnv(preLendingV11Amendments),
             {"violation of vault immutable data"},
             [&](Account const& a1, Account const& a2, ApplyContext& ac) {
                 auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
@@ -631,6 +764,7 @@ class InvariantsVault_test : public InvariantsBase
             precloseXrp);
 
         doInvariantCheck(
+            makeEnv(preLendingV11Amendments),
             {"violation of vault immutable data"},
             [&](Account const& a1, Account const& a2, ApplyContext& ac) {
                 auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
@@ -698,9 +832,12 @@ class InvariantsVault_test : public InvariantsBase
             TxAccount::A2);
 
         // Without fixCleanup3_4_0 the same state must NOT trip the invariant,
-        // preserving pre-amendment behavior (no fork risk).
+        // preserving pre-amendment behavior (no fork risk). Also remove
+        // featureLendingProtocolV1_1 so finalizeLoanManage's stricter checks
+        // (exactly one loan touched) do not fire from a bare vault mutation
+        // that does not touch a loan.
         doInvariantCheck(
-            makeEnv(all_ - fixCleanup3_4_0),
+            makeEnv(all_ - fixCleanup3_4_0 - featureLendingProtocolV1_1),
             {},
             [&](Account const& a1, Account const& a2, ApplyContext& ac) {
                 auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
@@ -728,6 +865,42 @@ class InvariantsVault_test : public InvariantsBase
             precloseXrp,
             TxAccount::A2);
 
+        // The cap check has two post-fixCleanup3_4_0 triggers: the transaction
+        // supplied sfAssetsMaximum, or the cap changed. The case above covers
+        // the cap-changed one (its ttVAULT_SET carries no fields). This covers
+        // the other: the cap is left alone at 30 XRP and the transaction
+        // carries sfAssetsMaximum, so only the isFieldPresent disjunct can
+        // fire. AssetsTotal is pushed past the cap here rather than in
+        // preclose because VaultSet::doApply refuses to set a cap below
+        // AssetsTotal, so the over-cap state is only reachable by fabrication.
+        // Raising AssetsTotal also trips the "must not change assets
+        // outstanding" check, hence two expected messages.
+        Number const vaultCap = XRP(30).number();
+        doInvariantCheck(
+            {"set must not change assets outstanding",
+             "set assets outstanding must not exceed assets maximum"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(ac.view(), keylet, kArgs(a2.id(), 0, [&](Adjustments& sample) {
+                                   sample.assetsTotal = XRP(1).value().xrp().drops();
+                               }));
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [&](STObject& tx) { tx[sfAssetsMaximum] = vaultCap; }},
+            {tecINVARIANT_FAILED, tecINVARIANT_FAILED},
+            [&](Account const& a1, Account const& a2, Env& env) -> bool {
+                env.fund(XRP(1000), a3, a4);
+                Vault const vault{env};
+                auto [tx, keylet] = vault.create({.owner = a1, .asset = xrpIssue()});
+                tx[sfAssetsMaximum] = vaultCap;
+                env(tx);
+                env(vault.deposit({.depositor = a1, .id = keylet.key, .amount = XRP(10)}));
+                env(vault.deposit({.depositor = a2, .id = keylet.key, .amount = XRP(10)}));
+                env(vault.deposit({.depositor = a3, .id = keylet.key, .amount = XRP(10)}));
+                return true;
+            },
+            TxAccount::A2);
+
         doInvariantCheck(
             {"assets maximum must not be negative"},
             [&](Account const& a1, Account const& a2, ApplyContext& ac) {
@@ -808,6 +981,746 @@ class InvariantsVault_test : public InvariantsBase
             precloseXrp,
             TxAccount::A2);
 
+        // ttLOAN_SET pre-featureLendingProtocolV1_1: finalizeLoanSet short-
+        // circuits and returns success without inspecting the loan or the
+        // vault. The same state that trips the principal-outstanding check
+        // under V1_1 must be silently accepted here.
+        doInvariantCheck(
+            makeEnv(all_ - featureLendingProtocolV1_1),
+            {},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(
+                    ac.view(),
+                    keylet,
+                    Adjustments{
+                        .assetsAvailable = -200,
+                        .vaultAssets = -200,
+                        .accountAssets = AccountAmount{.account = a2.id(), .amount = 200},
+                        .createLoan = LoanParams{
+                            .principalOutstanding = 300,
+                            .totalValueOutstanding = 300,
+                            .borrower = a1.id(),
+                        }});
+            },
+            XRPAmount{},
+            STTx{ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(200); }},
+            {tesSUCCESS, tesSUCCESS},
+            precloseXrp);
+
+        // ttLOAN_MANAGE: a loan is created rather than modified. This object-
+        // existence rule applies on both invariant passes.
+        doInvariantCheck(
+            {"Loan created by a transaction other than LoanSet"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(
+                    ac.view(),
+                    keylet,
+                    Adjustments{
+                        .createLoan = LoanParams{
+                            .principalOutstanding = 100,
+                            .totalValueOutstanding = 100,
+                            .borrower = a1.id(),
+                        }});
+            },
+            XRPAmount{},
+            STTx{ttLOAN_MANAGE, [](STObject& tx) { tx.setFieldU32(sfFlags, tfLoanImpair); }},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        // ttLOAN_MANAGE: loss unrealized driven negative
+        doInvariantCheck(
+            {"loss unrealized must not be negative"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(ac.view(), keylet, Adjustments{.lossUnrealized = -1});
+            },
+            XRPAmount{},
+            STTx{ttLOAN_MANAGE, [](STObject&) {}},
+            {tecINVARIANT_FAILED, tecINVARIANT_FAILED},
+            precloseXrp);
+
+        // Loan flags may only change under the transaction types that own
+        // those transitions.
+        {
+            struct Case
+            {
+                std::uint32_t before;
+                std::uint32_t after;
+                std::string expected;
+            };
+            auto const cases = std::to_array<Case>({
+                {.before = 0,
+                 .after = lsfLoanImpaired,
+                 .expected = "lsfLoanImpaired changed outside LoanManage or LoanPay"},
+                {.before = lsfLoanImpaired,
+                 .after = 0,
+                 .expected = "lsfLoanImpaired changed outside LoanManage or LoanPay"},
+                {.before = 0,
+                 .after = lsfLoanDefault,
+                 .expected = "lsfLoanDefault changed outside LoanManage"},
+            });
+
+            for (auto const& c : cases)
+            {
+                Env env{*this, all_};
+                Account const a1{"A1"};
+                Account const a2{"A2"};
+                env.fund(XRP(1000), a1, a2);
+                auto const keys = createClosedXrpBroker(a1, env);
+                if (!keys)
+                    continue;
+                auto const& brokerKeylet = keys->second;
+
+                OpenView ov{*env.current()};
+                auto const loanKeylet = keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+                {
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a1.id());
+                    sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(150);
+                    sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                    sleLoan->setFieldU32(sfFlags, c.before);
+                    ov.rawInsert(sleLoan);
+                }
+
+                STTx const tx{ttACCOUNT_SET, [](STObject&) {}};
+                test::StreamSink sink{beast::Severity::Warning};
+                beast::Journal const jlog{sink};
+                ApplyContext ac{
+                    env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+                CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+                auto sleLoan = ac.view().peek(loanKeylet);
+                if (!BEAST_EXPECT(sleLoan))
+                    continue;
+                sleLoan->setFieldU32(sfFlags, c.after);
+                ac.view().update(sleLoan);
+
+                auto transactor = makeTransactor(ac);
+                if (!BEAST_EXPECT(transactor))
+                    continue;
+                TER const result = transactor->checkInvariants(
+                    tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+                BEAST_EXPECT(result == tecINVARIANT_FAILED);
+                BEAST_EXPECT(sink.messages().str().contains(c.expected));
+            }
+        }
+
+        // ttLOAN_MANAGE (default): a defaulted loan atomically enters a
+        // terminal state, which drops sfNextPaymentDueDate from the ledger
+        // entry. Seed a loan that already carries lsfLoanDefault so the
+        // "must newly set" check passes, then leave sfNextPaymentDueDate
+        // present and non-zero on the after-image; the residual due-date
+        // check must then fire.
+        {
+            Env env{*this, all_};
+            Account const a1{"A1"};
+            Account const a2{"A2"};
+            env.fund(XRP(1000), a1, a2);
+            BEAST_EXPECT(precloseXrp(a1, a2, env));
+            env.close();
+
+            OpenView ov{*env.current()};
+
+            auto const brokerKeylet = keylet::loanBroker(a1.id(), SeqProxy::rawSequence(1));
+            auto const loanKeylet = keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+            // Pre-insert a loan that is not yet defaulted but has a
+            // NextPaymentDueDate set; the apply-view mutation below flips
+            // lsfLoanDefault (so the "must newly set" check passes) while
+            // leaving the due date behind.
+            {
+                auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                sleLoan->setFieldU32(sfNextPaymentDueDate, 123);
+                ov.rawInsert(sleLoan);
+            }
+
+            STTx const tx{
+                ttLOAN_MANAGE, [](STObject& t) { t.setFieldU32(sfFlags, tfLoanDefault); }};
+            test::StreamSink sink{beast::Severity::Warning};
+            beast::Journal const jlog{sink};
+            ApplyContext ac{
+                env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+            CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+            auto sleLoan = ac.view().peek(loanKeylet);
+            if (!BEAST_EXPECT(sleLoan))
+                return;
+            sleLoan->setFieldU32(sfFlags, lsfLoanDefault);
+            ac.view().update(sleLoan);
+
+            auto transactor = makeTransactor(ac);
+            if (!BEAST_EXPECT(transactor))
+                return;
+            TER const result = transactor->checkInvariants(
+                tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+            BEAST_EXPECT(result == tecINVARIANT_FAILED);
+            BEAST_EXPECT(sink.messages().str().contains(
+                "Loan with zero payments must have zero next payment due date"));
+        }
+
+        // ttLOAN_PAY pre-featureLendingProtocolV1_1: finalizeLoanPay short-
+        // circuits and returns success. The same "no vault balance change"
+        // state that trips the check under V1_1 must be silently accepted
+        // here.
+        doInvariantCheck(
+            makeEnv(all_ - featureLendingProtocolV1_1),
+            {},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(ac.view(), keylet, Adjustments{});
+            },
+            XRPAmount{},
+            STTx{ttLOAN_PAY, [](STObject& tx) { tx.setFieldAmount(sfAmount, XRPAmount(200)); }},
+            {tesSUCCESS, tesSUCCESS},
+            precloseXrp);
+
+        // ttLOAN_PAY: cash is credited to the vault and a loan is created
+        // rather than modified. This object-existence rule applies on both
+        // invariant passes.
+        doInvariantCheck(
+            {"Loan created by a transaction other than LoanSet"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(
+                    ac.view(),
+                    keylet,
+                    Adjustments{
+                        .assetsTotal = 50,
+                        .assetsAvailable = 50,
+                        .vaultAssets = 50,
+                        .accountAssets = AccountAmount{.account = a2.id(), .amount = -50},
+                        .createLoan = LoanParams{
+                            .principalOutstanding = 100,
+                            .totalValueOutstanding = 100,
+                            .borrower = a1.id(),
+                        }});
+            },
+            XRPAmount{},
+            STTx{ttLOAN_PAY, [](STObject& tx) { tx.setFieldAmount(sfAmount, XRPAmount(50)); }},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        // ttLOAN_PAY: loss unrealized driven negative. The cash inflow is
+        // valid, but loss unrealized is set below zero.
+        doInvariantCheck(
+            {"loss unrealized must not be negative"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                return kAdjust(
+                    ac.view(),
+                    keylet,
+                    Adjustments{
+                        .assetsTotal = 100,
+                        .assetsAvailable = 100,
+                        .lossUnrealized = -1,
+                        .vaultAssets = 100,
+                        .accountAssets = AccountAmount{.account = a2.id(), .amount = -100}});
+            },
+            XRPAmount{},
+            STTx{ttLOAN_PAY, [](STObject& tx) { tx.setFieldAmount(sfAmount, XRPAmount(200)); }},
+            {tecINVARIANT_FAILED, tecINVARIANT_FAILED},
+            precloseXrp);
+
+        // ttLOAN_PAY success post-conditions. A loan left with payments still
+        // remaining after a successful payment must show that payment in its
+        // balance and schedule: PrincipalOutstanding and PaymentRemaining both
+        // strictly decrease, and NextPaymentDueDate advances by a positive
+        // multiple of PaymentInterval. Each case seeds the same loan, then applies
+        // an after-image that breaks exactly one of those conditions.
+        {
+            struct Case
+            {
+                Number principal;
+                std::uint32_t remaining;
+                std::uint32_t dueDate;
+                std::string expected;
+            };
+            auto const cases = std::to_array<Case>({
+                {.principal = Number(100),
+                 .remaining = 1,
+                 .dueDate = 110,
+                 .expected = "loan pay must strictly decrease PrincipalOutstanding"},
+                {.principal = Number(50),
+                 .remaining = 2,
+                 .dueDate = 110,
+                 .expected = "loan pay must decrease PaymentRemaining"},
+                {.principal = Number(50),
+                 .remaining = 1,
+                 .dueDate = 100,
+                 .expected = "loan pay must advance NextPaymentDueDate"},
+                // Advanced, but not by a whole number of payment intervals.
+                {.principal = Number(50),
+                 .remaining = 1,
+                 .dueDate = 105,
+                 .expected = "loan pay must advance NextPaymentDueDate"},
+            });
+
+            for (auto const& c : cases)
+            {
+                Env env{*this, all_};
+                Account const a1{"A1"};
+                Account const a2{"A2"};
+                env.fund(XRP(1000), a1, a2);
+                auto const keys = createClosedXrpBroker(a1, env);
+                if (!keys)
+                    continue;
+                auto const& brokerKeylet = keys->second;
+
+                OpenView ov{*env.current()};
+                auto const loanKeylet = keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+                {
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                    sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(150);
+                    sleLoan->at(sfPaymentInterval) = 10u;
+                    sleLoan->setFieldU32(sfPaymentRemaining, 2);
+                    sleLoan->setFieldU32(sfNextPaymentDueDate, 100);
+                    ov.rawInsert(sleLoan);
+                }
+
+                STTx const tx{
+                    ttLOAN_PAY, [](STObject& t) { t.setFieldAmount(sfAmount, XRPAmount(50)); }};
+                test::StreamSink sink{beast::Severity::Warning};
+                beast::Journal const jlog{sink};
+                ApplyContext ac{
+                    env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+                CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+                auto sleLoan = ac.view().peek(loanKeylet);
+                if (!BEAST_EXPECT(sleLoan))
+                    continue;
+                sleLoan->at(sfPrincipalOutstanding) = c.principal;
+                sleLoan->setFieldU32(sfPaymentRemaining, c.remaining);
+                sleLoan->setFieldU32(sfNextPaymentDueDate, c.dueDate);
+                ac.view().update(sleLoan);
+
+                auto transactor = makeTransactor(ac);
+                if (!BEAST_EXPECT(transactor))
+                    continue;
+                TER const result = transactor->checkInvariants(
+                    tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+                BEAST_EXPECT(result == tecINVARIANT_FAILED);
+                BEAST_EXPECT(sink.messages().str().contains(c.expected));
+            }
+        }
+
+        // ttLOAN_MANAGE (default): the write-off is rounded downward at the
+        // pre-default AssetsTotal scale. A near-total IOU default can leave
+        // valid positive dust while moving the posterior AssetsTotal to a much
+        // finer scale. The dust must be bounded by the former scale rather than
+        // compared with one unit at the posterior scale.
+        {
+            Env env{*this, all_ | featureLendingProtocolV1_1};
+            Account const issuer{"issuer"};
+            Account const owner{"owner"};
+            Account const borrower{"borrower"};
+            env.fund(XRP(1000), issuer, owner, borrower);
+            env.close();
+
+            PrettyAsset const iouAsset{issuer["IOU"]};
+            auto const brokerKeylet = createLoanBroker(owner, env, iouAsset);
+            auto const sleBrokerBase = env.le(brokerKeylet);
+            if (!BEAST_EXPECT(sleBrokerBase))
+                return;
+            auto const vaultKeylet = keylet::vault(sleBrokerBase->at(sfVaultID));
+            env.close();
+
+            Number const assetsTotalBefore{1, 1};
+            Number const loanOwed{9'999'999'999'999'999LL, -15};
+            Number const assetsTotalAfter{1, -14};
+            auto const beforeScale = scale(assetsTotalBefore, iouAsset);
+            auto const afterScale = scale(assetsTotalAfter, iouAsset);
+            Number const residual = (assetsTotalAfter - assetsTotalBefore) - (-loanOwed);
+            Number const beforeTolerance{1, beforeScale};
+            Number const afterTolerance{1, afterScale};
+
+            BEAST_EXPECT(afterScale < beforeScale);
+            BEAST_EXPECT(residual > beast::kZero && residual < beforeTolerance);
+            BEAST_EXPECT(residual > afterTolerance);
+
+            OpenView ov{*env.current()};
+            {
+                auto const sleVaultRead = ov.read(vaultKeylet);
+                if (!BEAST_EXPECT(sleVaultRead))
+                    return;
+                auto sleVault = std::make_shared<SLE>(*sleVaultRead);
+                sleVault->at(sfAssetsTotal) = assetsTotalBefore;
+                sleVault->at(sfAssetsAvailable) = Number(0);
+                ov.rawReplace(sleVault);
+
+                auto const sharesKeylet = keylet::mptokenIssuance(sleVaultRead->at(sfShareMPTID));
+                auto const sleSharesRead = ov.read(sharesKeylet);
+                if (!BEAST_EXPECT(sleSharesRead))
+                    return;
+                auto sleShares = std::make_shared<SLE>(*sleSharesRead);
+                sleShares->at(sfOutstandingAmount) = 1;
+                ov.rawReplace(sleShares);
+            }
+            {
+                auto const sleBrokerRead = ov.read(brokerKeylet);
+                if (!BEAST_EXPECT(sleBrokerRead))
+                    return;
+                auto sleBroker = std::make_shared<SLE>(*sleBrokerRead);
+                sleBroker->at(sfDebtTotal) = loanOwed;
+                ov.rawReplace(sleBroker);
+            }
+            auto const loanKeylet = keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+            {
+                auto sleLoan = makeLoanSle(brokerKeylet.key, 1, borrower.id());
+                sleLoan->at(sfPrincipalOutstanding) = loanOwed;
+                sleLoan->at(sfTotalValueOutstanding) = loanOwed;
+                sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                ov.rawInsert(sleLoan);
+            }
+
+            STTx const tx{
+                ttLOAN_MANAGE, [](STObject& t) { t.setFieldU32(sfFlags, tfLoanDefault); }};
+            test::StreamSink sink{beast::Severity::Warning};
+            beast::Journal const jlog{sink};
+            ApplyContext ac{
+                env.app(), ov, tx, tesSUCCESS, env.current()->fees().base, TapNone, jlog};
+            CurrentTransactionRulesGuard const rulesGuard(ov.rules());
+
+            {
+                auto sleVault = ac.view().peek(vaultKeylet);
+                if (!BEAST_EXPECT(sleVault))
+                    return;
+                sleVault->at(sfAssetsTotal) = assetsTotalAfter;
+                ac.view().update(sleVault);
+            }
+            {
+                auto sleBroker = ac.view().peek(brokerKeylet);
+                if (!BEAST_EXPECT(sleBroker))
+                    return;
+                sleBroker->at(sfDebtTotal) = Number(0);
+                ac.view().update(sleBroker);
+            }
+            {
+                auto sleLoan = ac.view().peek(loanKeylet);
+                if (!BEAST_EXPECT(sleLoan))
+                    return;
+                sleLoan->at(sfPrincipalOutstanding) = Number(0);
+                sleLoan->at(sfTotalValueOutstanding) = Number(0);
+                sleLoan->setFieldU32(sfPaymentRemaining, 0);
+                sleLoan->setFieldU32(sfFlags, lsfLoanDefault);
+                ac.view().update(sleLoan);
+            }
+
+            auto transactor = makeTransactor(ac);
+            if (!BEAST_EXPECT(transactor))
+                return;
+            TER const result = transactor->checkInvariants(
+                tesSUCCESS, XRPAmount{}, Transactor::InvariantScope::Full);
+            BEAST_EXPECT(result == tesSUCCESS);
+        }
+
+        // A loan may only be deleted by a LoanDelete transaction, and only once
+        // it is fully paid off. Both branches are exercised by creating a real
+        // loan in the Preclose (so it exists in the base ledger with outstanding
+        // principal) and then erasing it in the Precheck.
+        {
+            Keylet loanKeylet = keylet::amendments();
+            auto const precloseLoan = [&loanKeylet, this](
+                                          Account const& a1, Account const& a2, Env& env) -> bool {
+                PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+                auto const brokerKeylet = createLoanBroker(a1, env, xrpAsset);
+                auto const brokerSle = env.le(brokerKeylet);
+                if (!BEAST_EXPECT(brokerSle))
+                    return false;
+                auto const vaultKeylet = keylet::vault(brokerSle->at(sfVaultID));
+                Vault const vault{env};
+                env(vault.deposit(
+                    {.depositor = a1, .id = vaultKeylet.key, .amount = xrpAsset(100)}));
+                env.close(std::chrono::seconds{61});
+
+                loanKeylet = keylet::loan(
+                    brokerKeylet.key, SeqProxy::rawSequence(brokerSle->at(sfLoanSequence)));
+                env(loan::set(a2, brokerKeylet.key, xrpAsset(50).value()),
+                    loan::kCounterparty(a1),
+                    Sig(sfCounterpartySignature, a1),
+                    loan::kPaymentInterval(60),
+                    loan::kPaymentTotal(1),
+                    Fee(env.current()->fees().base * 2));
+                env.close();
+                return BEAST_EXPECT(env.le(loanKeylet));
+            };
+
+            auto const eraseLoan = [&loanKeylet](Account const&, Account const&, ApplyContext& ac) {
+                auto sle = ac.view().peek(loanKeylet);
+                if (!sle)
+                    return false;
+                ac.view().erase(sle);
+                return true;
+            };
+
+            // Deleting the loan under any transaction type other than LoanDelete
+            // (here the neutral ttACCOUNT_SET) is a violation, even while the
+            // loan still has outstanding obligations: the transaction-type check
+            // fires before the not-fully-paid-off check.
+            doInvariantCheck(
+                {"Loan deleted by a transaction other than LoanDelete"},
+                eraseLoan,
+                XRPAmount{},
+                STTx{ttACCOUNT_SET, [](STObject&) {}},
+                {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+                precloseLoan);
+        }
+
+        STTx const loanSetTx{
+            ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(0); }};
+
+        // Loan interest due (total value less principal and management fee) must
+        // never be negative. The loan below carries a total value short of its
+        // principal, while every individual field stays non-negative. A real
+        // broker over an XRP vault is created in the preclose, both so the
+        // earlier broker-existence checks pass and so the deficit is measured
+        // in an integral asset domain, where no rounding tolerance applies.
+        {
+            Keylet brokerKeylet = keylet::amendments();
+            auto const precloseBroker = [&brokerKeylet, this](
+                                            Account const& a1, Account const&, Env& env) -> bool {
+                PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+                brokerKeylet = this->createLoanBroker(a1, env, xrpAsset);
+                env.close();
+                return BEAST_EXPECT(env.le(brokerKeylet));
+            };
+
+            doInvariantCheck(
+                {"Loan interest due is negative"},
+                [&](Account const&, Account const& a2, ApplyContext& ac) {
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                    sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(90);
+                    sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                    ac.view().insert(sleLoan);
+                    return true;
+                },
+                XRPAmount{},
+                loanSetTx,
+                {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+                precloseBroker);
+        }
+
+        // Each of these loan STNumber fields must never be negative. The loan
+        // is created directly with a single field set negative while the
+        // paid-off bookkeeping is kept consistent, so that only the "<field>
+        // is negative" check trips.
+        for (auto const field : {
+                 &sfLoanServiceFee,
+                 &sfLatePaymentFee,
+                 &sfClosePaymentFee,
+                 &sfPrincipalOutstanding,
+                 &sfTotalValueOutstanding,
+                 &sfManagementFeeOutstanding,
+             })
+        {
+            // The outstanding-balance fields also feed the paid-off checks, so
+            // a loan carrying one must still have payments remaining; a loan
+            // with only a negative fee stays fully paid off (zero remaining).
+            bool const isOutstanding = *field == sfPrincipalOutstanding ||
+                *field == sfTotalValueOutstanding || *field == sfManagementFeeOutstanding;
+            doInvariantCheck(
+                {field->getName() + " is negative"},
+                [&, field](Account const& a1, Account const& a2, ApplyContext& ac) {
+                    auto const brokerKeylet = keylet::loanBroker(a1.id(), SeqProxy::rawSequence(1));
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                    sleLoan->at(*field) = Number(-10);
+                    sleLoan->setFieldU32(sfPaymentRemaining, isOutstanding ? 1 : 0);
+                    ac.view().insert(sleLoan);
+                    return true;
+                },
+                XRPAmount{},
+                loanSetTx);
+        }
+
+        // Mirror of the loop above for the strictly-positive constraint: a
+        // loan's sfPeriodicPayment must always be > 0. Cover both boundary
+        // failure modes (zero and negative).
+        for (Number const& badValue : {Number(0), Number(-1)})
+        {
+            doInvariantCheck(
+                {std::string{sfPeriodicPayment.getName()} + " is zero or negative"},
+                [&, badValue](Account const& a1, Account const& a2, ApplyContext& ac) {
+                    auto const brokerKeylet = keylet::loanBroker(a1.id(), SeqProxy::rawSequence(1));
+                    auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                    sleLoan->at(sfPeriodicPayment) = badValue;
+                    ac.view().insert(sleLoan);
+                    return true;
+                },
+                XRPAmount{},
+                loanSetTx);
+        }
+
+        // A loan with sfPaymentRemaining == 0 must be fully paid off in every
+        // outstanding-balance dimension. Insert a bare loan that reports zero
+        // payments remaining but still carries a non-zero principal owed; the
+        // paid-off invariant must reject it before the later broker-existence
+        // check has a chance to run.
+        doInvariantCheck(
+            {"Loan with zero payments remaining has not been paid off"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const brokerKeylet = keylet::loanBroker(a1.id(), SeqProxy::rawSequence(1));
+                auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                sleLoan->at(sfPrincipalOutstanding) = Number(100);
+                sleLoan->at(sfTotalValueOutstanding) = Number(100);
+                sleLoan->at(sfPeriodicPayment) = Number(1);
+                sleLoan->setFieldU32(sfPaymentRemaining, 0);
+                ac.view().insert(sleLoan);
+                return true;
+            },
+            XRPAmount{},
+            loanSetTx);
+
+        // Converse: a loan whose outstanding balances are all zero has been
+        // fully paid off and must carry zero payments remaining. Insert a
+        // fully-zeroed loan with sfPaymentRemaining = 1 to trip the check.
+        doInvariantCheck(
+            {"Fully paid off Loan still has payments remaining"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const brokerKeylet = keylet::loanBroker(a1.id(), SeqProxy::rawSequence(1));
+                auto sleLoan = makeLoanSle(brokerKeylet.key, 1, a2.id());
+                sleLoan->setFieldU32(sfPaymentRemaining, 1);
+                ac.view().insert(sleLoan);
+                return true;
+            },
+            XRPAmount{},
+            loanSetTx);
+
+        // A loan must reference a live loan broker. A bare loan SLE is
+        // inserted with every other loan-level field kept consistent so the
+        // earlier ValidLoan checks pass; sfLoanBrokerID defaults to zero,
+        // which resolves to no broker, and the broker-existence check trips.
+        doInvariantCheck(
+            {"Loan broker does not exist"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto sleLoan = makeLoanSle(uint256{}, 1, a2.id());
+                ac.view().insert(sleLoan);
+                return true;
+            },
+            XRPAmount{},
+            loanSetTx);
+
+        // A loan's broker must in turn reference a live vault. A real broker
+        // is created in the preclose so its sfVaultID points at an existing
+        // vault; the precheck then erases that vault and inserts a loan
+        // referencing the broker, so the broker-existence check passes and
+        // the broker-vault-existence check trips.
+        {
+            Keylet brokerKeylet = keylet::amendments();
+            auto const precloseBroker = [&brokerKeylet, this](
+                                            Account const& a1, Account const&, Env& env) -> bool {
+                PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+                brokerKeylet = this->createLoanBroker(a1, env, xrpAsset);
+                env.close();
+                return BEAST_EXPECT(env.le(brokerKeylet));
+            };
+
+            doInvariantCheck(
+                {"Loan broker vault does not exist"},
+                [&brokerKeylet](Account const&, Account const&, ApplyContext& ac) {
+                    auto sleBroker = ac.view().peek(brokerKeylet);
+                    if (!sleBroker)
+                        return false;
+                    auto sleVault = ac.view().peek(keylet::vault(sleBroker->at(sfVaultID)));
+                    if (!sleVault)
+                        return false;
+                    ac.view().erase(sleVault);
+
+                    auto const loanKeylet =
+                        keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(1));
+                    auto sleLoan = std::make_shared<SLE>(loanKeylet);
+                    sleLoan->at(sfLoanBrokerID) = brokerKeylet.key;
+                    sleLoan->at(sfPrincipalOutstanding) = Number(0);
+                    sleLoan->at(sfTotalValueOutstanding) = Number(0);
+                    sleLoan->at(sfManagementFeeOutstanding) = Number(0);
+                    sleLoan->at(sfPeriodicPayment) = Number(1);
+                    sleLoan->setFieldU32(sfPaymentRemaining, 0);
+                    ac.view().insert(sleLoan);
+                    return true;
+                },
+                XRPAmount{},
+                loanSetTx,
+                {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+                precloseBroker);
+        }
+
+        // ttVAULT_SET: owner is immutable (enforced by
+        // NoModifiedUnmodifiableFields under featureLendingProtocolV1_1.
+        doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                sleVault->setAccountID(sfOwner, a2.id());
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        // ttVAULT_SET: withdrawal policy is immutable
+        doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                sleVault->setFieldU8(
+                    sfWithdrawalPolicy,
+                    static_cast<std::uint8_t>(sleVault->getFieldU8(sfWithdrawalPolicy) + 1));
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        // ttVAULT_SET: scale is immutable
+        doInvariantCheck(
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                sleVault->setFieldU8(
+                    sfScale, static_cast<std::uint8_t>(sleVault->getFieldU8(sfScale) + 1));
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
+        // featureLendingProtocolV1_1 moves the vault immutability checks from VaultInvariant to
+        // InvariantCheck.
+        doInvariantCheck(
+            makeEnv(all_),
+            {"changed an unchangeable field"},
+            [&](Account const& a1, Account const& a2, ApplyContext& ac) {
+                auto const keylet = keylet::vault(a1.id(), SeqProxy::rawSequence(ac.view().seq()));
+                auto sleVault = ac.view().peek(keylet);
+                if (!sleVault)
+                    return false;
+                sleVault->setFieldU8(
+                    sfWithdrawalPolicy,
+                    static_cast<std::uint8_t>(sleVault->getFieldU8(sfWithdrawalPolicy) + 1));
+                ac.view().update(sleVault);
+                return true;
+            },
+            XRPAmount{},
+            STTx{ttVAULT_SET, [](STObject& tx) {}},
+            {tecINVARIANT_FAILED, tefINVARIANT_FAILED},
+            precloseXrp);
+
         testcase << "Vault create";
         doInvariantCheck(
             {
@@ -1881,13 +2794,15 @@ class InvariantsVault_test : public InvariantsBase
                     "RedemptionDate";
 
         // A newly-created loan against a closed-ended vault must satisfy StartDate +
-        // PaymentInterval * PaymentRemaining < RedemptionDate. LoanSet::preclaim enforces the same
-        // bound; this test synthesises an invalid loan directly in the ApplyView so the invariant
-        // catches it even when preclaim is bypassed.
+        // PaymentInterval * PaymentRemaining + kLoanRedemptionBuffer <= RedemptionDate.
+        // LoanSet::preclaim enforces the same bound; this test synthesises a loan whose
+        // final payment is still before RedemptionDate (so the old unbuffered check would
+        // pass) but inside the buffer zone.
         Keylet closedEndedBrokerKeylet = keylet::amendments();
         std::uint32_t closedEndedRed = 0;
         doInvariantCheck(
-            {"closed-ended loan final payment must precede RedemptionDate"},
+            {"closed-ended loan final payment must precede RedemptionDate by at least "
+             "kLoanRedemptionBuffer"},
             [&](Account const& a1, Account const&, ApplyContext& ac) {
                 // Touch the vault so ValidVault::finalizeLoanSet sees an
                 // entry in afterVault_; the vault is in Investment, so
@@ -1904,16 +2819,14 @@ class InvariantsVault_test : public InvariantsBase
                     return false;
                 std::uint32_t const loanSeq = sleBroker->at(sfLoanSequence);
 
-                // Synthesize a Loan whose final scheduled payment lands
-                // exactly at RedemptionDate: StartDate = red, interval = 60,
-                // remaining = 1 => red + 60 >= red.
-                auto sleLoan = std::make_shared<SLE>(
-                    keylet::loan(closedEndedBrokerKeylet.key, SeqProxy::rawSequence(loanSeq)));
+                // Final payment at RedemptionDate - (kLoanRedemptionBuffer - 1): still
+                // strictly before RedemptionDate, but inside the buffer.
+                auto sleLoan = makeLoanSle(closedEndedBrokerKeylet.key, loanSeq, a1.id());
                 sleLoan->at(sfLoanBrokerID) = closedEndedBrokerKeylet.key;
                 sleLoan->at(sfLoanSequence) = loanSeq;
                 sleLoan->at(sfBorrower) = a1.id();
-                sleLoan->at(sfStartDate) = closedEndedRed;
-                sleLoan->at(sfPaymentInterval) = 60;
+                sleLoan->at(sfStartDate) = closedEndedRed - kLoanRedemptionBuffer;
+                sleLoan->at(sfPaymentInterval) = 1;
                 sleLoan->at(sfPaymentRemaining) = 1;
                 sleLoan->at(sfTotalValueOutstanding) = Number(100);
                 sleLoan->at(sfPeriodicPayment) = Number(1);
diff --git a/src/test/app/lending/LoanBroker_test.cpp b/src/test/app/lending/LoanBroker_test.cpp
index d75b359868..3bcda42c7e 100644
--- a/src/test/app/lending/LoanBroker_test.cpp
+++ b/src/test/app/lending/LoanBroker_test.cpp
@@ -1849,6 +1849,96 @@ class LoanBroker_test : public beast::unit_test::Suite
         BEAST_EXPECT(aliceBalanceAfter == aliceBalanceBefore);
     }
 
+    void
+    testLoanBrokerDeleteRequireAuthMPT(FeatureBitset features)
+    {
+        testcase << "LoanBrokerDelete - auth-required broker pseudo-account MPT "
+                 << (features[fixCleanup3_4_0] ? "post-fix" : "pre-fix");
+        using namespace jtx;
+        using namespace loan_broker;
+
+        Account const issuer("issuer");
+        Account const alice("alice");
+
+        Env env(*this, features);
+        env.fund(XRP(100'000), issuer, alice);
+        env.close();
+
+        // Create an auth-required MPT and authorize alice as a holder. The
+        // broker pseudo-account's cover MPToken is auto-created later
+        // (addEmptyHolding -> authorizeMPToken) with lsfMPTAuthorized clear;
+        // the pseudo-account is implicitly authorized to hold any MPT
+        // regardless of that flag.
+        auto tester = MPTTester(
+            {.env = env,
+             .issuer = issuer,
+             .holders = {alice},
+             .pay = 20'000,
+             .flags = tfMPTRequireAuth | tfMPTCanTransfer,
+             .authHolder = true});
+
+        PrettyAsset const mpt{tester.issuanceID()};
+
+        // Create vault
+        Vault const vault{env};
+        auto [tx, vaultKeylet] = vault.create({.owner = alice, .asset = mpt});
+        env(tx);
+        env.close();
+
+        // Deposit into vault
+        env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = mpt(10'000)}));
+        env.close();
+
+        // Create loan broker
+        auto const brokerKeylet =
+            keylet::loanBroker(alice.id(), SeqProxy::rawSequence(env.seq(alice)));
+        env(set(alice, vaultKeylet.key));
+        env.close();
+
+        // Deposit cover
+        env(coverDeposit(alice, brokerKeylet.key, mpt(5'000).value()));
+        env.close();
+
+        // Verify cover is deposited
+        auto const broker = env.le(brokerKeylet);
+        if (!BEAST_EXPECT(broker))
+            return;
+        BEAST_EXPECT(broker->at(sfCoverAvailable) > 0);
+
+        // Get the broker pseudo-account
+        auto const brokerPseudoID = broker->at(sfAccount);
+
+        // Verify the broker pseudo-account has an MPToken, and that it was
+        // never explicitly authorized (issuer cannot authorize a
+        // pseudo-account holder; see MPTokenAuthorize::preclaim).
+        auto const pseudoMptKey = keylet::mptoken(tester.issuanceID(), brokerPseudoID);
+        auto const pseudoMpt = env.le(pseudoMptKey);
+        if (!BEAST_EXPECT(pseudoMpt))
+            return;
+        BEAST_EXPECT(!pseudoMpt->isFlag(lsfMPTAuthorized));
+
+        // Record alice's balance before deletion
+        auto const aliceBalanceBefore = env.balance(alice, mpt);
+
+        // LoanBrokerDelete sends the remaining cover out of the broker pseudo-account, deletes its
+        // now-empty MPToken, and erases the pseudo AccountRoot. Before the fix,
+        // ValidMPTTransfer::isAuthorized evaluates isPseudoAccount() on the post-transaction view
+        // (where the pseudo-account is already gone) and falls back to the MPToken's
+        // lsfMPTAuthorized flag, which was never set, so the invariant treats the broker as an
+        // unauthorized sender and the whole transaction fails once fixCleanup3_4_0 makes the check
+        // enforcing.
+        env(del(alice, brokerKeylet.key), Ter(tesSUCCESS));
+        env.close();
+
+        // Broker and its pseudo-account MPToken are gone
+        BEAST_EXPECT(env.le(brokerKeylet) == nullptr);
+        BEAST_EXPECT(env.le(pseudoMptKey) == nullptr);
+
+        // Alice received the cover
+        auto const aliceBalanceAfter = env.balance(alice, mpt);
+        BEAST_EXPECT(aliceBalanceAfter > aliceBalanceBefore);
+    }
+
     void
     testCoverDepositFreezes()
     {
@@ -2550,7 +2640,7 @@ class LoanBroker_test : public beast::unit_test::Suite
         using namespace jtx;
         using namespace std::chrono_literals;
 
-        bool const fixEnabled = features[fixCleanup3_4_0];
+        bool const fix340Enabled = features[fixCleanup3_4_0];
 
         Env env(*this, features);
 
@@ -2611,7 +2701,7 @@ class LoanBroker_test : public beast::unit_test::Suite
         env(coverWithdrawToDest(), loan_broker::kDestination(dest), Ter{tecNO_PERMISSION});
         env.close();
 
-        if (!fixEnabled)
+        if (!fix340Enabled)
         {
             // Pre-fix: sfCredentialIDs in LoanBrokerCoverWithdraw is disabled
             env(coverWithdrawToDest(),
@@ -2878,126 +2968,6 @@ class LoanBroker_test : public beast::unit_test::Suite
         runTestCases(all_ - fixCleanup3_2_0);
     }
 
-    void
-    testCredentialPinsPseudoAccount()
-    {
-        using namespace test::jtx;
-        using namespace loan_broker;
-
-        // A credential issued to a LoanBroker pseudo-account can't be accepted
-        // or deleted by it, so it stays pinned in the pseudo-account's owner
-        // directory and blocks LoanBrokerDelete with tecHAS_OBLIGATIONS. A pin
-        // created before the cure activates is removed by LoanBrokerDelete once
-        // it does.
-        Account const alice{"alice"};  // vault & broker owner
-        Account const attacker{"attacker"};
-        char const credType[] = "FN36";
-
-        Env env{*this, all_ - fixCleanup3_3_0 - fixCleanup3_4_0};
-        env.fund(XRP(1'000'000), alice, attacker);
-        env.close();
-
-        Vault const vault{env};
-        auto [vtx, vkeylet] = vault.create({.owner = alice, .asset = xrpIssue()});
-        env(vtx);
-        env.close();
-        BEAST_EXPECT(env.le(vkeylet));
-
-        auto const brokerKeylet =
-            keylet::loanBroker(alice.id(), SeqProxy::rawSequence(env.seq(alice)));
-        env(set(alice.id(), vkeylet.key));
-        env.close();
-
-        auto const broker = env.le(brokerKeylet);
-        BEAST_EXPECT(broker);
-        Account const pseudo{"broker pseudo-account", broker->at(sfAccount)};
-        env.memoize(pseudo);
-
-        testcase("Credential pins broker pseudo-account");
-        env(credentials::create(pseudo, attacker, credType));
-        env.close();
-
-        auto const credKey = credentials::keylet(pseudo, attacker, credType);
-        BEAST_EXPECT(env.le(credKey));
-        BEAST_EXPECT(ownerCount(env, attacker) == 1);
-
-        env(del(alice.id(), brokerKeylet.key), Ter(tecHAS_OBLIGATIONS));
-        env.close();
-
-        env.enableFeature(fixCleanup3_4_0);
-        env.close();
-
-        // The pre-existing pin no longer blocks deletion; the credential is
-        // cleaned up and the issuer's owner count is restored.
-        testcase("LoanBrokerDelete removes pinned credential");
-        env(del(alice.id(), brokerKeylet.key));
-        env.close();
-
-        BEAST_EXPECT(!env.le(credKey));
-        BEAST_EXPECT(!env.le(brokerKeylet));
-        BEAST_EXPECT(!env.le(keylet::account(pseudo.id())));
-        BEAST_EXPECT(ownerCount(env, attacker) == 0);
-    }
-
-    void
-    testCredentialPinOverflow()
-    {
-        using namespace test::jtx;
-        using namespace loan_broker;
-        testcase("Credential pin cleanup is bounded (tecINCOMPLETE)");
-
-        // A pseudo-account can be pinned with more credentials than one
-        // transaction is allowed to clean up. LoanBrokerDelete then removes
-        // them a bounded batch at a time, returning tecINCOMPLETE until the
-        // last batch.
-        Account const alice{"alice"};
-        Account const attacker{"attacker"};
-
-        Env env{*this, all_ - fixCleanup3_3_0 - fixCleanup3_4_0};
-        env.fund(XRP(10'000'000), alice, attacker);
-        env.close();
-
-        Vault const vault{env};
-        auto [vtx, vkeylet] = vault.create({.owner = alice, .asset = xrpIssue()});
-        env(vtx);
-        env.close();
-        BEAST_EXPECT(env.le(vkeylet));
-
-        auto const brokerKeylet =
-            keylet::loanBroker(alice.id(), SeqProxy::rawSequence(env.seq(alice)));
-        env(set(alice.id(), vkeylet.key));
-        env.close();
-
-        auto const broker = env.le(brokerKeylet);
-        BEAST_EXPECT(broker);
-        Account const pseudo{"broker pseudo-account", broker->at(sfAccount)};
-        env.memoize(pseudo);
-
-        // Pin more than one cleanup batch's worth of credentials.
-        std::uint16_t const count = kMaxDeletablePseudoAccountCredentials + 3;
-        for (std::uint16_t i = 0; i < count; ++i)
-            env(credentials::create(pseudo, attacker, std::to_string(i)));
-        env.close();
-        BEAST_EXPECT(ownerCount(env, attacker) == count);
-
-        env.enableFeature(fixCleanup3_4_0);
-        env.close();
-
-        // First delete removes one bounded batch and reports it isn't finished.
-        env(del(alice.id(), brokerKeylet.key), Ter(tecINCOMPLETE));
-        env.close();
-        BEAST_EXPECT(env.le(brokerKeylet));  // broker still exists
-        auto const remaining = ownerCount(env, attacker);
-        BEAST_EXPECT(remaining > 0 && remaining < count);
-
-        // Second delete finishes the cleanup and removes the broker.
-        env(del(alice.id(), brokerKeylet.key));
-        env.close();
-        BEAST_EXPECT(!env.le(brokerKeylet));
-        BEAST_EXPECT(!env.le(keylet::account(pseudo.id())));
-        BEAST_EXPECT(ownerCount(env, attacker) == 0);
-    }
-
 public:
     void
     run() override
@@ -3016,8 +2986,6 @@ public:
 
         testDisabled();
         testLifecycle();
-        testCredentialPinsPseudoAccount();
-        testCredentialPinOverflow();
         testInvalidLoanBrokerDelete();
         testInvalidLoanBrokerSet();
         testRequireAuth();
@@ -3035,6 +3003,13 @@ public:
 
         testLoanBrokerDeleteFrozenIOU(all_);
         testLoanBrokerDeleteFrozenIOU(all_ - fixCleanup3_2_0);
+
+        // featureMPTokensV2 independently makes ValidMPTTransfer enforcing,
+        // but it's Supported::No (never enabled on real networks); exclude
+        // it here so fixCleanup3_4_0 alone is the deciding amendment, as it
+        // would be on mainnet.
+        testLoanBrokerDeleteRequireAuthMPT(all_ - featureMPTokensV2);
+        testLoanBrokerDeleteRequireAuthMPT(all_ - featureMPTokensV2 - fixCleanup3_4_0);
         // TODO: Write clawback failure tests with an issuer / MPT that doesn't
         // have the right flags set.
     }
diff --git a/src/test/app/lending/LoanCashBasis_test.cpp b/src/test/app/lending/LoanCashBasis_test.cpp
index a3ca28437d..e238838306 100644
--- a/src/test/app/lending/LoanCashBasis_test.cpp
+++ b/src/test/app/lending/LoanCashBasis_test.cpp
@@ -4,10 +4,12 @@
 #include <test/jtx/TestHelpers.h>
 #include <test/jtx/amount.h>
 #include <test/jtx/fee.h>
+#include <test/jtx/permissioned_domains.h>
 #include <test/jtx/ter.h>
 #include <test/jtx/vault.h>
 
 #include <xrpl/basics/Number.h>
+#include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/chrono.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/beast/utility/Zero.h>
@@ -25,6 +27,7 @@
 #include <chrono>
 #include <cstdint>
 #include <functional>
+#include <string>
 #include <tuple>
 
 namespace xrpl::test {
@@ -42,8 +45,9 @@ class LoanCashBasis_test : public LoanTestBase
 {
 private:
     // 1. LoanSet origination: Vault.AssetsTotal/LoanBroker.DebtTotal deltas,
-    // and the AssetsMaximum/DebtMaximum guards (which always check against
-    // principal + interestDue, regardless of the amendment).
+    // and the AssetsMaximum/DebtMaximum guards. Accrual AssetsMaximum still
+    // requires headroom for interestDue; cash-basis AssetsMaximum does not,
+    // because origination does not credit interest into AssetsTotal.
     void
     testCashBasisLoanSetOrigination()
     {
@@ -226,6 +230,10 @@ private:
             // Even far less headroom than interestDue still succeeds, since
             // cash-basis origination never adds interest to AssetsTotal.
             runVaultGuard(all_ | featureLendingProtocolV1_1, oneDrop, tesSUCCESS);
+            // Fully subscribed: AssetsTotal == AssetsMaximum. Accrual preclaim
+            // used to refuse this; origination must still succeed because it
+            // does not change AssetsTotal.
+            runVaultGuard(all_ | featureLendingProtocolV1_1, Number{0}, tesSUCCESS);
         }
 
         // DebtMaximum guard: cash-basis projects principal-only DebtTotal;
@@ -489,6 +497,252 @@ private:
         }
     }
 
+    // VaultSet must still succeed when cash-basis LoanPay has already pushed
+    // AssetsTotal above a nonzero AssetsMaximum. Before fixCleanup3_4_0,
+    // ValidVault rejects that with tecINVARIANT_FAILED even though
+    // VaultSet::doApply and the product rule allow the over-cap state when
+    // the excess is interest.
+    void
+    testVaultSetWhileAssetsTotalExceedsMaximum()
+    {
+        using namespace jtx;
+        using namespace loan;
+
+        PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+        BrokerParameters const brokerParams{
+            .vaultDeposit = 1'000'000,
+            .debtMax = 0,
+            .coverRateMin = TenthBips32{0},
+            .coverDeposit = 0,
+            .managementFeeRate = TenthBips16{0},
+            .coverRateLiquidation = TenthBips32{0}};
+
+        auto run =
+            [&](FeatureBitset features, TER expectedOverCapSet, bool native, bool vaultPrivate) {
+                bool const fix340Enabled = features[fixCleanup3_4_0];
+                testcase(
+                    std::string("cash-basis: VaultSet while AssetsTotal exceeds AssetsMaximum") +
+                    (native ? " XRP" : " IOU") + (vaultPrivate ? " private" : "") +
+                    (fix340Enabled ? " (fixCleanup3_4_0)" : " (pre-fix)"));
+
+                Account const issuer{"issuer"};
+                Account const lender{"lender"};
+                Account const borrower{"borrower"};
+                Env env(*this, features);
+
+                BrokerParameters params = brokerParams;
+                if (vaultPrivate)
+                    params.vaultFlags = tfVaultPrivate;
+
+                PrettyAsset vaultAsset = xrpAsset;
+                if (native)
+                {
+                    env.fund(XRP(10'000'000), lender, borrower);
+                    env.close();
+                }
+                else
+                {
+                    vaultAsset = createFundedIouAsset(env, issuer, lender, borrower);
+                }
+
+                BrokerInfo const broker{createVaultAndBroker(env, vaultAsset, lender, params)};
+                auto const vaultBefore = env.le(broker.vaultKeylet());
+                BEAST_EXPECT(vaultBefore);
+                // One unit at the vault's asset scale so the stored cap is
+                // strictly above AssetsTotal (a smaller ULP rounds away).
+                // Cash-basis origination does not credit interest, so LoanSet
+                // still succeeds.
+                Number const slack{1, -static_cast<int>(vaultBefore->at(sfScale))};
+                Number const assetsMaximum = Number(vaultBefore->at(sfAssetsTotal)) + slack;
+
+                Vault const vault{env};
+                {
+                    auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+                    tx[sfAssetsMaximum] = assetsMaximum;
+                    env(tx);
+                    env.close();
+                }
+
+                {
+                    auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+                    tx[sfData] = "AA";
+                    env(tx, Ter(tesSUCCESS));
+                    env.close();
+                }
+
+                auto const brokerBeforeLoan = env.le(broker.brokerKeylet());
+                BEAST_EXPECT(brokerBeforeLoan);
+                auto const loanKeylet = keylet::loan(
+                    broker.brokerID, SeqProxy::rawSequence(brokerBeforeLoan->at(sfLoanSequence)));
+
+                LoanParameters const loanParams{
+                    .account = borrower,
+                    .counter = lender,
+                    .principalRequest = 12'000,
+                    .interest = TenthBips32{percentageToTenthBips(12)},
+                    .payTotal = 4,
+                    .payInterval = 600,
+                    .gracePd = 300,
+                };
+                env(loanParams(env, broker));
+                env.close();
+
+                auto const vaultAfterLoan = env.le(broker.vaultKeylet());
+                BEAST_EXPECT(vaultAfterLoan);
+                BEAST_EXPECT(vaultAfterLoan->at(sfAssetsTotal) <= assetsMaximum);
+
+                LoanState const state = getCurrentState(env, broker, loanKeylet);
+                STAmount const payment{
+                    vaultAsset,
+                    roundPeriodicPayment(vaultAsset, state.periodicPayment, state.loanScale) *
+                        Number{3, -1} * 5};
+                env(pay(borrower, loanKeylet.key, payment), Ter(tesSUCCESS));
+                env.close();
+
+                auto const vaultAboveMaximum = env.le(broker.vaultKeylet());
+                BEAST_EXPECT(vaultAboveMaximum);
+                BEAST_EXPECT(vaultAboveMaximum->at(sfAssetsTotal) > assetsMaximum);
+                BEAST_EXPECT(vaultAboveMaximum->at(sfAssetsMaximum) == assetsMaximum);
+
+                {
+                    auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+                    tx[sfData] = "BB";
+                    env(tx, Ter(expectedOverCapSet));
+                    env.close();
+                }
+
+                if (vaultPrivate)
+                {
+                    pdomain::Credentials const credentials{
+                        {.issuer = lender, .credType = "credential"}};
+                    env(pdomain::setTx(lender, credentials));
+                    auto const domainId = pdomain::getNewDomain(env.meta());
+                    auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+                    tx[sfDomainID] = to_string(domainId);
+                    env(tx, Ter(expectedOverCapSet));
+                    env.close();
+                }
+
+                if (!fix340Enabled)
+                    return;
+
+                {
+                    auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+                    tx[sfAssetsMaximum] = assetsMaximum;
+                    env(tx, Ter(tecLIMIT_EXCEEDED));
+                    env.close();
+                }
+
+                {
+                    auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+                    tx[sfAssetsMaximum] = Number{0};
+                    env(tx, Ter(tesSUCCESS));
+                    env.close();
+                }
+            };
+
+        FeatureBitset const withFix = all_ | featureLendingProtocolV1_1;
+        FeatureBitset const withoutFix = withFix - fixCleanup3_4_0;
+
+        run(withFix, tesSUCCESS, true, true);
+        run(withoutFix, tecINVARIANT_FAILED, true, true);
+        run(withFix, tesSUCCESS, false, false);
+        run(withoutFix, tecINVARIANT_FAILED, false, false);
+    }
+
+    void
+    testCashBasisLoanSetAfterInterestExceedsCap()
+    {
+        testcase("cash-basis: LoanSet after interest pushes AssetsTotal past AssetsMaximum");
+
+        using namespace jtx;
+        using namespace loan;
+
+        PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+        BrokerParameters const brokerParams{
+            .vaultDeposit = 1'000'000,
+            .debtMax = 0,
+            .coverRateMin = TenthBips32{0},
+            .coverDeposit = 0,
+            .managementFeeRate = TenthBips16{0},
+            .coverRateLiquidation = TenthBips32{0}};
+
+        Account const lender{"lender"};
+        Account const borrower{"borrower"};
+        Env env(*this, all_ | featureLendingProtocolV1_1);
+        env.fund(XRP(10'000'000), lender, borrower);
+        env.close();
+
+        BrokerInfo const broker{createVaultAndBroker(env, xrpAsset, lender, brokerParams)};
+        auto const vaultBefore = env.le(broker.vaultKeylet());
+        BEAST_EXPECT(vaultBefore);
+        Number const assetsMaximum = Number(vaultBefore->at(sfAssetsTotal));
+
+        Vault const vault{env};
+        {
+            auto tx = vault.set({.owner = lender, .id = broker.vaultID});
+            tx[sfAssetsMaximum] = assetsMaximum;
+            env(tx);
+            env.close();
+        }
+
+        auto const brokerBeforeLoan = env.le(broker.brokerKeylet());
+        BEAST_EXPECT(brokerBeforeLoan);
+        auto const firstLoanKeylet = keylet::loan(
+            broker.brokerID, SeqProxy::rawSequence(brokerBeforeLoan->at(sfLoanSequence)));
+
+        Number const firstPrincipal = xrpAsset(12'000).value();
+        env(set(borrower, broker.brokerID, firstPrincipal),
+            kCounterparty(lender),
+            kInterestRate(TenthBips32{percentageToTenthBips(12)}),
+            kPaymentTotal(4),
+            kPaymentInterval(600),
+            Sig(sfCounterpartySignature, lender),
+            Fee(env.current()->fees().base * 2),
+            Ter(tesSUCCESS));
+        env.close();
+
+        auto const vaultAfterFirst = env.le(broker.vaultKeylet());
+        BEAST_EXPECT(vaultAfterFirst);
+        BEAST_EXPECT(vaultAfterFirst->at(sfAssetsTotal) == assetsMaximum);
+        BEAST_EXPECT(vaultAfterFirst->at(sfAssetsAvailable) == assetsMaximum - firstPrincipal);
+
+        LoanState const state = getCurrentState(env, broker, firstLoanKeylet);
+        STAmount const payment{
+            xrpAsset,
+            roundPeriodicPayment(xrpAsset, state.periodicPayment, state.loanScale) * Number{3, -1} *
+                5};
+        env(pay(borrower, firstLoanKeylet.key, payment), Ter(tesSUCCESS));
+        env.close();
+
+        auto const vaultAfterPay = env.le(broker.vaultKeylet());
+        BEAST_EXPECT(vaultAfterPay);
+        BEAST_EXPECT(vaultAfterPay->at(sfAssetsTotal) > assetsMaximum);
+        BEAST_EXPECT(vaultAfterPay->at(sfAssetsAvailable) > beast::kZero);
+
+        auto const brokerAfterPay = env.le(broker.brokerKeylet());
+        BEAST_EXPECT(brokerAfterPay);
+        auto const secondLoanKeylet = keylet::loan(
+            broker.brokerID, SeqProxy::rawSequence(brokerAfterPay->at(sfLoanSequence)));
+
+        Number const secondPrincipal = xrpAsset(1'000).value();
+        env(set(borrower, broker.brokerID, secondPrincipal),
+            kCounterparty(lender),
+            kInterestRate(TenthBips32{percentageToTenthBips(12)}),
+            kPaymentTotal(4),
+            kPaymentInterval(600),
+            Sig(sfCounterpartySignature, lender),
+            Fee(env.current()->fees().base * 2),
+            Ter(tesSUCCESS));
+        env.close();
+
+        auto const vaultAfterSecond = env.le(broker.vaultKeylet());
+        auto const secondLoan = env.le(secondLoanKeylet);
+        BEAST_EXPECT(vaultAfterSecond && secondLoan);
+        BEAST_EXPECT(vaultAfterSecond->at(sfAssetsTotal) == vaultAfterPay->at(sfAssetsTotal));
+        BEAST_EXPECT(secondLoan->at(sfPrincipalOutstanding) == secondPrincipal);
+    }
+
     // 3. LoanManage: impair, unimpair, and default.
     void
     testCashBasisLoanManage()
@@ -1013,6 +1267,8 @@ public:
     {
         testCashBasisLoanSetOrigination();
         testCashBasisLoanPay();
+        testVaultSetWhileAssetsTotalExceedsMaximum();
+        testCashBasisLoanSetAfterInterestExceedsCap();
         testCashBasisLoanManage();
         testLegacyVaultKeepsAccrualAfterAmendmentEnabled();
         testCashBasisEndToEndTrajectory();
diff --git a/src/test/app/lending/LoanInvariants_test.cpp b/src/test/app/lending/LoanInvariants_test.cpp
index 264dbdcd24..b3d4803aff 100644
--- a/src/test/app/lending/LoanInvariants_test.cpp
+++ b/src/test/app/lending/LoanInvariants_test.cpp
@@ -25,7 +25,9 @@
 #include <xrpl/protocol/SeqProxy.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFlags.h>
+#include <xrpl/protocol/Units.h>
 
+#include <algorithm>
 #include <cstdint>
 #include <optional>
 
@@ -383,6 +385,85 @@ private:
             isRounded(broker.asset, newState.principalOutstanding, originalState.loanScale));
     }
 
+    // Verify an overpayment cannot reduce principal without covering and
+    // advancing at least one scheduled instalment: reject an extra-only amount,
+    // but accept an instalment plus extra. Enable V1_1 explicitly because
+    // LoanTestBase::all_ excludes it.
+    void
+    testLoanPayOverpaymentScheduleInvariant(FeatureBitset features)
+    {
+        testcase("LoanPay overpayment schedule advancement");
+
+        using namespace jtx;
+        using namespace loan;
+
+        Env env{*this, features | featureLendingProtocolV1_1};
+
+        Account const lender{"lender"};
+        Account const borrower{"borrower"};
+
+        env.fund(XRP(10'000'000), lender, borrower);
+        env.close();
+
+        PrettyAsset const asset{xrpIssue(), 1000};
+
+        BrokerInfo const broker = createVaultAndBroker(
+            env,
+            asset,
+            lender,
+            {
+                .vaultDeposit = asset(100'000).value(),
+                .managementFeeRate = TenthBips16(10'000),
+            });
+
+        auto const loanSetFee = Fee(env.current()->fees().base * 2);
+
+        // Principal 10,000 over 3 payments, overpayment enabled. One scheduled
+        // payment is ~3,333, so an amount well below that cannot cover one.
+        auto const loanKeylet = nextLoanKeylet(env, broker);
+        env(loan::set(borrower, broker.brokerID, asset(10'000).value(), tfLoanOverpayment),
+            Sig(sfCounterpartySignature, lender),
+            loan::kPaymentInterval(86400 * 30),
+            loan::kPaymentTotal(3),
+            loan::kOverpaymentInterestRate(TenthBips32(percentageToTenthBips(20))),
+            loanSetFee);
+        env.close();
+
+        auto const before = getCurrentState(env, broker, loanKeylet);
+        BEAST_EXPECT(before.paymentRemaining == 3);
+
+        STAmount const belowOnePayment = asset(1'000).value();
+        BEAST_EXPECT((belowOnePayment < STAmount{asset, before.periodicPayment}));
+
+        auto const payFee = Fee(env.current()->fees().base * 2);
+
+        // The amount does not cover a scheduled payment, so makeRegularPayment makes zero scheduled
+        // payments and returns tecINSUFFICIENT_PAYMENT before the Extra branch runs. Were the
+        // payment to succeed while touching only principal, PaymentRemaining and NextPaymentDueDate
+        // would silently fail to advance.
+        env(pay(borrower, loanKeylet.key, belowOnePayment, tfLoanOverpayment),
+            payFee,
+            Ter(tecINSUFFICIENT_PAYMENT));
+        env.close();
+
+        auto const afterReject = getCurrentState(env, broker, loanKeylet);
+        BEAST_EXPECT(afterReject.paymentRemaining == before.paymentRemaining);
+        BEAST_EXPECT(afterReject.principalOutstanding == before.principalOutstanding);
+        BEAST_EXPECT(afterReject.nextPaymentDate == before.nextPaymentDate);
+
+        // PaymentRemaining drops by one, NextPaymentDueDate advances by one interval, and
+        // PrincipalOutstanding strictly decreases (by more than a plain payment thanks to the
+        // extra).
+        STAmount const onePaymentPlusExtra = asset(5'000).value();
+        env(pay(borrower, loanKeylet.key, onePaymentPlusExtra, tfLoanOverpayment), payFee);
+        env.close();
+
+        auto const afterPay = getCurrentState(env, broker, loanKeylet);
+        BEAST_EXPECT(afterPay.paymentRemaining == before.paymentRemaining - 1);
+        BEAST_EXPECT(afterPay.principalOutstanding < before.principalOutstanding);
+        BEAST_EXPECT(afterPay.nextPaymentDate == before.nextPaymentDate + before.paymentInterval);
+    }
+
     void
     testAccountSendMptMinAmountInvariant(FeatureBitset features)
     {
@@ -851,12 +932,175 @@ private:
             });
     }
 
+    void
+    testLoanSetRecipientScaleInvariant()
+    {
+        using namespace jtx;
+        using namespace loan;
+
+        auto const runCase = [&](bool coarseBorrower) {
+            testcase(
+                coarseBorrower ? "LoanSet borrower balance uses coarsest scale"
+                               : "LoanSet broker owner balance uses coarsest scale");
+
+            Env env(*this, all_ | featureLendingProtocolV1_1);
+            Account const issuer{"issuer"};
+            Account const lender{"lender"};
+            Account const borrower{"borrower"};
+
+            Number const coarseBalance{100'000'000'000LL};
+            Number const regularBalance{100'000'000};
+            PrettyAsset const asset = createFundedRippleIouAsset(
+                env,
+                issuer,
+                lender,
+                borrower,
+                coarseBorrower ? regularBalance : coarseBalance,
+                coarseBorrower ? coarseBalance : regularBalance);
+
+            BrokerParameters const brokerParams{
+                .vaultDeposit = 1'000'000,
+                .debtMax = 0,
+                .coverRateMin = TenthBips32{0},
+                .coverDeposit = 0,
+                .managementFeeRate = TenthBips16{0},
+                .coverRateLiquidation = TenthBips32{0}};
+            BrokerInfo const broker = createVaultAndBroker(env, asset, lender, brokerParams);
+
+            Number const principal{1'012'345, -5};
+            Number const originationFee{123'456, -6};
+            Account const& recipient = coarseBorrower ? borrower : lender;
+            Number const expected = coarseBorrower ? principal : originationFee;
+            auto const before = env.balance(recipient, asset);
+
+            if (coarseBorrower)
+            {
+                env(set(borrower, broker.brokerID, principal),
+                    kCounterparty(lender),
+                    Sig(sfCounterpartySignature, lender),
+                    kInterestRate(TenthBips32{0}),
+                    kPaymentTotal(1),
+                    Fee(env.current()->fees().base * 2),
+                    Ter(tesSUCCESS));
+            }
+            else
+            {
+                env(set(borrower, broker.brokerID, principal),
+                    kCounterparty(lender),
+                    Sig(sfCounterpartySignature, lender),
+                    kLoanOriginationFee(originationFee),
+                    kInterestRate(TenthBips32{0}),
+                    kPaymentTotal(1),
+                    Fee(env.current()->fees().base * 2),
+                    Ter(tesSUCCESS));
+            }
+            env.close();
+
+            auto const after = env.balance(recipient, asset);
+            Number const received = after.number() - before.number();
+            auto const recipientScale =
+                std::max(before.value().exponent(), after.value().exponent());
+            auto const vaultScale = broker.vaultScale(env);
+            Number const tolerance{1, recipientScale};
+
+            BEAST_EXPECT(recipientScale > vaultScale);
+            BEAST_EXPECT(received != expected);
+            BEAST_EXPECT(
+                abs(roundToAsset(asset, received, recipientScale) -
+                    roundToAsset(asset, expected, recipientScale)) <= tolerance);
+        };
+
+        runCase(/*coarseBorrower=*/true);
+        runCase(/*coarseBorrower=*/false);
+    }
+
+    // Under featureLendingProtocolV1_1, ValidLoan::finalize enforces
+    //   TotalValueOutstanding >= PrincipalOutstanding + ManagementFeeOutstanding
+    // ("interest due is non-negative"). This test drives the transactor
+    // through a multi-payment scenario with a non-zero management fee and
+    // messy IOU-scale rounding; if any rounding path in LoanPay were to
+    // inflate PrincipalOutstanding or ManagementFeeOutstanding relative to
+    // TotalValueOutstanding by even one ULP, the invariant would fire and
+    // the LoanPay would return tecINVARIANT_FAILED instead of tesSUCCESS.
+    void
+    testLoanPayInterestDueNonNegativeInvariant()
+    {
+        testcase("LoanPay interest-due non-negative invariant");
+
+        using namespace jtx;
+        using namespace loan;
+
+        Env env(*this, all_ | featureLendingProtocolV1_1);
+
+        Account const issuer{"issuer"};
+        Account const lender{"lender"};
+        Account const borrower{"borrower"};
+
+        PrettyAsset const iouAsset = createFundedIouAsset(env, issuer, lender, borrower);
+
+        // Default broker params carry managementFeeRate = 100 tenth-bips
+        // (1%), which is what makes managementFeeOutstanding accumulate
+        // non-trivially through the payment schedule.
+        BrokerInfo const broker{createVaultAndBroker(env, iouAsset, lender)};
+
+        auto const loanSetFee = Fee(env.current()->fees().base * 2);
+        auto const loanKeylet = nextLoanKeylet(env, broker);
+
+        // Messy interest rate, non-trivial payment count. Values chosen so
+        // that periodicPayment and each roundedInterest/managementFee share
+        // are unlikely to be representable exactly at loanScale.
+        env(set(borrower, broker.brokerID, Number{1'000}),
+            Sig(sfCounterpartySignature, lender),
+            kInterestRate(TenthBips32{24'346}),
+            kPaymentTotal(24),
+            kPaymentInterval(86400 * 30),
+            loanSetFee);
+        env.close();
+
+        auto const payFee = Fee(env.current()->fees().base * 2);
+        // Boundary check up front on the freshly-created loan.
+        {
+            auto const initial = getCurrentState(env, broker, loanKeylet);
+            BEAST_EXPECT(
+                initial.totalValue >=
+                initial.principalOutstanding + initial.managementFeeOutstanding);
+        }
+
+        // Six regular scheduled payments. If the invariant fires the
+        // Ter(tesSUCCESS) assertion below catches it; the identity check
+        // then re-asserts it in the test for a clearer failure message.
+        std::uint32_t prevPaymentRemaining = 24;
+        for (int i = 0; i < 6; ++i)
+        {
+            auto const loanSle = env.le(loanKeylet);
+            if (!BEAST_EXPECT(loanSle))
+                return;
+            // Match the amount LoanPay expects for a scheduled payment:
+            // periodicPayment rounded at loanScale, plus the flat service
+            // fee (0 here by default, but included for robustness).
+            auto const payAmount = STAmount{
+                iouAsset,
+                roundPeriodicPayment(
+                    iouAsset, loanSle->at(sfPeriodicPayment), loanSle->at(sfLoanScale)) +
+                    loanSle->at(sfLoanServiceFee)};
+            env(pay(borrower, loanKeylet.key, payAmount), payFee, Ter(tesSUCCESS));
+            env.close();
+
+            auto const state = getCurrentState(env, broker, loanKeylet);
+            BEAST_EXPECT(
+                state.totalValue >= state.principalOutstanding + state.managementFeeOutstanding);
+            BEAST_EXPECT(state.paymentRemaining == prevPaymentRemaining - 1);
+            prevPaymentRemaining = state.paymentRemaining;
+        }
+    }
+
     // Tests run under each entry in amendmentCombinations().
     void
     runAmendmentSensitive(FeatureBitset features)
     {
         testLoanPayComputePeriodicPaymentInvariants(features);
         testLoanPayDebtDecreaseInvariant(features);
+        testLoanPayOverpaymentScheduleInvariant(features);
         testAccountSendMptMinAmountInvariant(features);
         testMinimumBrokerCoverConsistency(features);
     }
@@ -865,6 +1109,8 @@ public:
     void
     run() override
     {
+        testLoanSetRecipientScaleInvariant();
+        testLoanPayInterestDueNonNegativeInvariant();
         for (auto const& features : jtx::amendmentCombinations(
                  {fixCleanup3_1_3, fixCleanup3_2_0, featureMPTokensV2}, all_))
             runAmendmentSensitive(features);
diff --git a/src/test/app/lending/LoanLifecycle_test.cpp b/src/test/app/lending/LoanLifecycle_test.cpp
index dae6f6ce16..45420529c6 100644
--- a/src/test/app/lending/LoanLifecycle_test.cpp
+++ b/src/test/app/lending/LoanLifecycle_test.cpp
@@ -205,8 +205,14 @@ private:
         if (!BEAST_EXPECT(!createJson.isMember(jss::Signers)))
             counterpartyJson[sfSigners] = createJson[sfSigners];
 
-        // The duplicated signature works
-        createJson = env.json(createJson, Json(sfCounterpartySignature, counterpartyJson));
+        // The duplicated signature does not work: the counterparty signs a
+        // different prefix than the account.
+        env(env.json(createJson, Json(sfCounterpartySignature, counterpartyJson)),
+            Ter(telENV_RPC_FAILED));
+
+        // Signing the counterparty field itself works, even though the lender
+        // is both the borrower and the counterparty.
+        createJson = env.json(createJson, Sig(sfCounterpartySignature, lender));
         env(createJson);
 
         env.close();
diff --git a/src/test/app/lending/LoanMisc_test.cpp b/src/test/app/lending/LoanMisc_test.cpp
index c5a7d54311..7c4db3e2bf 100644
--- a/src/test/app/lending/LoanMisc_test.cpp
+++ b/src/test/app/lending/LoanMisc_test.cpp
@@ -113,21 +113,26 @@ private:
             txJson[sfTransactionType] = "AccountSet";
             txJson[sfAccount] = borrower.human();
 
-            auto const borrowerSignParams = [&]() {
-                json::Value params{json::ValueType::Object};
-                params[jss::passphrase] = borrowerPass;
-                params[jss::key_type] = "ed25519";
-                params[jss::signature_target] = "Destination";
-                params[jss::tx_json] = txJson;
-                return params;
-            }();
-            auto const jSignBorrower = env.rpc("json", "sign", to_string(borrowerSignParams));
-            BEAST_EXPECT(
-                jSignBorrower.isMember(jss::result) &&
-                jSignBorrower[jss::result].isMember(jss::error) &&
-                jSignBorrower[jss::result][jss::error] == "invalidParams" &&
-                jSignBorrower[jss::result].isMember(jss::error_message) &&
-                jSignBorrower[jss::result][jss::error_message] == "Destination");
+            // "Destination" is not an inner object at all. "Book" is one, but
+            // it holds no transaction signature, so it is not a target either.
+            for (char const* target : {"Destination", "Book", "Signer"})
+            {
+                auto const borrowerSignParams = [&]() {
+                    json::Value params{json::ValueType::Object};
+                    params[jss::passphrase] = borrowerPass;
+                    params[jss::key_type] = "ed25519";
+                    params[jss::signature_target] = target;
+                    params[jss::tx_json] = txJson;
+                    return params;
+                }();
+                auto const jSignBorrower = env.rpc("json", "sign", to_string(borrowerSignParams));
+                BEAST_EXPECT(
+                    jSignBorrower.isMember(jss::result) &&
+                    jSignBorrower[jss::result].isMember(jss::error) &&
+                    jSignBorrower[jss::result][jss::error] == "invalidParams" &&
+                    jSignBorrower[jss::result].isMember(jss::error_message) &&
+                    jSignBorrower[jss::result][jss::error_message] == target);
+            }
         }
         {
             testcase("RPC LoanSet - sign and submit borrower initiated");
diff --git a/src/test/app/lending/LoanPay_test.cpp b/src/test/app/lending/LoanPay_test.cpp
index 038ef4067b..7cd31b7988 100644
--- a/src/test/app/lending/LoanPay_test.cpp
+++ b/src/test/app/lending/LoanPay_test.cpp
@@ -37,6 +37,7 @@
 #include <cstdint>
 #include <limits>
 #include <memory>
+#include <string>
 #include <type_traits>
 
 namespace xrpl::test {
@@ -1419,6 +1420,69 @@ private:
         BEAST_EXPECT(stateAfter.nextPaymentDate == exactDueDate);
     }
 
+    // LoanPay does not call canAddHolding. addEmptyHolding recreates the
+    // broker-owner holding when the borrower is also the broker owner. After
+    // fixCleanup3_4_0 an existing line is a no-op even if DefaultRipple is
+    // off; pre-fix that path dies with tecINTERNAL.
+    void
+    testLoanPaySelfBrokerExistingLineDefaultRipple()
+    {
+        using namespace jtx;
+        using namespace loan;
+
+        auto run = [this](FeatureBitset features, TER expected) {
+            testcase(
+                std::string(
+                    "LoanPay broker-owner borrower existing line after "
+                    "issuer clears asfDefaultRipple (") +
+                (features[fixCleanup3_4_0] ? "post" : "pre") + "-fixCleanup3_4_0)");
+
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const alice{"alice"};
+
+            env.fund(XRP(10'000), issuer, alice);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            env(trust(alice, usd(10'000'000)));
+            env.close();
+            env(pay(issuer, alice, usd(2'000'000)));
+            env.close();
+
+            auto const broker = createVaultAndBroker(env, usd, alice);
+            auto const brokerSle = env.le(keylet::loanBroker(broker.brokerID));
+            if (!BEAST_EXPECT(brokerSle))
+                return;
+            auto const loanKeylet =
+                keylet::loan(broker.brokerID, SeqProxy::rawSequence(brokerSle->at(sfLoanSequence)));
+
+            Number const serviceFee = usd(2).value();
+            env(set(alice, broker.brokerID, usd(1'000).value()),
+                Sig(sfCounterpartySignature, alice),
+                kLoanServiceFee(serviceFee),
+                Fee(env.current()->fees().base * 2));
+            env.close();
+
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+            BEAST_EXPECT(env.le(keylet::trustLine(alice.id(), usd.raw().get<Issue>())));
+
+            auto const state = getCurrentState(env, broker, loanKeylet);
+            STAmount const payment{
+                usd,
+                roundPeriodicPayment(usd, state.periodicPayment + serviceFee, state.loanScale)};
+
+            env(pay(alice, loanKeylet.key, payment), Ter(expected));
+            env.close();
+        };
+
+        run(all_ - fixCleanup3_4_0, tecINTERNAL);
+        run(all_, tesSUCCESS);
+    }
+
     void
     runAmendmentIndependent()
     {
@@ -1429,6 +1493,7 @@ private:
         testLoanPayCatchUpFeeAtExactDueDatePostAmendment();
         testLoanPayCatchUpFeeAtExactDueDatePreAmendment();
         testRepayIntoUnauthorizedVault();
+        testLoanPaySelfBrokerExistingLineDefaultRipple();
     }
 
     // Tests run under each entry in amendmentCombinations().
diff --git a/src/test/app/lending/LoanSecurity_test.cpp b/src/test/app/lending/LoanSecurity_test.cpp
index 463273e227..54c972b505 100644
--- a/src/test/app/lending/LoanSecurity_test.cpp
+++ b/src/test/app/lending/LoanSecurity_test.cpp
@@ -5,6 +5,7 @@
 #include <test/jtx/amount.h>
 #include <test/jtx/fee.h>
 #include <test/jtx/noop.h>
+#include <test/jtx/sponsor.h>
 #include <test/jtx/ter.h>
 #include <test/jtx/txflags.h>
 #include <test/jtx/vault.h>
@@ -1090,9 +1091,74 @@ private:
         }
     }
 
+    // Every signature on a transaction covered the same bytes before
+    // fixCleanup3_4_0, so a signature could be moved from the role that made
+    // it into another role. Here the lender signs a LoanSet as the
+    // counterparty, and the borrower copies that signature into the
+    // SponsorSignature, making the lender pay the fee without the lender ever
+    // agreeing to sponsor it.
+    void
+    testSignatureCopiedBetweenRoles(bool fixEnabled)
+    {
+        testcase(
+            std::string("Counterparty signature copied into the sponsor slot") +
+            (fixEnabled ? "" : " (pre-amendment)"));
+
+        using namespace jtx;
+        using namespace loan;
+
+        Env env(*this, fixEnabled ? all_ : all_ - fixCleanup3_4_0);
+        BEAST_EXPECT(env.enabled(fixCleanup3_4_0) == fixEnabled);
+
+        Account const lender{"lender"};
+        Account const borrower{"borrower"};
+
+        env.fund(XRP(100'000'000), lender, borrower);
+        env.close();
+
+        PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
+        auto const broker = createVaultAndBroker(env, xrpAsset, lender);
+
+        auto const feeAmt = XRP(1);
+
+        // The lender agrees to the loan by signing the Counterparty slot of a
+        // LoanSet that names the lender as the fee sponsor. The lender signs
+        // nothing else.
+        auto loanSet = env.json(
+            set(borrower, broker.brokerID, broker.asset(Number{1, 3}).value()),
+            sponsor::As(lender, spfSponsorFee),
+            Sig(sfCounterpartySignature, lender),
+            Fee(feeAmt));
+
+        // The borrower copies the lender's signature into the sponsor slot.
+        loanSet[sfSponsorSignature.jsonName] = loanSet[sfCounterpartySignature.jsonName];
+
+        auto const lenderBalance = env.balance(lender);
+        auto const borrowerBalance = env.balance(borrower);
+
+        env(loanSet, Ter(fixEnabled ? TER{telENV_RPC_FAILED} : TER{tesSUCCESS}));
+        env.close();
+
+        if (fixEnabled)
+        {
+            // The copied signature does not verify in the sponsor slot, so
+            // nothing happens at all.
+            BEAST_EXPECT(env.balance(lender) == lenderBalance);
+            BEAST_EXPECT(env.balance(borrower) == borrowerBalance);
+        }
+        else
+        {
+            // The lender paid the fee, and the borrower got the loan.
+            BEAST_EXPECT(env.balance(lender) == lenderBalance - feeAmt);
+            BEAST_EXPECT(env.balance(borrower).value() > borrowerBalance.value());
+        }
+    }
+
     void
     runAmendmentIndependent()
     {
+        testSignatureCopiedBetweenRoles(true);
+        testSignatureCopiedBetweenRoles(false);
         testRIPD3901();
         testImpairmentPaymentDateUnchanged();
         testImpairmentPaymentDatePreAmendment();
diff --git a/src/test/app/lending/LoanSet_test.cpp b/src/test/app/lending/LoanSet_test.cpp
index 3571853b47..5eea6f83fe 100644
--- a/src/test/app/lending/LoanSet_test.cpp
+++ b/src/test/app/lending/LoanSet_test.cpp
@@ -26,10 +26,12 @@
 #include <xrpl/protocol/TxFlags.h>
 #include <xrpl/protocol/Units.h>
 #include <xrpl/protocol/XRPAmount.h>
+#include <xrpl/tx/transactors/lending/LoanSet.h>
 
 #include <array>
 #include <cstdint>
 #include <functional>
+#include <string>
 #include <utility>
 #include <vector>
 
@@ -602,6 +604,8 @@ private:
         testcase("LoanSet closed-ended: phase and maturity bound");
         using namespace jtx;
         using namespace loan;
+        using d = NetClock::duration;
+        using tp = NetClock::time_point;
 
         Account const issuer{"issuer"};
         Account const lender{"lender"};
@@ -663,9 +667,9 @@ private:
             setLoan(env, broker, tesSUCCESS);
         });
 
-        // 4. Rejected during Investment when the loan's final payment would land on or after
-        // RedemptionDate. Use a tight redemptionOffset and a schedule whose final payment is well
-        // past that boundary.
+        // 4. Rejected during Investment when the loan's final payment would land fewer than
+        // kLoanRedemptionBuffer seconds before RedemptionDate. Use a tight redemptionOffset and a
+        // schedule whose final payment is well past that boundary.
         withEnv([&](Env& env, PrettyAsset const& asset) {
             constexpr std::uint32_t kRedemptionOffset = 3u * 24u * 3600u;
             auto const broker = createVaultAndBroker(
@@ -684,16 +688,16 @@ private:
             env.close();
         });
 
-        // 5. Boundary: schedule whose finalPayment lands exactly (RedemptionDate - 1) is accepted,
-        // and one second later (== RedemptionDate) is rejected. Uses payTotal = 1 so the arithmetic
-        // is simple: finalPayment = startDate + interval.
+        // 5. Boundary: a finalPayment exactly kLoanRedemptionBuffer seconds before
+        // RedemptionDate is accepted; one second later is rejected. Uses payTotal = 1 so
+        // finalPayment = startDate + interval.
         withEnv([&](Env& env, PrettyAsset const& asset) {
             auto const broker = createVaultAndBroker(
                 env, asset, lender, BrokerParameters{.vaultKind = VaultKind::ClosedEnded});
             BEAST_EXPECT(broker.redemptionDate.has_value());
 
             auto const startDate = env.now().time_since_epoch().count();
-            auto const acceptInterval = *broker.redemptionDate - 1 - startDate;
+            auto const acceptInterval = *broker.redemptionDate - kLoanRedemptionBuffer - startDate;
             env(set(lender, broker.brokerID, broker.asset(100).value()),
                 kCounterparty(borrower),
                 Sig(sfCounterpartySignature, borrower),
@@ -703,8 +707,8 @@ private:
                 Ter(tesSUCCESS));
             env.close();
 
-            auto const rejectInterval =
-                *broker.redemptionDate - env.now().time_since_epoch().count();
+            auto const rejectInterval = *broker.redemptionDate - (kLoanRedemptionBuffer - 1) -
+                env.now().time_since_epoch().count();
             env(set(lender, broker.brokerID, broker.asset(100).value()),
                 kCounterparty(borrower),
                 Sig(sfCounterpartySignature, borrower),
@@ -714,6 +718,114 @@ private:
                 Ter(tecNO_PERMISSION));
             env.close();
         });
+
+        // 6. A vault whose Investment window is exactly kMinInvestmentPeriod can originate a
+        // minimum-interval, single-payment loan at the start of Investment, and rejects the same
+        // schedule once StartDate no longer leaves kLoanRedemptionBuffer before RedemptionDate.
+        // Do not pin an unrounded wall-clock instant: Env::close rounds to the close-time
+        // resolution. Read env.now() (the same clock LoanSet::preclaim uses) and assert the
+        // buffer relationship before each LoanSet.
+        withEnv([&](Env& env, PrettyAsset const& asset) {
+            auto const broker = createVaultAndBroker(
+                env,
+                asset,
+                lender,
+                BrokerParameters{
+                    .vaultKind = VaultKind::ClosedEnded,
+                    .subscriptionOffset = 300u,
+                    .redemptionOffset = kMinInvestmentPeriod,
+                    .skipPhaseAdvance = true});
+            BEAST_EXPECT(broker.subscriptionDate.has_value());
+            BEAST_EXPECT(broker.redemptionDate.has_value());
+
+            auto const red = *broker.redemptionDate;
+            auto const startDate = [&]() { return env.now().time_since_epoch().count(); };
+            auto const minLoan = [&](TER expected) {
+                env(set(lender, broker.brokerID, broker.asset(100).value()),
+                    kCounterparty(borrower),
+                    Sig(sfCounterpartySignature, borrower),
+                    Fee(env.current()->fees().base * 5),
+                    kPaymentTotal(1u),
+                    kPaymentInterval(LoanSet::kMinPaymentInterval),
+                    Ter(expected));
+                env.close();
+            };
+
+            // First Investment ledger: the minimum schedule still clears the buffer.
+            env.close(tp{d{*broker.subscriptionDate + 1}});
+            BEAST_EXPECT(startDate() > *broker.subscriptionDate);
+            BEAST_EXPECT(startDate() + LoanSet::kMinPaymentInterval + kLoanRedemptionBuffer <= red);
+            minLoan(tesSUCCESS);
+
+            // Still Investment, but the minimum schedule no longer clears the buffer.
+            while (startDate() + LoanSet::kMinPaymentInterval + kLoanRedemptionBuffer <= red)
+                env.close();
+            BEAST_EXPECT(startDate() < red);
+            minLoan(tecNO_PERMISSION);
+        });
+    }
+
+    // LoanSet used to call canAddHolding unconditionally, so an existing
+    // borrower line still failed with terNO_RIPPLE after the issuer cleared
+    // DefaultRipple. After fixCleanup3_4_0, skip that gate when the holding
+    // already exists.
+    void
+    testLoanSetExistingLineAfterIssuerClearsDefaultRipple()
+    {
+        using namespace jtx;
+        using namespace loan;
+
+        auto run = [this](FeatureBitset features, TER expected) {
+            testcase(
+                std::string(
+                    "LoanSet existing borrower line after issuer "
+                    "clears asfDefaultRipple (") +
+                (features[fixCleanup3_4_0] ? "post" : "pre") + "-fixCleanup3_4_0)");
+
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const lender{"lender"};
+            Account const borrower{"borrower"};
+
+            env.fund(XRP(10'000), issuer, lender, borrower);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            env(trust(lender, usd(10'000'000)));
+            env(trust(borrower, usd(10'000'000)));
+            env.close();
+            env(pay(issuer, lender, usd(2'000'000)));
+            env(pay(issuer, borrower, usd(1'000)));
+            env.close();
+            BEAST_EXPECT(env.le(keylet::trustLine(borrower.id(), usd.raw().get<Issue>())));
+
+            auto const broker = createVaultAndBroker(env, usd, lender);
+
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+
+            Number const destBefore = env.balance(borrower, usd.raw()).number();
+            env(set(borrower, broker.brokerID, usd(100).value()),
+                Sig(sfCounterpartySignature, lender),
+                Fee(env.current()->fees().base * 2),
+                Ter(expected));
+            env.close();
+
+            Number const destAfter = env.balance(borrower, usd.raw()).number();
+            if (isTesSuccess(expected))
+            {
+                BEAST_EXPECT(destAfter == destBefore + Number{100});
+            }
+            else
+            {
+                BEAST_EXPECT(destAfter == destBefore);
+            }
+        };
+
+        run(all_ - fixCleanup3_4_0, terNO_RIPPLE);
+        run(all_, tesSUCCESS);
     }
 
 public:
@@ -725,6 +837,7 @@ public:
             testLoanSet(features);
 
         testLoanSetClosedEnded();
+        testLoanSetExistingLineAfterIssuerClearsDefaultRipple();
     }
 };
 
diff --git a/src/test/app/lending/LoanTestBase.h b/src/test/app/lending/LoanTestBase.h
index c9d4a3185b..13dffb6b9e 100644
--- a/src/test/app/lending/LoanTestBase.h
+++ b/src/test/app/lending/LoanTestBase.h
@@ -101,6 +101,10 @@ protected:
         TenthBips32 coverRateLiquidation = percentageToTenthBips(25);
         std::string data = {};  // NOLINT(readability-redundant-member-init)
         std::uint32_t flags = 0;
+        // VaultCreate flags (e.g. tfVaultPrivate). Distinct from `flags`,
+        // which are passed to LoanBrokerSet.
+        std::optional<std::uint32_t> vaultFlags =
+            std::nullopt;  // NOLINT(readability-redundant-member-init)
         // If set, the vault is created with this sfScale value. Useful for
         // tests that need finer loanScale to exercise rounding edge cases.
         std::optional<std::uint8_t> vaultScale =
@@ -115,8 +119,8 @@ protected:
         std::uint32_t subscriptionOffset = 60;
         // Seconds between SubscriptionDate and RedemptionDate. Must be >= kMinInvestmentPeriod, <
         // kMaxInvestmentPeriod, and generous enough to fit any loan schedule the test runs
-        // (finalPayment must be strictly before RedemptionDate). Default sized to comfortably
-        // exceed any schedule realistic tests are likely to configure.
+        // (finalPayment must precede RedemptionDate by at least kLoanRedemptionBuffer). Default
+        // sized to comfortably exceed any schedule realistic tests are likely to configure.
         std::uint32_t redemptionOffset = 10u * 365u * 24u * 60u * 60u;
         // When true, createVaultAndBroker skips its automatic clock advance past SubscriptionDate.
         // Useful for tests that need to observe the vault while it is still in the Subscription
@@ -526,6 +530,7 @@ protected:
         auto [tx, vaultKeylet] = vault.create(
             {.owner = lender,
              .asset = asset,
+             .flags = params.vaultFlags,
              .vaultKind = effectiveVaultKind == VaultKind::OpenEnded
                  ? std::optional<std::uint8_t>{}
                  : std::optional<std::uint8_t>{std::to_underlying(effectiveVaultKind)},
diff --git a/src/test/app/lending/LoanValidation_test.cpp b/src/test/app/lending/LoanValidation_test.cpp
index 169a02c462..566633b690 100644
--- a/src/test/app/lending/LoanValidation_test.cpp
+++ b/src/test/app/lending/LoanValidation_test.cpp
@@ -6,7 +6,6 @@
 #include <test/jtx/envconfig.h>
 #include <test/jtx/fee.h>
 #include <test/jtx/flags.h>
-#include <test/jtx/jtx_json.h>
 #include <test/jtx/mpt.h>
 #include <test/jtx/pay.h>
 #include <test/jtx/sponsor.h>
@@ -522,15 +521,13 @@ private:
         auto const loanSetFee = Fee(env.current()->fees().base * 2);
         Number const principalRequest{1, 3};
 
-        auto createJson = env.json(set(lender, broker.brokerID, principalRequest), Fee(loanSetFee));
-
-        json::Value counterpartyJson{json::ValueType::Object};
-        counterpartyJson[sfTxnSignature] = createJson[sfTxnSignature];
-        counterpartyJson[sfSigningPubKey] = createJson[sfSigningPubKey];
-        if (!BEAST_EXPECT(!createJson.isMember(jss::Signers)))
-            counterpartyJson[sfSigners] = createJson[sfSigners];
-
-        createJson = env.json(createJson, Json(sfCounterpartySignature, counterpartyJson));
+        // The lender is both the borrower and the counterparty here, but the
+        // two roles sign different bytes, so each signature must be made for
+        // the field it goes into.
+        auto const createJson = env.json(
+            set(lender, broker.brokerID, principalRequest),
+            Sig(sfCounterpartySignature, lender),
+            Fee(loanSetFee));
         env(createJson);
 
         env.close();
diff --git a/src/test/app/tx/apply_test.cpp b/src/test/app/tx/apply_test.cpp
index 8f71d47fcf..39289a6264 100644
--- a/src/test/app/tx/apply_test.cpp
+++ b/src/test/app/tx/apply_test.cpp
@@ -1,12 +1,23 @@
 // Copyright (c) 2020 Dev Null Productions
 
+#include <test/jtx/Account.h>
 #include <test/jtx/Env.h>
+#include <test/jtx/JTx.h>
+#include <test/jtx/TestHelpers.h>
+#include <test/jtx/amount.h>
+#include <test/jtx/fee.h>
+#include <test/jtx/noop.h>
+#include <test/jtx/sig.h>
+#include <test/jtx/sponsor.h>
 
 #include <xrpl/basics/Slice.h>
 #include <xrpl/basics/StringUtilities.h>
 #include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/TxFlags.h>
 #include <xrpl/tx/apply.h>
 
 #include <functional>
@@ -22,6 +33,136 @@ public:
     {
         testcase("Require Fully Canonical Signature");
         testFullyCanonicalSigs();
+        testRoleSignatureCacheIsEraSpecific();
+        testForcedValidityIgnoresPrefixEra();
+    }
+
+    // forceValidity means the caller verified nothing and wants the result
+    // trusted, so it has to hold in both prefix eras. If it marked only the
+    // ordinary slot, a role-signature transaction would still be verified
+    // under pre-fix rules, defeating the cluster path and the configurations
+    // that turn signature checks off.
+    void
+    testForcedValidityIgnoresPrefixEra()
+    {
+        testcase("Forced validity ignores the prefix era");
+
+        using namespace test::jtx;
+
+        Env preFix{*this, testableAmendments() - fixCleanup3_4_0};
+        Env postFix{*this, testableAmendments()};
+        auto const preFixRules = preFix.current()->rules();
+
+        Account const alice{"alice"};
+        Account const sponsor{"sponsor"};
+        postFix.fund(XRP(10'000), alice, sponsor);
+        postFix.close();
+
+        // Signed under the post-fix rules, so this signature does not verify
+        // under the pre-fix prefix. Only the forced verdict can make the check
+        // below pass.
+        auto const jt = postFix.jt(
+            noop(alice),
+            Fee(XRP(1)),
+            sponsor::As(sponsor, spfSponsorFee),
+            Sig(sfSponsorSignature, sponsor));
+        if (!BEAST_EXPECT(jt.stx))
+            return;
+
+        // A router that has never seen this transaction, so the only cached
+        // state is what forceValidity writes.
+        auto& router = preFix.app().getHashRouter();
+        forceValidity(router, jt.stx->getTransactionID(), Validity::SigGoodOnly);
+        BEAST_EXPECT(checkValidity(router, *jt.stx, preFixRules).first != Validity::SigBad);
+    }
+
+    // A signature verdict reached under one prefix era must not be honored in
+    // the other, because the two eras require the sponsor signature to cover
+    // different bytes. Each direction below uses one HashRouter and differs
+    // only in the rules, which is what the flag ledger looks like in practice:
+    // relay and submit verify against the validated rules, which lag the open
+    // ledger rules that preflight2 verifies against, so one transaction gets
+    // checked under both prefixes at the same time.
+    void
+    testRoleSignatureCacheIsEraSpecific()
+    {
+        testcase("Role signature cache is era specific");
+
+        using namespace test::jtx;
+
+        Env preFix{*this, testableAmendments() - fixCleanup3_4_0};
+        Env postFix{*this, testableAmendments()};
+        auto const preFixRules = preFix.current()->rules();
+        auto const postFixRules = postFix.current()->rules();
+
+        Account const alice{"alice"};
+        Account const sponsor{"sponsor"};
+        Account const counterparty{"counterparty"};
+        for (auto* env : {&preFix, &postFix})
+        {
+            env->fund(XRP(10'000), alice, sponsor, counterparty);
+            env->close();
+        }
+
+        // Both directions for a transaction whose role signature sits in the
+        // field that makeTx signs. makeTx builds the transaction in the Env it
+        // is given, so the role signature carries that era's prefix.
+        auto checkBothDirections = [&](std::function<JTx(test::jtx::Env&)> const& makeTx) {
+            // Direction 1: a good verdict under the old prefix must not let a
+            // signature moved between roles survive the amendment.
+            {
+                auto const jt = makeTx(preFix);
+                if (!BEAST_EXPECT(jt.stx))
+                    return;
+
+                auto& router = preFix.app().getHashRouter();
+                BEAST_EXPECT(checkValidity(router, *jt.stx, preFixRules).first == Validity::Valid);
+
+                // Same router, asked again under the post-fix rules. The Valid
+                // verdict above was reached under the old prefix and must not
+                // be reused, or a signature moved between roles would survive
+                // the amendment.
+                BEAST_EXPECT(
+                    checkValidity(router, *jt.stx, postFixRules).first == Validity::SigBad);
+            }
+
+            // Direction 2: a bad verdict under the old prefix must not condemn
+            // a transaction that the new prefixes accept. A node whose
+            // validated rules still lag the open ledger will run this check
+            // pre-fix first and reject a correctly new-prefix-signed
+            // transaction; the post-fix check must then verify it afresh
+            // instead of reusing the pre-fix verdict.
+            {
+                auto const jt = makeTx(postFix);
+                if (!BEAST_EXPECT(jt.stx))
+                    return;
+
+                auto& router = postFix.app().getHashRouter();
+                BEAST_EXPECT(checkValidity(router, *jt.stx, preFixRules).first == Validity::SigBad);
+                BEAST_EXPECT(checkValidity(router, *jt.stx, postFixRules).first == Validity::Valid);
+            }
+        };
+
+        // sfSponsorSignature, which uses the SPN and SPM prefixes.
+        checkBothDirections([&](Env& env) {
+            return env.jt(
+                noop(alice),
+                Fee(XRP(1)),
+                sponsor::As(sponsor, spfSponsorFee),
+                Sig(sfSponsorSignature, sponsor));
+        });
+
+        // sfCounterpartySignature, which uses its own prefixes, CPT and CPM,
+        // and only appears on a LoanSet. The transaction does not have to be
+        // applicable: checkValidity verifies signatures without consulting the
+        // ledger, so a placeholder LoanBrokerID is enough.
+        checkBothDirections([&](Env& env) {
+            return env.jt(
+                loan::set(alice, uint256{1}, Number{1}),
+                loan::kCounterparty(counterparty),
+                Fee(XRP(1)),
+                Sig(sfCounterpartySignature, counterparty));
+        });
     }
 
     void
diff --git a/src/test/app/vault/VaultBugs_test.cpp b/src/test/app/vault/VaultBugs_test.cpp
index e3e0c40bc2..cc30bd6091 100644
--- a/src/test/app/vault/VaultBugs_test.cpp
+++ b/src/test/app/vault/VaultBugs_test.cpp
@@ -7,16 +7,22 @@
 #include <test/jtx/credentials.h>
 #include <test/jtx/fee.h>
 #include <test/jtx/flags.h>
+#include <test/jtx/mpt.h>
 #include <test/jtx/pay.h>
+#include <test/jtx/permissioned_domains.h>
 #include <test/jtx/sig.h>
+#include <test/jtx/sponsor.h>
 #include <test/jtx/ter.h>
 #include <test/jtx/trust.h>
 #include <test/jtx/vault.h>
 
 #include <xrpl/basics/Number.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/chrono.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/json/json_forwards.h>
 #include <xrpl/json/json_value.h>
+#include <xrpl/ledger/helpers/VaultHelpers.h>
 #include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Indexes.h>
@@ -26,9 +32,11 @@
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STNumber.h>  // IWYU pragma: keep
 #include <xrpl/protocol/SeqProxy.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFlags.h>
+#include <xrpl/protocol/UintTypes.h>
 
 #include <chrono>
 #include <cstdint>
@@ -425,6 +433,9 @@ private:
             testcase(
                 "bug: VaultDeposit below Vault precision canonicalized to zero "
                 "(pre-fixCleanup3_2_0)");
+            // Also remove fixCleanup3_4_0 so the VaultDeposit clamp
+            // introduced by that amendment does not short-circuit this
+            // pre-fixCleanup3_2_0 scenario with tecPRECISION_LOSS.
             runScenario(
                 testableAmendments() - fixCleanup3_2_0 - fixCleanup3_4_0, tecINVARIANT_FAILED);
         }
@@ -806,6 +817,128 @@ private:
         }
     }
 
+    // Scale 15 seed + deposit 5: pre-fix credited > paid; post-fix credited <= paid.
+    // fixCleanup3_2_0 is off so roundToVaultScale does not shrink the deposit first.
+    void
+    testBugVaultDepositOvercreditsAcrossScaleBoundary()
+    {
+        using namespace test::jtx;
+
+        auto runScenario = [this](FeatureBitset features, bool expectOvercredit) {
+            Env env(*this, features);
+            Account const owner{"owner"};
+            Account const issuer{"issuer"};
+            Account const depositor{"depositor"};
+            env.fund(XRP(1'000'000), owner, issuer, depositor);
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            Number const seed{9'999'999'999'999'999LL, -15};
+            Number const deposit{5};
+
+            env(trust(depositor, usd(1'000'000'000)));
+            env.close();
+            env(pay(issuer, depositor, usd(deposit)));
+            env.close();
+
+            Vault const vault{env};
+            auto [tx, keylet] = vault.create({.owner = owner, .asset = usd.raw()});
+            tx[sfScale] = 15;
+            env(tx);
+            env.close();
+            env(vault.deposit({.depositor = issuer, .id = keylet.key, .amount = usd(seed)}));
+            env.close();
+
+            Number const totalBefore = env.le(keylet)->at(sfAssetsTotal);
+            Number const depositorBefore = env.balance(depositor, usd.raw()).number();
+
+            env(vault.deposit({.depositor = depositor, .id = keylet.key, .amount = usd(deposit)}));
+            env.close();
+
+            Number const totalAfter = env.le(keylet)->at(sfAssetsTotal);
+            Number const depositorAfter = env.balance(depositor, usd.raw()).number();
+            Number const paid = depositorBefore - depositorAfter;
+            Number const credited = totalAfter - totalBefore;
+
+            if (expectOvercredit)
+            {
+                BEAST_EXPECTS(
+                    credited > paid,
+                    "AssetsTotal credited " + to_string(credited) + " for a payment of " +
+                        to_string(paid) + ", expected an overcredit");
+            }
+            else
+            {
+                BEAST_EXPECTS(
+                    credited <= paid,
+                    "AssetsTotal credited " + to_string(credited) + " for a payment of " +
+                        to_string(paid));
+            }
+        };
+
+        testcase(
+            "bug: VaultDeposit overcredits across an IOU scale boundary "
+            "(pre-fixCleanup3_4_0)");
+        runScenario(all_ - fixCleanup3_2_0 - fixCleanup3_4_0, true);
+
+        testcase(
+            "bug: VaultDeposit no longer overcredits across an IOU scale boundary "
+            "(post-fixCleanup3_4_0)");
+        runScenario(all_, false);
+    }
+
+    // 1e17 IOU at scale 0. Withdraw all-but-one, then the last share:
+    // pre-fix tecINVARIANT_FAILED, post-fix tesSUCCESS.
+    void
+    testBugVaultLockedByPartialWithdraw()
+    {
+        using namespace test::jtx;
+
+        auto runScenario = [this](FeatureBitset features, TER expected) {
+            Env env(*this, features);
+            Account const owner{"owner"};
+            Account const issuer{"issuer"};
+            Account const holder{"holder"};
+            env.fund(XRP(1'000'000), owner, issuer, holder);
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            env(trust(holder, usd(Number{1, 18})));
+            env.close();
+            env(pay(issuer, holder, usd(Number{1, 17})));
+            env.close();
+
+            Vault const vault{env};
+            auto [tx, keylet] = vault.create({.owner = owner, .asset = usd.raw()});
+            tx[sfScale] = 0;
+            env(tx);
+            env.close();
+            env(vault.deposit(
+                {.depositor = holder, .id = keylet.key, .amount = usd(Number{1, 17})}));
+            env.close();
+
+            MPTIssue const share{env.le(keylet)->at(sfShareMPTID)};
+            std::int64_t const allButOne = 100'000'000'000'000'000LL - 1;
+            env(vault.withdraw(
+                {.depositor = holder, .id = keylet.key, .amount = STAmount{share, allButOne}}));
+            env.close();
+
+            env(vault.withdraw(
+                    {.depositor = holder, .id = keylet.key, .amount = STAmount{share, 1}}),
+                Ter(expected));
+            env.close();
+        };
+
+        testcase(
+            "bug: VaultWithdraw permanently locks a large IOU vault "
+            "(pre-fixCleanup3_4_0)");
+        runScenario(all_ - fixCleanup3_4_0, tecINVARIANT_FAILED);
+        testcase(
+            "bug: VaultWithdraw no longer locks a large IOU vault "
+            "(post-fixCleanup3_4_0)");
+        runScenario(all_, tesSUCCESS);
+    }
+
     // VaultDeposit::preclaim uses accountHolds(..., SpendableHandling::
     // shFULL_BALANCE), which for an IOU asset adds the counterparty's
     // LowLimit/HighLimit to the depositor's raw balance (TokenHelpers.cpp:
@@ -1223,115 +1356,1389 @@ private:
         }
     }
 
-    void
-    testCredentialPinsPseudoAccount()
+    struct ImpairedLoanVault
+    {
+        test::jtx::Account issuer;
+        test::jtx::Account holder;
+        PrettyAsset usd;
+        test::jtx::Vault vault;
+        Keylet vaultKeylet;
+        MPTID shareId;
+    };
+
+    // Impairing a 1,000 loan in a 10,000 vault leaves AssetsAvailable=9,000
+    // and AssetsTotal=10,000. otherDeposit > 0 splits the shares, 0 leaves
+    // holder as the sole shareholder.
+    std::optional<ImpairedLoanVault>
+    makeImpairedLoanVault(test::jtx::Env& env, int otherDeposit)
     {
         using namespace test::jtx;
+        using namespace loan_broker;
+        using namespace loan;
 
-        // A credential issued to a vault pseudo-account can't be accepted or
-        // deleted by it (pseudo-accounts can't sign), so it stays pinned in the
-        // pseudo-account's owner directory and blocks VaultDelete with
-        // tecHAS_OBLIGATIONS. A pin created before the cure activates is removed
-        // by VaultDelete once it does.
+        Account const issuer{"issuer"};
         Account const owner{"owner"};
-        Account const attacker{"attacker"};
-        char const credType[] = "FN36";
+        Account const holder{"holder"};
+        Account const other{"other"};
+        Account const borrower{"borrower"};
 
-        Env env{*this, all_ - fixCleanup3_3_0 - fixCleanup3_4_0};
-        env.fund(XRP(1'000'000), owner, attacker);
+        env.fund(XRP(100'000), issuer, owner, holder, other, borrower);
+        env.close();
+
+        env(fset(issuer, asfAllowTrustLineClawback));
+        env(fset(issuer, asfDefaultRipple));
+        env.close();
+
+        PrettyAsset const usd = issuer["USD"];
+        env.trust(usd(100'000), owner);
+        env.trust(usd(100'000), holder);
+        env.trust(usd(100'000), other);
+        env.trust(usd(100'000), borrower);
+        env.close();
+
+        int const holderDeposit = 10'000 - otherDeposit;
+        env(pay(issuer, holder, usd(holderDeposit)));
+        if (otherDeposit != 0)
+        {
+            env(pay(issuer, other, usd(otherDeposit)));
+        }
         env.close();
 
         Vault const vault{env};
-        PrettyAsset const asset = xrpIssue();
-        auto [tx, keylet] = vault.create({.owner = owner, .asset = asset});
-        env(tx);
+        auto const [createTx, vaultKeylet, subscriptionDate] = vault.createClosedEnded(
+            {.owner = owner, .asset = usd, .subscriptionOffset = std::chrono::seconds{60}});
+        env(createTx);
         env.close();
 
-        auto const vaultSle = env.le(keylet);
-        BEAST_EXPECT(vaultSle);
-        Account const pseudo{"vault pseudo-account", vaultSle->at(sfAccount)};
-        env.memoize(pseudo);
+        auto const vaultSle = env.le(vaultKeylet);
+        if (!BEAST_EXPECT(vaultSle))
+            return std::nullopt;
+        MPTID const shareId = vaultSle->at(sfShareMPTID);
 
-        // The pseudo-account owns the share issuance; the pin must not change
-        // its owner count (an unaccepted credential is owned by the issuer).
-        auto const pseudoOwnerCount = ownerCount(env, pseudo);
-
-        testcase("Credential pins vault pseudo-account");
-        env(credentials::create(pseudo, attacker, credType));
+        env(vault.deposit(
+            {.depositor = holder, .id = vaultKeylet.key, .amount = usd(holderDeposit)}));
+        if (otherDeposit != 0)
+        {
+            env(vault.deposit(
+                {.depositor = other, .id = vaultKeylet.key, .amount = usd(otherDeposit)}));
+        }
         env.close();
 
-        auto const credKey = credentials::keylet(pseudo, attacker, credType);
-        BEAST_EXPECT(env.le(credKey));
-        BEAST_EXPECT(ownerCount(env, attacker) == 1);
-        BEAST_EXPECT(ownerCount(env, pseudo) == pseudoOwnerCount);
+        vault.closePastSubscription(subscriptionDate);
 
-        // The pin blocks deletion of an otherwise-empty vault.
-        env(vault.del({.owner = owner, .id = keylet.key}), Ter(tecHAS_OBLIGATIONS));
+        auto const brokerKeylet =
+            keylet::loanBroker(owner.id(), SeqProxy::rawSequence(env.seq(owner)));
+        env(set(owner, vaultKeylet.key));
         env.close();
 
-        env.enableFeature(fixCleanup3_4_0);
+        auto const sleBroker = env.le(brokerKeylet);
+        if (!BEAST_EXPECT(sleBroker))
+            return std::nullopt;
+        auto const loanKeylet =
+            keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(sleBroker->at(sfLoanSequence)));
+
+        env(set(borrower, brokerKeylet.key, usd(1'000).value()),
+            loan::kInterestRate(percentageToTenthBips(0)),
+            kGracePeriod(60),
+            kPaymentInterval(120),
+            kPaymentTotal(10),
+            Sig(sfCounterpartySignature, owner),
+            Fee(env.current()->fees().base * 2),
+            Ter(tesSUCCESS));
         env.close();
 
-        // The pre-existing pin no longer blocks deletion; the credential is
-        // cleaned up and the issuer's owner count is restored.
-        testcase("VaultDelete removes pinned credential");
-        env(vault.del({.owner = owner, .id = keylet.key}));
+        // Under fixCleanup3_4_0, LoanManage rejects tfLoanImpair with
+        // tecTOO_SOON unless the payment is already late; advance the ledger
+        // past sfNextPaymentDueDate so impairment succeeds. No-op otherwise.
+        if (env.current()->rules().enabled(fixCleanup3_4_0))
+        {
+            auto const loanBefore = env.le(loanKeylet);
+            if (!BEAST_EXPECT(loanBefore))
+                return std::nullopt;
+            std::uint32_t const dueDate = loanBefore->at(sfNextPaymentDueDate);
+            env.close(NetClock::time_point{NetClock::duration{dueDate}} + std::chrono::seconds{1});
+        }
+
+        env(manage(owner, loanKeylet.key, tfLoanImpair), Ter(tesSUCCESS));
         env.close();
 
-        BEAST_EXPECT(!env.le(credKey));
-        BEAST_EXPECT(!env.le(keylet));
-        BEAST_EXPECT(!env.le(::xrpl::keylet::account(pseudo.id())));
-        BEAST_EXPECT(ownerCount(env, attacker) == 0);
+        auto const vaultAfter = env.le(vaultKeylet);
+        if (!BEAST_EXPECT(vaultAfter))
+            return std::nullopt;
+        BEAST_EXPECT(vaultAfter->at(sfAssetsAvailable) == usd(9'000).value());
+        BEAST_EXPECT(vaultAfter->at(sfLossUnrealized) == usd(1'000).value());
+
+        return ImpairedLoanVault{
+            .issuer = issuer,
+            .holder = holder,
+            .usd = usd,
+            .vault = vault,
+            .vaultKeylet = vaultKeylet,
+            .shareId = shareId};
     }
 
+    // Legacy clawback pricing burns every share; fixCleanup3_4_0 leaves 10%
+    // outstanding, backed by the impaired receivable.
     void
-    testCredentialPinOverflow()
+    testBugClawbackAfterLoanImpair()
     {
         using namespace test::jtx;
-        testcase("Credential pin cleanup is bounded (tecINCOMPLETE)");
 
-        // A pseudo-account can be pinned with more credentials than one
-        // transaction is allowed to clean up. VaultDelete then removes them a
-        // bounded batch at a time, returning tecINCOMPLETE until the last batch.
+        auto clawbackHolder = [](ImpairedLoanVault const& setup, STAmount const& amount) {
+            return setup.vault.clawback(
+                {.issuer = setup.issuer,
+                 .id = setup.vaultKeylet.key,
+                 .holder = setup.holder,
+                 .amount = amount});
+        };
+
+        auto runSole = [this, &clawbackHolder](FeatureBitset features, TER expected) {
+            testcase(
+                features[fixCleanup3_4_0]
+                    ? "VaultClawback after impaired loan (post-fixCleanup3_4_0)"
+                    : "VaultClawback after impaired loan (pre-fixCleanup3_4_0)");
+
+            Env env(*this, features);
+            auto const maybeSetup = makeImpairedLoanVault(env, 0);
+            if (!maybeSetup)
+            {
+                BEAST_EXPECT(false);
+                return;
+            }
+            ImpairedLoanVault const& setup = *maybeSetup;
+
+            auto const tokenBefore = env.le(keylet::mptoken(setup.shareId, setup.holder.id()));
+            auto const vaultBefore = env.le(setup.vaultKeylet);
+            auto const issuanceBefore = env.le(keylet::mptokenIssuance(setup.shareId));
+            if (!BEAST_EXPECT(tokenBefore) || !BEAST_EXPECT(vaultBefore) ||
+                !BEAST_EXPECT(issuanceBefore))
+                return;
+            std::uint64_t const sharesBefore = tokenBefore->getFieldU64(sfMPTAmount);
+
+            // The clawback of 19,000 exceeds AssetsAvailable (9,000), so
+            // VaultClawback clamps sharesDestroyed to whatever redeems
+            // exactly AssetsAvailable; compute that expected value using the
+            // same conversion helper VaultClawback itself uses, rather than
+            // assuming an exact 90/10 split holds under truncation.
+            auto const maybeSharesDestroyed = assetsToSharesWithdraw(
+                vaultBefore,
+                issuanceBefore,
+                setup.usd(9'000).value(),
+                TruncateShares::Yes,
+                WaiveUnrealizedLoss::Yes);
+            if (!BEAST_EXPECT(maybeSharesDestroyed))
+                return;
+            std::uint64_t const expectedSharesAfter =
+                sharesBefore - maybeSharesDestroyed->mpt().value();
+
+            env(clawbackHolder(setup, setup.usd(19'000).value()), Ter(expected));
+            env.close();
+            if (expected != tesSUCCESS)
+                return;
+
+            auto const vaultAfter = env.le(setup.vaultKeylet);
+            if (!BEAST_EXPECT(vaultAfter))
+                return;
+            BEAST_EXPECT(vaultAfter->at(sfAssetsAvailable) == setup.usd(0).value());
+            BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == setup.usd(1'000).value());
+            BEAST_EXPECT(vaultAfter->at(sfLossUnrealized) == setup.usd(1'000).value());
+            auto const tokenAfter = env.le(keylet::mptoken(setup.shareId, setup.holder.id()));
+            if (!BEAST_EXPECT(tokenAfter))
+                return;
+            BEAST_EXPECT(tokenAfter->getFieldU64(sfMPTAmount) == expectedSharesAfter);
+        };
+
+        runSole(all_ - fixCleanup3_4_0, tecINVARIANT_FAILED);
+        runSole(all_, tesSUCCESS);
+
+        testcase("VaultClawback after impaired loan, non-sole holder");
+        {
+            Env env(*this, all_);
+            auto const maybeSetup = makeImpairedLoanVault(env, 1'000);
+            if (!maybeSetup)
+            {
+                BEAST_EXPECT(false);
+                return;
+            }
+            ImpairedLoanVault const& setup = *maybeSetup;
+            // The waiver does not apply, so the holder's 9,000 shares are
+            // still priced at the discounted rate and cannot cover 9,000.
+            env(clawbackHolder(setup, setup.usd(9'000).value()), Ter(tecINSUFFICIENT_FUNDS));
+        }
+    }
+
+    // Bug: a fully impaired vault may pay zero assets for a share burn.
+    // Sending zero MPT is a no-op, so the vault pseudo-account's asset
+    // MPToken is never written and ValidVault, which only records deltas for
+    // created, modified or deleted entries, sees no vault delta at all.
+    //
+    // Pre-fixCleanup3_4_0 that alone makes the withdrawal impossible:
+    // zeroDeltaIsLegitimate is gated on the amendment, so the absent vault
+    // delta fails "withdrawal must change vault balance". Every pre-amendment
+    // arm below dies there, before any destination-side check runs.
+    //
+    // The destination side differs per arm, and only the vault-delta return
+    // hides that pre-amendment. With Alice's asset MPToken already present
+    // nothing touches it, so she has no delta either. With it missing,
+    // doWithdraw still called addEmptyHolding for a self-destination on a
+    // zero payout and created her MPToken at amount 0; a created MPToken is
+    // recorded even at zero, so she arrives with a present-and-zero delta,
+    // which for an integral MPT asset the destination check would reject if
+    // it were reached.
+    //
+    // ValidMPTIssuance is a separate checker and still runs. It only trips on
+    // the one arm that both creates and deletes an MPToken: Alice's last
+    // share with the asset MPToken missing, where addEmptyHolding creates the
+    // asset token while her share token is deleted (created + deleted > 1).
+    // Leftover shares with the token missing is create-only, and a last share
+    // with the token present is delete-only; neither exceeds one. Bob still
+    // owns shares throughout, so this is never the vault's final outstanding
+    // share.
+    //
+    // Post-fixCleanup3_4_0, doWithdraw skips addEmptyHolding on a zero
+    // payout and zeroDeltaIsLegitimate lets the vault-delta and
+    // missing-recipient-delta checks accept the transfer. A present
+    // destination delta of zero is still rejected.
+    void
+    testBugMptZeroWithdrawMissingHolding()
+    {
+        using namespace test::jtx;
+        using namespace loan_broker;
+        using namespace loan;
+        using namespace std::chrono_literals;
+
+        auto runScenario = [this](
+                               FeatureBitset features,
+                               bool removeAssetToken,
+                               bool withdrawAllAliceShares,
+                               TER expected) {
+            testcase(
+                std::string{"bug: MPT vault zero-value withdraw "} +
+                (removeAssetToken ? "without asset MPToken" : "with asset MPToken") +
+                (withdrawAllAliceShares ? ", Alice's last share" : ", Alice has leftover shares") +
+                (features[fixCleanup3_4_0] ? " (post-fixCleanup3_4_0)" : " (pre-fixCleanup3_4_0)"));
+
+            Env env(*this, features);
+
+            Account const issuer{"issuer"};
+            Account const owner{"owner"};
+            Account const alice{"alice"};
+            Account const bob{"bob"};
+            Account const borrower{"borrower"};
+
+            env.fund(XRP(100'000), issuer, owner, alice, bob, borrower);
+            env.close();
+
+            MPTTester mptt{env, issuer, kMptInitNoFund};
+            mptt.create({.flags = tfMPTCanTransfer});
+            PrettyAsset const asset = mptt.issuanceID();
+            mptt.authorize({.account = owner});
+            mptt.authorize({.account = alice});
+            mptt.authorize({.account = bob});
+            mptt.authorize({.account = borrower});
+            env.close();
+
+            env(pay(issuer, alice, asset(2)));
+            env(pay(issuer, bob, asset(8)));
+            env.close();
+
+            Vault const vault{env};
+            auto const [createTx, vaultKeylet, subscriptionDate] = vault.createClosedEnded(
+                {.owner = owner, .asset = asset, .subscriptionOffset = 60s});
+            env(createTx);
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = asset(2)}));
+            env(vault.deposit({.depositor = bob, .id = vaultKeylet.key, .amount = asset(8)}));
+            env.close();
+
+            vault.closePastSubscription(subscriptionDate);
+
+            auto const brokerKeylet =
+                keylet::loanBroker(owner.id(), SeqProxy::rawSequence(env.seq(owner)));
+            env(set(owner, vaultKeylet.key));
+            env.close();
+
+            auto const sleBroker = env.le(brokerKeylet);
+            if (!BEAST_EXPECT(sleBroker))
+                return;
+            auto const loanKeylet = keylet::loan(
+                brokerKeylet.key, SeqProxy::rawSequence(sleBroker->at(sfLoanSequence)));
+
+            env(set(borrower, brokerKeylet.key, asset(10).value()),
+                kInterestRate(percentageToTenthBips(0)),
+                kGracePeriod(60),
+                kPaymentInterval(120),
+                kPaymentTotal(10),
+                Sig(sfCounterpartySignature, owner),
+                Fee(env.current()->fees().base * 2),
+                Ter(tesSUCCESS));
+            env.close();
+
+            auto const loanBefore = env.le(loanKeylet);
+            if (!BEAST_EXPECT(loanBefore))
+                return;
+            std::uint32_t const dueDate = loanBefore->at(sfNextPaymentDueDate);
+            env.close(NetClock::time_point{NetClock::duration{dueDate}} + 1s);
+
+            env(manage(owner, loanKeylet.key, tfLoanImpair), Ter(tesSUCCESS));
+            env.close();
+
+            auto const vaultImpaired = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultImpaired))
+                return;
+            BEAST_EXPECT(vaultImpaired->at(sfAssetsAvailable) == asset(0).value());
+            BEAST_EXPECT(vaultImpaired->at(sfAssetsTotal) == vaultImpaired->at(sfLossUnrealized));
+            Number const totalBefore = vaultImpaired->at(sfAssetsTotal);
+            Number const lossBefore = vaultImpaired->at(sfLossUnrealized);
+
+            MPTID const shareId = vaultImpaired->at(sfShareMPTID);
+            auto const issuanceBefore = env.le(keylet::mptokenIssuance(shareId));
+            if (!BEAST_EXPECT(issuanceBefore))
+                return;
+            std::uint64_t const outstandingBefore =
+                issuanceBefore->getFieldU64(sfOutstandingAmount);
+
+            auto const tokenAlice = env.le(keylet::mptoken(shareId, alice.id()));
+            if (!BEAST_EXPECT(tokenAlice))
+                return;
+            std::uint64_t const sharesBefore = tokenAlice->getFieldU64(sfMPTAmount);
+            BEAST_EXPECT(sharesBefore == 2);
+            std::uint64_t const sharesToRedeem = withdrawAllAliceShares ? sharesBefore : 1;
+            STAmount const redeemShares{MPTIssue{shareId}, Number(sharesToRedeem)};
+
+            auto const assetTokenKeylet = keylet::mptoken(mptt.issuanceID(), alice.id());
+            if (removeAssetToken)
+            {
+                mptt.authorize({.account = alice, .flags = tfMPTUnauthorize});
+                env.close();
+                BEAST_EXPECT(!env.le(assetTokenKeylet));
+            }
+            else
+            {
+                auto const existing = env.le(assetTokenKeylet);
+                if (!BEAST_EXPECT(existing))
+                    return;
+                BEAST_EXPECT(existing->getFieldU64(sfMPTAmount) == 0);
+            }
+
+            std::uint32_t const redemptionDate = vaultImpaired->at(sfRedemptionDate);
+            env.close(NetClock::time_point{NetClock::duration{redemptionDate}} + 1s);
+
+            env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = redeemShares}),
+                Ter(expected));
+            env.close();
+            if (expected != tesSUCCESS)
+                return;
+
+            if (removeAssetToken)
+            {
+                BEAST_EXPECT(!env.le(assetTokenKeylet));
+            }
+            else
+            {
+                auto const assetAfter = env.le(assetTokenKeylet);
+                if (!BEAST_EXPECT(assetAfter))
+                    return;
+                BEAST_EXPECT(assetAfter->getFieldU64(sfMPTAmount) == 0);
+            }
+
+            auto const shareAfter = env.le(keylet::mptoken(shareId, alice.id()));
+            if (withdrawAllAliceShares)
+            {
+                BEAST_EXPECT(!shareAfter);
+            }
+            else if (BEAST_EXPECT(shareAfter))
+            {
+                BEAST_EXPECT(shareAfter->getFieldU64(sfMPTAmount) == sharesBefore - sharesToRedeem);
+            }
+
+            auto const vaultAfter = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultAfter))
+                return;
+            BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == totalBefore);
+            BEAST_EXPECT(vaultAfter->at(sfLossUnrealized) == lossBefore);
+            BEAST_EXPECT(vaultAfter->at(sfAssetsAvailable) == asset(0).value());
+
+            auto const issuanceAfter = env.le(keylet::mptokenIssuance(shareId));
+            if (!BEAST_EXPECT(issuanceAfter))
+                return;
+            BEAST_EXPECT(
+                issuanceAfter->getFieldU64(sfOutstandingAmount) ==
+                outstandingBefore - sharesToRedeem);
+        };
+
+        runScenario(
+            all_, false /* removeAssetToken */, false /* withdrawAllAliceShares */, tesSUCCESS);
+        runScenario(
+            all_, false /* removeAssetToken */, true /* withdrawAllAliceShares */, tesSUCCESS);
+        runScenario(
+            all_, true /* removeAssetToken */, false /* withdrawAllAliceShares */, tesSUCCESS);
+        runScenario(
+            all_, true /* removeAssetToken */, true /* withdrawAllAliceShares */, tesSUCCESS);
+        runScenario(
+            all_ - fixCleanup3_4_0,
+            false /* removeAssetToken */,
+            false /* withdrawAllAliceShares */,
+            tecINVARIANT_FAILED);
+        runScenario(
+            all_ - fixCleanup3_4_0,
+            false /* removeAssetToken */,
+            true /* withdrawAllAliceShares */,
+            tecINVARIANT_FAILED);
+        runScenario(
+            all_ - fixCleanup3_4_0,
+            true /* removeAssetToken */,
+            false /* withdrawAllAliceShares */,
+            tecINVARIANT_FAILED);
+        runScenario(
+            all_ - fixCleanup3_4_0,
+            true /* removeAssetToken */,
+            true /* withdrawAllAliceShares */,
+            tecINVARIANT_FAILED);
+    }
+
+    // IOU analogue of the missing-MPToken case above. Alice removes her
+    // zero-balance trust line after depositing, then burns one unit from her
+    // scaled share balance after the vault is fully impaired. Bob's share
+    // balance keeps this out of the sole-shareholder loss-waiver and
+    // final-outstanding-share paths. A zero payout must not recreate Alice's
+    // unsolicited trust line.
+    void
+    testBugIouZeroWithdrawMissingTrustLine()
+    {
+        using namespace test::jtx;
+        using namespace loan_broker;
+        using namespace loan;
+        using namespace std::chrono_literals;
+
+        Env env(*this, all_);
+
+        Account const issuer{"issuer"};
         Account const owner{"owner"};
-        Account const attacker{"attacker"};
+        Account const alice{"alice"};
+        Account const bob{"bob"};
+        Account const borrower{"borrower"};
 
-        Env env{*this, all_ - fixCleanup3_3_0 - fixCleanup3_4_0};
-        env.fund(XRP(10'000'000), owner, attacker);
+        env.fund(XRP(100'000), issuer, owner, alice, bob, borrower);
+        env.close();
+        env(fset(issuer, asfDefaultRipple));
+        env.close();
+
+        PrettyAsset const asset = issuer["USD"];
+        env.trust(asset(100), owner);
+        env.trust(asset(100), alice);
+        env.trust(asset(100), bob);
+        env.trust(asset(100), borrower);
+        env.close();
+
+        env(pay(issuer, alice, asset(2)));
+        env(pay(issuer, bob, asset(8)));
         env.close();
 
         Vault const vault{env};
-        auto [tx, keylet] = vault.create({.owner = owner, .asset = xrpIssue()});
-        env(tx);
-        env.close();
-        auto const vaultSle = env.le(keylet);
-        BEAST_EXPECT(vaultSle);
-        Account const pseudo{"vault pseudo-account", vaultSle->at(sfAccount)};
-        env.memoize(pseudo);
-
-        // Pin more than one cleanup batch's worth of credentials.
-        std::uint16_t const count = kMaxDeletablePseudoAccountCredentials + 3;
-        for (std::uint16_t i = 0; i < count; ++i)
-            env(credentials::create(pseudo, attacker, std::to_string(i)));
-        env.close();
-        BEAST_EXPECT(ownerCount(env, attacker) == count);
-
-        env.enableFeature(fixCleanup3_4_0);
+        auto const [createTx, vaultKeylet, subscriptionDate] =
+            vault.createClosedEnded({.owner = owner, .asset = asset, .subscriptionOffset = 60s});
+        env(createTx);
         env.close();
 
-        // First delete removes one bounded batch and reports it isn't finished.
-        env(vault.del({.owner = owner, .id = keylet.key}), Ter(tecINCOMPLETE));
+        env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = asset(2)}));
+        env(vault.deposit({.depositor = bob, .id = vaultKeylet.key, .amount = asset(8)}));
         env.close();
-        BEAST_EXPECT(env.le(keylet));  // vault still exists
-        auto const remaining = ownerCount(env, attacker);
-        BEAST_EXPECT(remaining > 0 && remaining < count);
 
-        // Second delete finishes the cleanup and removes the vault.
-        env(vault.del({.owner = owner, .id = keylet.key}));
+        auto const assetLine = keylet::trustLine(alice, asset.raw().get<Issue>());
+        if (!BEAST_EXPECT(env.le(assetLine)))
+            return;
+        env.trust(asset(0), alice);
         env.close();
-        BEAST_EXPECT(!env.le(keylet));
-        BEAST_EXPECT(!env.le(::xrpl::keylet::account(pseudo.id())));
-        BEAST_EXPECT(ownerCount(env, attacker) == 0);
+        BEAST_EXPECT(!env.le(assetLine));
+
+        vault.closePastSubscription(subscriptionDate);
+
+        auto const brokerKeylet =
+            keylet::loanBroker(owner.id(), SeqProxy::rawSequence(env.seq(owner)));
+        env(set(owner, vaultKeylet.key));
+        env.close();
+
+        auto const sleBroker = env.le(brokerKeylet);
+        if (!BEAST_EXPECT(sleBroker))
+            return;
+        auto const loanKeylet =
+            keylet::loan(brokerKeylet.key, SeqProxy::rawSequence(sleBroker->at(sfLoanSequence)));
+
+        env(set(borrower, brokerKeylet.key, asset(10).value()),
+            kInterestRate(percentageToTenthBips(0)),
+            kGracePeriod(60),
+            kPaymentInterval(120),
+            kPaymentTotal(10),
+            Sig(sfCounterpartySignature, owner),
+            Fee(env.current()->fees().base * 2),
+            Ter(tesSUCCESS));
+        env.close();
+
+        auto const loanBefore = env.le(loanKeylet);
+        if (!BEAST_EXPECT(loanBefore))
+            return;
+        std::uint32_t const dueDate = loanBefore->at(sfNextPaymentDueDate);
+        env.close(NetClock::time_point{NetClock::duration{dueDate}} + 1s);
+
+        env(manage(owner, loanKeylet.key, tfLoanImpair), Ter(tesSUCCESS));
+        env.close();
+
+        auto const vaultImpaired = env.le(vaultKeylet);
+        if (!BEAST_EXPECT(vaultImpaired))
+            return;
+        BEAST_EXPECT(vaultImpaired->at(sfAssetsAvailable) == asset(0).value());
+        BEAST_EXPECT(vaultImpaired->at(sfAssetsTotal) == vaultImpaired->at(sfLossUnrealized));
+        Number const totalBefore = vaultImpaired->at(sfAssetsTotal);
+        Number const lossBefore = vaultImpaired->at(sfLossUnrealized);
+
+        MPTID const shareId = vaultImpaired->at(sfShareMPTID);
+        auto const tokenAlice = env.le(keylet::mptoken(shareId, alice.id()));
+        if (!BEAST_EXPECT(tokenAlice))
+            return;
+        std::uint64_t const sharesBefore = tokenAlice->getFieldU64(sfMPTAmount);
+        // Default IOU vault scale is 6, so 2 USD mints 2e6 shares. Redeem one
+        // leftover share; do not require 1:1 like the MPT case.
+        BEAST_EXPECT(sharesBefore > 1);
+        STAmount const redeemShares{MPTIssue{shareId}, Number(1)};
+
+        std::uint32_t const redemptionDate = vaultImpaired->at(sfRedemptionDate);
+        env.close(NetClock::time_point{NetClock::duration{redemptionDate}} + 1s);
+
+        env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = redeemShares}),
+            Ter(tesSUCCESS));
+        env.close();
+
+        // A regression in the View guard would recreate this line even though
+        // no asset value was paid.
+        BEAST_EXPECT(!env.le(assetLine));
+
+        auto const shareAfter = env.le(keylet::mptoken(shareId, alice.id()));
+        if (!BEAST_EXPECT(shareAfter))
+            return;
+        BEAST_EXPECT(shareAfter->getFieldU64(sfMPTAmount) == sharesBefore - 1);
+
+        auto const vaultAfter = env.le(vaultKeylet);
+        if (!BEAST_EXPECT(vaultAfter))
+            return;
+        BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == totalBefore);
+        BEAST_EXPECT(vaultAfter->at(sfLossUnrealized) == lossBefore);
+        BEAST_EXPECT(vaultAfter->at(sfAssetsAvailable) == asset(0).value());
+    }
+
+    // Same zero-payout withdrawal as testBugMptZeroWithdrawMissingHolding, but
+    // the vault asset is XRP. addEmptyHolding is a no-op for native assets.
+    // Sequence processing still touches the sender AccountRoot; a sponsored
+    // fee leaves that XRP balance economically unchanged. After the
+    // sponsored-withdraw fee-payer fix, deltaAssetsForParty collapses that
+    // economically-zero XRP delta to absence, so tesSUCCESS takes the
+    // missing-recipient-delta arm gated by zeroDeltaIsLegitimate. This test
+    // covers that live SUCCESS path. Pre-fixCleanup3_4_0 still fails the
+    // invariant.
+    void
+    testBugXrpZeroWithdrawSponsoredFee()
+    {
+        using namespace test::jtx;
+        using namespace loan_broker;
+        using namespace loan;
+        using namespace std::chrono_literals;
+
+        auto runScenario = [this](FeatureBitset features, TER expected) {
+            testcase(
+                std::string{"bug: XRP vault zero-value withdraw with sponsored fee"} +
+                (features[fixCleanup3_4_0] ? " (post-fixCleanup3_4_0)" : " (pre-fixCleanup3_4_0)"));
+
+            Env env(*this, features);
+
+            Account const owner{"owner"};
+            Account const alice{"alice"};
+            Account const bob{"bob"};
+            Account const borrower{"borrower"};
+            Account const sponsor{"sponsor"};
+
+            env.fund(XRP(100'000), owner, alice, bob, borrower, sponsor);
+            env.close();
+
+            PrettyAsset const asset{xrpIssue()};
+            Vault const vault{env};
+            auto const [createTx, vaultKeylet, subscriptionDate] = vault.createClosedEnded(
+                {.owner = owner, .asset = asset, .subscriptionOffset = 60s});
+            env(createTx);
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = asset(2)}));
+            env(vault.deposit({.depositor = bob, .id = vaultKeylet.key, .amount = asset(8)}));
+            env.close();
+
+            vault.closePastSubscription(subscriptionDate);
+
+            auto const brokerKeylet =
+                keylet::loanBroker(owner.id(), SeqProxy::rawSequence(env.seq(owner)));
+            env(set(owner, vaultKeylet.key));
+            env.close();
+
+            auto const sleBroker = env.le(brokerKeylet);
+            if (!BEAST_EXPECT(sleBroker))
+                return;
+            auto const loanKeylet = keylet::loan(
+                brokerKeylet.key, SeqProxy::rawSequence(sleBroker->at(sfLoanSequence)));
+
+            env(set(borrower, brokerKeylet.key, asset(10).value()),
+                kInterestRate(percentageToTenthBips(0)),
+                kGracePeriod(60),
+                kPaymentInterval(120),
+                kPaymentTotal(10),
+                Sig(sfCounterpartySignature, owner),
+                Fee(env.current()->fees().base * 2),
+                Ter(tesSUCCESS));
+            env.close();
+
+            auto const loanBefore = env.le(loanKeylet);
+            if (!BEAST_EXPECT(loanBefore))
+                return;
+            std::uint32_t const dueDate = loanBefore->at(sfNextPaymentDueDate);
+            env.close(NetClock::time_point{NetClock::duration{dueDate}} + 1s);
+
+            env(manage(owner, loanKeylet.key, tfLoanImpair), Ter(tesSUCCESS));
+            env.close();
+
+            auto const vaultImpaired = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultImpaired))
+                return;
+            BEAST_EXPECT(vaultImpaired->at(sfAssetsAvailable) == asset(0).value());
+            BEAST_EXPECT(vaultImpaired->at(sfAssetsTotal) == vaultImpaired->at(sfLossUnrealized));
+            Number const totalBefore = vaultImpaired->at(sfAssetsTotal);
+            Number const lossBefore = vaultImpaired->at(sfLossUnrealized);
+
+            MPTID const shareId = vaultImpaired->at(sfShareMPTID);
+            auto const tokenAlice = env.le(keylet::mptoken(shareId, alice.id()));
+            if (!BEAST_EXPECT(tokenAlice))
+                return;
+            std::uint64_t const sharesBefore = tokenAlice->getFieldU64(sfMPTAmount);
+            BEAST_EXPECT(sharesBefore == 2);
+            STAmount const redeemShares{MPTIssue{shareId}, Number(1)};
+
+            std::uint32_t const redemptionDate = vaultImpaired->at(sfRedemptionDate);
+            env.close(NetClock::time_point{NetClock::duration{redemptionDate}} + 1s);
+
+            auto const aliceBalanceBefore = env.balance(alice);
+            auto const sponsorBalanceBefore = env.balance(sponsor);
+            auto const fee = env.current()->fees().base;
+
+            env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = redeemShares}),
+                Fee(fee),
+                sponsor::As(sponsor, spfSponsorFee),
+                Sig(sfSponsorSignature, sponsor),
+                Ter(expected));
+            env.close();
+
+            BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore - fee);
+            BEAST_EXPECT(env.balance(alice) == aliceBalanceBefore);
+
+            if (expected != tesSUCCESS)
+                return;
+
+            auto const shareAfter = env.le(keylet::mptoken(shareId, alice.id()));
+            if (!BEAST_EXPECT(shareAfter))
+                return;
+            BEAST_EXPECT(shareAfter->getFieldU64(sfMPTAmount) == sharesBefore - 1);
+
+            auto const vaultAfter = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultAfter))
+                return;
+            BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == totalBefore);
+            BEAST_EXPECT(vaultAfter->at(sfLossUnrealized) == lossBefore);
+            BEAST_EXPECT(vaultAfter->at(sfAssetsAvailable) == asset(0).value());
+        };
+
+        runScenario(all_, tesSUCCESS);
+        runScenario(all_ - fixCleanup3_4_0, tecINVARIANT_FAILED);
+    }
+
+    // addEmptyHolding() used to check isGlobalFrozen(issuer) and
+    // !lsfDefaultRipple before the "line already exists" tecDUPLICATE
+    // short circuit. doWithdraw() calls addEmptyHolding() for a
+    // self-destination payout and only tolerates tecDUPLICATE, so
+    // tecINTERNAL from a missing DefaultRipple flag aborted the
+    // withdrawal. fixCleanup3_4_0 checks existence first and maps the
+    // create-path DefaultRipple miss to terNO_RIPPLE. Global freeze on an
+    // existing line is still rejected later by checkWithdrawFreeze.
+    void
+    testBugSelfWithdrawAfterIssuerClearsDefaultRipple()
+    {
+        using namespace test::jtx;
+
+        auto runExistingLine = [this](
+                                   FeatureBitset features,
+                                   TER selfExpected,
+                                   bool issuerGlobalFreeze = false) {
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const alice{"alice"};
+            Account const bob{"bob"};
+
+            env.fund(XRP(10'000), issuer, alice, bob);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            Issue const usdIssue = usd.raw().get<Issue>();
+            env(trust(alice, usd(10'000)));
+            env(trust(bob, usd(10'000)));
+            env.close();
+            env(pay(issuer, alice, usd(1'000)));
+            env.close();
+
+            Vault const vault{env};
+            auto [vaultTx, vaultKeylet] = vault.create({.owner = alice, .asset = usd});
+            env(vaultTx);
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = usd(500)}));
+            env.close();
+
+            env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = usd(50)}));
+            env.close();
+
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+            if (issuerGlobalFreeze)
+            {
+                env(fset(issuer, asfGlobalFreeze));
+                env.close();
+            }
+
+            BEAST_EXPECT(env.le(keylet::trustLine(alice.id(), usdIssue)));
+
+            // Alice's USD line is unchanged; a later deposit still succeeds
+            // unless the issuer is globally frozen.
+            if (!issuerGlobalFreeze)
+            {
+                env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = usd(10)}));
+                env.close();
+            }
+
+            Number const destBefore = env.balance(alice, usd.raw()).number();
+            Number const vaultBefore = env.le(vaultKeylet)->at(sfAssetsTotal);
+            Number const withdrawAmt{50};
+
+            env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = usd(50)}),
+                Ter(selfExpected));
+            env.close();
+
+            Number const destAfter = env.balance(alice, usd.raw()).number();
+            Number const vaultAfter = env.le(vaultKeylet)->at(sfAssetsTotal);
+            if (isTesSuccess(selfExpected))
+            {
+                BEAST_EXPECT(destAfter == destBefore + withdrawAmt);
+                BEAST_EXPECT(vaultAfter == vaultBefore - withdrawAmt);
+            }
+            else
+            {
+                BEAST_EXPECT(destAfter == destBefore);
+                BEAST_EXPECT(vaultAfter == vaultBefore);
+            }
+
+            if (!issuerGlobalFreeze)
+            {
+                auto destTx =
+                    vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = usd(50)});
+                destTx[sfDestination] = bob.human();
+                env(destTx);
+                env.close();
+            }
+        };
+
+        auto runDeletedLine = [this](FeatureBitset features, TER selfExpected) {
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const alice{"alice"};
+
+            env.fund(XRP(10'000), issuer, alice);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            Issue const usdIssue = usd.raw().get<Issue>();
+            env(trust(alice, usd(10'000)));
+            env.close();
+            env(pay(issuer, alice, usd(500)));
+            env.close();
+
+            Vault const vault{env};
+            auto [vaultTx, vaultKeylet] = vault.create({.owner = alice, .asset = usd});
+            env(vaultTx);
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = usd(500)}));
+            env.close();
+
+            env(trust(alice, usd(0)));
+            env.close();
+            BEAST_EXPECT(!env.le(keylet::trustLine(alice.id(), usdIssue)));
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+
+            env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = usd(50)}),
+                Ter(selfExpected));
+            env.close();
+        };
+
+        auto runCoverWithdraw = [this](FeatureBitset features, TER selfExpected) {
+            using namespace loan_broker;
+
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const alice{"alice"};
+
+            env.fund(XRP(10'000), issuer, alice);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            Issue const usdIssue = usd.raw().get<Issue>();
+            env(trust(alice, usd(10'000)));
+            env.close();
+            env(pay(issuer, alice, usd(1'000)));
+            env.close();
+
+            Vault const vault{env};
+            auto const [createTx, vaultKeylet, subscriptionDate] = vault.createClosedEnded(
+                {.owner = alice, .asset = usd, .subscriptionOffset = std::chrono::seconds{60}});
+            (void)subscriptionDate;
+            env(createTx);
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = usd(500)}));
+            env.close();
+
+            auto const brokerKeylet =
+                keylet::loanBroker(alice.id(), SeqProxy::rawSequence(env.seq(alice)));
+            env(set(alice, vaultKeylet.key));
+            env.close();
+            env(coverDeposit(alice, brokerKeylet.key, usd(100).value()));
+            env.close();
+
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+            BEAST_EXPECT(env.le(keylet::trustLine(alice.id(), usdIssue)));
+
+            Number const destBefore = env.balance(alice, usd.raw()).number();
+            Number const coverBefore = env.le(brokerKeylet)->at(sfCoverAvailable);
+            Number const withdrawAmt{50};
+
+            env(coverWithdraw(alice, brokerKeylet.key, usd(50).value()), Ter(selfExpected));
+            env.close();
+
+            Number const destAfter = env.balance(alice, usd.raw()).number();
+            Number const coverAfter = env.le(brokerKeylet)->at(sfCoverAvailable);
+            if (isTesSuccess(selfExpected))
+            {
+                BEAST_EXPECT(destAfter == destBefore + withdrawAmt);
+                BEAST_EXPECT(coverAfter == coverBefore - withdrawAmt);
+            }
+            else
+            {
+                BEAST_EXPECT(destAfter == destBefore);
+                BEAST_EXPECT(coverAfter == coverBefore);
+            }
+        };
+
+        auto runDeletedCoverWithdraw = [this](FeatureBitset features, TER selfExpected) {
+            using namespace loan_broker;
+
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const alice{"alice"};
+
+            env.fund(XRP(10'000), issuer, alice);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            Issue const usdIssue = usd.raw().get<Issue>();
+            env(trust(alice, usd(10'000)));
+            env.close();
+            env(pay(issuer, alice, usd(600)));
+            env.close();
+
+            Vault const vault{env};
+            auto const [createTx, vaultKeylet, subscriptionDate] = vault.createClosedEnded(
+                {.owner = alice, .asset = usd, .subscriptionOffset = std::chrono::seconds{60}});
+            (void)subscriptionDate;
+            env(createTx);
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = usd(500)}));
+            env.close();
+
+            auto const brokerKeylet =
+                keylet::loanBroker(alice.id(), SeqProxy::rawSequence(env.seq(alice)));
+            env(set(alice, vaultKeylet.key));
+            env.close();
+            env(coverDeposit(alice, brokerKeylet.key, usd(100).value()));
+            env.close();
+
+            env(trust(alice, usd(0)));
+            env.close();
+            BEAST_EXPECT(!env.le(keylet::trustLine(alice.id(), usdIssue)));
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+
+            env(coverWithdraw(alice, brokerKeylet.key, usd(50).value()), Ter(selfExpected));
+            env.close();
+        };
+
+        auto runPrivateVault = [this](FeatureBitset features, TER selfExpected) {
+            Env env(*this, features);
+            Account const issuer{"issuer"};
+            Account const alice{"alice"};
+            Account const pdOwner{"pdOwner"};
+            Account const credIssuer{"credIssuer"};
+            std::string const credType = "credential";
+
+            env.fund(XRP(10'000), issuer, alice, pdOwner, credIssuer);
+            env.close();
+            env(fset(issuer, asfDefaultRipple));
+            env.close();
+
+            PrettyAsset const usd{issuer["USD"]};
+            env(trust(alice, usd(10'000)));
+            env.close();
+            env(pay(issuer, alice, usd(1'000)));
+            env.close();
+
+            Vault const vault{env};
+            auto [vaultTx, vaultKeylet] =
+                vault.create({.owner = alice, .asset = usd, .flags = tfVaultPrivate});
+            env(vaultTx);
+            env.close();
+
+            pdomain::Credentials const credentials{{.issuer = credIssuer, .credType = credType}};
+            env(pdomain::setTx(pdOwner, credentials));
+            auto const domainId = pdomain::getNewDomain(env.meta());
+            {
+                auto domainTx = vault.set({.owner = alice, .id = vaultKeylet.key});
+                domainTx[sfDomainID] = to_string(domainId);
+                env(domainTx);
+                env.close();
+            }
+
+            env(credentials::create(alice, credIssuer, credType));
+            env(credentials::accept(alice, credIssuer, credType));
+            env.close();
+
+            env(vault.deposit({.depositor = alice, .id = vaultKeylet.key, .amount = usd(500)}));
+            env.close();
+
+            env(fclear(issuer, asfDefaultRipple));
+            env.close();
+
+            env(vault.withdraw({.depositor = alice, .id = vaultKeylet.key, .amount = usd(50)}),
+                Ter(selfExpected));
+            env.close();
+        };
+
+        testcase(
+            "bug: VaultWithdraw to self fails with tecINTERNAL after issuer "
+            "clears asfDefaultRipple even though the trust line exists "
+            "(pre-fixCleanup3_4_0)");
+        runExistingLine(all_ - fixCleanup3_4_0, tecINTERNAL);
+
+        testcase(
+            "bug: VaultWithdraw to self succeeds after issuer clears "
+            "asfDefaultRipple when the trust line exists (post-fixCleanup3_4_0)");
+        runExistingLine(all_, tesSUCCESS);
+
+        testcase(
+            "bug: VaultWithdraw to self with an existing line still gets "
+            "tecFROZEN under asfGlobalFreeze (post-fixCleanup3_4_0)");
+        runExistingLine(all_, tecFROZEN, true);
+
+        testcase(
+            "bug: VaultWithdraw to self fails with tecINTERNAL after issuer "
+            "clears asfDefaultRipple and the trust line was deleted "
+            "(pre-fixCleanup3_4_0)");
+        runDeletedLine(all_ - fixCleanup3_4_0, tecINTERNAL);
+
+        testcase(
+            "bug: VaultWithdraw to self fails with terNO_RIPPLE after issuer "
+            "clears asfDefaultRipple and the trust line was deleted "
+            "(post-fixCleanup3_4_0)");
+        runDeletedLine(all_, terNO_RIPPLE);
+
+        testcase(
+            "bug: LoanBrokerCoverWithdraw to self fails with tecINTERNAL after "
+            "issuer clears asfDefaultRipple even though the trust line exists "
+            "(pre-fixCleanup3_4_0)");
+        runCoverWithdraw(all_ - fixCleanup3_4_0, tecINTERNAL);
+
+        testcase(
+            "bug: LoanBrokerCoverWithdraw to self succeeds after issuer clears "
+            "asfDefaultRipple when the trust line exists (post-fixCleanup3_4_0)");
+        runCoverWithdraw(all_, tesSUCCESS);
+
+        testcase(
+            "bug: LoanBrokerCoverWithdraw to self fails with tecINTERNAL after "
+            "issuer clears asfDefaultRipple and the trust line was deleted "
+            "(pre-fixCleanup3_4_0)");
+        runDeletedCoverWithdraw(all_ - fixCleanup3_4_0, tecINTERNAL);
+
+        testcase(
+            "bug: LoanBrokerCoverWithdraw to self fails with terNO_RIPPLE after "
+            "issuer clears asfDefaultRipple and the trust line was deleted "
+            "(post-fixCleanup3_4_0)");
+        runDeletedCoverWithdraw(all_, terNO_RIPPLE);
+
+        testcase(
+            "bug: private VaultWithdraw to self fails with tecINTERNAL after "
+            "issuer clears asfDefaultRipple even though the trust line exists "
+            "(pre-fixCleanup3_4_0)");
+        runPrivateVault(all_ - fixCleanup3_4_0, tecINTERNAL);
+
+        testcase(
+            "bug: private VaultWithdraw to self succeeds after issuer clears "
+            "asfDefaultRipple when the trust line exists (post-fixCleanup3_4_0)");
+        runPrivateVault(all_, tesSUCCESS);
+    }
+
+    // Bug 1: a sponsored XRP VaultWithdraw to a distinct destination is
+    // rejected because the vault invariant treats the holder's touched
+    // but economically unchanged AccountRoot as a second payout
+    // recipient. Sequence/ticket processing still touches the holder
+    // while the sponsor pays the fee, so the holder's XRP delta is
+    // present-zero and is not normalized away. If this happens on the
+    // last Subscription ledger of a closed-ended vault, the holder
+    // cannot retry until Redemption (tecTOO_SOON during Investment).
+    //
+    // Fixed by ValidVault::deltaAssetsForParty always collapsing an
+    // economically-zero XRP delta to absence, regardless of who paid the
+    // fee.
+    void
+    testBugSponsoredWithdrawZeroDeltaMisclassifiedAsSecondRecipient()
+    {
+        using namespace test::jtx;
+
+        auto runScenario = [this](FeatureBitset features, TER expected) {
+            Env env{*this, features};
+            Account const owner{"owner"};
+            Account const holder{"holder"};
+            Account const destination{"destination"};
+            Account const sponsor{"sponsor"};
+            env.fund(XRP(10'000), owner, holder, destination, sponsor);
+            env.close();
+
+            constexpr std::uint32_t investmentPeriod = 14u * 24u * 60u * 60u;
+            auto const [vault, vaultKeylet, subscriptionDate, redemptionDate] =
+                makeClosedEndedVault(env, owner, xrpIssue(), 120u, investmentPeriod);
+            BEAST_EXPECT(redemptionDate - subscriptionDate == investmentPeriod);
+
+            env(vault.deposit(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()}));
+            env.close();
+
+            // Inclusive SubscriptionDate boundary: still Subscription, so an
+            // ordinary withdrawal is allowed.
+            closeToTime(env, tp{d{subscriptionDate}});
+
+            auto const vaultBefore = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultBefore))
+                return;
+            auto const assetsTotalBefore = vaultBefore->at(sfAssetsTotal);
+            auto const holderBalanceBefore = env.balance(holder);
+            auto const destinationBalanceBefore = env.balance(destination);
+            auto const sponsorBalanceBefore = env.balance(sponsor);
+            auto const fee = env.current()->fees().base;
+
+            auto withdraw = vault.withdraw(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()});
+            withdraw[sfDestination] = destination.human();
+            env(withdraw,
+                Fee(fee),
+                sponsor::As(sponsor, spfSponsorFee),
+                Sig(sfSponsorSignature, sponsor),
+                Ter(expected));
+            env.close();
+
+            auto const vaultAfter = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultAfter))
+                return;
+            BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore - fee);
+
+            if (expected == tesSUCCESS)
+            {
+                BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore - XRP(100).value());
+                BEAST_EXPECT(env.balance(holder) == holderBalanceBefore);
+                BEAST_EXPECT(env.balance(destination) == destinationBalanceBefore + XRP(100));
+                return;
+            }
+
+            // Invariant rollback: the payout and share burn are undone, but
+            // sequence processing and the sponsored fee charge remain.
+            BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore);
+            BEAST_EXPECT(env.balance(holder) == holderBalanceBefore);
+            BEAST_EXPECT(env.balance(destination) == destinationBalanceBefore);
+
+            // Once the ledger advances into Investment, the same holder
+            // cannot retry until Redemption.
+            auto retry = vault.withdraw(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()});
+            retry[sfDestination] = destination.human();
+            env(retry, Ter(tecTOO_SOON));
+        };
+
+        testcase(
+            "bug: sponsored XRP withdrawal to a distinct destination misreads a "
+            "touched-but-zero sender delta as a second recipient "
+            "(pre-fixCleanup3_4_0)");
+        runScenario(all_ - fixCleanup3_4_0, tecINVARIANT_FAILED);
+
+        testcase(
+            "bug: sponsored XRP withdrawal to a distinct destination succeeds "
+            "(post-fixCleanup3_4_0)");
+        runScenario(all_, tesSUCCESS);
+    }
+
+    // Bug 2: a co-signed fee sponsor named as the withdrawal's own
+    // destination pays its fee from the same AccountRoot it is paid into,
+    // so its net XRP delta is (payout - fee). The invariant never fee-
+    // corrected the destination side at all, so this always failed the
+    // equal-amount check against the vault's outflow (payout).
+    //
+    // Fixed by ValidVault::deltaAssetsForParty adding the fee back onto
+    // whichever inspected party's AccountRoot actually paid it -- the
+    // sender, or a distinct destination -- not just the sender.
+    void
+    testBugSponsorAsDestinationFeeMisappliedToPayout()
+    {
+        using namespace test::jtx;
+
+        auto runScenario = [this](FeatureBitset features, TER expected) {
+            Env env{*this, features};
+            Account const owner{"owner"};
+            Account const holder{"holder"};
+            Account const sponsor{"sponsor"};
+            env.fund(XRP(10'000), owner, holder, sponsor);
+            env.close();
+
+            Vault const vault{env};
+            auto [vaultTx, vaultKeylet] = vault.create({.owner = owner, .asset = xrpIssue()});
+            env(vaultTx);
+            env.close();
+
+            env(vault.deposit(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()}));
+            env.close();
+
+            auto const vaultBefore = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultBefore))
+                return;
+            auto const assetsTotalBefore = vaultBefore->at(sfAssetsTotal);
+            auto const sponsorBalanceBefore = env.balance(sponsor);
+            auto const fee = env.current()->fees().base;
+
+            // The sponsor both receives the withdrawal (as sfDestination)
+            // and pays its own fee (co-signed) from the same AccountRoot.
+            auto withdraw = vault.withdraw(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()});
+            withdraw[sfDestination] = sponsor.human();
+            env(withdraw,
+                Fee(fee),
+                sponsor::As(sponsor, spfSponsorFee),
+                Sig(sfSponsorSignature, sponsor),
+                Ter(expected));
+            env.close();
+
+            auto const vaultAfter = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultAfter))
+                return;
+
+            if (expected == tesSUCCESS)
+            {
+                BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore - XRP(100).value());
+                // Paid the withdrawal, then separately debited for the fee
+                // it chose to cover; net effect is payout minus fee.
+                BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore + XRP(100) - fee);
+                return;
+            }
+
+            BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore);
+            BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore - fee);
+        };
+
+        testcase(
+            "bug: co-signed sponsor named as withdrawal destination has its "
+            "own fee debit misread as breaking the payout equality "
+            "(pre-fixCleanup3_4_0)");
+        runScenario(all_ - fixCleanup3_4_0, tecINVARIANT_FAILED);
+
+        testcase(
+            "bug: co-signed sponsor named as withdrawal destination succeeds "
+            "(post-fixCleanup3_4_0)");
+        runScenario(all_, tesSUCCESS);
+    }
+
+    // Pre-funded fee sponsorship draws the fee from ltSponsorship.sfFeeAmount,
+    // so feePayerAccountRoot must return nullopt rather than the sponsor's
+    // AccountRoot. A bystander sponsor leaves that branch unexercised: the
+    // result is only consulted by deltaAssetsForParty via `payer && *payer ==
+    // id`. Naming the sponsor as sfDestination makes the early return
+    // load-bearing -- returning the sponsor's id instead of nullopt would add
+    // the fee back onto a balance that never paid it, and the equal-amount
+    // check against the vault outflow would fail.
+    //
+    // Contrast testBugSponsorAsDestinationFeeMisappliedToPayout, where the
+    // sponsor co-signs and so really does pay from its own AccountRoot.
+    void
+    testPrefundedFeeWithdraw()
+    {
+        using namespace test::jtx;
+
+        auto runScenario = [this](
+                               FeatureBitset features,
+                               TER expected,
+                               bool const sponsorIsDestination) {
+            Env env{*this, features};
+            Account const owner{"owner"};
+            Account const holder{"holder"};
+            Account const destination{"destination"};
+            Account const sponsor{"sponsor"};
+            env.fund(XRP(10'000), owner, holder, destination, sponsor);
+            env.close();
+
+            Vault const vault{env};
+            auto [vaultTx, vaultKeylet] = vault.create({.owner = owner, .asset = xrpIssue()});
+            env(vaultTx);
+            env.close();
+
+            env(vault.deposit(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()}));
+            env.close();
+
+            auto const fee = env.current()->fees().base;
+            env(sponsor::set_fee(sponsor, 0, fee), sponsor::SponseeAcc(holder));
+            env.close();
+
+            auto const vaultBefore = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultBefore))
+                return;
+            auto const assetsTotalBefore = vaultBefore->at(sfAssetsTotal);
+            auto const holderBalanceBefore = env.balance(holder);
+            auto const destinationBalanceBefore = env.balance(destination);
+            auto const sponsorBalanceBefore = env.balance(sponsor);
+
+            Account const& recipient = sponsorIsDestination ? sponsor : destination;
+            auto withdraw = vault.withdraw(
+                {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()});
+            withdraw[sfDestination] = recipient.human();
+            env(withdraw, Fee(fee), sponsor::As(sponsor, spfSponsorFee), Ter(expected));
+            env.close();
+
+            auto const vaultAfter = env.le(vaultKeylet);
+            if (!BEAST_EXPECT(vaultAfter))
+                return;
+            // Holder is economically unchanged (sequence only); the fee is
+            // taken from the sponsorship object, not any AccountRoot.
+            BEAST_EXPECT(env.balance(holder) == holderBalanceBefore);
+
+            if (expected == tesSUCCESS)
+            {
+                BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore - XRP(100).value());
+                if (sponsorIsDestination)
+                {
+                    // The sponsor receives the payout and is not debited for
+                    // the fee. The sponsor has to BE the destination for
+                    // FeePayerType::SponsorPreFunded to matter.
+                    BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore + XRP(100));
+                }
+                else
+                {
+                    BEAST_EXPECT(env.balance(destination) == destinationBalanceBefore + XRP(100));
+                    BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore);
+                }
+                auto const sponsorship = env.le(keylet::sponsorship(sponsor, holder));
+                if (!BEAST_EXPECT(sponsorship))
+                    return;
+                BEAST_EXPECT(!sponsorship->isFieldPresent(sfFeeAmount));
+                return;
+            }
+
+            BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore);
+            BEAST_EXPECT(env.balance(sponsor) == sponsorBalanceBefore);
+            if (!sponsorIsDestination)
+                BEAST_EXPECT(env.balance(destination) == destinationBalanceBefore);
+        };
+
+        testcase(
+            "pre-funded fee XRP withdrawal to a distinct destination succeeds "
+            "(post-fixCleanup3_4_0)");
+        runScenario(all_, tesSUCCESS, false);
+
+        testcase(
+            "bug: pre-funded sponsor named as withdrawal destination misreads "
+            "the sender's touched-but-zero delta as a second recipient "
+            "(pre-fixCleanup3_4_0)");
+        runScenario(all_ - fixCleanup3_4_0, tecINVARIANT_FAILED, true);
+
+        testcase(
+            "bug: pre-funded sponsor named as withdrawal destination receives "
+            "the full payout (post-fixCleanup3_4_0)");
+        runScenario(all_, tesSUCCESS, true);
+    }
+
+    // Unsponsored third-party XRP withdrawal: the sender's AccountRoot moves
+    // by exactly -fee. Pre-amendment, the sender-only fee correction then
+    // collapses that to absence so the dual-recipient guard does not fire.
+    void
+    testUnsponsoredWithdrawToDistinctDestinationPreAmendment()
+    {
+        using namespace test::jtx;
+
+        testcase(
+            "unsponsored XRP withdrawal to a distinct destination succeeds "
+            "(pre-fixCleanup3_4_0)");
+
+        Env env{*this, all_ - fixCleanup3_4_0};
+        Account const owner{"owner"};
+        Account const holder{"holder"};
+        Account const destination{"destination"};
+        env.fund(XRP(10'000), owner, holder, destination);
+        env.close();
+
+        Vault const vault{env};
+        auto [vaultTx, vaultKeylet] = vault.create({.owner = owner, .asset = xrpIssue()});
+        env(vaultTx);
+        env.close();
+
+        env(vault.deposit(
+            {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()}));
+        env.close();
+
+        auto const vaultBefore = env.le(vaultKeylet);
+        if (!BEAST_EXPECT(vaultBefore))
+            return;
+        auto const assetsTotalBefore = vaultBefore->at(sfAssetsTotal);
+        auto const holderBalanceBefore = env.balance(holder);
+        auto const destinationBalanceBefore = env.balance(destination);
+        auto const fee = env.current()->fees().base;
+
+        auto withdraw = vault.withdraw(
+            {.depositor = holder, .id = vaultKeylet.key, .amount = XRP(100).value()});
+        withdraw[sfDestination] = destination.human();
+        env(withdraw, Fee(fee), Ter(tesSUCCESS));
+        env.close();
+
+        auto const vaultAfter = env.le(vaultKeylet);
+        if (!BEAST_EXPECT(vaultAfter))
+            return;
+        BEAST_EXPECT(vaultAfter->at(sfAssetsTotal) == assetsTotalBefore - XRP(100).value());
+        BEAST_EXPECT(env.balance(holder) == holderBalanceBefore - fee);
+        BEAST_EXPECT(env.balance(destination) == destinationBalanceBefore + XRP(100));
     }
 
 public:
@@ -1346,12 +2753,21 @@ public:
         testBugDepositShareTruncationSubUlp();
         testVaultWithdrawCanonicalizeToZero();
         testBugVaultDustDebitCanonicalizesToNoOp();
+        testBugVaultDepositOvercreditsAcrossScaleBoundary();
+        testBugVaultLockedByPartialWithdraw();
         testVaultDepositNegativeBalanceFromOppositeLimit();
-        testCredentialPinsPseudoAccount();
-        testCredentialPinOverflow();
         testBug6LimitBypassWithShares();
         testBugClawbackRoundTripOvershoot();
         testBugWithdrawRoundTripOvershoot();
+        testBugClawbackAfterLoanImpair();
+        testBugMptZeroWithdrawMissingHolding();
+        testBugIouZeroWithdrawMissingTrustLine();
+        testBugXrpZeroWithdrawSponsoredFee();
+        testBugSelfWithdrawAfterIssuerClearsDefaultRipple();
+        testBugSponsoredWithdrawZeroDeltaMisclassifiedAsSecondRecipient();
+        testBugSponsorAsDestinationFeeMisappliedToPayout();
+        testPrefundedFeeWithdraw();
+        testUnsponsoredWithdrawToDistinctDestinationPreAmendment();
     }
 };
 
diff --git a/src/test/app/vault/VaultClosedEnded_test.cpp b/src/test/app/vault/VaultClosedEnded_test.cpp
index 252a7f4990..5ed242f8a4 100644
--- a/src/test/app/vault/VaultClosedEnded_test.cpp
+++ b/src/test/app/vault/VaultClosedEnded_test.cpp
@@ -81,7 +81,7 @@ private:
 
         /*
          * Valid closed-ended creation with a comfortably interior gap (well above
-         * MIN_INVESTMENT_PERIOD and well below MAX_INVESTMENT_PERIOD).
+         * kMinInvestmentPeriod and well below kMaxInvestmentPeriod).
          */
         withEnv(testableAmendments(), [&](Env& env, Account const& owner, Vault& vault) {
             auto const sub = env.now().time_since_epoch().count() + 60;
@@ -145,7 +145,7 @@ private:
         });
 
         /*
-         * Gap smaller than MIN_INVESTMENT_PERIOD => temMALFORMED. Includes the SubscriptionDate >=
+         * Gap smaller than kMinInvestmentPeriod => temMALFORMED. Includes the SubscriptionDate >=
          * RedemptionDate degenerate cases: the red == sub boundary and the strictly-reversed red <
          * sub case, the latter yielding a negative signed int64 gap that is caught by the
          * sub-minimum branch of the gap check.
@@ -206,8 +206,9 @@ private:
             env(tx, Ter{temMALFORMED});
         });
 
-        // Happy path: gap exactly equal to MIN_INVESTMENT_PERIOD is accepted (lower bound is
-        // inclusive).
+        // Happy path: gap exactly equal to kMinInvestmentPeriod is accepted (lower bound is
+        // inclusive). A min-gap vault can originate a minimum-interval loan; see
+        // LoanSet_test::testLoanSetClosedEnded.
         withEnv(testableAmendments(), [&](Env& env, Account const& owner, Vault& vault) {
             auto const sub = env.now().time_since_epoch().count() + 60;
             auto const red = sub + minPeriod;
@@ -547,7 +548,7 @@ private:
 
         Asset const asset = xrpIssue();
         // Widen the Investment window so a single-payment loan (min payment
-        // interval kMinPaymentInterval = 60s) fits before RedemptionDate.
+        // interval 60s plus kLoanRedemptionBuffer) fits before RedemptionDate.
         auto const [vault, keylet, sub, red] =
             makeClosedEndedVault(env, owner, asset, 60u, kMinInvestmentPeriod + 3600u);
 
@@ -627,7 +628,7 @@ private:
         auto const closedEnded = std::to_underlying(VaultKind::ClosedEnded);
         Asset const asset = xrpIssue();
         // Widen the Investment window so a single-payment loan (min payment interval
-        // kMinPaymentInterval = 60s) fits before RedemptionDate with headroom.
+        // 60s plus kLoanRedemptionBuffer) fits before RedemptionDate with headroom.
         auto const [vault, keylet, sub, red] =
             makeClosedEndedVault(env, owner, asset, 300u, kMinInvestmentPeriod + 3600u);
 
diff --git a/src/test/app/vault/VaultHelpers_test.cpp b/src/test/app/vault/VaultHelpers_test.cpp
new file mode 100644
index 0000000000..d52b732a60
--- /dev/null
+++ b/src/test/app/vault/VaultHelpers_test.cpp
@@ -0,0 +1,484 @@
+#include <test/jtx/Account.h>
+
+#include <xrpl/basics/Number.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/ledger/helpers/VaultHelpers.h>
+#include <xrpl/protocol/Asset.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/Issue.h>
+#include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STIssue.h>
+#include <xrpl/protocol/STLedgerEntry.h>
+#include <xrpl/protocol/STNumber.h>  // IWYU pragma: keep
+#include <xrpl/protocol/STTakesAsset.h>
+#include <xrpl/protocol/TER.h>
+#include <xrpl/protocol/UintTypes.h>
+
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <expected>
+#include <memory>
+#include <optional>
+#include <string>
+
+namespace xrpl {
+
+// True unit test of `clampToAssetsTotalScale`. The function under test only
+// reads sfAsset and sfAssetsTotal from the vault SLE and never touches a
+// ledger view or Rules, so a bare in-memory ltVAULT SLE is enough; there is
+// no jtx::Env and no transaction submitted anywhere in this file.
+//
+// Number regime: this suite relies on the default thread_local Number
+// mantissa range, which src/libxrpl/basics/Number.cpp initializes to
+// Large330 (19-digit mantissa, post-fixCleanup3_3_0 cusp-rounding behavior):
+//
+//   thread_local std::reference_wrapper<MantissaRange const> Number::kRange =
+//       MantissaRange::Access::mantissaRange(MantissaRange::MantissaScale::Large330);
+//
+// Unlike transaction processing, this test never constructs a ledger `Rules`
+// object, so `STAmount::operator=(Number const&)` always takes its
+// `!getCurrentTransactionRules()` branch and calls `fromNumber`, independent
+// of amendment state. testProbeLarge330Regime() below asserts directly on a
+// value that only round-trips exactly under Large330, pinning the regime
+// rather than merely asserting it by comment.
+class VaultHelpers_test : public beast::unit_test::Suite
+{
+private:
+    // A single row of the clampToAssetsTotalScale table. `assetsTotal` and
+    // `delta` must already be genuine, on-grid STAmount values for `asset`.
+    struct Case
+    {
+        char const* name = nullptr;
+        Number assetsTotal;
+        Number delta;
+        std::optional<Number> expected;  // nullopt means tecPRECISION_LOSS
+    };
+
+    // Builds a bare ltVAULT SLE with only sfAsset and sfAssetsTotal set,
+    // mirroring what a transactor does: set the STNumber field, then call
+    // associateAsset() so it is quantized to the asset's STAmount grid, the
+    // same way VaultDeposit::doApply does for a real vault (see
+    // src/libxrpl/tx/transactors/vault/VaultDeposit.cpp).
+    static std::shared_ptr<SLE>
+    makeVault(Asset const& asset, Number const& assetsTotal)
+    {
+        auto vault = std::make_shared<SLE>(keylet::vault(uint256(1)));
+        vault->setFieldIssue(sfAsset, STIssue{sfAsset, asset});
+        vault->at(sfAssetsTotal) = assetsTotal;
+        associateAsset(*vault, asset);
+        return vault;
+    }
+
+    // Runs every case in `cases` against `asset`, once per ambient rounding
+    // mode. The function must give the same answer under all four modes,
+    // and its answer must match the hand-derived `expected` value.
+    template <std::size_t N>
+    void
+    runCases(Asset const& asset, std::array<Case, N> const& cases)
+    {
+        std::array<Number::RoundingMode, 4> const modes{
+            Number::RoundingMode::ToNearest,
+            Number::RoundingMode::Downward,
+            Number::RoundingMode::Upward,
+            Number::RoundingMode::TowardsZero};
+
+        for (auto const& c : cases)
+        {
+            testcase(c.name);
+
+            auto const vault = makeVault(asset, c.assetsTotal);
+            BEAST_EXPECTS(
+                Number(vault->at(sfAssetsTotal)) == c.assetsTotal,
+                std::string(c.name) +
+                    ": assetsTotal is not a genuine on-grid STAmount value (associateAsset "
+                    "changed it)");
+
+            STAmount const delta{asset, c.delta};
+            BEAST_EXPECTS(
+                Number(delta) == c.delta,
+                std::string(c.name) + ": delta is not a genuine on-grid STAmount value");
+
+            std::optional<std::expected<STAmount, TER>> reference;
+            for (auto const mode : modes)
+            {
+                NumberRoundModeGuard const rg(mode);
+                auto const result = clampToAssetsTotalScale(vault, delta);
+
+                // The function must be insensitive to the caller's ambient
+                // rounding mode: every mode must agree with the first one
+                // tried.
+                if (!reference)
+                {
+                    reference = result;
+                }
+                else
+                {
+                    BEAST_EXPECTS(
+                        result.has_value() == reference->has_value(),
+                        std::string(c.name) + ": result depends on ambient rounding mode");
+                    if (result.has_value() && reference->has_value())
+                    {
+                        BEAST_EXPECTS(
+                            *result == **reference,
+                            std::string(c.name) + ": value depends on ambient rounding mode");
+                    }
+                    else if (!result.has_value() && !reference->has_value())
+                    {
+                        BEAST_EXPECTS(
+                            result.error() == reference->error(),
+                            std::string(c.name) + ": error depends on ambient rounding mode");
+                    }
+                }
+
+                if (!c.expected)
+                {
+                    BEAST_EXPECTS(
+                        !result.has_value(),
+                        std::string(c.name) + ": expected tecPRECISION_LOSS, got success value " +
+                            (result.has_value() ? result->getText() : std::string()));
+                    if (!result.has_value())
+                    {
+                        BEAST_EXPECTS(
+                            result.error() == tecPRECISION_LOSS,
+                            std::string(c.name) + ": expected tecPRECISION_LOSS, got " +
+                                transToken(result.error()));
+                    }
+                    continue;
+                }
+
+                STAmount const expected{asset, *c.expected};
+                if (!BEAST_EXPECTS(
+                        result.has_value(),
+                        std::string(c.name) + ": expected success (" + expected.getText() +
+                            "), got " + transToken(result.error())))
+                {
+                    continue;
+                }
+
+                BEAST_EXPECTS(
+                    *result == expected,
+                    std::string(c.name) + ": expected " + expected.getText() + ", got " +
+                        result->getText());
+
+                // The result must always be positive...
+                BEAST_EXPECT(Number(*result) > Number{0});
+
+                // ...and never larger in magnitude than the requested delta.
+                BEAST_EXPECT(abs(Number(*result)) <= abs(c.delta));
+
+                // For IOU rows, re-flooring the result on the posterior grid
+                // must be a no-op: the result is already exactly
+                // representable at that scale.
+                //
+                // For debits this holds directly at postScale, because the
+                // result IS `roundToScale(magnitude, postScale, Downward)` by
+                // construction. For credits the result is
+                // `roundedPosterior - assetsTotal`, where roundedPosterior
+                // sits exactly on the postScale grid but assetsTotal sits on
+                // its own (possibly finer) natural grid; the difference of a
+                // multiple of 10^postScale and a multiple of 10^assetsScale
+                // is only guaranteed exact at the FINER of the two scales.
+                // Row 7 below ("overcredit fix across a scale boundary") is
+                // exactly this case: assetsTotal's own scale (-15) is finer
+                // than postScale (-14), so checking exactness at postScale
+                // alone fails even though the implementation is correct.
+                if (!asset.integral())
+                {
+                    bool const isDebit = c.delta.mantissa() < 0;
+                    Number const posterior =
+                        isDebit ? c.assetsTotal - Number(*result) : c.assetsTotal + Number(*result);
+                    int const postScale = scale(posterior, asset);
+                    int const checkScale =
+                        isDebit ? postScale : std::min(postScale, scale(c.assetsTotal, asset));
+                    STAmount const reFloored =
+                        roundToScale(*result, checkScale, Number::RoundingMode::Downward);
+                    BEAST_EXPECTS(
+                        reFloored == *result,
+                        std::string(c.name) + ": result " + result->getText() +
+                            " is not exact on the posterior grid (scale " +
+                            std::to_string(checkScale) + ")");
+                }
+            }
+        }
+    }
+
+    // Pins the Number mantissa regime this suite relies on. Under Large330,
+    // a 19-digit mantissa (max 10^19-1) is exact where a legacy 16-digit
+    // ("Small", max 10^16-1) regime would have to round it down to 16
+    // significant digits, changing both mantissa and exponent.
+    void
+    testProbeLarge330Regime()
+    {
+        testcase("probe: default Number regime is Large330 (19-digit mantissa)");
+
+        BEAST_EXPECT(Number::getMantissaScale() == MantissaRange::MantissaScale::Large330);
+
+        // std::numeric_limits<std::int64_t>::max(), 19 significant digits.
+        // This is already inside Large330's [10^18, 10^19-1] range, so
+        // constructing it is a no-op; under "Small" it would have to lose
+        // its low 3 digits.
+        Number const probe{9'223'372'036'854'775'807LL, 0};
+        BEAST_EXPECT(probe.mantissa() == 9'223'372'036'854'775'807LL);
+        BEAST_EXPECT(probe.exponent() == 0);
+    }
+
+    // -------------------------------------------------------------------
+    // IOU debits (delta negative).
+    // -------------------------------------------------------------------
+    void
+    testIouDebits(Asset const& iou)
+    {
+        std::array<Case, 5> const cases{
+            Case{
+                // T = 1000000.000000005, delta = -1e-9.
+                // Posterior = 1000000.000000004, still 16 significant
+                // digits at exponent -9 (no rounding, no decade change).
+                // postScale = -9. magnitude 1e-9 has its own exponent -24
+                // (finer than -9), so it must be actually floored: 1e-9 is
+                // exactly 1 ULP at scale -9, so flooring is a no-op.
+                .name = "IOU debit: on-grid, same decade",
+                .assetsTotal = Number{1'000'000'000'000'005LL, -9},
+                .delta = Number{-1, -9},
+                .expected = Number{1, -9},
+            },
+            Case{
+                // T = 1000000, delta = -7.3e-10.
+                // Posterior = 999999.99999999927 exactly (17 significant
+                // digits: 15 nines, then "27"). Rounding to 16 digits
+                // (ToNearest) rounds the trailing "...92.7" up to
+                // "...93", giving mantissa 9999999999999993 at exponent
+                // -10 -- postScale = -10, ONE DIGIT FINER than the naive
+                // "posterior stays in T's decade at -9" guess, because
+                // subtracting anything positive from an exact power-of-ten
+                // total necessarily drops into the next lower decade
+                // (1000000 has 7 integer digits, 999999.x has 6).
+                // At scale -10 the ULP is 1e-10, and floor(7.3) = 7, so
+                // the debit is NOT sub-ULP: it floors to 7e-10, not to
+                // zero. See discrepancy note in the report.
+                .name = "IOU debit: sub-ULP at the naive scale, but not at the true postScale",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{-73, -11},
+                .expected = Number{7, -10},
+            },
+            Case{
+                // T = 1000000, delta = -5.3e-9.
+                // Posterior = 999999.9999999947 exactly -- this needs only
+                // 16 significant digits (14 nines, then "47"), so it is
+                // exactly representable with NO rounding at exponent -10.
+                // postScale = -10 (again one digit finer than T's own -9,
+                // for the same power-of-ten-boundary reason as the row
+                // above). At that grid 5.3e-9 is exactly 53 ULPs (integer),
+                // so it floors to itself, unchanged.
+                .name = "IOU debit: exact at the true (finer) postScale",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{-53, -10},
+                .expected = Number{53, -10},
+            },
+            Case{
+                // T = 1.000000000000000, delta = -7.3e-16.
+                // Posterior = 0.99999999999999927 exactly (17 significant
+                // digits: 15 nines then "27"). Rounding to 16 digits
+                // (ToNearest) gives mantissa 9999999999999993 at exponent
+                // -16 -- postScale = -16. At that grid, 7.3e-16 is 7.3
+                // ULPs (not integral), so it floors to 7e-16, not to
+                // itself. See discrepancy note in the report.
+                .name = "IOU debit: decade-crossing debit, floored (not exact) at finer grid",
+                .assetsTotal = Number{1, 0},
+                .delta = Number{-73, -17},
+                .expected = Number{7, -16},
+            },
+            Case{
+                // T = 1000000, delta = -999999.9999999999 (9.999999999999999e5).
+                // Posterior = 0.0000000001 = 1e-10 exactly. postScale is
+                // the exponent of 1e-10 as a canonical STAmount, i.e. -25 --
+                // far finer than the magnitude's own exponent (-10).
+                // roundToScale short-circuits ("value.exponent() >= scale")
+                // and returns the magnitude unchanged.
+                .name = "IOU debit: near-total debit, unchanged (finer postScale than magnitude)",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{-9'999'999'999'999'999LL, -10},
+                .expected = Number{9'999'999'999'999'999LL, -10},
+            },
+        };
+
+        runCases(iou, cases);
+    }
+
+    // -------------------------------------------------------------------
+    // IOU credits (delta positive).
+    // -------------------------------------------------------------------
+    void
+    testIouCredits(Asset const& iou)
+    {
+        std::array<Case, 6> const cases{
+            Case{
+                // T = 1000000, delta = +2e-9. Posterior = 1000000.000000002,
+                // exactly 16 significant digits at exponent -9
+                // (postScale = -9, unchanged from T -- addition never
+                // crosses below the 1e6 boundary the way subtraction does).
+                // magnitude is already exact at that scale, so it passes
+                // through unchanged.
+                .name = "IOU credit: on-grid",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{2, -9},
+                .expected = Number{2, -9},
+            },
+            Case{
+                // T = 9.999999999999999, delta = +5.
+                // Exact posterior = 14.999999999999999 (17 significant
+                // digits: "14" then 15 nines). postScale is computed under
+                // ToNearest at the Number (19-digit) level: normalized
+                // mantissa 1499999999999999900 (exponent -17) divided by
+                // 1000 (to reach 16-digit IOU precision) gives
+                // 1499999999999999.9, which rounds UP to 1500000000000000
+                // -- i.e. exactly 15, at exponent -14. postScale = -14.
+                // Downward-guarded posterior (exact, no rounding needed
+                // since 17 digits < 19): 14.999999999999999. Flooring THAT
+                // to 16 digits at scale -14 (Downward) gives
+                // 1499999999999999 * 10^-14 = 14.99999999999999 (postScale
+                // already matches the STAmount's own exponent, so no
+                // further roundToScale is applied).
+                // actualDelta = 14.99999999999999 - 9.999999999999999
+                //             = 4.999999999999991.
+                // This mirrors testBugVaultDepositOvercreditsAcrossScaleBoundary
+                // in VaultBugs_test.cpp (same seed/deposit values), which
+                // asserts post-fix `credited <= paid` rather than an exact
+                // number; this row pins the exact value.
+                .name = "IOU credit: overcredit fix across a scale boundary",
+                .assetsTotal = Number{9'999'999'999'999'999LL, -15},
+                .delta = Number{5, 0},
+                .expected = Number{4'999'999'999'999'991LL, -15},
+            },
+            Case{
+                // Finding-1 regression: T = 1000000, delta = +9.999999999999999e-10.
+                // The exact sum needs ~25 significant digits (1000000 at
+                // position 6, delta's last digit at position -25), far
+                // beyond Number's 19-digit mantissa.
+                //
+                // postScale (computed under ToNearest): the digits of delta
+                // that land within the 19-digit window (positions -10..-12,
+                // "999") plus an all-nines remainder below position -12
+                // round UP under ToNearest, carrying all the way through
+                // the intervening zeros: the sum rounds to exactly
+                // 1000000.000000001, i.e. postScale = -9.
+                //
+                // But the credit branch computes the *posterior* under a
+                // Downward guard, not ToNearest: positions -10..-12 stay
+                // "999" (no carry), giving posterior = 1000000.000000000999
+                // exactly. Flooring that (Downward) to scale -9 truncates
+                // the "999" entirely, landing back on exactly 1000000 --
+                // i.e. the same as T. actualDelta = 0 => tecPRECISION_LOSS.
+                // This is the ambient-rounding leak the Downward guard on
+                // the credit-side sum exists to close; this row is a
+                // regression test that the guard is doing its job.
+                .name = "IOU credit: Finding-1 regression, ToNearest sum would overcredit",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{9'999'999'999'999'999LL, -25},
+                .expected = std::nullopt,
+            },
+            Case{
+                // Same shape as the row above, but delta = +9.995e-10 is a
+                // 19-digit half-even tie at the position-(-12) cusp: the
+                // remainder below the retained "999" digits is exactly
+                // 0.5 ULP, and ToNearest ties-to-even rounds the (odd) "9"
+                // up, carrying the same way. Downward-guarded posterior
+                // still truncates to "...000999" and floors back to T, so
+                // the outcome is identical: tecPRECISION_LOSS.
+                .name = "IOU credit: Finding-1 regression, 19-digit half-even tie",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{9'995, -13},
+                .expected = std::nullopt,
+            },
+            Case{
+                // T = 0, delta = +3.7e-5. Posterior grid is delta's own
+                // scale (postScale = -20, the canonical exponent of
+                // 3.7e-5), so the magnitude is trivially unchanged.
+                .name = "IOU credit: zero-total vault",
+                .assetsTotal = Number{0},
+                .delta = Number{37, -6},
+                .expected = Number{37, -6},
+            },
+            Case{
+                // T = 1000000, delta = +4e-10. Exact sum needs 17
+                // significant digits (leading "1" at position 6, trailing
+                // "4" at position -10); rounding to 16 digits drops the "4"
+                // entirely (0.4 ULP at scale -9 rounds down under both
+                // ToNearest and Downward), so postScale = -9 and the
+                // Downward-guarded posterior floors straight back to T.
+                // actualDelta = 0 => tecPRECISION_LOSS.
+                .name = "IOU credit: sub-ULP credit",
+                .assetsTotal = Number{1'000'000, 0},
+                .delta = Number{4, -10},
+                .expected = std::nullopt,
+            },
+        };
+
+        runCases(iou, cases);
+    }
+
+    // -------------------------------------------------------------------
+    // Integral assets (XRP, MPT): rounding is a no-op, magnitude is
+    // returned unchanged and positive regardless of delta's sign. This is
+    // a regression test for a signed-return bug: the function must not
+    // hand back a negative delta for a debit.
+    // -------------------------------------------------------------------
+    void
+    testIntegralAssets(Asset const& mpt, Asset const& xrp)
+    {
+        std::array<Case, 2> const mptCases{
+            Case{
+                .name = "MPT debit: magnitude is positive, not the signed delta",
+                .assetsTotal = Number{1'000'000},
+                .delta = Number{-5},
+                .expected = Number{5},
+            },
+            Case{
+                .name = "MPT credit: unchanged",
+                .assetsTotal = Number{1'000'000},
+                .delta = Number{7},
+                .expected = Number{7},
+            },
+        };
+        runCases(mpt, mptCases);
+
+        std::array<Case, 2> const xrpCases{
+            Case{
+                .name = "XRP debit: magnitude is positive, not the signed delta",
+                .assetsTotal = Number{100'000},
+                .delta = Number{-3},
+                .expected = Number{3},
+            },
+            Case{
+                .name = "XRP credit: unchanged",
+                .assetsTotal = Number{100'000},
+                .delta = Number{10},
+                .expected = Number{10},
+            },
+        };
+        runCases(xrp, xrpCases);
+    }
+
+public:
+    void
+    run() override
+    {
+        testProbeLarge330Regime();
+
+        test::jtx::Account const issuer{"issuer"};
+        Issue const iou{toCurrency("USD"), issuer.id()};
+        MPTIssue const mpt{makeMptID(1, issuer.id())};
+        Issue const xrp = xrpIssue();
+
+        testIouDebits(iou);
+        testIouCredits(iou);
+        testIntegralAssets(mpt, xrp);
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(VaultHelpers, app, xrpl);
+
+}  // namespace xrpl
diff --git a/src/test/app/vault/VaultPrecisionFixture.h b/src/test/app/vault/VaultPrecisionFixture.h
index d1067e245d..22a3276fdf 100644
--- a/src/test/app/vault/VaultPrecisionFixture.h
+++ b/src/test/app/vault/VaultPrecisionFixture.h
@@ -35,14 +35,9 @@ namespace xrpl::test {
 
 // Shared fixture for VaultInvariantPrecision_test and
 // VaultTransactorPrecision_test.
-//
-// Layout:
-//   - A-1 (impairAndPaySibling=false): 1000 USD vault + one ordinary loan.
-//     assetsTotal ~= 1000.353..., assetsAvailable == 993, lossUnrealized == 0.
-//   - A-3 (impairAndPaySibling=true):  add a second loan of principal 11,
-//     impair the first loan, and pay off the second in full.  This drives
-//     the vault to the lossUnrealized == (assetsTotal - assetsAvailable)
-//     boundary where the loss invariant used to spuriously fire.
+// impairAndPaySibling=false: 1000 USD vault and one ordinary loan.
+// impairAndPaySibling=true: a second loan is impaired then a sibling is paid
+// off, leaving lossUnrealized at assetsTotal - assetsAvailable.
 class VaultPrecisionFixture : public LoanTestBase
 {
 protected:
@@ -84,11 +79,16 @@ protected:
     {
         Asset asset;
         MPTIssue share;
+        // The {} initializers are not redundant: Number's default constructor is explicit, so
+        // fields omitted from the designated initializer in read() below would otherwise fail
+        // copy-list-initialization.
+        // NOLINTBEGIN(readability-redundant-member-init)
         Number assetsTotal{};      // sfAssetsTotal
         Number assetsAvailable{};  // sfAssetsAvailable
         Number lossUnrealized{};   // sfLossUnrealized
         Number pseudo{};           // vault pseudo-account balance in the asset
         Number sharesTotal{};      // sfOutstandingAmount on the share MPT
+        // NOLINTEND(readability-redundant-member-init)
     };
 
     static Numbers
diff --git a/src/test/app/vault/VaultScale_test.cpp b/src/test/app/vault/VaultScale_test.cpp
index b2ce4a5abf..c2858a204d 100644
--- a/src/test/app/vault/VaultScale_test.cpp
+++ b/src/test/app/vault/VaultScale_test.cpp
@@ -898,6 +898,117 @@ private:
                 BEAST_EXPECT(env.balance(d.depositor, d.shares) == d.share(400));
             }
         });
+
+        // peek() writes the open ledger only; do not close() before le().
+        auto seedLargeTotal = [](Env& env,
+                                 Data& d,
+                                 Number const& total,
+                                 Number const& available,
+                                 std::uint64_t outstanding) {
+            auto tx = d.vault.deposit(
+                {.depositor = d.depositor,
+                 .id = d.keylet.key,
+                 .amount = STAmount(d.asset, Number(100, 0))});
+            env(tx);
+            env.close();
+            d.peek([&](SLE& vault, SLE& shares) -> bool {
+                vault[sfAssetsTotal] = total;
+                vault[sfAssetsAvailable] = available;
+                shares[sfOutstandingAmount] = outstanding;
+                return true;
+            });
+        };
+
+        auto expectVault = [this](
+                               Env& env,
+                               Data const& d,
+                               Number const& total,
+                               Number const& available,
+                               STAmount const& shareBalance) {
+            auto const sle = env.le(d.keylet);
+            BEAST_EXPECT(sle != nullptr);
+            BEAST_EXPECT(sle->at(sfAssetsTotal) == total);
+            BEAST_EXPECT(sle->at(sfAssetsAvailable) == available);
+            BEAST_EXPECT(env.balance(d.depositor, d.shares) == shareBalance);
+        };
+
+        // T-6 is exact after the decade; recover 6.
+        testCase(0, [&, this](Env& env, Data d) {
+            testcase("Scale clawback uses posterior scale across decade boundary");
+
+            Number const midGridTotal{10000000000000005ll};
+            Number const available{6};
+            seedLargeTotal(env, d, midGridTotal, available, 10000000000000005ull);
+
+            auto tx =
+                d.vault.clawback({.issuer = d.issuer, .id = d.keylet.key, .holder = d.depositor});
+            env(tx, Ter(tesSUCCESS));
+            expectVault(env, d, midGridTotal - available, Number(0), d.share(94));
+        });
+
+        // T stays on the 10-asset grid; 6 is unrepresentable.
+        testCase(0, [&, this](Env& env, Data d) {
+            testcase("Scale clawback rejects amount below posterior scale");
+
+            Number const midGridTotal{12345678901234567ll};
+            Number const available{6};
+            seedLargeTotal(env, d, midGridTotal, available, 12345678901234567ull);
+
+            auto tx =
+                d.vault.clawback({.issuer = d.issuer, .id = d.keylet.key, .holder = d.depositor});
+            env(tx, Ter(tecPRECISION_LOSS));
+            expectVault(env, d, midGridTotal, available, d.share(100));
+        });
+
+        // A recovery larger than the anterior ULP also lands exactly on the finer posterior grid.
+        testCase(0, [&, this](Env& env, Data d) {
+            testcase("Scale clawback preserves exact posterior amount");
+
+            Number const midGridTotal{10000000000000005ll};
+            Number const available{15};
+            seedLargeTotal(env, d, midGridTotal, available, 10000000000000005ull);
+
+            auto tx =
+                d.vault.clawback({.issuer = d.issuer, .id = d.keylet.key, .holder = d.depositor});
+            env(tx, Ter(tesSUCCESS));
+            expectVault(env, d, midGridTotal - available, Number(0), d.share(85));
+        });
+
+        testCase(0, [&, this](Env& env, Data d) {
+            testcase("Scale deposit rejects amount below posterior scale");
+
+            Number const midGridTotal{10000000000000005ll};
+            Number const available{100};
+            seedLargeTotal(env, d, midGridTotal, available, 10000000000000005ull);
+
+            auto const assetsBefore = env.balance(d.depositor, d.assets);
+            auto tx = d.vault.deposit(
+                {.depositor = d.depositor,
+                 .id = d.keylet.key,
+                 .amount = STAmount(d.asset, Number(6))});
+            env(tx, Ter(tecPRECISION_LOSS));
+            expectVault(env, d, midGridTotal, available, d.share(100));
+            BEAST_EXPECT(env.balance(d.depositor, d.assets) == assetsBefore);
+        });
+
+        testCase(0, [&, this](Env& env, Data d) {
+            testcase("Scale withdraw uses posterior scale across decade boundary");
+
+            Number const midGridTotal{10000000000000005ll};
+            Number const available{100};
+            seedLargeTotal(env, d, midGridTotal, available, 10000000000000005ull);
+
+            auto const assetsBefore = env.balance(d.depositor, d.assets);
+            auto tx = d.vault.withdraw(
+                {.depositor = d.depositor,
+                 .id = d.keylet.key,
+                 .amount = STAmount(d.share, Number(15))});
+            env(tx, Ter(tesSUCCESS));
+            expectVault(env, d, midGridTotal - Number(15), Number(85), d.share(85));
+            BEAST_EXPECT(
+                env.balance(d.depositor, d.assets) ==
+                STAmount(d.asset, assetsBefore.number() + Number(15)));
+        });
     }
 
     void
diff --git a/src/test/app/vault/VaultTransactorPrecision_test.cpp b/src/test/app/vault/VaultTransactorPrecision_test.cpp
new file mode 100644
index 0000000000..8e8ee2d629
--- /dev/null
+++ b/src/test/app/vault/VaultTransactorPrecision_test.cpp
@@ -0,0 +1,362 @@
+#include <test/app/vault/VaultPrecisionFixture.h>
+#include <test/jtx/Env.h>
+#include <test/jtx/amount.h>
+#include <test/jtx/envconfig.h>
+#include <test/jtx/ter.h>
+#include <test/jtx/vault.h>
+
+#include <xrpl/basics/Number.h>
+#include <xrpl/beast/unit_test/suite.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/TER.h>
+
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <optional>
+#include <string>
+#include <tuple>
+
+namespace xrpl::test {
+
+// With fixCleanup3_4_0, deposit/withdraw/clawback apply one amount on the
+// sfAssetsTotal grid. These tests require T, A, and the pseudo-account to
+// change by the same Number; the invariant suite still allows a one-unit gap.
+class VaultTransactorPrecision_test : public VaultPrecisionFixture
+{
+    jtx::Env
+    makeEnv()
+    {
+        return jtx::Env{*this, jtx::envconfig(), all_, nullptr, beast::Severity::Disabled};
+    }
+
+    bool
+    ready(Fixture const& f)
+    {
+        return BEAST_EXPECT(f.asset && f.broker) && f.asset;
+    }
+
+    void
+    assertEqualDeltas(Numbers const& before, Numbers const& after, std::string const& tag)
+    {
+        Number const tDelta = before.assetsTotal - after.assetsTotal;
+        Number const aDelta = before.assetsAvailable - after.assetsAvailable;
+        Number const pDelta = before.pseudo - after.pseudo;
+        BEAST_EXPECTS(tDelta == aDelta, tag + " tDelta != aDelta");
+        BEAST_EXPECTS(tDelta == pDelta, tag + " tDelta != pDelta");
+    }
+
+    void
+    testDeposit()
+    {
+        using namespace jtx;
+
+        testcase("deposit clamp does not over-credit");
+
+        std::array<int, 4> const kAmounts{1, 7, 1'000, 10'000'000};
+
+        for (auto const amount : kAmounts)
+        {
+            Env env = makeEnv();
+            auto f = setupSingleLoanVault(env, /*impairAndPaySibling=*/false);
+            if (!ready(f))
+                continue;
+            // ready() above guarantees f.asset is engaged; the guard is opaque to clang-tidy.
+            // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+            jtx::PrettyAsset const& asset = f.asset.value();
+
+            auto const before = read(env, f);
+
+            Vault const v{env};
+            env(v.deposit(
+                    {.depositor = f.depositor,
+                     .id = f.vaultKeylet.key,
+                     .amount = asset(amount).value()}),
+                Ter(std::ignore));
+            env.close();
+
+            if (env.ter() != tesSUCCESS)
+                continue;
+
+            auto const after = read(env, f);
+            Number const tDelta = after.assetsTotal - before.assetsTotal;
+            Number const requested = asset(amount).number();
+            BEAST_EXPECTS(
+                tDelta <= requested,
+                "amount=" + std::to_string(amount) + " tDelta exceeds requested");
+
+            Number const sharesMinted = after.sharesTotal - before.sharesTotal;
+            if (before.sharesTotal == Number{0})
+                continue;
+            Number const shareValue = (before.assetsTotal * sharesMinted) / before.sharesTotal;
+            // The depositor is never charged more than the shares they received are worth.
+            BEAST_EXPECTS(
+                tDelta <= shareValue,
+                "amount=" + std::to_string(amount) + " assetsTaken > shareValue");
+            // Discount is strictly less than one ULP of the new AssetsTotal
+            BEAST_EXPECTS(
+                shareValue - tDelta < oneUnit(asset.raw(), after.assetsTotal),
+                "amount=" + std::to_string(amount) + " discount is not below one unit");
+        }
+
+        {
+            Env env = makeEnv();
+            auto f = setupSingleLoanVault(env, /*impairAndPaySibling=*/false);
+            if (!ready(f))
+                return;
+            // ready() above guarantees f.asset is engaged; the guard is opaque to clang-tidy.
+            // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+            jtx::PrettyAsset const& asset = f.asset.value();
+
+            Vault const v{env};
+            env(v.deposit(
+                    {.depositor = f.depositor,
+                     .id = f.vaultKeylet.key,
+                     .amount = asset(99'000'000).value()}),
+                Ter(std::ignore));
+            env.close();
+
+            auto const before = read(env, f);
+            Number const kLowerBound{1, 6};
+            BEAST_EXPECT(before.assetsTotal > kLowerBound);
+
+            auto const tinyAmount = asset(Number{1, -10}).value();
+            env(v.deposit(
+                    {.depositor = f.depositor, .id = f.vaultKeylet.key, .amount = tinyAmount}),
+                Ter(std::ignore));
+            env.close();
+
+            BEAST_EXPECTS(
+                env.ter() == tecPRECISION_LOSS,
+                std::string{"expected tecPRECISION_LOSS, got "} + transToken(env.ter()));
+
+            auto const after = read(env, f);
+            BEAST_EXPECT(after.assetsTotal == before.assetsTotal);
+            BEAST_EXPECT(after.assetsAvailable == before.assetsAvailable);
+            BEAST_EXPECT(after.sharesTotal == before.sharesTotal);
+        }
+    }
+
+    void
+    testWithdraw()
+    {
+        using namespace jtx;
+
+        testcase("withdraw deltas are equal");
+
+        Env env = makeEnv();
+        auto f = setupSingleLoanVault(env, /*impairAndPaySibling=*/false);
+        if (!ready(f))
+            return;
+        // ready() above guarantees f.asset is engaged; the guard is opaque to clang-tidy.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        jtx::PrettyAsset const& asset = f.asset.value();
+
+        Vault const v{env};
+        env(v.deposit(
+                {.depositor = f.depositor,
+                 .id = f.vaultKeylet.key,
+                 .amount = asset(1'000'000).value()}),
+            Ter(std::ignore));
+        env.close();
+
+        auto checkSuccess = [&](STAmount const& amount, std::string const& tag) {
+            auto const before = read(env, f);
+            env(v.withdraw({.depositor = f.depositor, .id = f.vaultKeylet.key, .amount = amount}),
+                Ter(std::ignore));
+            env.close();
+            if (env.ter() != tesSUCCESS)
+                return;
+
+            auto const after = read(env, f);
+            assertEqualDeltas(before, after, tag);
+
+            Number const sharesBurned = before.sharesTotal - after.sharesTotal;
+            if (before.sharesTotal == Number{0})
+                return;
+            Number const shareValue = (before.assetsTotal * sharesBurned) / before.sharesTotal;
+            Number const tDelta = before.assetsTotal - after.assetsTotal;
+            BEAST_EXPECTS(tDelta <= shareValue, tag + " payout > shareValue");
+        };
+
+        std::array<std::uint64_t, 3> const kShareCounts{99'999u, 333'333u, 1'234'567u};
+        for (auto const count : kShareCounts)
+        {
+            auto const before = read(env, f);
+            if (before.sharesTotal < count)
+                continue;
+            STAmount const shareAmount{MPTIssue{f.share}, Number{static_cast<std::int64_t>(count)}};
+            checkSuccess(shareAmount, "shares=" + std::to_string(count));
+        }
+
+        std::array<int, 3> const kAssetAmounts{1, 7, 99};
+        for (auto const amount : kAssetAmounts)
+            checkSuccess(asset(amount).value(), "assets=" + std::to_string(amount));
+    }
+
+    // Withdraw more than sfAssetsAvailable must return tecINSUFFICIENT_FUNDS,
+    // not tecPRECISION_LOSS.
+    void
+    testWithdrawInsufficientFundsPrecedence()
+    {
+        using namespace jtx;
+
+        testcase("withdraw over available returns insufficient funds, not precision loss");
+
+        Env env = makeEnv();
+        auto f = setupSingleLoanVault(env, /*impairAndPaySibling=*/false);
+        if (!ready(f))
+            return;
+        // ready() above guarantees f.asset is engaged; the guard is opaque to clang-tidy.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        jtx::PrettyAsset const& asset = f.asset.value();
+
+        Vault const v{env};
+        env(v.deposit(
+                {.depositor = f.depositor,
+                 .id = f.vaultKeylet.key,
+                 .amount = asset(1'000'000).value()}),
+            Ter(std::ignore));
+        env.close();
+
+        auto const before = read(env, f);
+        if (!BEAST_EXPECT(before.assetsAvailable > Number{0}))
+            return;
+
+        STAmount const request = asset(before.assetsAvailable + Number{1}).value();
+        env(v.withdraw({.depositor = f.depositor, .id = f.vaultKeylet.key, .amount = request}),
+            Ter(std::ignore));
+        env.close();
+
+        BEAST_EXPECTS(
+            env.ter() == tecINSUFFICIENT_FUNDS,
+            std::string{"expected tecINSUFFICIENT_FUNDS, got "} + transToken(env.ter()));
+    }
+
+    void
+    testClawback()
+    {
+        using namespace jtx;
+
+        testcase("clawback deltas are equal");
+
+        Env env = makeEnv();
+        auto f = setupSingleLoanVault(
+            env,
+            /*impairAndPaySibling=*/false,
+            /*allowClawback=*/true);
+        if (!ready(f))
+            return;
+        // ready() above guarantees f.asset is engaged; the guard is opaque to clang-tidy.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        jtx::PrettyAsset const& asset = f.asset.value();
+
+        Vault const v{env};
+        env(v.deposit(
+                {.depositor = f.depositor,
+                 .id = f.vaultKeylet.key,
+                 .amount = asset(2'000).value()}),
+            Ter(std::ignore));
+        env.close();
+
+        auto checkSuccess = [&](std::optional<STAmount> const& amount, std::string const& tag) {
+            auto const before = read(env, f);
+            if (before.sharesTotal == Number{0})
+                return;
+
+            env(v.clawback(
+                    {.issuer = f.issuer,
+                     .id = f.vaultKeylet.key,
+                     .holder = f.depositor,
+                     .amount = amount}),
+                Ter(std::ignore));
+            env.close();
+            if (env.ter() != tesSUCCESS)
+                return;
+
+            assertEqualDeltas(before, read(env, f), tag);
+        };
+
+        std::array<int, 3> const kAmounts{1, 7, 99};
+        for (auto const amount : kAmounts)
+            checkSuccess(asset(amount).value(), "amount=" + std::to_string(amount));
+
+        checkSuccess(std::nullopt, "sfAmount absent");
+    }
+
+    void
+    testImpairedVault()
+    {
+        using namespace jtx;
+
+        testcase("impaired vault loss stays within assetsTotal - assetsAvailable");
+
+        Env env = makeEnv();
+        auto f = setupSingleLoanVault(env, /*impairAndPaySibling=*/true);
+        if (!ready(f))
+            return;
+        // ready() above guarantees f.asset is engaged; the guard is opaque to clang-tidy.
+        // NOLINTNEXTLINE(bugprone-unchecked-optional-access)
+        jtx::PrettyAsset const& asset = f.asset.value();
+
+        Vault const v{env};
+        env(v.deposit(
+                {.depositor = f.depositor,
+                 .id = f.vaultKeylet.key,
+                 .amount = asset(5'000).value()}),
+            Ter(std::ignore));
+        env.close();
+
+        auto checkInvariant = [&](std::string const& tag) {
+            TER const actual = env.ter();
+            BEAST_EXPECTS(actual != tecINVARIANT_FAILED, tag + " unexpected invariant failure");
+            if (actual != tesSUCCESS)
+                return;
+            auto const after = read(env, f);
+            BEAST_EXPECTS(
+                after.lossUnrealized <= after.assetsTotal - after.assetsAvailable,
+                tag + " lossUnrealized exceeds assetsTotal - assetsAvailable");
+        };
+
+        std::array<int, 4> const kAmounts{1, 7, 51, 137};
+        for (std::size_t i = 0; i + 1 < kAmounts.size(); i += 2)
+        {
+            int const depositAmount = kAmounts[i];
+            int const withdrawAmount = kAmounts[i + 1];
+
+            env(v.deposit(
+                    {.depositor = f.depositor,
+                     .id = f.vaultKeylet.key,
+                     .amount = asset(depositAmount).value()}),
+                Ter(std::ignore));
+            env.close();
+            checkInvariant("deposit=" + std::to_string(depositAmount));
+
+            env(v.withdraw(
+                    {.depositor = f.depositor,
+                     .id = f.vaultKeylet.key,
+                     .amount = asset(withdrawAmount).value()}),
+                Ter(std::ignore));
+            env.close();
+            checkInvariant("withdraw=" + std::to_string(withdrawAmount));
+        }
+    }
+
+public:
+    void
+    run() override
+    {
+        testDeposit();
+        testWithdraw();
+        testWithdrawInsufficientFundsPrecedence();
+        testClawback();
+        testImpairedVault();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(VaultTransactorPrecision, app, xrpl);
+
+}  // namespace xrpl::test
diff --git a/src/test/jtx/impl/mpt.cpp b/src/test/jtx/impl/mpt.cpp
index c6cd49fa26..0c1ff14eab 100644
--- a/src/test/jtx/impl/mpt.cpp
+++ b/src/test/jtx/impl/mpt.cpp
@@ -17,7 +17,7 @@
 #include <xrpl/basics/strHex.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/json/json_value.h>
-#include <xrpl/ledger/helpers/TokenHelpers.h>
+#include <xrpl/ledger/helpers/MPTokenHelpers.h>
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/ConfidentialTransfer.h>
@@ -648,6 +648,38 @@ MPTTester::checkImmutableFlags(std::uint32_t expectedFlags) const
     });
 }
 
+[[nodiscard]] bool
+MPTTester::checkKeyEpochs(
+    std::optional<std::uint32_t> issuerKeyEpoch,
+    std::optional<std::uint32_t> auditorKeyEpoch) const
+{
+    return forObject([&](SLEP const& sle) -> bool {
+        return (*sle)[~sfIssuerKeyEpoch] == issuerKeyEpoch &&
+            (*sle)[~sfAuditorKeyEpoch] == auditorKeyEpoch;
+    });
+}
+
+[[nodiscard]] bool
+MPTTester::checkEncryptionKeys(
+    std::optional<Account> const& issuerKeyOwner,
+    std::optional<Account> const& auditorKeyOwner) const
+{
+    auto const matches =
+        [this](SLEP const& sle, SF_VL const& field, std::optional<Account> const& owner) {
+            if (!owner)
+                return !sle->isFieldPresent(field);
+
+            auto const expected = getPubKey(*owner);
+            return expected && sle->isFieldPresent(field) &&
+                strHex((*sle)[field]) == strHex(*expected);
+        };
+
+    return forObject([&](SLEP const& sle) -> bool {
+        return matches(sle, sfIssuerEncryptionKey, issuerKeyOwner) &&
+            matches(sle, sfAuditorEncryptionKey, auditorKeyOwner);
+    });
+}
+
 void
 MPTTester::pay(
     Account const& src,
diff --git a/src/test/jtx/impl/multisign.cpp b/src/test/jtx/impl/multisign.cpp
index d948042bda..e04e1bb58a 100644
--- a/src/test/jtx/impl/multisign.cpp
+++ b/src/test/jtx/impl/multisign.cpp
@@ -60,10 +60,12 @@ signers(Account const& account, NoneT)
 //------------------------------------------------------------------------------
 
 void
-Msig::operator()(Env& env, JTx& jt) const
+Msig::operator()(Env&, JTx& jt) const
 {
     auto const mySigners = signers;
-    auto callback = [subField = subField, mySigners, &env](Env&, JTx& jtx) {
+    auto callback = [subField = subField, mySigners](Env& env, JTx& jtx) {
+        auto const prefix =
+            signingPrefix(jtx::signatureRole(subField), true, env.current()->rules());
         // Where to put the signature. Supports sfCounterPartySignature and
         // sfSponsorSignature.
         auto& sigObject = subField ? jtx[*subField] : jtx.jv;
@@ -95,7 +97,7 @@ Msig::operator()(Env& env, JTx& jt) const
             jo[jss::Account] = e.acct.human();
             jo[jss::SigningPubKey] = strHex(e.sig.pk().slice());
 
-            Serializer const ss{buildMultiSigningData(*st, e.acct.id())};
+            Serializer const ss{buildMultiSigningData(*st, e.acct.id(), prefix)};
             auto const sig = xrpl::sign(*publicKeyType(e.sig.pk().slice()), e.sig.sk(), ss.slice());
             jo[sfTxnSignature.getJsonName()] = strHex(Slice{sig.data(), sig.size()});
         }
diff --git a/src/test/jtx/impl/sig.cpp b/src/test/jtx/impl/sig.cpp
index e0123073b1..41833c8802 100644
--- a/src/test/jtx/impl/sig.cpp
+++ b/src/test/jtx/impl/sig.cpp
@@ -4,6 +4,8 @@
 #include <test/jtx/JTx.h>
 #include <test/jtx/utility.h>
 
+#include <xrpl/protocol/Sign.h>
+
 namespace xrpl::test::jtx {
 
 void
@@ -17,11 +19,15 @@ Sig::operator()(Env&, JTx& jt) const
     {
         // VFALCO Inefficient pre-C++14
         auto const account = *account_;
-        auto callback = [subField = subField_, account](Env&, JTx& jtx) {
+        auto callback = [subField = subField_, account](Env& env, JTx& jtx) {
             // Where to put the signature. Supports sfCounterPartySignature and sfSponsorSignature.
             auto& sigObject = subField ? jtx[*subField] : jtx.jv;
 
-            jtx::sign(jtx.jv, account, sigObject);
+            jtx::sign(
+                jtx.jv,
+                account,
+                sigObject,
+                signingPrefix(jtx::signatureRole(subField), false, env.current()->rules()));
         };
         if (subField_ == nullptr)
         {
diff --git a/src/test/jtx/impl/utility.cpp b/src/test/jtx/impl/utility.cpp
index c298cee684..f83cb7772c 100644
--- a/src/test/jtx/impl/utility.cpp
+++ b/src/test/jtx/impl/utility.cpp
@@ -19,9 +19,11 @@
 #include <xrpl/protocol/STParsedJSON.h>
 #include <xrpl/protocol/SecretKey.h>
 #include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/Sign.h>
 #include <xrpl/protocol/XRPAmount.h>
 #include <xrpl/protocol/jss.h>
 
+#include <stdexcept>
 #include <utility>
 #include <vector>
 
@@ -36,12 +38,22 @@ parse(json::Value const& jv)
     return std::move(*p.object);
 }
 
+SignatureRole
+signatureRole(SField const* subField)
+{
+    if (subField == nullptr)
+        return SignatureRole::Transaction;
+    if (auto const role = xrpl::signatureRole(*subField))
+        return *role;
+    Throw<std::runtime_error>(subField->getName() + " does not hold a transaction signature.");
+}
+
 void
-sign(json::Value& jv, Account const& account, json::Value& sigObject)
+sign(json::Value& jv, Account const& account, json::Value& sigObject, HashPrefix prefix)
 {
     sigObject[jss::SigningPubKey] = strHex(account.pk().slice());
     Serializer ss;
-    ss.add32(HashPrefix::TxSign);
+    ss.add32(prefix);
     parse(jv).addWithoutSigningFields(ss);
     auto const sig = xrpl::sign(account.pk(), account.sk(), ss.slice());
     sigObject[jss::TxnSignature] = strHex(Slice{sig.data(), sig.size()});
diff --git a/src/test/jtx/impl/vault.cpp b/src/test/jtx/impl/vault.cpp
index 4688e8c4a6..5bf8ac9981 100644
--- a/src/test/jtx/impl/vault.cpp
+++ b/src/test/jtx/impl/vault.cpp
@@ -39,6 +39,8 @@ Vault::create(CreateArgs const& args) const
         jv[sfSubscriptionDate] = *args.subscriptionDate;
     if (args.redemptionDate)
         jv[sfRedemptionDate] = *args.redemptionDate;
+    if (args.leVersion)
+        jv[sfLEVersion] = std::to_underlying(*args.leVersion);
     return {jv, keylet};
 }
 
diff --git a/src/test/jtx/mpt.h b/src/test/jtx/mpt.h
index 35ab7264bd..26329ad78c 100644
--- a/src/test/jtx/mpt.h
+++ b/src/test/jtx/mpt.h
@@ -612,6 +612,21 @@ public:
     [[nodiscard]] bool
     checkImmutableFlags(std::uint32_t expectedFlags) const;
 
+    // Checks both key epochs on the issuance. Pass std::nullopt for an epoch
+    // that is expected to be absent, which means the key is never rotated.
+    [[nodiscard]] bool
+    checkKeyEpochs(
+        std::optional<std::uint32_t> issuerKeyEpoch,
+        std::optional<std::uint32_t> auditorKeyEpoch) const;
+
+    // Checks that the issuance carries the encryption keys of the given
+    // accounts. Pass std::nullopt for a key that is expected to be absent,
+    // which means the key is never registered.
+    [[nodiscard]] bool
+    checkEncryptionKeys(
+        std::optional<Account> const& issuerKeyOwner,
+        std::optional<Account> const& auditorKeyOwner) const;
+
     [[nodiscard]] Account const&
     issuer() const
     {
diff --git a/src/test/jtx/utility.h b/src/test/jtx/utility.h
index 289afec8b3..5a37abd920 100644
--- a/src/test/jtx/utility.h
+++ b/src/test/jtx/utility.h
@@ -5,7 +5,10 @@
 #include <xrpl/beast/utility/Journal.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/ledger/ReadView.h>
+#include <xrpl/protocol/HashPrefix.h>
+#include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STObject.h>
+#include <xrpl/protocol/Sign.h>
 
 #include <stdexcept>
 #include <string>
@@ -33,12 +36,29 @@ struct ParseError : std::logic_error
 STObject
 parse(json::Value const& jv);
 
+/**
+ * The role that signs into an optional signature subfield.
+ *
+ * @param subField The signature field, or nullptr for the transaction's own
+ * signature. Throws if the field does not hold a transaction signature.
+ */
+SignatureRole
+signatureRole(SField const* subField);
+
 /**
  * Sign automatically into a specific Json field of the jv object.
+ *
+ * @param prefix Prefix to insert before the serialized transaction when
+ * hashing. Use signingPrefix to get the prefix that matches the field that
+ * holds sigObject.
  * @note This only works on accounts with multi-signing off.
  */
 void
-sign(json::Value& jv, Account const& account, json::Value& sigObject);
+sign(
+    json::Value& jv,
+    Account const& account,
+    json::Value& sigObject,
+    HashPrefix prefix = HashPrefix::TxSign);
 
 /**
  * Sign automatically.
diff --git a/src/test/jtx/vault.h b/src/test/jtx/vault.h
index 6b2ffddfb3..000e8a20ea 100644
--- a/src/test/jtx/vault.h
+++ b/src/test/jtx/vault.h
@@ -7,6 +7,7 @@
 #include <xrpl/json/json_value.h>
 #include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/Keylet.h>
+#include <xrpl/protocol/Protocol.h>
 
 #include <chrono>
 #include <cstdint>
@@ -33,6 +34,8 @@ struct Vault
             std::nullopt;  // NOLINT(readability-redundant-member-init)
         std::optional<std::uint32_t> redemptionDate =
             std::nullopt;  // NOLINT(readability-redundant-member-init)
+        std::optional<VaultVersion> leVersion =
+            std::nullopt;  // NOLINT(readability-redundant-member-init)
     };
 
     /**
diff --git a/src/test/protocol/STTx_test.cpp b/src/test/protocol/STTx_test.cpp
index 777234be83..f310274e56 100644
--- a/src/test/protocol/STTx_test.cpp
+++ b/src/test/protocol/STTx_test.cpp
@@ -1,9 +1,13 @@
+#include <xrpl/basics/Number.h>
 #include <xrpl/basics/Slice.h>
 #include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/safe_cast.h>
+#include <xrpl/basics/strHex.h>
 #include <xrpl/beast/hash/uhash.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/json/to_string.h>  // IWYU pragma: keep
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/KeyType.h>
 #include <xrpl/protocol/PublicKey.h>
 #include <xrpl/protocol/Rules.h>
@@ -11,10 +15,12 @@
 #include <xrpl/protocol/SOTemplate.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STArray.h>
+#include <xrpl/protocol/STNumber.h>
 #include <xrpl/protocol/STObject.h>
 #include <xrpl/protocol/STParsedJSON.h>
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/SecretKey.h>
+#include <xrpl/protocol/Seed.h>
 #include <xrpl/protocol/Serializer.h>
 #include <xrpl/protocol/Sign.h>
 #include <xrpl/protocol/TxFormats.h>
@@ -24,6 +30,7 @@
 #include <cstdint>
 #include <cstring>
 #include <exception>
+#include <functional>
 #include <memory>
 #include <ostream>
 #include <regex>
@@ -55,6 +62,279 @@ public:
         testSTTx(KeyType::Ed25519);
         testObjectCtorErrors();
         testBatchInnerCtorErrors();
+        testSigningPrefixes();
+        testRoleSignatureBinding();
+        testRoleMultiSignatureBinding();
+    }
+
+    // Rules with no amendments enabled, and rules with only fixCleanup3_4_0
+    // enabled. Rules keep a reference to the presets, so the presets must
+    // outlive the Rules; both are returned together.
+    struct RulesFixture
+    {
+        std::unordered_set<uint256, beast::Uhash<>> const noPresets;
+        std::unordered_set<uint256, beast::Uhash<>> const fixPresets{fixCleanup3_4_0};
+        Rules const legacy{noPresets};
+        Rules const fixed{fixPresets};
+    };
+
+    // A transaction with fixed contents, so its signing data is stable from
+    // run to run.
+    static STTx
+    makeFixedTx()
+    {
+        auto const keypair = generateKeyPair(KeyType::Secp256k1, generateSeed("masterpassphrase"));
+        return STTx(ttACCOUNT_SET, [&keypair](auto& obj) {
+            obj.setAccountID(sfAccount, calcAccountID(keypair.first));
+            obj.setFieldAmount(sfFee, STAmount(10ull));
+            obj.setFieldU32(sfSequence, 1);
+            obj.setFieldVL(sfSigningPubKey, keypair.first.slice());
+        });
+    }
+
+    void
+    testSigningPrefixes()
+    {
+        testcase("signing prefixes");
+
+        // The prefixes are protocol constants. Spell them out so that a typo
+        // in a prefix character fails here, and not in a downstream library.
+        static_assert(safeCast<std::uint32_t>(HashPrefix::TxSign) == 0x53545800);
+        static_assert(safeCast<std::uint32_t>(HashPrefix::TxMultiSign) == 0x534D5400);
+        static_assert(safeCast<std::uint32_t>(HashPrefix::CounterpartyTxSign) == 0x43505400);
+        static_assert(safeCast<std::uint32_t>(HashPrefix::CounterpartyTxMultiSign) == 0x43504D00);
+        static_assert(safeCast<std::uint32_t>(HashPrefix::SponsorTxSign) == 0x53504E00);
+        static_assert(safeCast<std::uint32_t>(HashPrefix::SponsorTxMultiSign) == 0x53504D00);
+
+        RulesFixture const r;
+
+        // Every role gets its own prefix once the fix is enabled.
+        BEAST_EXPECT(
+            signingPrefix(SignatureRole::Transaction, false, r.fixed) == HashPrefix::TxSign);
+        BEAST_EXPECT(
+            signingPrefix(SignatureRole::Transaction, true, r.fixed) == HashPrefix::TxMultiSign);
+        BEAST_EXPECT(
+            signingPrefix(SignatureRole::Counterparty, false, r.fixed) ==
+            HashPrefix::CounterpartyTxSign);
+        BEAST_EXPECT(
+            signingPrefix(SignatureRole::Counterparty, true, r.fixed) ==
+            HashPrefix::CounterpartyTxMultiSign);
+        BEAST_EXPECT(
+            signingPrefix(SignatureRole::Sponsor, false, r.fixed) == HashPrefix::SponsorTxSign);
+        BEAST_EXPECT(
+            signingPrefix(SignatureRole::Sponsor, true, r.fixed) == HashPrefix::SponsorTxMultiSign);
+
+        // Before the fix, every role signs the same bytes.
+        for (auto const role :
+             {SignatureRole::Transaction, SignatureRole::Counterparty, SignatureRole::Sponsor})
+        {
+            BEAST_EXPECT(signingPrefix(role, false, r.legacy) == HashPrefix::TxSign);
+            BEAST_EXPECT(signingPrefix(role, true, r.legacy) == HashPrefix::TxMultiSign);
+        }
+
+        // Each role's field, and each signature field's role, agree.
+        BEAST_EXPECT(signatureField(SignatureRole::Transaction) == nullptr);
+        BEAST_EXPECT(*signatureField(SignatureRole::Counterparty) == sfCounterpartySignature);
+        BEAST_EXPECT(*signatureField(SignatureRole::Sponsor) == sfSponsorSignature);
+        BEAST_EXPECT(signatureRole(sfCounterpartySignature) == SignatureRole::Counterparty);
+        BEAST_EXPECT(signatureRole(sfSponsorSignature) == SignatureRole::Sponsor);
+        BEAST_EXPECT(!signatureRole(sfBook));
+        BEAST_EXPECT(!signatureRole(sfSigner));
+
+        // The bytes signed by an ordinary transaction must not move. Both the
+        // single- and the multi-signing data are pinned, and neither depends
+        // on the amendment.
+        auto const tx = makeFixedTx();
+        for (Rules const& rules : {r.legacy, r.fixed})
+        {
+            Serializer single;
+            single.add32(signingPrefix(SignatureRole::Transaction, false, rules));
+            tx.addWithoutSigningFields(single);
+            // 53545800 STX prefix, 120003 AccountSet, 2400000001 Sequence,
+            // 68400000000000000A Fee, 7321... SigningPubKey, 8114... Account.
+            BEAST_EXPECT(
+                strHex(single.peekData()) ==
+                "53545800"
+                "120003"
+                "2400000001"
+                "68400000000000000A"
+                "73210330E7FC9D56BB25D6893BA3F317AE5BCF33B3291BD63DB32654A313222F7FD020"
+                "8114B5F762798A53D543A014CAF8B297CFF8F2F937E8");
+            BEAST_EXPECT(
+                to_string(single.getSHA512Half()) ==
+                "AB7473EA8D05527A7465229447B0E9B05365C72B87E921762AD30742B253F3E6");
+
+            auto const signer = calcAccountID(
+                generateKeyPair(KeyType::Secp256k1, generateSeed("multisigner")).first);
+            Serializer const multi = buildMultiSigningData(
+                tx, signer, signingPrefix(SignatureRole::Transaction, true, rules));
+
+            // The multi-signing data is the single-signing data with a
+            // different prefix and the signer's account appended.
+            Serializer expected;
+            expected.add32(HashPrefix::TxMultiSign);
+            tx.addWithoutSigningFields(expected);
+            expected.addBitString(signer);
+            BEAST_EXPECT(strHex(multi.peekData()) == strHex(expected.peekData()));
+        }
+    }
+
+    void
+    testRoleSignatureBinding()
+    {
+        testcase("role signature binding");
+
+        RulesFixture const r;
+
+        auto const keypair = generateKeyPair(KeyType::Secp256k1, generateSeed("masterpassphrase"));
+        auto const account = calcAccountID(keypair.first);
+
+        // A transaction signed by its own account, with that signature copied
+        // into an alternate signature field. sfSponsorSignature is a common
+        // field; sfCounterpartySignature is only on a LoanSet.
+        auto makeCopiedSig = [&keypair, &account](SField const& sigField) {
+            bool const counterparty = sigField == sfCounterpartySignature;
+            STTx tx(counterparty ? ttLOAN_SET : ttACCOUNT_SET, [&](auto& obj) {
+                obj.setAccountID(sfAccount, account);
+                obj.setFieldAmount(sfFee, STAmount(10ull));
+                obj.setFieldU32(sfSequence, 1);
+                obj.setFieldVL(sfSigningPubKey, keypair.first.slice());
+                if (counterparty)
+                {
+                    obj.setFieldH256(sfLoanBrokerID, uint256{1});
+                    obj.setFieldNumber(
+                        sfPrincipalRequested, STNumber{sfPrincipalRequested, Number{1}});
+                }
+                else
+                {
+                    obj.setAccountID(sfSponsor, account);
+                    obj.setFieldU32(sfSponsorFlags, 0);
+                }
+            });
+            tx.sign(keypair.first, keypair.second);
+
+            STObject sigObject(sigField);
+            sigObject.setFieldVL(sfSigningPubKey, keypair.first.slice());
+            sigObject.setFieldVL(sfTxnSignature, tx.getSignature());
+
+            // NOLINTNEXTLINE(cppcoreguidelines-slicing)
+            STObject copy{tx};
+            copy.setFieldObject(sigField, sigObject);
+            return STTx{std::move(copy)};
+        };
+
+        for (SField const& sigField :
+             {std::cref(sfCounterpartySignature), std::cref(sfSponsorSignature)})
+        {
+            auto const tx = makeCopiedSig(sigField);
+
+            // Before the fix, the copied signature verifies in the other role.
+            BEAST_EXPECT(tx.checkSign(r.legacy));
+
+            // With the fix, it does not, and the error names the role that
+            // failed so the two role checks cannot be confused.
+            auto const ret = tx.checkSign(r.fixed);
+            BEAST_EXPECT(!ret);
+            if (!ret)
+            {
+                char const* const rolePrefix =
+                    sigField == sfCounterpartySignature ? "Counterparty: " : "Sponsor: ";
+                BEAST_EXPECT(ret.error().starts_with(rolePrefix));
+                BEAST_EXPECT(matches(ret.error().c_str(), "Invalid signature"));
+            }
+        }
+    }
+
+    // Multi-sign analogue of testRoleSignatureBinding. Both the top-level
+    // Signers array and a role slot's Signers array carry the same signer
+    // entry, signed under HashPrefix::TxMultiSign. Before the fix every role
+    // uses that same prefix, so the copied entry verifies in the role slot;
+    // after the fix the role slot verifies against CounterpartyTxMultiSign
+    // (CPM) or SponsorTxMultiSign (SPM) and the entry no longer matches.
+    void
+    testRoleMultiSignatureBinding()
+    {
+        testcase("role multi-signature binding");
+
+        RulesFixture const r;
+
+        auto const acctKp = generateKeyPair(KeyType::Secp256k1, generateSeed("masterpassphrase"));
+        auto const account = calcAccountID(acctKp.first);
+        // The signer must differ from the top-level account so that the
+        // multiSignHelper "account owner may not multisign for themselves"
+        // check passes for the top-level Signers array.
+        auto const signerKp = generateKeyPair(KeyType::Secp256k1, generateSeed("multisigner"));
+        auto const signerId = calcAccountID(signerKp.first);
+
+        auto makeCopiedMultiSig = [&](SField const& sigField) {
+            bool const counterparty = sigField == sfCounterpartySignature;
+            STTx const tx(counterparty ? ttLOAN_SET : ttACCOUNT_SET, [&](auto& obj) {
+                obj.setAccountID(sfAccount, account);
+                obj.setFieldAmount(sfFee, STAmount(10ull));
+                obj.setFieldU32(sfSequence, 1);
+                // Empty SigningPubKey selects the multi-sign path.
+                obj.setFieldVL(sfSigningPubKey, Slice{});
+                if (counterparty)
+                {
+                    obj.setFieldH256(sfLoanBrokerID, uint256{1});
+                    obj.setFieldNumber(
+                        sfPrincipalRequested, STNumber{sfPrincipalRequested, Number{1}});
+                }
+                else
+                {
+                    obj.setAccountID(sfSponsor, account);
+                    obj.setFieldU32(sfSponsorFlags, 0);
+                }
+            });
+
+            // Sign the top-level tx with TxMultiSign, which is what a
+            // multi-signer of the transaction itself would use.
+            Serializer const ss = buildMultiSigningData(tx, signerId, HashPrefix::TxMultiSign);
+            auto const sig = xrpl::sign(signerKp.first, signerKp.second, ss.slice());
+
+            STObject entry(sfSigner);
+            entry.setAccountID(sfAccount, signerId);
+            entry.setFieldVL(sfSigningPubKey, signerKp.first.slice());
+            entry.setFieldVL(sfTxnSignature, sig);
+            STArray signers(sfSigners, 1);
+            signers.pushBack(entry);
+
+            // Attach the Signers array to the top level so its own signature
+            // check succeeds, then copy the identical array into the role
+            // slot. Both arrays carry TxMultiSign-based signatures.
+            // NOLINTNEXTLINE(cppcoreguidelines-slicing)
+            STObject copy{tx};
+            copy.setFieldArray(sfSigners, signers);
+
+            STObject sigObject(sigField);
+            sigObject.setFieldVL(sfSigningPubKey, Slice{});
+            sigObject.setFieldArray(sfSigners, signers);
+            copy.setFieldObject(sigField, sigObject);
+            return STTx{std::move(copy)};
+        };
+
+        for (SField const& sigField :
+             {std::cref(sfCounterpartySignature), std::cref(sfSponsorSignature)})
+        {
+            auto const tx = makeCopiedMultiSig(sigField);
+
+            // Before the fix, both signature checks use TxMultiSign, so the
+            // copied Signers array verifies in the role slot as well.
+            BEAST_EXPECT(tx.checkSign(r.legacy));
+
+            // With the fix, the role slot uses its own multi-sign prefix
+            // (CPM or SPM) and the copied signature no longer verifies. The
+            // error must name the role that failed.
+            auto const ret = tx.checkSign(r.fixed);
+            BEAST_EXPECT(!ret);
+            if (!ret)
+            {
+                char const* const rolePrefix =
+                    sigField == sfCounterpartySignature ? "Counterparty: " : "Sponsor: ";
+                BEAST_EXPECT(ret.error().starts_with(rolePrefix));
+                BEAST_EXPECT(matches(ret.error().c_str(), "Invalid signature"));
+            }
+        }
     }
 
     void
@@ -1555,7 +1835,7 @@ public:
         auto const id2 = calcAccountID(kp2.first);
 
         // Get the stream of the transaction for use in multi-signing.
-        Serializer const s = buildMultiSigningData(txn, id2);
+        Serializer const s = buildMultiSigningData(txn, id2, HashPrefix::TxMultiSign);
 
         auto const saMultiSignature = sign(kp2.first, kp2.second, s.slice());
 
diff --git a/src/test/rpc/BookChanges_test.cpp b/src/test/rpc/BookChanges_test.cpp
index 98a9372982..f0b4a4e187 100644
--- a/src/test/rpc/BookChanges_test.cpp
+++ b/src/test/rpc/BookChanges_test.cpp
@@ -1,3 +1,4 @@
+#include <test/jtx/Account.h>
 #include <test/jtx/Env.h>
 #include <test/jtx/WSClient.h>
 #include <test/jtx/amount.h>
@@ -8,13 +9,33 @@
 #include <test/jtx/permissioned_dex.h>
 #include <test/jtx/sendmax.h>
 
+#include <xrpld/rpc/BookChanges.h>
+
 #include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/chrono.h>
+#include <xrpl/beast/hash/uhash.h>
 #include <xrpl/beast/unit_test/suite.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/json/to_string.h>
+#include <xrpl/ledger/Ledger.h>
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STArray.h>
+#include <xrpl/protocol/STObject.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/Serializer.h>
+#include <xrpl/protocol/TxFormats.h>
 #include <xrpl/protocol/jss.h>
 
+#include <cstdint>
+#include <memory>
+#include <stdexcept>
+#include <string>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
 namespace xrpl::test {
 
 class BookChanges_test : public beast::unit_test::Suite
@@ -115,6 +136,195 @@ public:
         BEAST_EXPECT(jrr[jss::changes][0u][jss::domain].asString() == to_string(domainID));
     }
 
+    void
+    testSkipsOverflowingRate()
+    {
+        testcase("book_changes skips overflowing rate");
+        using namespace jtx;
+
+        Env env(*this);
+        Account const gw{"gw"};
+        Account const iouGw{"iouGw"};
+
+        auto const big = MPT{gw.id(), 1};
+        auto const usd = iouGw["USD"];
+
+        // This metadata represents a partial MPT/IOU offer fill whose deltas
+        // make divide(deltaGets, deltaPays) overflow before MPTokensV2 skips
+        // the unrepresentable book-change rate.
+        STObject finalFields = STObject::makeInnerObject(sfFinalFields);
+        finalFields.setFieldU32(sfSequence, 1);
+        finalFields.setFieldAmount(sfTakerGets, big(1'800'000'000'000'000'000ull));
+        finalFields.setFieldAmount(sfTakerPays, usd(9));
+
+        STObject previousFields = STObject::makeInnerObject(sfPreviousFields);
+        previousFields.setFieldU32(sfSequence, 1);
+        previousFields.setFieldAmount(sfTakerGets, big(3'600'000'000'000'000'000ull));
+        previousFields.setFieldAmount(sfTakerPays, usd(18));
+
+        STObject modifiedOffer{sfModifiedNode};
+        modifiedOffer.setFieldU16(sfLedgerEntryType, ltOFFER);
+        modifiedOffer.setFieldObject(sfFinalFields, finalFields);
+        modifiedOffer.setFieldObject(sfPreviousFields, previousFields);
+
+        STArray affectedNodes{sfAffectedNodes};
+        affectedNodes.pushBack(std::move(modifiedOffer));
+
+        auto metadata = std::make_shared<STObject>(sfTransactionMetaData);
+        metadata->setFieldArray(sfAffectedNodes, affectedNodes);
+
+        auto tx = std::make_shared<STTx const>(ttOFFER_CREATE, [](STObject&) {});
+
+        auto const test = [&](std::unordered_set<uint256, beast::Uhash<>> const& features) {
+            auto ledger = std::make_shared<Ledger>(
+                2,
+                NetClock::time_point{},
+                Rules{features},
+                env.current()->fees(),
+                env.app().getNodeFamily());
+
+            auto txSerializer = std::make_shared<Serializer>();
+            tx->add(*txSerializer);
+
+            auto metaSerializer = std::make_shared<Serializer>();
+            metadata->add(*metaSerializer);
+
+            ledger->rawTxInsert(uint256{1}, txSerializer, metaSerializer);
+            ledger->setImmutable();
+            ledger->setValidated();
+
+            try
+            {
+                auto const result =
+                    xrpl::rpc::computeBookChanges(std::static_pointer_cast<Ledger const>(ledger));
+                BEAST_EXPECT(result[jss::type] == "bookChanges");
+                BEAST_EXPECT(result[jss::changes].size() == 0);
+            }
+            catch (std::overflow_error const&)
+            {
+                fail("Overflowing book-change rate shouldn't throw");
+            }
+        };
+
+        test(std::unordered_set<uint256, beast::Uhash<>>{});
+        test(std::unordered_set<uint256, beast::Uhash<>>{featureMPTokensV2});
+    }
+
+    // Build a ledger whose transactions are OfferCreates carrying the supplied
+    // consumed-offer deltas, then run computeBookChanges over it. Each pair is
+    // (TakerGets, TakerPays) fully consumed off a resting offer.
+    static json::Value
+    bookChangesFor(jtx::Env& env, std::vector<std::pair<STAmount, STAmount>> const& crossings)
+    {
+        auto ledger = std::make_shared<Ledger>(
+            2,
+            NetClock::time_point{},
+            Rules{std::unordered_set<uint256, beast::Uhash<>>{featureMPTokensV2}},
+            env.current()->fees(),
+            env.app().getNodeFamily());
+
+        std::uint32_t seq = 0;
+        for (auto const& [gets, pays] : crossings)
+        {
+            ++seq;
+
+            STObject finalFields = STObject::makeInnerObject(sfFinalFields);
+            finalFields.setFieldU32(sfSequence, seq);
+            finalFields.setFieldAmount(sfTakerGets, STAmount{gets.asset()});
+            finalFields.setFieldAmount(sfTakerPays, STAmount{pays.asset()});
+
+            STObject previousFields = STObject::makeInnerObject(sfPreviousFields);
+            previousFields.setFieldU32(sfSequence, seq);
+            previousFields.setFieldAmount(sfTakerGets, gets);
+            previousFields.setFieldAmount(sfTakerPays, pays);
+
+            STObject modifiedOffer{sfModifiedNode};
+            modifiedOffer.setFieldU16(sfLedgerEntryType, ltOFFER);
+            modifiedOffer.setFieldObject(sfFinalFields, finalFields);
+            modifiedOffer.setFieldObject(sfPreviousFields, previousFields);
+
+            STArray affectedNodes{sfAffectedNodes};
+            affectedNodes.pushBack(std::move(modifiedOffer));
+
+            auto metadata = std::make_shared<STObject>(sfTransactionMetaData);
+            metadata->setFieldArray(sfAffectedNodes, affectedNodes);
+
+            STTx const tx{ttOFFER_CREATE, [](STObject&) {}};
+
+            auto txSerializer = std::make_shared<Serializer>();
+            tx.add(*txSerializer);
+
+            auto metaSerializer = std::make_shared<Serializer>();
+            metadata->add(*metaSerializer);
+
+            ledger->rawTxInsert(uint256{seq}, txSerializer, metaSerializer);
+        }
+
+        ledger->setImmutable();
+        ledger->setValidated();
+
+        return xrpl::rpc::computeBookChanges(std::static_pointer_cast<Ledger const>(ledger));
+    }
+
+    void
+    testSkipsOverflowingVolume()
+    {
+        testcase("book_changes skips overflowing volume");
+        using namespace jtx;
+
+        Env env(*this);
+
+        // Two crossings in one book, accumulated by the `+=` in the tally's
+        // else branch. The rate is 1 either way, so the divide() guard is not
+        // what is under test here.
+        //
+        // MPT: kMaxMpTokenAmount is INT64_MAX, so two halves sum past it. The
+        // add is a raw int64 add, which wraps to a negative amount rather than
+        // throwing, and canonicalize() only bounds the magnitude -- so before
+        // the fix this reported a negative volume.
+        {
+            auto const mptA = MPT{Account{"gw"}.id(), 1};
+            auto const mptB = MPT{Account{"gw"}.id(), 2};
+            auto const half = 5'000'000'000'000'000'000ull;  // 2 * half > INT64_MAX
+
+            auto const result =
+                bookChangesFor(env, {{mptA(half), mptB(half)}, {mptA(half), mptB(half)}});
+
+            BEAST_EXPECT(result[jss::type] == "bookChanges");
+            if (BEAST_EXPECT(result[jss::changes].size() == 1))
+            {
+                auto const& change = result[jss::changes][0u];
+                // The second crossing is dropped, so the first one's volume
+                // stands. Above all it must not be negative.
+                BEAST_EXPECT(change[jss::volume_a].asString() == std::to_string(half));
+                BEAST_EXPECT(change[jss::volume_b].asString() == std::to_string(half));
+            }
+        }
+
+        // IOU: the addition throws std::overflow_error once the summed
+        // exponent passes IOUAmount::kMaxExponent. Before the fix that
+        // escaped computeBookChanges entirely.
+        {
+            Account const gwA{"gwA"};
+            Account const gwB{"gwB"};
+            // Mantissa in range, exponent at the maximum: two of these sum to
+            // one exponent past it.
+            STAmount const bigA{gwA["USD"].issue(), UINT64_C(9'000'000'000'000'000), 80};
+            STAmount const bigB{gwB["EUR"].issue(), UINT64_C(9'000'000'000'000'000), 80};
+
+            try
+            {
+                auto const result = bookChangesFor(env, {{bigA, bigB}, {bigA, bigB}});
+                BEAST_EXPECT(result[jss::type] == "bookChanges");
+                BEAST_EXPECT(result[jss::changes].size() == 1);
+            }
+            catch (std::overflow_error const&)
+            {
+                fail("Overflowing book-change volume shouldn't throw");
+            }
+        }
+    }
+
     void
     run() override
     {
@@ -122,6 +332,8 @@ public:
         testLedgerInputDefaultBehavior();
 
         testDomainOffer();
+        testSkipsOverflowingRate();
+        testSkipsOverflowingVolume();
         // Note: Other aspects of the book_changes rpc are fertile grounds
         // for unit-testing purposes. It can be included in future work
     }
diff --git a/src/test/rpc/LedgerRPC_test.cpp b/src/test/rpc/LedgerRPC_test.cpp
index af93108ff2..e7c5dd4a80 100644
--- a/src/test/rpc/LedgerRPC_test.cpp
+++ b/src/test/rpc/LedgerRPC_test.cpp
@@ -5,6 +5,7 @@
 #include <test/jtx/envconfig.h>
 #include <test/jtx/fee.h>
 #include <test/jtx/last_ledger_sequence.h>
+#include <test/jtx/mpt.h>
 #include <test/jtx/noop.h>
 #include <test/jtx/offer.h>
 #include <test/jtx/pay.h>
@@ -20,6 +21,7 @@
 #include <xrpl/json/to_string.h>
 #include <xrpl/protocol/ErrorCodes.h>
 #include <xrpl/protocol/TER.h>
+#include <xrpl/protocol/TxFlags.h>
 #include <xrpl/protocol/jss.h>
 
 #include <memory>
@@ -258,6 +260,102 @@ class LedgerRPC_test : public beast::unit_test::Suite
         BEAST_EXPECT(jrr[jss::ledger][jss::accountState].size() == 3u);
     }
 
+    void
+    testLedgerOwnerFundsMPTOffer()
+    {
+        testcase("Ledger owner_funds with MPT offer");
+        using namespace test::jtx;
+
+        Env env{*this};
+        Account const gw{"gateway"};
+        Account const alice{"alice"};
+        auto const usd = gw["USD"];
+
+        env.fund(XRP(10'000), gw, alice);
+        env.close();
+        env.trust(usd(1'000), alice);
+        env(pay(gw, alice, usd(100)));
+        MPTTester mpt(
+            {.env = env,
+             .issuer = gw,
+             .holders = {alice},
+             .pay = 100,
+             .flags = tfMPTRequireAuth | kMptDexFlags,
+             .authHolder = true,
+             .close = false});
+        MPT const mptAsset = mpt;
+        env.close();
+
+        env(noop(alice));
+        // These offers differ only by TakerGets asset type. Omitting
+        // owner_funds serializes the tx JSON without computing offer balances;
+        // owner_funds=true asks LedgerToJson to compute accountFunds(TakerGets)
+        // for both offers, which is where IOU and MPT used to diverge.
+        env(offer(alice, XRP(10), usd(10)));
+        env(offer(alice, XRP(10), mptAsset(10)));
+        // The MPT offer was created while authorized. Unauthorizing in the
+        // same ledger makes owner_funds depend on AuthHandling::IgnoreAuth.
+        mpt.authorize({.account = gw, .holder = alice, .flags = tfMPTUnauthorize});
+        env(noop(alice));
+        env.close();
+
+        auto const ledgerHash = to_string(env.closed()->header().hash);
+
+        auto const getTransactions = [&](bool includeOwnerFunds) {
+            json::Value params;
+            params[jss::ledger_hash] = ledgerHash;
+            params[jss::transactions] = true;
+            params[jss::expand] = true;
+            // The baseline omits owner_funds, which the RPC treats as false.
+            // Setting it true requests the same ledger, but asks the ledger
+            // serializer to add owner_funds to offer transactions in that
+            // ledger's transaction array.
+            if (includeOwnerFunds)
+                params[jss::owner_funds] = true;
+
+            auto const result = env.rpc("json", "ledger", to_string(params))[jss::result];
+            BEAST_EXPECT(!result.isMember(jss::error));
+            BEAST_EXPECT(result[jss::ledger][jss::transactions].isArray());
+            return result[jss::ledger][jss::transactions];
+        };
+
+        auto const findOffer = [](json::Value const& txs, bool mpt) -> json::Value const* {
+            for (auto i = 0u; i < txs.size(); ++i)
+            {
+                auto const& tx = txs[i].isMember(jss::tx_json) ? txs[i][jss::tx_json] : txs[i];
+                if (tx[jss::TransactionType] == jss::OfferCreate &&
+                    tx[jss::TakerGets].isMember(jss::mpt_issuance_id) == mpt)
+                {
+                    return &txs[i];
+                }
+            }
+            return nullptr;
+        };
+
+        // Baseline: same ledger request without owner_funds fields.
+        auto const baseline = getTransactions(false);
+        BEAST_EXPECT(baseline.size() == 5u);
+        BEAST_EXPECT(findOffer(baseline, false) != nullptr);
+        BEAST_EXPECT(findOffer(baseline, true) != nullptr);
+
+        // Same ledger request with owner_funds added to eligible offer txs.
+        auto const withOwnerFunds = getTransactions(true);
+        // Requesting owner_funds must not change which ledger transactions are
+        // returned, even when one offer's TakerGets is MPT.
+        BEAST_EXPECT(withOwnerFunds.size() == baseline.size());
+
+        // The IOU offer is the control case for expected owner_funds output.
+        auto const* iouOfferTx = findOffer(withOwnerFunds, false);
+        if (BEAST_EXPECT(iouOfferTx != nullptr))
+            BEAST_EXPECT((*iouOfferTx)[jss::owner_funds] == "100");
+
+        // MPT owner_funds should match the IOU behavior, even though Alice is
+        // unauthorized by the ledger snapshot used for serialization.
+        auto const* mptOfferTx = findOffer(withOwnerFunds, true);
+        if (BEAST_EXPECT(mptOfferTx != nullptr))
+            BEAST_EXPECT((*mptOfferTx)[jss::owner_funds] == "100");
+    }
+
     /**
      * @brief ledger RPC requests as a way to drive
      * input options to lookupLedger. The point of this test is
@@ -719,6 +817,7 @@ public:
         testLedgerFull();
         testLedgerFullNonAdmin();
         testLedgerAccounts();
+        testLedgerOwnerFundsMPTOffer();
         testLookupLedger();
         testNoQueue();
         testQueue();
diff --git a/src/tests/libxrpl/protocol_autogen/ledger_entries/MPTokenIssuanceTests.cpp b/src/tests/libxrpl/protocol_autogen/ledger_entries/MPTokenIssuanceTests.cpp
index 974d0e81d7..e8c1b645d8 100644
--- a/src/tests/libxrpl/protocol_autogen/ledger_entries/MPTokenIssuanceTests.cpp
+++ b/src/tests/libxrpl/protocol_autogen/ledger_entries/MPTokenIssuanceTests.cpp
@@ -36,6 +36,8 @@ TEST(MPTokenIssuanceTests, BuilderSettersRoundTrip)
     auto const referenceHoldingValue = canonical_UINT256();
     auto const issuerEncryptionKeyValue = canonical_VL();
     auto const auditorEncryptionKeyValue = canonical_VL();
+    auto const issuerKeyEpochValue = canonical_UINT32();
+    auto const auditorKeyEpochValue = canonical_UINT32();
     auto const confidentialOutstandingAmountValue = canonical_UINT64();
 
     MPTokenIssuanceBuilder builder{
@@ -57,6 +59,8 @@ TEST(MPTokenIssuanceTests, BuilderSettersRoundTrip)
     builder.setReferenceHolding(referenceHoldingValue);
     builder.setIssuerEncryptionKey(issuerEncryptionKeyValue);
     builder.setAuditorEncryptionKey(auditorEncryptionKeyValue);
+    builder.setIssuerKeyEpoch(issuerKeyEpochValue);
+    builder.setAuditorKeyEpoch(auditorKeyEpochValue);
     builder.setConfidentialOutstandingAmount(confidentialOutstandingAmountValue);
 
     builder.setLedgerIndex(index);
@@ -184,6 +188,22 @@ TEST(MPTokenIssuanceTests, BuilderSettersRoundTrip)
         EXPECT_TRUE(entry.hasAuditorEncryptionKey());
     }
 
+    {
+        auto const& expected = issuerKeyEpochValue;
+        auto const actualOpt = entry.getIssuerKeyEpoch();
+        ASSERT_TRUE(actualOpt.has_value());
+        expectEqualField(expected, *actualOpt, "sfIssuerKeyEpoch");
+        EXPECT_TRUE(entry.hasIssuerKeyEpoch());
+    }
+
+    {
+        auto const& expected = auditorKeyEpochValue;
+        auto const actualOpt = entry.getAuditorKeyEpoch();
+        ASSERT_TRUE(actualOpt.has_value());
+        expectEqualField(expected, *actualOpt, "sfAuditorKeyEpoch");
+        EXPECT_TRUE(entry.hasAuditorKeyEpoch());
+    }
+
     {
         auto const& expected = confidentialOutstandingAmountValue;
         auto const actualOpt = entry.getConfidentialOutstandingAmount();
@@ -221,6 +241,8 @@ TEST(MPTokenIssuanceTests, BuilderFromSleRoundTrip)
     auto const referenceHoldingValue = canonical_UINT256();
     auto const issuerEncryptionKeyValue = canonical_VL();
     auto const auditorEncryptionKeyValue = canonical_VL();
+    auto const issuerKeyEpochValue = canonical_UINT32();
+    auto const auditorKeyEpochValue = canonical_UINT32();
     auto const confidentialOutstandingAmountValue = canonical_UINT64();
 
     auto sle = std::make_shared<SLE>(MPTokenIssuance::entryType, index);
@@ -241,6 +263,8 @@ TEST(MPTokenIssuanceTests, BuilderFromSleRoundTrip)
     sle->at(sfReferenceHolding) = referenceHoldingValue;
     sle->at(sfIssuerEncryptionKey) = issuerEncryptionKeyValue;
     sle->at(sfAuditorEncryptionKey) = auditorEncryptionKeyValue;
+    sle->at(sfIssuerKeyEpoch) = issuerKeyEpochValue;
+    sle->at(sfAuditorKeyEpoch) = auditorKeyEpochValue;
     sle->at(sfConfidentialOutstandingAmount) = confidentialOutstandingAmountValue;
 
     MPTokenIssuanceBuilder builderFromSle{sle};
@@ -442,6 +466,32 @@ TEST(MPTokenIssuanceTests, BuilderFromSleRoundTrip)
         expectEqualField(expected, *fromBuilderOpt, "sfAuditorEncryptionKey");
     }
 
+    {
+        auto const& expected = issuerKeyEpochValue;
+
+        auto const fromSleOpt = entryFromSle.getIssuerKeyEpoch();
+        auto const fromBuilderOpt = entryFromBuilder.getIssuerKeyEpoch();
+
+        ASSERT_TRUE(fromSleOpt.has_value());
+        ASSERT_TRUE(fromBuilderOpt.has_value());
+
+        expectEqualField(expected, *fromSleOpt, "sfIssuerKeyEpoch");
+        expectEqualField(expected, *fromBuilderOpt, "sfIssuerKeyEpoch");
+    }
+
+    {
+        auto const& expected = auditorKeyEpochValue;
+
+        auto const fromSleOpt = entryFromSle.getAuditorKeyEpoch();
+        auto const fromBuilderOpt = entryFromBuilder.getAuditorKeyEpoch();
+
+        ASSERT_TRUE(fromSleOpt.has_value());
+        ASSERT_TRUE(fromBuilderOpt.has_value());
+
+        expectEqualField(expected, *fromSleOpt, "sfAuditorKeyEpoch");
+        expectEqualField(expected, *fromBuilderOpt, "sfAuditorKeyEpoch");
+    }
+
     {
         auto const& expected = confidentialOutstandingAmountValue;
 
@@ -539,6 +589,10 @@ TEST(MPTokenIssuanceTests, OptionalFieldsReturnNullopt)
     EXPECT_FALSE(entry.getIssuerEncryptionKey().has_value());
     EXPECT_FALSE(entry.hasAuditorEncryptionKey());
     EXPECT_FALSE(entry.getAuditorEncryptionKey().has_value());
+    EXPECT_FALSE(entry.hasIssuerKeyEpoch());
+    EXPECT_FALSE(entry.getIssuerKeyEpoch().has_value());
+    EXPECT_FALSE(entry.hasAuditorKeyEpoch());
+    EXPECT_FALSE(entry.getAuditorKeyEpoch().has_value());
     EXPECT_FALSE(entry.hasConfidentialOutstandingAmount());
     EXPECT_FALSE(entry.getConfidentialOutstandingAmount().has_value());
 }
diff --git a/src/tests/libxrpl/shamap/SHAMapNodeID.cpp b/src/tests/libxrpl/shamap/SHAMapNodeID.cpp
new file mode 100644
index 0000000000..95b7497c9c
--- /dev/null
+++ b/src/tests/libxrpl/shamap/SHAMapNodeID.cpp
@@ -0,0 +1,193 @@
+#include <xrpl/shamap/SHAMapNodeID.h>
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/protocol/Serializer.h>
+#include <xrpl/shamap/SHAMap.h>
+
+#include <gtest/gtest.h>
+
+#include <stdexcept>
+
+namespace xrpl::tests {
+
+// An arbitrary 32-byte key reused across tests below that don't care about its specific value,
+// only that it is a well-formed key.
+constexpr uint256 kTestKey("b92891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8");
+
+TEST(SHAMapNodeIDTest, root_is_prefix_of_every_key)
+{
+    SHAMapNodeID const root;
+    EXPECT_EQ(root.getDepth(), 0u);
+    EXPECT_TRUE(root.isPrefixOf(uint256{}));
+    EXPECT_TRUE(root.isPrefixOf(kTestKey));
+}
+
+TEST(SHAMapNodeIDTest, child_id_is_prefix_of_keys_in_that_branch)
+{
+    // Walking the branches spelled by the key's own nibbles must keep every
+    // intermediate ID a prefix of that key.
+    SHAMapNodeID id;
+    for (auto depth = 0u; depth < SHAMap::kLeafDepth; ++depth)
+    {
+        id = id.getChildNodeID(selectBranch(id, kTestKey));
+        EXPECT_EQ(id.getDepth(), depth + 1);
+        EXPECT_TRUE(id.isPrefixOf(kTestKey)) << "depth " << id.getDepth();
+    }
+}
+
+TEST(SHAMapNodeIDTest, wrong_branch_is_not_prefix_of_key)
+{
+    SHAMapNodeID const root;
+    auto const correct = selectBranch(root, kTestKey);
+    ASSERT_EQ(correct, 0xbu);
+
+    // An ID built from the wrong branch still has a valid depth and a self-consistent mask, so
+    // isPrefixOf(kTestKey) below is what actually distinguishes the correct branch from the rest.
+    for (auto branch = 0u; branch < SHAMap::kBranchFactor; ++branch)
+    {
+        auto const child = root.getChildNodeID(branch);
+        EXPECT_EQ(child.getDepth(), 1u);
+        EXPECT_EQ(child.isPrefixOf(kTestKey), branch == correct) << "branch " << branch;
+    }
+}
+
+TEST(SHAMapNodeIDTest, prefix_check_is_depth_sensitive)
+{
+    // kTestKey and kOther agree on the first two nibbles ("b9") and then diverge.
+    constexpr uint256 kOther("b99891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca8");
+
+    auto id = SHAMapNodeID{}.getChildNodeID(selectBranch(SHAMapNodeID{}, kTestKey));
+    EXPECT_TRUE(id.isPrefixOf(kTestKey));
+    EXPECT_TRUE(id.isPrefixOf(kOther)) << "shared first nibble";
+
+    id = id.getChildNodeID(selectBranch(id, kTestKey));
+    EXPECT_TRUE(id.isPrefixOf(kTestKey));
+    EXPECT_TRUE(id.isPrefixOf(kOther)) << "shared second nibble";
+
+    // Third nibble differs, so the deeper ID no longer covers kOther.
+    id = id.getChildNodeID(selectBranch(id, kTestKey));
+    EXPECT_TRUE(id.isPrefixOf(kTestKey));
+    EXPECT_FALSE(id.isPrefixOf(kOther));
+}
+
+TEST(SHAMapNodeIDTest, leaf_id_from_key_is_prefix_of_that_key)
+{
+    SHAMapNodeID const leaf{SHAMap::kLeafDepth, kTestKey};
+    EXPECT_TRUE(leaf.isPrefixOf(kTestKey));
+
+    // At full depth the prefix is the whole key, so nothing else matches.
+    constexpr uint256 kOther("b92891fe4ef6cee585fdc6fda1e09eb4d386363158ec3321b8123e5a772c6ca9");
+    EXPECT_FALSE(leaf.isPrefixOf(kOther));
+}
+
+TEST(SHAMapNodeIDTest, create_id_masks_key_to_depth)
+{
+    for (auto depth = 0u; depth <= SHAMap::kLeafDepth; ++depth)
+    {
+        auto const id = SHAMapNodeID::createID(depth, kTestKey);
+        EXPECT_EQ(id.getDepth(), depth);
+        EXPECT_TRUE(id.isPrefixOf(kTestKey)) << "depth " << depth;
+    }
+}
+
+// The guards below must hold with XRPL_ASSERT compiled out (NDEBUG), so each one
+// has to be a real runtime check rather than an assert.
+
+TEST(SHAMapNodeIDTest, child_of_leaf_depth_id_throws)
+{
+    auto const leafDepthID = SHAMapNodeID::createID(SHAMap::kLeafDepth, kTestKey);
+    ASSERT_EQ(leafDepthID.getDepth(), SHAMap::kLeafDepth);
+    EXPECT_THROW((void)leafDepthID.getChildNodeID(0), std::logic_error);
+}
+
+TEST(SHAMapNodeIDDeathTest, out_of_range_depth_is_clamped)
+{
+    // A depth past kLeafDepth has no mask in depthMask's 65-entry table, so both the constructor
+    // and createID clamp it. createID needs its own clamp: it picks the mask while evaluating the
+    // constructor's argument, so the constructor's clamp cannot cover that read.
+    //
+    // Both clamps are marked UNREACHABLE, which is an assert and therefore fatal wherever asserts
+    // are live. Only a build with them compiled out (or routed to Antithesis's non-fatal handler)
+    // reaches the clamp itself, so that is the only configuration that can assert on the result.
+#if defined(NDEBUG) || defined(ENABLE_VOIDSTAR)
+    for (auto const depth : {SHAMap::kLeafDepth + 1u, 100u, 255u, 256u, 320u})
+    {
+        auto const id = SHAMapNodeID::createID(depth, kTestKey);
+
+        // Clamped to a real depth, not the depth asked for, and not a byte-narrowed version of it:
+        // 256 would otherwise become 0 and name the root, 320 would become 64.
+        EXPECT_EQ(id.getDepth(), SHAMap::kLeafDepth) << "depth " << depth;
+
+        // id_ and depth_ still agree, so the object is usable rather than merely non-crashing.
+        EXPECT_TRUE(id.isPrefixOf(kTestKey)) << "depth " << depth;
+        EXPECT_EQ(id, SHAMapNodeID::createID(SHAMap::kLeafDepth, kTestKey)) << "depth " << depth;
+
+        // The clamp holds through the wire format too, which encodes the depth in one byte.
+        auto const roundTripped = deserializeSHAMapNodeID(id.getRawString());
+        ASSERT_TRUE(roundTripped.has_value()) << "depth " << depth;
+        EXPECT_EQ(roundTripped->getDepth(), SHAMap::kLeafDepth) << "depth " << depth;
+    }
+
+    // The constructor clamps on its own, for the paths that do not go through createID.
+    SHAMapNodeID const direct{SHAMap::kLeafDepth + 1u, uint256{}};
+    EXPECT_EQ(direct.getDepth(), SHAMap::kLeafDepth);
+#else
+    EXPECT_DEATH(
+        (void)SHAMapNodeID::createID(SHAMap::kLeafDepth + 1u, kTestKey), "depth within tree");
+#endif
+}
+
+TEST(SHAMapNodeIDDeathTest, select_branch_clamps_leaf_depth)
+{
+    // selectBranch's own precondition is depth < kLeafDepth: a depth-64 ID has no nibble left
+    // to select. That makes it unlike the guards above, which have a throw/return reachable
+    // even with XRPL_ASSERT compiled out; selectBranch has no such path, so the two build
+    // configurations have to be tested differently.
+    //
+    // Under ENABLE_VOIDSTAR, XRPL_ASSERT routes to Antithesis's assert_impl, which only records
+    // the hit and returns rather than aborting, even though NDEBUG is undefined there (voidstar
+    // requires a Debug build). So the assert is live in name but never fatal, the same as the
+    // NDEBUG case below.
+    auto const leafDepthID = SHAMapNodeID::createID(SHAMap::kLeafDepth, kTestKey);
+
+#if defined(NDEBUG) || defined(ENABLE_VOIDSTAR)
+    // With the assert compiled out or routed to a non-fatal handler, the clamp is what stands
+    // between this call and reading past the end of the 32-byte key. Clamping means it reads the
+    // same byte, and returns the same branch, as the deepest ID that still has one: depth 63.
+    auto const deepestWithBranchID = SHAMapNodeID::createID(SHAMap::kLeafDepth - 1u, kTestKey);
+    auto const branch = selectBranch(leafDepthID, kTestKey);
+    EXPECT_LT(branch, SHAMap::kBranchFactor);
+    EXPECT_EQ(branch, selectBranch(deepestWithBranchID, kTestKey));
+#else
+    // In a debug build the assert is live and must reject this call outright, in a forked
+    // process so a failure here cannot take down the rest of the suite.
+    EXPECT_DEATH((void)selectBranch(leafDepthID, kTestKey), "depth below leaf depth");
+#endif
+}
+
+TEST(SHAMapNodeIDTest, deserialize_rejects_out_of_range_depth)
+{
+    // getRawString() only serializes a depth already accepted by the constructor's own
+    // assertion, so an out-of-range depth here is built by hand instead.
+    auto serializeWithRawDepth = [](unsigned int depth) {
+        Serializer s;
+        s.addBitString(uint256{});
+        s.add8(static_cast<unsigned char>(depth));
+        return s.getString();
+    };
+
+    for (auto const depth : {65u, 100u, 255u})
+    {
+        EXPECT_FALSE(deserializeSHAMapNodeID(serializeWithRawDepth(depth)).has_value())
+            << "depth " << depth;
+    }
+
+    // A depth-64 ID is legal, since leaves live there, but it has no children.
+    auto const id =
+        deserializeSHAMapNodeID(SHAMapNodeID{SHAMap::kLeafDepth, uint256{}}.getRawString());
+    ASSERT_TRUE(id.has_value());
+    // NOLINTNEXTLINE(bugprone-unchecked-optional-access) has_value checked above
+    EXPECT_THROW((void)id->getChildNodeID(0), std::logic_error);
+}
+
+}  // namespace xrpl::tests
diff --git a/src/xrpld/app/ledger/detail/LedgerToJson.cpp b/src/xrpld/app/ledger/detail/LedgerToJson.cpp
index 9d3820e9f7..1d789aa604 100644
--- a/src/xrpld/app/ledger/detail/LedgerToJson.cpp
+++ b/src/xrpld/app/ledger/detail/LedgerToJson.cpp
@@ -4,8 +4,7 @@
 #include <xrpld/app/misc/DeliverMax.h>
 #include <xrpld/app/misc/TxQ.h>
 #include <xrpld/rpc/Context.h>
-#include <xrpld/rpc/DeliveredAmount.h>
-#include <xrpld/rpc/MPTokenIssuanceID.h>
+#include <xrpld/rpc/detail/SyntheticFields.h>
 
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/base_uint.h>
@@ -19,6 +18,7 @@
 #include <xrpl/protocol/LedgerHeader.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STObject.h>
+#include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/Serializer.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxFormats.h>
@@ -141,19 +141,12 @@ fillJsonTx(
         {
             txJson[jss::meta] = stMeta->getJson(JsonOptions::Values::None);
 
-            // If applicable, insert delivered amount
-            if (txnType == ttPAYMENT || txnType == ttCHECK_CASH)
-            {
-                rpc::insertDeliveredAmount(
-                    txJson[jss::meta],
-                    fill.ledger,
-                    txn,
-                    {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
-            }
-
-            // If applicable, insert mpt issuance id
-            rpc::insertMPTokenIssuanceID(
-                txJson[jss::meta], txn, {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
+            // Insert all synthetic fields
+            rpc::insertAllSyntheticInJson(
+                txJson[jss::meta],
+                fill.ledger,
+                txn,
+                {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
         }
 
         if (!fill.ledger.open())
@@ -177,19 +170,12 @@ fillJsonTx(
         {
             txJson[jss::metaData] = stMeta->getJson(JsonOptions::Values::None);
 
-            // If applicable, insert delivered amount
-            if (txnType == ttPAYMENT || txnType == ttCHECK_CASH)
-            {
-                rpc::insertDeliveredAmount(
-                    txJson[jss::metaData],
-                    fill.ledger,
-                    txn,
-                    {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
-            }
-
-            // If applicable, insert mpt issuance id
-            rpc::insertMPTokenIssuanceID(
-                txJson[jss::metaData], txn, {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
+            // Insert all synthetic fields
+            rpc::insertAllSyntheticInJson(
+                txJson[jss::metaData],
+                fill.ledger,
+                txn,
+                {txn->getTransactionID(), fill.ledger.seq(), *stMeta});
         }
     }
 
@@ -208,6 +194,7 @@ fillJsonTx(
                 account,
                 amount,
                 FreezeHandling::IgnoreFreeze,
+                AuthHandling::IgnoreAuth,
                 beast::Journal{beast::Journal::getNullSink()});
             txJson[jss::owner_funds] = ownerFunds.getText();
         }
diff --git a/src/xrpld/app/misc/NetworkOPs.cpp b/src/xrpld/app/misc/NetworkOPs.cpp
index 31fe60d1fb..da900cbb06 100644
--- a/src/xrpld/app/misc/NetworkOPs.cpp
+++ b/src/xrpld/app/misc/NetworkOPs.cpp
@@ -28,9 +28,8 @@
 #include <xrpld/overlay/predicates.h>
 #include <xrpld/rpc/BookChanges.h>
 #include <xrpld/rpc/CTID.h>
-#include <xrpld/rpc/DeliveredAmount.h>
-#include <xrpld/rpc/MPTokenIssuanceID.h>
 #include <xrpld/rpc/ServerHandler.h>
+#include <xrpld/rpc/detail/SyntheticFields.h>
 
 #include <xrpl/basics/Log.h>
 #include <xrpl/basics/ToString.h>
@@ -74,10 +73,11 @@
 #include <xrpl/ledger/OpenView.h>
 #include <xrpl/ledger/OrderBookDB.h>
 #include <xrpl/ledger/ReadView.h>
-#include <xrpl/ledger/helpers/AccountRootHelpers.h>
 #include <xrpl/ledger/helpers/DirectoryHelpers.h>
+#include <xrpl/ledger/helpers/MPTokenHelpers.h>
 #include <xrpl/ledger/helpers/TokenHelpers.h>
 #include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/AmountConversions.h>
 #include <xrpl/protocol/ApiVersion.h>
 #include <xrpl/protocol/Book.h>
 #include <xrpl/protocol/BuildInfo.h>
@@ -85,10 +85,12 @@
 #include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/Fees.h>
 #include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/KeyType.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/MPTAmount.h>
+#include <xrpl/protocol/MPTIssue.h>
 #include <xrpl/protocol/MultiApiJson.h>
-#include <xrpl/protocol/NFTSyntheticSerializer.h>
 #include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/PublicKey.h>
 #include <xrpl/protocol/RPCErr.h>
@@ -1458,11 +1460,17 @@ NetworkOPsImp::preProcessTransaction(std::shared_ptr<Transaction>& transaction)
 
     // NOTE ximinez - I think this check is redundant,
     // but I'm not 100% sure yet.
-    // If so, only cost is looking up HashRouter flags.
-    auto const [validity, reason] =
-        checkValidity(registry_.get().getHashRouter(), sttx, view->rules());
-    XRPL_ASSERT(
-        validity == Validity::Valid, "xrpl::NetworkOPsImp::processTransaction : valid validity");
+    //
+    // For an ordinary transaction it is: the relay and submit paths have
+    // already run checkValidity, so this costs a HashRouter lookup. It is not
+    // redundant for a role-signature transaction while fixCleanup3_4_0 is
+    // activating. Those paths verify against the validated rules, which lag
+    // the open ledger rules used here, and checkValidity scopes a cached
+    // verdict to the rules that reached it, so this call can verify the
+    // signature again and come to a different answer. SigBad is therefore
+    // reachable, and the handler below is the correct response to it.
+    auto const& viewRules = view->rules();
+    auto const [validity, reason] = checkValidity(registry_.get().getHashRouter(), sttx, viewRules);
 
     // Not concerned with local checks at this point.
     if (validity == Validity::SigBad)
@@ -1470,7 +1478,15 @@ NetworkOPsImp::preProcessTransaction(std::shared_ptr<Transaction>& transaction)
         JLOG(journal_.info()) << "Transaction has bad signature: " << reason;
         transaction->setStatus(TransStatus::INVALID);
         transaction->setResult(temBAD_SIGNATURE);
-        registry_.get().getHashRouter().setFlags(transaction->getID(), HashRouterFlags::BAD);
+        // See the matching guard in PeerImp::checkTransaction: only cache
+        // BAD for a role-signature transaction once fixCleanup3_4_0 is
+        // enabled on this node. Remove together with the amendment.
+        if (viewRules.enabled(fixCleanup3_4_0) ||
+            (!sttx.isFieldPresent(sfSponsorSignature) &&
+             !sttx.isFieldPresent(sfCounterpartySignature)))
+        {
+            registry_.get().getHashRouter().setFlags(transaction->getID(), HashRouterFlags::BAD);
+        }
         return false;
     }
 
@@ -3491,9 +3507,7 @@ NetworkOPsImp::transJson(
     if (meta)
     {
         jvObj[jss::meta] = meta->get().getJson(JsonOptions::Values::None);
-        rpc::insertDeliveredAmount(jvObj[jss::meta], *ledger, transaction, meta->get());
-        rpc::insertNFTSyntheticInJson(jvObj, transaction, meta->get());
-        rpc::insertMPTokenIssuanceID(jvObj[jss::meta], transaction, meta->get());
+        rpc::insertAllSyntheticInJson(jvObj[jss::meta], *ledger, transaction, meta->get());
     }
 
     // add CTID where the needed data for it exists
@@ -4822,8 +4836,7 @@ NetworkOPsImp::getBookPage(
 
     ReadView const& view = *lpLedger;
 
-    bool const bGlobalFreeze =
-        isGlobalFrozen(view, book.out.getIssuer()) || isGlobalFrozen(view, book.in.getIssuer());
+    bool const bGlobalFreeze = isGlobalFrozen(view, book.out) || isGlobalFrozen(view, book.in);
 
     bool bDone = false;
     bool bDirectAdvance = true;
@@ -4833,7 +4846,7 @@ NetworkOPsImp::getBookPage(
     unsigned int uBookEntry = 0;
     STAmount saDirRate;
 
-    auto const rate = transferRate(view, book.out.getIssuer());
+    auto const rate = transferRate(view, book.out);
     auto viewJ = registry_.get().getJournal("View");
 
     while (!bDone && iLimit-- > 0)
@@ -4882,12 +4895,37 @@ NetworkOPsImp::getBookPage(
                 auto const& saTakerPays = sleOffer->getFieldAmount(sfTakerPays);
                 STAmount saOwnerFunds;
                 bool firstOwnerOffer(true);
+                auto foundBalance = [&]() {
+                    auto umBalanceEntry = umBalance.find(uOfferOwnerID);
+                    if (umBalanceEntry == umBalance.end())
+                        return false;
+
+                    // Found in running balance table.
+                    saOwnerFunds = umBalanceEntry->second;
+                    firstOwnerOffer = false;
+                    return true;
+                };
 
                 if (book.out.getIssuer() == uOfferOwnerID)
                 {
-                    // If an offer is selling issuer's own IOUs, it is fully
-                    // funded.
-                    saOwnerFunds = saTakerGets;
+                    book.out.visit(
+                        [&](Issue const&) {
+                            // If an offer is selling issuer's own IOUs, it is
+                            // fully funded.
+                            saOwnerFunds = saTakerGets;
+                        },
+                        [&](MPTIssue const& issue) {
+                            // MPT issuers have bounded self-issuance. Use the
+                            // running balance table so multiple issuer-owned
+                            // offers share the same remaining issuance
+                            // headroom.
+                            if (!foundBalance())
+                            {
+                                // Did not find balance in table.
+
+                                saOwnerFunds = issuerFundsToSelfIssue(view, issue);
+                            }
+                        });
                 }
                 else if (bGlobalFreeze)
                 {
@@ -4897,15 +4935,7 @@ NetworkOPsImp::getBookPage(
                 }
                 else
                 {
-                    auto umBalanceEntry = umBalance.find(uOfferOwnerID);
-                    if (umBalanceEntry != umBalance.end())
-                    {
-                        // Found in running balance table.
-
-                        saOwnerFunds = umBalanceEntry->second;
-                        firstOwnerOffer = false;
-                    }
-                    else
+                    if (!foundBalance())
                     {
                         // Did not find balance in table.
 
@@ -4941,7 +4971,28 @@ NetworkOPsImp::getBookPage(
                 {
                     // Need to charge a transfer fee to offer owner.
                     offerRate = rate;
-                    saOwnerFundsLimit = divide(saOwnerFunds, offerRate);
+                    // Why MPT does not use divide(): divide() is built for an
+                    // IOU mantissa, which is always normalized into
+                    // [1e15, 1e16]. An MPT mantissa is the raw int64 balance,
+                    // and divide() scales the numerator by 1e17, so a balance
+                    // over ~1.8e17 leaves uint64 range and throws -- failing
+                    // the whole RPC rather than this one offer.
+                    //
+                    // Why mulRatio is safe: it evaluates in 128 bits, and here
+                    // it cannot overflow either. offerRate is
+                    // 1e9 + 10'000 * TransferFee, so this branch runs only with
+                    // offerRate > kParityRate, making the quotient smaller than
+                    // saOwnerFunds. Rounded down, so reported liquidity is
+                    // never overstated.
+                    saOwnerFundsLimit = saOwnerFunds.holds<MPTIssue>()
+                        ? toSTAmount(
+                              mulRatio(
+                                  saOwnerFunds.mpt(),
+                                  kParityRate.value,
+                                  offerRate.value,
+                                  /*roundUp*/ false),
+                              saOwnerFunds.asset())
+                        : divide(saOwnerFunds, offerRate);
                 }
 
                 if (saOwnerFundsLimit >= saTakerGets)
@@ -4998,6 +5049,8 @@ NetworkOPsImp::getBookPage(
 
 // This is the new code that uses the book iterators
 // It has temporarily been disabled
+// If this path is re-enabled, add MPT support mirroring the functional
+// getBookPage() implementation above.
 
 void
 NetworkOPsImp::getBookPage(
diff --git a/src/xrpld/overlay/detail/PeerImp.cpp b/src/xrpld/overlay/detail/PeerImp.cpp
index 3f0b4453b8..c56ea5797f 100644
--- a/src/xrpld/overlay/detail/PeerImp.cpp
+++ b/src/xrpld/overlay/detail/PeerImp.cpp
@@ -44,6 +44,7 @@
 #include <xrpl/ledger/Ledger.h>
 #include <xrpl/peerfinder/Slot.h>
 #include <xrpl/peerfinder/Types.h>
+#include <xrpl/protocol/Feature.h>
 #include <xrpl/protocol/KeyType.h>
 #include <xrpl/protocol/LedgerHeader.h>
 #include <xrpl/protocol/Protocol.h>
@@ -3087,8 +3088,9 @@ PeerImp::checkTransaction(
         if (checkSignature)
         {
             // Check the signature before handing off to the job queue.
-            if (auto [valid, validReason] = checkValidity(
-                    app_.getHashRouter(), *stx, app_.getLedgerMaster().getValidatedRules());
+            auto const& validatedRules = app_.getLedgerMaster().getValidatedRules();
+            if (auto [valid, validReason] =
+                    checkValidity(app_.getHashRouter(), *stx, validatedRules);
                 valid != Validity::Valid)
             {
                 if (!validReason.empty())
@@ -3096,9 +3098,20 @@ PeerImp::checkTransaction(
                     JLOG(pJournal_.debug()) << "Exception checking transaction: " << validReason;
                 }
 
-                // Probably not necessary to set HashRouterFlags::BAD, but
-                // doesn't hurt.
-                app_.getHashRouter().setFlags(stx->getTransactionID(), HashRouterFlags::BAD);
+                // For a role-signature transaction, only cache BAD once
+                // fixCleanup3_4_0 is enabled on this node: the SigBad verdict
+                // then covers the post-fix prefix and cannot flip back.
+                // Before the amendment activates, checkValidity's own
+                // era-scoped cache handles the repeat lookups; setting BAD
+                // would block a correctly new-prefix-signed transaction until
+                // the router entry ages out. Remove the guard together with
+                // the amendment.
+                if (validatedRules.enabled(fixCleanup3_4_0) ||
+                    (!stx->isFieldPresent(sfSponsorSignature) &&
+                     !stx->isFieldPresent(sfCounterpartySignature)))
+                {
+                    app_.getHashRouter().setFlags(stx->getTransactionID(), HashRouterFlags::BAD);
+                }
                 charge(resource::kFeeInvalidSignature, "check transaction signature failure");
                 return;
             }
diff --git a/src/xrpld/rpc/AGENTS.md b/src/xrpld/rpc/AGENTS.md
new file mode 100644
index 0000000000..14fdd7a03e
--- /dev/null
+++ b/src/xrpld/rpc/AGENTS.md
@@ -0,0 +1,5 @@
+# AGENTS.md — rpc
+
+See the repo-level [AGENTS.md](../../../AGENTS.md) for general build/test/style guidance.
+
+Any change to a public RPC method's behavior (new/changed/removed fields, parameters, or error conditions) needs a corresponding entry in [`API-CHANGELOG.md`](../../../API-CHANGELOG.md), under the `## Unreleased` section (`### Additions`, `### Deprecations`, etc. as appropriate).
diff --git a/src/xrpld/rpc/BookChanges.h b/src/xrpld/rpc/BookChanges.h
index 16f7ea8e43..1912b0512e 100644
--- a/src/xrpld/rpc/BookChanges.h
+++ b/src/xrpld/rpc/BookChanges.h
@@ -7,6 +7,7 @@
 #include <xrpl/protocol/Issue.h>
 #include <xrpl/protocol/LedgerFormats.h>
 #include <xrpl/protocol/MPTIssue.h>
+#include <xrpl/protocol/Protocol.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STObject.h>
@@ -18,6 +19,7 @@
 #include <memory>
 #include <optional>
 #include <sstream>
+#include <stdexcept>
 #include <string>
 #include <tuple>
 
@@ -50,6 +52,36 @@ computeBookChanges(std::shared_ptr<L const> const& lpAccepted)
             std::optional<uint256>>>  // optional: domain id
         tally;
 
+    // Accumulating volume can exceed what the asset can represent, and the two
+    // types fail differently: STAmount's IOU addition throws, while its MPT
+    // addition is a raw int64 add that wraps past kMaxMpTokenAmount to a
+    // negative amount. Reject both so that one extreme crossing cannot poison
+    // this ledger's report, which is otherwise permanent -- the ledger is
+    // immutable and the computation deterministic.
+    auto const checkedAdd = [](STAmount& acc, STAmount const& delta) {
+        return acc.asset().visit(
+            [&](Issue const&) {
+                try
+                {
+                    acc += delta;
+                }
+                catch (std::overflow_error const&)
+                {
+                    return false;
+                }
+                return true;
+            },
+            [&](MPTIssue const&) {
+                // Both volumes are non-negative by the time they reach the
+                // tally, so this cannot underflow.
+                auto const room = static_cast<std::int64_t>(kMaxMpTokenAmount) - acc.mpt().value();
+                if (delta.mpt().value() > room)
+                    return false;
+                acc += delta;
+                return true;
+            });
+    };
+
     for (auto& tx : lpAccepted->txs)
     {
         if (!tx.first || !tx.second || !tx.first->isFieldPresent(sfTransactionType))
@@ -123,7 +155,16 @@ computeBookChanges(std::shared_ptr<L const> const& lpAccepted)
             if (second == beast::kZero)
                 continue;
 
-            STAmount const rate = divide(first, second, noIssue());
+            std::optional<STAmount> maybeRate;
+            try
+            {
+                maybeRate = divide(first, second, noIssue());
+            }
+            catch (std::overflow_error const&)
+            {
+                continue;
+            }
+            STAmount const rate = *maybeRate;
 
             if (first < beast::kZero)
                 first = -first;
@@ -161,8 +202,15 @@ computeBookChanges(std::shared_ptr<L const> const& lpAccepted)
                 // increment volume
                 auto& entry = tally[key];
 
-                std::get<0>(entry) += first;   // side A vol
-                std::get<1>(entry) += second;  // side B vol
+                // Commit both sides or neither, so an overflow on the second
+                // cannot leave the entry half-updated. Skipping the crossing
+                // matches how an unrepresentable rate is handled above.
+                STAmount volA = std::get<0>(entry);
+                STAmount volB = std::get<1>(entry);
+                if (!checkedAdd(volA, first) || !checkedAdd(volB, second))
+                    continue;
+                std::get<0>(entry) = volA;  // side A vol
+                std::get<1>(entry) = volB;  // side B vol
 
                 if (std::get<2>(entry) < rate)  // high
                     std::get<2>(entry) = rate;
diff --git a/src/xrpld/rpc/CLAUDE.md b/src/xrpld/rpc/CLAUDE.md
new file mode 120000
index 0000000000..47dc3e3d86
--- /dev/null
+++ b/src/xrpld/rpc/CLAUDE.md
@@ -0,0 +1 @@
+AGENTS.md
\ No newline at end of file
diff --git a/src/xrpld/rpc/detail/AccountAssets.cpp b/src/xrpld/rpc/detail/AccountAssets.cpp
index 67b9174fe3..0e71836b74 100644
--- a/src/xrpld/rpc/detail/AccountAssets.cpp
+++ b/src/xrpld/rpc/detail/AccountAssets.cpp
@@ -49,7 +49,7 @@ accountSourceAssets(
     {
         for (auto const& rspEntry : *mpts)
         {
-            if (!rspEntry.isZeroBalance() && !rspEntry.isMaxedOut())
+            if (rspEntry.canSend(account))
                 assets.insert(rspEntry.getMptID());
         }
     }
@@ -86,8 +86,10 @@ accountDestAssets(
     {
         for (auto const& rspEntry : *mpts)
         {
-            if (rspEntry.isZeroBalance() && !rspEntry.isMaxedOut())
-                assets.insert(rspEntry.getMptID());
+            // Any cached MPT entry means this account already has an issuance
+            // or MPToken object. A maxed-out issuance does not prevent
+            // receiving existing MPT from another holder.
+            assets.insert(rspEntry.getMptID());
         }
     }
 
diff --git a/src/xrpld/rpc/detail/MPT.h b/src/xrpld/rpc/detail/MPT.h
index 93c8517539..68054b2d0b 100644
--- a/src/xrpld/rpc/detail/MPT.h
+++ b/src/xrpld/rpc/detail/MPT.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/MPTIssue.h>
 #include <xrpl/protocol/UintTypes.h>
 
 namespace xrpl {
@@ -31,14 +33,11 @@ public:
         return mptID_;
     }
     [[nodiscard]] bool
-    isZeroBalance() const
+    canSend(AccountID const& account) const
     {
-        return zeroBalance_;
-    }
-    [[nodiscard]] bool
-    isMaxedOut() const
-    {
-        return maxedOut_;
+        // A maxed-out issuance only prevents the issuer from creating more
+        // MPT. Holders can still send existing balances.
+        return account == getMPTIssuer(mptID_) ? !maxedOut_ : !zeroBalance_;
     }
 };
 
diff --git a/src/xrpld/rpc/detail/PathRequest.cpp b/src/xrpld/rpc/detail/PathRequest.cpp
index fb132199bc..0a01031ae2 100644
--- a/src/xrpld/rpc/detail/PathRequest.cpp
+++ b/src/xrpld/rpc/detail/PathRequest.cpp
@@ -416,20 +416,22 @@ PathRequest::parseJson(json::Value const& jvParams)
                 // If the assets don't match, ignore the source asset.
                 if (srcPathAsset == saSendMax_->asset())
                 {
-                    // If neither is the source and they are not equal, then the
-                    // source issuer is illegal.
-                    if (srcIssuerID != *raSrcAccount_ &&
-                        saSendMax_->getIssuer() != *raSrcAccount_ &&
-                        srcIssuerID != saSendMax_->getIssuer())
-                    {
-                        jvStatus_ = rpcError(RpcSrcIsrMalformed);
-                        return PFR_PJ_INVALID;
-                    }
-
-                    // If both are the source, use the source.
-                    // Otherwise, use the one that's not the source.
-                    srcPathAsset.visit(
+                    auto const status = srcPathAsset.visit(
                         [&](Currency const& currency) {
+                            // If neither is the source and they are not equal,
+                            // then the source issuer is illegal. srcIssuerID
+                            // comes from the optional IOU source_currencies
+                            // issuer field, so this reconciliation is IOU-only.
+                            if (srcIssuerID != *raSrcAccount_ &&
+                                saSendMax_->getIssuer() != *raSrcAccount_ &&
+                                srcIssuerID != saSendMax_->getIssuer())
+                            {
+                                jvStatus_ = rpcError(RpcSrcIsrMalformed);
+                                return PFR_PJ_INVALID;
+                            }
+
+                            // If both are the source, use the source.
+                            // Otherwise, use the one that's not the source.
                             if (srcIssuerID != *raSrcAccount_)
                             {
                                 sciSourceAssets_.insert(Issue{currency, srcIssuerID});
@@ -438,11 +440,18 @@ PathRequest::parseJson(json::Value const& jvParams)
                             {
                                 sciSourceAssets_.insert(Issue{currency, saSendMax_->getIssuer()});
                             }
+                            else
                             {
                                 sciSourceAssets_.insert(Issue{currency, *raSrcAccount_});
                             }
+                            return PFR_PJ_NOCHANGE;
                         },
-                        [&](MPTID const& mpt) { sciSourceAssets_.insert(mpt); });
+                        [&](MPTID const& mpt) {
+                            sciSourceAssets_.insert(mpt);
+                            return PFR_PJ_NOCHANGE;
+                        });
+                    if (status == PFR_PJ_INVALID)
+                        return status;
                 }
             }
             else
diff --git a/src/xrpld/rpc/detail/Pathfinder.cpp b/src/xrpld/rpc/detail/Pathfinder.cpp
index 642b5c4253..1f530a1165 100644
--- a/src/xrpld/rpc/detail/Pathfinder.cpp
+++ b/src/xrpld/rpc/detail/Pathfinder.cpp
@@ -224,7 +224,7 @@ Pathfinder::Pathfinder(
     , dstAmount_(saDstAmount)
     , srcPathAsset_(uSrcPathAsset)
     , srcIssuer_(uSrcIssuer)
-    , srcAmount_(amountFromPathAsset(uSrcPathAsset, uSrcIssuer, uSrcAccount))
+    , srcAmount_(srcAmount.value_or(amountFromPathAsset(uSrcPathAsset, uSrcIssuer, uSrcAccount)))
     , convertAll_(convertAllCheck(dstAmount_))
     , domain_(domain)
     , ledger_(cache->getLedger())
@@ -815,8 +815,8 @@ Pathfinder::getPathsOut(
                 {
                     for (auto const& mpt : *mpts)
                     {
-                        if (pathAsset.get<MPTID>() != mpt.getMptID() || mpt.isZeroBalance() ||
-                            mpt.isMaxedOut() || bAuthRequired)
+                        if (pathAsset.get<MPTID>() != mpt.getMptID() || !mpt.canSend(account) ||
+                            bAuthRequired)
                             continue;
                         if (isDstAsset && dstAccount == getMPTIssuer(mpt))
                         {
@@ -1079,7 +1079,10 @@ Pathfinder::addLink(
                             }
                             if constexpr (kIsMpt)
                             {
-                                return asset.isZeroBalance() || asset.isMaxedOut() ||
+                                // `asset` came from uEndAccount's cached MPTs.
+                                // `acct` is the next issuer hop, not the
+                                // account whose balance is being tested.
+                                return !asset.canSend(uEndAccount) ||
                                     requireAuth(*ledger_, MPTIssue{asset}, acct);
                             }
                         };
diff --git a/src/xrpld/rpc/detail/SyntheticFields.cpp b/src/xrpld/rpc/detail/SyntheticFields.cpp
new file mode 100644
index 0000000000..9acf3abb36
--- /dev/null
+++ b/src/xrpld/rpc/detail/SyntheticFields.cpp
@@ -0,0 +1,40 @@
+#include <xrpld/rpc/detail/SyntheticFields.h>
+
+#include <xrpld/rpc/DeliveredAmount.h>
+#include <xrpld/rpc/MPTokenIssuanceID.h>
+
+#include <xrpl/json/json_value.h>
+#include <xrpl/protocol/NFTokenID.h>
+#include <xrpl/protocol/NFTokenOfferID.h>
+
+#include <memory>
+
+namespace xrpl::rpc {
+
+void
+insertAllSyntheticInJson(
+    json::Value& metadata,
+    ReadView const& ledger,
+    std::shared_ptr<STTx const> const& transaction,
+    TxMeta const& transactionMeta)
+{
+    insertDeliveredAmount(metadata, ledger, transaction, transactionMeta);
+    insertNFTokenID(metadata, transaction, transactionMeta);
+    insertNFTokenOfferID(metadata, transaction, transactionMeta);
+    insertMPTokenIssuanceID(metadata, transaction, transactionMeta);
+}
+
+void
+insertAllSyntheticInJson(
+    json::Value& metadata,
+    JsonContext const& context,
+    std::shared_ptr<STTx const> const& transaction,
+    TxMeta const& transactionMeta)
+{
+    insertDeliveredAmount(metadata, context, transaction, transactionMeta);
+    insertNFTokenID(metadata, transaction, transactionMeta);
+    insertNFTokenOfferID(metadata, transaction, transactionMeta);
+    insertMPTokenIssuanceID(metadata, transaction, transactionMeta);
+}
+
+}  // namespace xrpl::rpc
diff --git a/src/xrpld/rpc/detail/SyntheticFields.h b/src/xrpld/rpc/detail/SyntheticFields.h
new file mode 100644
index 0000000000..6ece4bbcd5
--- /dev/null
+++ b/src/xrpld/rpc/detail/SyntheticFields.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <xrpl/json/json_forwards.h>
+#include <xrpl/protocol/STTx.h>
+#include <xrpl/protocol/TxMeta.h>
+
+#include <memory>
+
+namespace xrpl {
+
+class ReadView;
+
+namespace rpc {
+
+struct JsonContext;
+
+/**
+ * Adds all synthetic fields to transaction metadata JSON.
+ * This includes delivered amount, NFT synthetic fields, and MPToken issuance
+ * ID.
+ */
+/** @{ */
+void
+insertAllSyntheticInJson(
+    json::Value& metadata,
+    ReadView const&,
+    std::shared_ptr<STTx const> const&,
+    TxMeta const&);
+
+void
+insertAllSyntheticInJson(
+    json::Value& metadata,
+    JsonContext const&,
+    std::shared_ptr<STTx const> const&,
+    TxMeta const&);
+/** @} */
+
+}  // namespace rpc
+}  // namespace xrpl
diff --git a/src/xrpld/rpc/detail/TransactionSign.cpp b/src/xrpld/rpc/detail/TransactionSign.cpp
index 9c97577b27..3e9f62214e 100644
--- a/src/xrpld/rpc/detail/TransactionSign.cpp
+++ b/src/xrpld/rpc/detail/TransactionSign.cpp
@@ -460,7 +460,8 @@ transactionPreProcessImpl(
     Role role,
     SigningForParams& signingArgs,
     std::chrono::seconds validatedLedgerAge,
-    Application& app)
+    Application& app,
+    Rules const& rules)
 {
     auto j = app.getJournal("RPCHandler");
 
@@ -482,13 +483,16 @@ transactionPreProcessImpl(
     }();
 
     // Make sure the signature target field is valid, if specified, and save the
-    // template for use later
+    // template for use later. Only a field that holds a transaction signature
+    // is a valid target; the signature is bound to that field's role.
     auto const signatureTemplate = signatureTarget
         ? InnerObjectFormats::getInstance().findSOTemplateBySField(*signatureTarget)
         : nullptr;
+    auto const signatureRoleOpt =
+        signatureTarget ? signatureRole(signatureTarget->get()) : SignatureRole::Transaction;
     if (signatureTarget)
     {
-        if (signatureTemplate == nullptr)
+        if (!signatureRoleOpt || signatureTemplate == nullptr)
         {  // Invalid target field
             return rpc::makeError(RpcInvalidParams, signatureTarget->get().getName());
         }
@@ -687,7 +691,8 @@ transactionPreProcessImpl(
     // If multisign then return multiSignature, else set TxnSignature field.
     if (signingArgs.isMultiSigning())
     {
-        Serializer const s = buildMultiSigningData(*stTx, signingArgs.getSigner());
+        Serializer const s = buildMultiSigningData(
+            *stTx, signingArgs.getSigner(), signingPrefix(*signatureRoleOpt, true, rules));
 
         auto multisig = xrpl::sign(pk, sk, s.slice());
 
@@ -695,7 +700,7 @@ transactionPreProcessImpl(
     }
     else if (signingArgs.isSingleSigning())
     {
-        stTx->sign(pk, sk, signatureTarget);
+        stTx->sign(pk, sk, *signatureRoleOpt, rules);
     }
 
     return TransactionPreProcessResult{std::move(stTx)};
@@ -1007,18 +1012,20 @@ transactionSign(
 {
     using namespace detail;
 
+    // Sign and verify against the same ruleset: a ledger close in between
+    // could change the signing prefix of an alternate signature field.
+    std::shared_ptr<ReadView const> const ledger = app.getOpenLedger().current();
     auto j = app.getJournal("RPCHandler");
     JLOG(j.debug()) << "transactionSign: " << jvRequest;
 
     // Add and amend fields based on the transaction type.
     SigningForParams signForParams;
-    TransactionPreProcessResult const preprocResult =
-        transactionPreProcessImpl(jvRequest, role, signForParams, validatedLedgerAge, app);
+    TransactionPreProcessResult const preprocResult = transactionPreProcessImpl(
+        jvRequest, role, signForParams, validatedLedgerAge, app, ledger->rules());
 
     if (!preprocResult.second)
         return preprocResult.first;
 
-    std::shared_ptr<ReadView const> const ledger = app.getOpenLedger().current();
     // Make sure the STTx makes a legitimate Transaction.
     std::pair<json::Value, Transaction::pointer> const txn =
         transactionConstructImpl(preprocResult.second, ledger->rules(), app);
@@ -1050,8 +1057,8 @@ transactionSubmit(
 
     // Add and amend fields based on the transaction type.
     SigningForParams signForParams;
-    TransactionPreProcessResult const preprocResult =
-        transactionPreProcessImpl(jvRequest, role, signForParams, validatedLedgerAge, app);
+    TransactionPreProcessResult const preprocResult = transactionPreProcessImpl(
+        jvRequest, role, signForParams, validatedLedgerAge, app, ledger->rules());
 
     if (!preprocResult.second)
         return preprocResult.first;
@@ -1218,8 +1225,8 @@ transactionSignFor(
     // Add and amend fields based on the transaction type.
     SigningForParams signForParams(*signerAccountID);
 
-    TransactionPreProcessResult const preprocResult =
-        transactionPreProcessImpl(jvRequest, role, signForParams, validatedLedgerAge, app);
+    TransactionPreProcessResult const preprocResult = transactionPreProcessImpl(
+        jvRequest, role, signForParams, validatedLedgerAge, app, ledger->rules());
 
     if (!preprocResult.second)
         return preprocResult.first;
diff --git a/src/xrpld/rpc/handlers/account/AccountTx.cpp b/src/xrpld/rpc/handlers/account/AccountTx.cpp
index 7b0c34e048..5385776b36 100644
--- a/src/xrpld/rpc/handlers/account/AccountTx.cpp
+++ b/src/xrpld/rpc/handlers/account/AccountTx.cpp
@@ -4,12 +4,11 @@
 #include <xrpld/app/misc/Transaction.h>
 #include <xrpld/app/rdb/backend/SQLiteDatabase.h>
 #include <xrpld/rpc/Context.h>
-#include <xrpld/rpc/DeliveredAmount.h>
-#include <xrpld/rpc/MPTokenIssuanceID.h>
 #include <xrpld/rpc/Role.h>
 #include <xrpld/rpc/Status.h>
 #include <xrpld/rpc/detail/RPCHelpers.h>
 #include <xrpld/rpc/detail/RPCLedgerHelpers.h>
+#include <xrpld/rpc/detail/SyntheticFields.h>
 #include <xrpld/rpc/detail/Tuning.h>
 
 #include <xrpl/basics/Log.h>
@@ -22,7 +21,6 @@
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/ErrorCodes.h>
 #include <xrpl/protocol/LedgerShortcut.h>
-#include <xrpl/protocol/NFTSyntheticSerializer.h>
 #include <xrpl/protocol/RPCErr.h>
 #include <xrpl/protocol/RippleLedgerHash.h>
 #include <xrpl/protocol/jss.h>
@@ -378,9 +376,7 @@ populateJsonResponse(
                     if (txnMeta)
                     {
                         jvObj[jss::meta] = txnMeta->getJson(JsonOptions::Values::IncludeDate);
-                        insertDeliveredAmount(jvObj[jss::meta], context, txn, *txnMeta);
-                        rpc::insertNFTSyntheticInJson(jvObj, sttx, *txnMeta);
-                        rpc::insertMPTokenIssuanceID(jvObj[jss::meta], sttx, *txnMeta);
+                        rpc::insertAllSyntheticInJson(jvObj[jss::meta], context, sttx, *txnMeta);
                     }
                     else
                     {
diff --git a/src/xrpld/rpc/handlers/transaction/Simulate.cpp b/src/xrpld/rpc/handlers/transaction/Simulate.cpp
index 8441add08b..61cdddafde 100644
--- a/src/xrpld/rpc/handlers/transaction/Simulate.cpp
+++ b/src/xrpld/rpc/handlers/transaction/Simulate.cpp
@@ -4,7 +4,7 @@
 #include <xrpld/app/misc/TxQ.h>
 #include <xrpld/rpc/Context.h>
 #include <xrpld/rpc/DeliveredAmount.h>
-#include <xrpld/rpc/MPTokenIssuanceID.h>
+#include <xrpld/rpc/detail/SyntheticFields.h>
 #include <xrpld/rpc/detail/TransactionSign.h>
 
 #include <xrpl/basics/Log.h>
@@ -20,7 +20,6 @@
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/ErrorCodes.h>
 #include <xrpl/protocol/Indexes.h>
-#include <xrpl/protocol/NFTSyntheticSerializer.h>
 #include <xrpl/protocol/RPCErr.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STParsedJSON.h>
@@ -290,12 +289,8 @@ simulateTxn(rpc::JsonContext& context, std::shared_ptr<Transaction> transaction)
         else
         {
             jvResult[jss::meta] = result.metadata->getJson(JsonOptions::Values::None);
-            rpc::insertDeliveredAmount(
+            rpc::insertAllSyntheticInJson(
                 jvResult[jss::meta], view, transaction->getSTransaction(), *result.metadata);
-            rpc::insertNFTSyntheticInJson(
-                jvResult, transaction->getSTransaction(), *result.metadata);
-            rpc::insertMPTokenIssuanceID(
-                jvResult[jss::meta], transaction->getSTransaction(), *result.metadata);
         }
     }
 
diff --git a/src/xrpld/rpc/handlers/transaction/Tx.cpp b/src/xrpld/rpc/handlers/transaction/Tx.cpp
index ee7110bf6b..cebe427af8 100644
--- a/src/xrpld/rpc/handlers/transaction/Tx.cpp
+++ b/src/xrpld/rpc/handlers/transaction/Tx.cpp
@@ -5,8 +5,9 @@
 #include <xrpld/rpc/CTID.h>
 #include <xrpld/rpc/Context.h>
 #include <xrpld/rpc/DeliveredAmount.h>
-#include <xrpld/rpc/MPTokenIssuanceID.h>
 #include <xrpld/rpc/Status.h>
+#include <xrpld/rpc/detail/RPCHelpers.h>
+#include <xrpld/rpc/detail/SyntheticFields.h>
 
 #include <xrpl/basics/Blob.h>
 #include <xrpl/basics/RangeSet.h>
@@ -18,7 +19,6 @@
 #include <xrpl/core/NetworkIDService.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/protocol/ErrorCodes.h>
-#include <xrpl/protocol/NFTSyntheticSerializer.h>
 #include <xrpl/protocol/RPCErr.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STBase.h>
@@ -253,9 +253,7 @@ populateJsonResponse(
             if (meta)
             {
                 response[jss::meta] = meta->getJson(JsonOptions::Values::None);
-                insertDeliveredAmount(response[jss::meta], context, result.txn, *meta);
-                rpc::insertNFTSyntheticInJson(response, sttx, *meta);
-                rpc::insertMPTokenIssuanceID(response[jss::meta], sttx, *meta);
+                rpc::insertAllSyntheticInJson(response[jss::meta], context, sttx, *meta);
             }
         }
         response[jss::validated] = result.validated;