chore: Bump version to 3.4.0

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

.cspell.config.yaml

@@ -141,6 +141,7 @@ words:
   - hwrap
   - ifndef
   - inequation
+  - Injectivity
   - insuf
   - insuff
   - invasively
@@ -366,7 +367,6 @@ words:
   - venv
   - vfalco
   - vinnie
-  - vkeylet
   - wasmi
   - wextra
   - wptr
@@ -387,3 +387,4 @@ words:
   - xxhasher
   - zstdio
   - CGNAT
+  - ungated

.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

.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.

.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.

.github/scripts/strategy-matrix/generate.py

@@ -15,6 +15,14 @@ _BASE_CMAKE_ARGS = [
     "-Drust=ON",
 ]
 
+# The package formats a config can be packaged as, each with its own
+# install-test job in reusable-package.yml.
+PACKAGE_TYPES = ("deb", "rpm")
+
+# The package name a variant suffixes, as build_pkg.py's BASE_NAME spells it:
+# the two have to agree, or the artifact globs miss what was built.
+BASE_NAME = "xrpld"
+
 # Maps sanitizer names (as used in cmake) to short config-name suffixes.
 _SANITIZER_SUFFIX: dict[str, str] = {
     "address": "asan",
@@ -23,6 +31,19 @@ _SANITIZER_SUFFIX: dict[str, str] = {
 }
 
 
+def config_name(
+    distro: str,
+    compiler: str,
+    build_type: str,
+    arch: str,
+    suffix: str = "",
+    sanitizer: str = "",
+) -> str:
+    """Name a config. Its artifacts are named after it, so packaging reuses this."""
+    parts = [s for s in [suffix, _SANITIZER_SUFFIX.get(sanitizer, "")] if s]
+    return "-".join([f"{distro}-{compiler}-{build_type.lower()}-{arch}", *parts])
+
+
 def get_cmake_args(build_type: str, extra_args: str) -> str:
     """Get the full list of CMake arguments for a config."""
     args = _BASE_CMAKE_ARGS.copy()
@@ -37,17 +58,37 @@ def get_cmake_args(build_type: str, extra_args: str) -> str:
 
 
 # Every config must declare 'minimal'. Minimal configs form the reduced matrix
-# built for pull requests by default; the full matrix adds the rest. Packaging
-# configs declare it too, but packaging is gated in the workflow, not by it.
+# built for pull requests by default; the full matrix adds the rest.
 #
-# Configs may also opt into 'benchmark' to smoke-run the benchmarks. Note that
-# the flag applies to every entry a config expands into, so only set it on
-# configs that expand to a single combination.
+# Configs may also opt into 'benchmark' to smoke-run the benchmarks, or carry a
+# 'package' map to be packaged as well. Note that either applies to every entry
+# a config expands into, so only set them on configs that expand to a single
+# combination.
+
+
+@dataclasses.dataclass
+class PackageConfig:
+    """The 'package' map of a config whose binaries are also packaged."""
+
+    type: str  # has to match what the image provides
+    # The packaging container image: a vanilla distro image, not the nix image
+    # the config itself builds in.
+    image: str
+    # A flavour of the package, named xrpld-<variant>, for a config whose
+    # binaries are not the plain release build. A variant needs no counterpart
+    # in the other format.
+    variant: str = ""
+
+    def __post_init__(self) -> None:
+        assert self.type in PACKAGE_TYPES, (
+            f"unsupported package type {self.type!r}: "
+            f"use one of {', '.join(PACKAGE_TYPES)}."
+        )
 
 
 @dataclasses.dataclass
 class LinuxConfig:
-    """One entry in linux.json's 'configs' or 'package_configs' arrays."""
+    """One entry in a linux.json 'configs' array."""
 
     compiler: list[str]
     build_type: list[str]
@@ -57,9 +98,11 @@ class LinuxConfig:
     sanitizers: list[str] = dataclasses.field(default_factory=list)
     suffix: str = ""
     extra_cmake_args: str = ""
-    # The two below are only used by package_configs entries.
-    image: str = ""
-    package_type: str = ""  # "deb" or "rpm"; has to match what image provides
+    package: PackageConfig | None = None  # set to also package this config
+
+    def __post_init__(self) -> None:
+        if isinstance(self.package, dict):
+            self.package = PackageConfig(**self.package)
 
 
 @dataclasses.dataclass
@@ -68,22 +111,16 @@ class LinuxFile:
 
     image_tag: str
     configs: dict[str, list[LinuxConfig]]  # distro → configs
-    package_configs: dict[str, list[LinuxConfig]]  # distro → packaging configs
 
     @classmethod
     def load(cls, path: Path) -> "LinuxFile":
         data = json.loads(path.read_text())
-
-        def parse(section: dict) -> dict[str, list[LinuxConfig]]:
-            return {
-                distro: [LinuxConfig(**c) for c in cfgs]
-                for distro, cfgs in section.items()
-            }
-
         return cls(
             image_tag=data["image_tag"],
-            configs=parse(data["configs"]),
-            package_configs=parse(data.get("package_configs", {})),
+            configs={
+                distro: [LinuxConfig(**c) for c in cfgs]
+                for distro, cfgs in data["configs"].items()
+            },
         )
 
 
@@ -159,6 +196,8 @@ class PackagingEntry:
     validator_keys_artifact_name: str
     image: str
     package_type: str  # "deb" or "rpm"; drives the format-specific steps
+    package_variant: str  # passed to build_pkg.py --variant; empty for xrpld
+    package_name: str  # the name it builds under, which the artifact globs use
 
 
 # ---------------------------------------------------------------------------
@@ -199,13 +238,9 @@ def expand_linux_matrix(linux: LinuxFile, minimal: bool) -> list[MatrixEntry]:
                 effective_sanitizers,
                 effective_archs.items(),
             ):
-                name = f"{distro}-{compiler}-{build_type.lower()}-{arch}"
-                suffix_parts = [
-                    s for s in [cfg.suffix, _SANITIZER_SUFFIX.get(sanitizer, "")] if s
-                ]
-                if suffix_parts:
-                    name += "-" + "-".join(suffix_parts)
-
+                name = config_name(
+                    distro, compiler, build_type, arch, cfg.suffix, sanitizer
+                )
                 entries.append(
                     MatrixEntry(
                         config_name=name,
@@ -225,33 +260,59 @@ def expand_linux_matrix(linux: LinuxFile, minimal: bool) -> list[MatrixEntry]:
 
 
 def expand_linux_packaging(linux: LinuxFile) -> list[PackagingEntry]:
-    """Generate the packaging matrix from a LinuxFile's package_configs section.
+    """Generate the packaging matrix from the configs that carry a 'package' map.
 
-    Packaging uses vanilla distro images (debian:bookworm, almalinux:9) instead of
-    the nix-based build images, because deb/rpm tooling (debhelper, rpm-build)
-    is taken from the distro's archive rather than from nixpkgs. Each config
-    entry carries its own 'image'.
+    Packaging consumes the binaries that config's build job uploaded, so the
+    artifact names come from the same config name, and a packaged config is one
+    that passes -Dvalidator_keys=ON.
 
-    The artifact names must match what the build job uploads: one artifact per
-    binary, each named after the build config.
+    Packaging itself runs in vanilla distro images (debian:trixie, almalinux:10)
+    instead of the nix-based build images, because deb/rpm tooling (debhelper,
+    rpm-build) is taken from the distro's archive rather than from nixpkgs.
     """
     entries = []
-    for distro, configs in linux.package_configs.items():
+    for distro, configs in linux.configs.items():
         for cfg in configs:
-            for compiler, build_type in itertools.product(cfg.compiler, cfg.build_type):
-                config_name = f"{distro}-{compiler}-{build_type.lower()}-amd64"
+            if cfg.package is None:
+                continue
+            for compiler, build_type, arch in itertools.product(
+                cfg.compiler, cfg.build_type, cfg.arch
+            ):
+                # The packaging workflow hardcodes an amd64 runner.
+                assert arch == "amd64", f"cannot package {distro} on {arch}"
+                name = config_name(distro, compiler, build_type, arch, cfg.suffix)
                 entries.append(
                     PackagingEntry(
-                        xrpld_artifact_name=f"xrpld-{config_name}",
-                        validator_keys_artifact_name=f"validator-keys-{config_name}",
-                        image=cfg.image,
-                        package_type=cfg.package_type,
+                        xrpld_artifact_name=f"xrpld-{name}",
+                        validator_keys_artifact_name=f"validator-keys-{name}",
+                        image=cfg.package.image,
+                        package_type=cfg.package.type,
+                        package_variant=cfg.package.variant,
+                        package_name=(
+                            f"{BASE_NAME}-{cfg.package.variant}"
+                            if cfg.package.variant
+                            else BASE_NAME
+                        ),
                     )
                 )
 
     return entries
 
 
+def package_names_by_type(entries: list[PackagingEntry]) -> dict[str, list[str]]:
+    """The names of the packages in 'entries', keyed by format.
+
+    Derived from the packaging matrix rather than listed again, so the packages
+    the install-test jobs look for are the packages that were built.
+    """
+    return {
+        package_type: sorted(
+            {e.package_name for e in entries if e.package_type == package_type}
+        )
+        for package_type in PACKAGE_TYPES
+    }
+
+
 def expand_platform_matrix(pf: PlatformFile, minimal: bool) -> list[MatrixEntry]:
     """Expand a PlatformFile (macOS or Windows) into matrix entries.
 
@@ -320,6 +381,10 @@ if __name__ == "__main__":
 
     if args.packaging:
         matrix = expand_linux_packaging(LinuxFile.load(THIS_DIR / "linux.json"))
+        # One list per format, so each install-test job installs the packages its
+        # own format produced.
+        for package_type, names in package_names_by_type(matrix).items():
+            print(f"{package_type}_package_names={json.dumps(names)}")
     else:
         if args.config in ("linux", None):
             matrix += expand_linux_matrix(

.github/scripts/strategy-matrix/linux.json

@@ -71,7 +71,24 @@
         "build_type": ["Release"],
         "arch": ["amd64"],
         "minimal": false,
-        "extra_cmake_args": "-Dvalidator_keys=ON"
+        "extra_cmake_args": "-Dvalidator_keys=ON",
+        "package": {
+          "type": "deb",
+          "image": "ghcr.io/xrplf/xrpld/packaging-debian:sha-49cdc10"
+        }
+      },
+      {
+        "compiler": ["gcc"],
+        "build_type": ["Release"],
+        "arch": ["amd64"],
+        "minimal": false,
+        "suffix": "assert",
+        "extra_cmake_args": "-Dvalidator_keys=ON -Dassert=ON",
+        "package": {
+          "type": "deb",
+          "image": "ghcr.io/xrplf/xrpld/packaging-debian:sha-49cdc10",
+          "variant": "assert"
+        }
       }
     ],
 
@@ -81,30 +98,11 @@
         "build_type": ["Release"],
         "arch": ["amd64"],
         "minimal": false,
-        "extra_cmake_args": "-Dvalidator_keys=ON"
-      }
-    ]
-  },
-  "package_configs": {
-    "debian": [
-      {
-        "compiler": ["gcc"],
-        "build_type": ["Release"],
-        "arch": ["amd64"],
-        "minimal": false,
-        "image": "ghcr.io/xrplf/xrpld/packaging-debian:sha-45e4b88",
-        "package_type": "deb"
-      }
-    ],
-
-    "rhel": [
-      {
-        "compiler": ["gcc"],
-        "build_type": ["Release"],
-        "arch": ["amd64"],
-        "minimal": false,
-        "image": "ghcr.io/xrplf/xrpld/packaging-rhel:sha-45e4b88",
-        "package_type": "rpm"
+        "extra_cmake_args": "-Dvalidator_keys=ON",
+        "package": {
+          "type": "rpm",
+          "image": "ghcr.io/xrplf/xrpld/packaging-rhel:sha-49cdc10"
+        }
       }
     ]
   }

.github/workflows/build-nix-images.yml

@@ -60,7 +60,7 @@ 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

.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' }}

.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

.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
 

.github/workflows/on-pr.yml

@@ -85,6 +85,7 @@ jobs:
             .github/workflows/reusable-build-test.yml
             .github/workflows/reusable-check-autogen.yml
             .github/workflows/reusable-clang-tidy.yml
+            .github/workflows/reusable-package-test-install.yml
             .github/workflows/reusable-package.yml
             .github/workflows/reusable-rust.yml
             .github/workflows/reusable-strategy-matrix.yml

.github/workflows/on-trigger.yml

@@ -23,6 +23,7 @@ on:
       - ".github/workflows/reusable-build-test.yml"
       - ".github/workflows/reusable-check-autogen.yml"
       - ".github/workflows/reusable-clang-tidy.yml"
+      - ".github/workflows/reusable-package-test-install.yml"
       - ".github/workflows/reusable-package.yml"
       - ".github/workflows/reusable-rust.yml"
       - ".github/workflows/reusable-strategy-matrix.yml"

.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" }'

.github/workflows/publish-docs.yml

@@ -47,7 +47,7 @@ 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
 

.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 }}
 

.github/workflows/reusable-clang-tidy.yml

@@ -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
 

.github/workflows/reusable-package-test-install.yml

@@ -0,0 +1,120 @@
+# Install one package format on every distro family it targets, one job per
+# package name and image, and run the binaries there. Called once per format by
+# reusable-package.yml, which owns the names and the image lists.
+name: Install packages
+
+on:
+  workflow_call:
+    inputs:
+      package_type:
+        description: 'The package format to install ("deb" or "rpm").'
+        required: true
+        type: string
+      package_names:
+        description: "JSON array of package names built for this format."
+        required: true
+        type: string
+      images:
+        description: "JSON array of container images to install in."
+        required: true
+        type: string
+
+defaults:
+  run:
+    shell: bash
+
+env:
+  PACKAGE_DIR: packages
+
+jobs:
+  install:
+    strategy:
+      fail-fast: false
+      matrix:
+        package_name: ${{ fromJson(inputs.package_names) }}
+        image: ${{ fromJson(inputs.images) }}
+    name: "${{ matrix.package_name }} on ${{ matrix.image }}"
+    permissions:
+      contents: read
+    runs-on: ubuntu-latest
+    container: ${{ matrix.image }}
+    timeout-minutes: 5
+
+    steps:
+      # Every package lands in one directory; the step below picks its own,
+      # which keeps this 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_NAME: ${{ matrix.package_name }}
+          PACKAGE_TYPE: ${{ inputs.package_type }}
+        run: |
+          # The version follows the name, separated by '_' in a DEB and '-' in an
+          # RPM. Requiring a digit after it is what keeps 'xrpld' from picking up
+          # another package, such as 'xrpld-assert'.
+          pattern="${PACKAGE_NAME}[_-][0-9]*.${PACKAGE_TYPE}"
+          package="$(find "${PACKAGE_DIR}" -type f -name "${pattern}" -print -quit)"
+          test -n "${package}" || {
+              echo "no ${pattern} 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: ${{ inputs.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: ${{ inputs.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

.github/workflows/reusable-package.yml

@@ -1,11 +1,16 @@
-# 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 distro, taken from "package_configs" in linux.json
-#   - each entry names its 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-deb' and 'test-install-rpm' call
+#     reusable-package-test-install.yml to install what was built on a range of
+#     distros and run 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:
@@ -39,12 +44,15 @@ defaults:
 
 env:
   BUILD_DIR: build
+  PACKAGE_DIR: packages
 
 jobs:
   generate-matrix:
     runs-on: ubuntu-latest
     outputs:
       matrix: ${{ steps.generate.outputs.matrix }}
+      deb_package_names: ${{ steps.generate.outputs.deb_package_names }}
+      rpm_package_names: ${{ steps.generate.outputs.rpm_package_names }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -70,12 +78,17 @@ 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:
@@ -98,6 +111,7 @@ jobs:
       - name: Build package
         env:
           PACKAGE_TYPE: ${{ matrix.package_type }}
+          PACKAGE_VARIANT: ${{ matrix.package_variant }}
           PKG_RELEASE: ${{ steps.release_info.outputs.pkg_release }}
           CHANNEL: ${{ steps.release_info.outputs.channel }}
         run: |
@@ -105,35 +119,123 @@ jobs:
               --package-type "${PACKAGE_TYPE}" \
               --build-dir "${BUILD_DIR}" \
               --pkg-release "${PKG_RELEASE}" \
+              --variant "${PACKAGE_VARIANT}" \
               --channel "${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. In the globs below the
+      # version follows the name, separated by '_' in a DEB and '-' in an RPM. A
+      # version starts with a digit and a longer name does not, so that one digit
+      # is what tells 'xrpld-3.4.1-...' from 'xrpld-assert-3.4.1-...'.
       - 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
+            ${{ env.BUILD_DIR }}/debbuild/${{ matrix.package_name }}_[0-9]*.deb
+            ${{ env.BUILD_DIR }}/rpmbuild/RPMS/**/${{ matrix.package_name }}-[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: |
+            ${{ env.BUILD_DIR }}/debbuild/${{ matrix.package_name }}-dbgsym_[0-9]*.deb
+            ${{ env.BUILD_DIR }}/debbuild/${{ matrix.package_name }}-dbgsym_[0-9]*.ddeb
+            ${{ env.BUILD_DIR }}/rpmbuild/RPMS/**/${{ matrix.package_name }}-debuginfo-[0-9]*.rpm
+          if-no-files-found: error
+
+  # One call per format, so a variant packaged for one format is installed for
+  # that format alone. The images are every distro family that format targets,
+  # oldest release first, so both ends of the dependency range the packages
+  # declare are exercised.
+  test-install-deb:
+    needs: [generate-matrix, package]
+    name: install deb
+    uses: ./.github/workflows/reusable-package-test-install.yml
+    with:
+      package_type: deb
+      package_names: ${{ needs.generate-matrix.outputs.deb_package_names }}
+      images: |
+        [
+          "debian:11",
+          "debian:12",
+          "debian:13",
+          "ubuntu:20.04",
+          "ubuntu:22.04",
+          "ubuntu:24.04",
+          "ubuntu:26.04"
+        ]
+
+  test-install-rpm:
+    needs: [generate-matrix, package]
+    name: install rpm
+    uses: ./.github/workflows/reusable-package-test-install.yml
+    with:
+      package_type: rpm
+      package_names: ${{ needs.generate-matrix.outputs.rpm_package_names }}
+      images: |
+        [
+          "almalinux:9",
+          "almalinux:10",
+          "rockylinux/rockylinux:9",
+          "rockylinux/rockylinux:10",
+          "registry.access.redhat.com/ubi9/ubi",
+          "registry.access.redhat.com/ubi10/ubi"
+        ]
+
+  publish:
+    needs: [generate-matrix, package, test-install-deb, test-install-rpm]
+    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}

.github/workflows/reusable-upload-recipe.yml

@@ -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

.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
 

.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__

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).

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
 

CLAUDE.md

@@ -0,0 +1 @@
+AGENTS.md

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

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
             ;;
 

cmake/XrplPackaging.cmake

@@ -44,12 +44,18 @@ else()
     set(pkg_type rpm)
 endif()
 
+# Unquoted below, so an empty value adds no argument at all.
+set(pkg_variant_option "")
+if(assert)
+    set(pkg_variant_option --variant=assert)
+endif()
+
 add_custom_target(
     package
     COMMAND
         ${CMAKE_SOURCE_DIR}/package/build_pkg.py --package-type=${pkg_type}
         --build-dir=${CMAKE_BINARY_DIR} --pkg-release=${pkg_release}
-        --channel=UNRELEASED
+        ${pkg_variant_option} --channel=UNRELEASED
     WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
     DEPENDS xrpld validator-keys
     COMMENT "Building Linux ${pkg_type} package"

conanfile.py

@@ -149,6 +149,7 @@ class Xrpl(ConanFile):
         self.requires("xxhash/0.8.3", transitive_headers=True)
 
     exports_sources = (
+        "bin/default-loader-path.sh",
         "CMakeLists.txt",
         "cfg/*",
         "cmake/*",

docs/install.md

@@ -6,14 +6,15 @@
 
 `xrpld` is published as DEB and RPM packages for 64-bit x86 Linux.
 Use APT on Debian-based distributions such as Debian and Ubuntu,
-and YUM on Red Hat-based distributions such as RHEL, AlmaLinux, and Rocky Linux.
+and DNF on Red Hat-based distributions such as RHEL, AlmaLinux, and Rocky Linux,
+where `yum` is a symlink to `dnf`.
 To build from source instead, see [BUILD.md](../BUILD.md).
 
 ## Release channels
 
 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)
@@ -81,7 +82,7 @@ wherever it appears in the repository configuration.
     sudo apt -y install xrpld
     ```
 
-### With the YUM package manager
+### With the DNF package manager
 
 1.  Add the XRPL Foundation package-signing key:
 
@@ -109,9 +110,23 @@ wherever it appears in the repository configuration.
 3.  Install the `xrpld` package:
 
     ```bash
-    sudo yum install -y xrpld
+    sudo dnf install -y xrpld
     ```
 
+### Optional: the assert-enabled build
+
+Every channel also carries `xrpld-assert` as a DEB, the same build with assertions
+enabled, for diagnosing a problem on a non-production server.
+It installs the same files as `xrpld` and replaces it, so install one or the other:
+
+```bash
+sudo apt -y install xrpld-assert # APT removes xrpld itself
+```
+
+Switching stops the service, since it is a removal and an installation rather than an upgrade,
+and APT starts it again.
+Install `xrpld` the same way to switch back.
+
 ## The xrpld service
 
 Both package managers install a systemd unit and enable it, so `xrpld` starts on boot.
@@ -121,7 +136,7 @@ Check whether it is already running:
 systemctl status xrpld.service
 ```
 
-The APT packages start it immediately as well; the YUM packages do not, so start it yourself:
+The DEB packages start it immediately as well; the RPM packages do not, so start it yourself:
 
 ```bash
 sudo systemctl start xrpld.service

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

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)));
 }
 
 /**

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);

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(

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,

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);

include/xrpl/nodestore/detail/DatabaseNodeImp.h

@@ -92,7 +92,7 @@ public:
     void
     importDatabase(Database& source) override
     {
-        importInternal(*backend_.get(), source);
+        importInternal(*backend_, source);
     }
 
     void

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>

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

include/xrpl/protocol/NFTSyntheticSerializer.h

@@ -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

include/xrpl/protocol/PathAsset.h

@@ -5,9 +5,11 @@
 #include <xrpl/protocol/Concepts.h>
 #include <xrpl/protocol/UintTypes.h>
 
+#include <cstdint>
 #include <ostream>
 #include <stdexcept>
 #include <string>
+#include <type_traits>
 #include <variant>
 
 namespace xrpl {
@@ -121,9 +123,32 @@ operator==(PathAsset const& lhs, PathAsset const& rhs)
 
 template <typename Hasher>
 void
-hash_append(Hasher& h, PathAsset const& pathAsset)
+hash_append(Hasher& h, PathAsset const& pathAsset) noexcept
 {
-    std::visit([&]<ValidPathAsset T>(T const& e) { hash_append(h, e); }, pathAsset.value());
+    using beast::hash_append;
+    using Variant = std::remove_cvref_t<decltype(pathAsset.value())>;
+
+    static_assert(
+        std::variant_size_v<Variant> < 0xFFu,
+        "PathAsset's discriminant must fit in a byte, leaving 0xFF reserved.");
+
+    // std::visit is not noexcept: it throws bad_variant_access when the variant
+    // is valueless_by_exception.
+    if (pathAsset.value().valueless_by_exception()) [[unlikely]]
+    {
+        hash_append(h, static_cast<std::uint8_t>(0xFFu));
+        return;
+    }
+
+    hash_append(h, static_cast<std::uint8_t>(pathAsset.value().index()));
+    std::visit(
+        [&]<ValidPathAsset T>(T const& e) noexcept {
+            static_assert(
+                noexcept(hash_append(h, e)),
+                "Every PathAsset alternative must be nothrow-hashable.");
+            hash_append(h, e);
+        },
+        pathAsset.value());
 }
 
 inline bool

include/xrpl/protocol/Protocol.h

@@ -348,13 +348,24 @@ 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();
 
@@ -396,16 +407,6 @@ 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
  */

include/xrpl/protocol/STPathSet.h

@@ -12,6 +12,8 @@
 #include <xrpl/protocol/UintTypes.h>
 
 #include <cstddef>
+#include <cstdint>
+#include <memory>
 #include <optional>
 #include <utility>
 #include <vector>
@@ -65,7 +67,7 @@ public:
         PathAsset const& asset,
         AccountID const& issuer);
 
-    [[nodiscard]] auto
+    [[nodiscard]] std::uint32_t
     getNodeType() const;
 
     [[nodiscard]] bool
@@ -109,9 +111,6 @@ public:
     [[nodiscard]] bool
     isType(Type const& pe) const;
 
-    [[nodiscard]] size_t
-    getHash() const;
-
     bool
     operator==(STPathElement const& t) const;
 
@@ -120,6 +119,17 @@ private:
     getHash(STPathElement const& element);
 };
 
+template <class Hasher>
+void
+hash_append(Hasher& h, STPathElement const& e) noexcept
+{
+    using beast::hash_append;
+    hash_append(h, (e.getNodeType() & STPathElement::TypeAccount) != 0u);
+    hash_append(h, e.getAccountID());
+    hash_append(h, e.getPathAsset());
+    hash_append(h, e.getIssuerID());
+}
+
 class STPath final : public CountedObject<STPath>
 {
     std::vector<STPathElement> path_;
@@ -176,9 +186,10 @@ template <class Hasher>
 void
 hash_append(Hasher& h, STPath const& p) noexcept
 {
+    using beast::hash_append;
     for (auto const& e : p)
     {
-        beast::hash_append(h, e.getHash());
+        hash_append(h, e);
     }
 }
 
@@ -188,13 +199,39 @@ hash_append(Hasher& h, STPath const& p) noexcept
 class STPathSet final : public STBase, public CountedObject<STPathSet>
 {
     std::vector<STPath> value_;
-    xrpl::hardened_hash_set<STPath> seenHashes_;
+
+    /**
+     * Deduplication index over `value_`, for pathfinding.
+     * The use of a std::unique_ptr is intentional as it
+     * only requires 8 additional bytes of storage for the pointer
+     * as opposed to 64 bytes with an optional.  This keeps the size
+     * of the STPathSet to within the `STVar::kMaxSize` limit of 72 bytes.
+     */
+    std::unique_ptr<hardened_hash_set<STPath>> seen_;
 
 public:
+    struct DeduplicationTag
+    {
+    };
+
     STPathSet() = default;
+    /**
+     * Deduplication tagged constructor.
+     * Use when you want to ensure that the STPathSet does not contain duplicate paths.
+     */
+    explicit STPathSet(DeduplicationTag);
 
     STPathSet(SField const& n);
     STPathSet(SerialIter& sit, SField const& name);
+    STPathSet(STPathSet const& other);
+    STPathSet(STPathSet&&) = default;
+
+    STPathSet&
+    operator=(STPathSet const& other);
+    STPathSet&
+    operator=(STPathSet&&) = default;
+
+    ~STPathSet() override = default;
 
     void
     add(Serializer& s) const override;
@@ -204,6 +241,16 @@ public:
     [[nodiscard]] SerializedTypeID
     getSType() const override;
 
+    /**
+     * @brief assembleAdd adds a path to the set by combining a base path and a tail element.
+     *
+     * @param base The base path.
+     * @param tail The tail element.
+     * @return true if the path was added, false if it was a duplicate and not added.
+     * @remarks Requires the STPathSet to be constructed with the DeduplicationTag. The return value
+     * indicates whether the combined path was inserted (true) or rejected as a duplicate (false).
+     * It is fine for callers to ignore the return value.
+     */
     bool
     assembleAdd(STPath const& base, STPathElement const& tail);
 
@@ -229,22 +276,61 @@ public:
     [[nodiscard]] bool
     empty() const;
 
-    void
+    /**
+     * @brief pushBack adds a path to the set.
+     *
+     * @param e The path to add.
+     * @return true if the path was added, false if it was a duplicate and not added.
+     * @remarks If the STPathSet was constructed with the DeduplicationTag, then this method will
+     *          check for duplicates and only add the path if it is not already present in the
+     *          set. If the STPathSet was constructed without the DeduplicationTag,
+     *          then this method will always add the path to the set, regardless of duplicates.
+     *          It is fine for callers to ignore the return value.
+     */
+    bool
     pushBack(STPath const& e);
 
+    /**
+     * @brief emplaceBack adds a path to the set.
+     *
+     * @param args The arguments to construct the path with.
+     * @return true if the path was added, false if it was a duplicate and not added.
+     * @remarks If the STPathSet was constructed with the DeduplicationTag, then this method will
+     *          check for duplicates and only add the path if it is not already present in the
+     *          set. If the STPathSet was constructed without the DeduplicationTag,
+     *          then this method will always add the path to the set, regardless of duplicates.
+     *          It is fine for callers to ignore the return value.
+     * @note The path is constructed before the duplicate check, so on a false
+     *       return the constructed path is discarded and any argument
+     *       forwarded as an rvalue is left in a moved-from state.  Use
+     *       pushBack when the caller needs to keep its path on rejection.
+     */
     template <typename... Args>
-    void
+    bool
     emplaceBack(Args&&... args);
 
-    [[nodiscard]] bool
-    contains(STPath const& path) const;
-
 private:
     STBase*
     copy(std::size_t n, void* buf) const override;
     STBase*
     move(std::size_t n, void* buf) override;
 
+    /**
+     * @brief Append a path via `append`, then register it in the deduplication index.
+     *
+     * @param append Invoked with `value_`; must append exactly one path to it.
+     * @return true if the path was kept, false if it was a duplicate and was rolled back.
+     * @remarks Appends to the vector before touching the index, so that a failed allocation
+     *          there leaves both containers untouched rather than leaving the index holding
+     *          a path the vector does not.  If the index insert reports a duplicate, or
+     *          throws, the append is rolled back so the two containers stay consistent; in
+     *          the throwing case the exception propagates.  With no index (constructed
+     *          without the DeduplicationTag) the append is unconditional.
+     */
+    template <typename Append>
+    bool
+    appendUnique(Append&& append);
+
     friend class detail::STVar;
 };
 
@@ -336,7 +422,7 @@ inline STPathElement::STPathElement(
     hashValue_ = getHash(*this);
 }
 
-inline auto
+inline std::uint32_t
 STPathElement::getNodeType() const
 {
     return type_;
@@ -545,25 +631,50 @@ STPathSet::empty() const
     return value_.empty();
 }
 
-inline void
-STPathSet::pushBack(STPath const& e)
+template <typename Append>
+inline bool
+STPathSet::appendUnique(Append&& append)
 {
-    value_.push_back(e);
-    seenHashes_.emplace(value_.back());
-}
+    // Append to the vector first, so that a failed allocation there leaves both
+    // containers untouched rather than leaving the index holding a path the
+    // vector does not.
+    append(value_);
 
-template <typename... Args>
-inline void
-STPathSet::emplaceBack(Args&&... args)
-{
-    value_.emplace_back(std::forward<Args>(args)...);
-    seenHashes_.emplace(value_.back());
+    if (seen_ == nullptr)
+    {
+        return true;
+    }
+
+    try
+    {
+        if (!seen_->insert(value_.back()).second)
+        {
+            // Already present: roll back the append.
+            value_.pop_back();
+            return false;
+        }
+    }
+    catch (...)
+    {
+        // The index insert failed, so roll back the append to keep the vector
+        // and the index consistent.
+        value_.pop_back();
+        throw;
+    }
+    return true;
 }
 
 inline bool
-STPathSet::contains(STPath const& path) const
+STPathSet::pushBack(STPath const& e)
 {
-    return seenHashes_.contains(path);
+    return appendUnique([&](auto& value) { value.push_back(e); });
+}
+
+template <typename... Args>
+inline bool
+STPathSet::emplaceBack(Args&&... args)
+{
+    return appendUnique([&](auto& value) { value.emplace_back(std::forward<Args>(args)...); });
 }
 
 }  // namespace xrpl

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();

include/xrpl/protocol/STValidation.h

@@ -124,6 +124,13 @@ public:
     [[nodiscard]] NodeID const&
     getNodeID() const noexcept;
 
+    /**
+     * Whether this validation carries a good signature.
+     *
+     * Reports false if the signature cannot be checked at all, so a caller
+     * cannot tell that apart from a bad signature. Either way the validation is
+     * unusable, and the reason is logged. Only a computed answer is remembered.
+     */
     [[nodiscard]] bool
     isValid() const noexcept;
 

include/xrpl/protocol/Serializer.h

@@ -10,6 +10,7 @@
 #include <xrpl/protocol/HashPrefix.h>
 #include <xrpl/protocol/SField.h>
 
+#include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <stdexcept>
@@ -25,6 +26,101 @@ private:
     Blob data_;
 
 public:
+    /**
+     * A header is never longer than this. The encoder fills a buffer of this
+     * size and writes only the bytes it used.
+     */
+    static constexpr int kMaxNumberOfBytesInHeader = 3;
+
+    // A field whose size varies is stored as a header holding its length, then
+    // the field data. The header is 1, 2 or 3 bytes long. Nothing outside it says
+    // which, so the decoder reads the first byte and its value says how long the
+    // header is:
+    //
+    //     0 ... 192   kMin/kMaxValueOfFirstByteFor1ByteHeader
+    //   193 ... 240   kMin/kMaxValueOfFirstByteFor2ByteHeader
+    //   241 ... 254   kMin/kMaxValueOfFirstByteFor3ByteHeader
+    //         255     belongs to no header
+    //
+    // Each range starts one past the end of the range before it.
+
+    static constexpr int kMinValueOfFirstByteFor1ByteHeader = 0;
+    static constexpr int kMaxValueOfFirstByteFor1ByteHeader = 192;
+
+    static constexpr int kMinValueOfFirstByteFor2ByteHeader =
+        kMaxValueOfFirstByteFor1ByteHeader + 1;
+    static constexpr int kMaxValueOfFirstByteFor2ByteHeader = 240;
+
+    static constexpr int kMinValueOfFirstByteFor3ByteHeader =
+        kMaxValueOfFirstByteFor2ByteHeader + 1;
+
+    static constexpr int kMaxValueOfFirstByteFor3ByteHeader = 254;
+
+    // A length x too big for one byte is split across the header. For 2 bytes:
+    //
+    //     first byte  = 193 + (x - 193) / 256
+    //     second byte = (x - 193) % 256
+    //
+    // so 300 is stored as 193, 107. For 3 bytes it is the same, from 241, with
+    // the remainder split across two bytes: 20,000 is stored as 241, 29, 95.
+
+    static constexpr int kNumberOfValuesInOneByte = 256;
+    static constexpr int kNumberOfValuesInTwoBytes =
+        kNumberOfValuesInOneByte * kNumberOfValuesInOneByte;
+
+    // Each header length therefore covers a range of field lengths:
+    //
+    //        0 ...     192   kMin/kMaxValueOfLengthFor1ByteHeader
+    //      193 ...  12,480   kMin/kMaxValueOfLengthFor2ByteHeader
+    //   12,481 ... 918,744   kMin/kMaxValueOfLengthFor3ByteHeader
+    //
+    // The encoder always uses the shortest header that fits.
+
+    /**
+     * A 1 byte header holds the length in the byte itself, so both ends of
+     * this range are the same numbers as the first byte's own range.
+     */
+    static constexpr int kMinValueOfLengthFor1ByteHeader = kMinValueOfFirstByteFor1ByteHeader;
+    static constexpr int kMaxValueOfLengthFor1ByteHeader = kMaxValueOfFirstByteFor1ByteHeader;
+
+    static constexpr int kMinValueOfLengthFor2ByteHeader = kMaxValueOfLengthFor1ByteHeader + 1;
+
+    /**
+     * 48 values of the first byte mean a 2 byte header, and each of them covers
+     * 256 lengths. The 48 is worked out from the two range ends above, so it
+     * stays right if either of them changes.
+     */
+    static constexpr int kMaxValueOfLengthFor2ByteHeader = kMinValueOfLengthFor2ByteHeader +
+        ((kMaxValueOfFirstByteFor2ByteHeader - kMaxValueOfFirstByteFor1ByteHeader) *
+         kNumberOfValuesInOneByte) -
+        1;
+
+    static constexpr int kMinValueOfLengthFor3ByteHeader = kMaxValueOfLengthFor2ByteHeader + 1;
+
+    /**
+     * 14 values of the first byte mean a 3 byte header, and each of them covers
+     * 65,536 lengths. Counted the same way, that gives the largest length any
+     * header can state.
+     *
+     * Nothing is accepted or rejected against this. The assertion below uses it
+     * to check that every length the encoder writes is one a header can state.
+     */
+    static constexpr int kMaxRepresentableLength = kMinValueOfLengthFor3ByteHeader +
+        ((kMaxValueOfFirstByteFor3ByteHeader - kMaxValueOfFirstByteFor2ByteHeader) *
+         kNumberOfValuesInTwoBytes) -
+        1;
+
+    /**
+     * The largest length the encoder will write. This is the one number here
+     * that is picked rather than worked out. The decoder accepts nothing above
+     * it, so both sides agree on the same set of lengths.
+     */
+    static constexpr int kMaxValueOfLengthFor3ByteHeader = 918744;
+
+    static_assert(
+        kMaxValueOfLengthFor3ByteHeader <= kMaxRepresentableLength,
+        "a length the encoder writes must be one a header can state");
+
     explicit Serializer(int n = 256)
     {
         data_.reserve(n);
@@ -61,7 +157,7 @@ public:
 
     // assemble functions
     int
-    add8(unsigned char i);
+    add8(unsigned char byteValue);
     int
     add16(std::uint16_t i);
 
@@ -270,18 +366,90 @@ public:
         return v.data_ == data_;
     }
 
+    /**
+     * Works out how long a header is, from its first byte.
+     *
+     * Each overload of decodeVLLength below reads one header length, so call
+     * this first to learn which of them to call.
+     *
+     * @param firstByte First byte of the header, as read from the stream.
+     * @return How many bytes the whole header takes, counting firstByte: 1, 2
+     * or 3.
+     * @throws std::overflow_error if firstByte is the one value that starts no
+     * header.
+     */
     static int
-    decodeLengthLength(int b1);
+    decodeLengthLength(std::byte firstByte);
+
+    /**
+     * Reads the field length out of a 1 byte header.
+     *
+     * @param firstByte The single header byte, which is the length itself.
+     * @return Field length in bytes, from kMinValueOfLengthFor1ByteHeader to
+     * kMaxValueOfLengthFor1ByteHeader.
+     * @throws std::overflow_error if firstByte is big enough to mean a longer
+     * header, in which case it is not a length by itself.
+     */
     static int
-    decodeVLLength(int b1);
+    decodeVLLength(std::byte firstByte);
+
+    /**
+     * Reads the field length out of a 2 byte header.
+     *
+     * @param firstByte First header byte. Its value means a 2 byte header, and
+     * how far it sits into that range gives the top part of the length.
+     * @param secondByte Second header byte, holding the rest of the length.
+     * @return Field length in bytes, from kMinValueOfLengthFor2ByteHeader to
+     * kMaxValueOfLengthFor2ByteHeader.
+     * @throws std::overflow_error if firstByte is outside the range that means
+     * a 2 byte header.
+     */
     static int
-    decodeVLLength(int b1, int b2);
+    decodeVLLength(std::byte firstByte, std::byte secondByte);
+
+    /**
+     * Reads the field length out of a 3 byte header.
+     *
+     * @param firstByte First header byte. Its value means a 3 byte header, and
+     * how far it sits into that range gives the top part of the length.
+     * @param secondByte Second header byte, holding the middle part of the
+     * length.
+     * @param thirdByte Third header byte, holding the low part.
+     * @return Field length in bytes, from kMinValueOfLengthFor3ByteHeader to
+     * kMaxValueOfLengthFor3ByteHeader.
+     * @throws std::overflow_error if firstByte is outside the range that means
+     * a 3 byte header, or if the three bytes together state a length above
+     * kMaxValueOfLengthFor3ByteHeader, which the encoder would not write back.
+     */
     static int
-    decodeVLLength(int b1, int b2, int b3);
+    decodeVLLength(std::byte firstByte, std::byte secondByte, std::byte thirdByte);
 
 private:
+    /**
+     * Works out how many bytes the header needs for the given length.
+     *
+     * This deliberately repeats the width choice addEncoded makes, so that
+     * addVL's assertion can compare the two. It has no other caller; do not
+     * reach for it as a utility.
+     *
+     * @param length Field length in bytes.
+     * @return How many header bytes it needs: 1, 2 or 3.
+     * @throws std::overflow_error if length is negative, or above
+     * kMaxValueOfLengthFor3ByteHeader.
+     */
     static int
-    encodeLengthLength(int length);  // length to encode length
+    encodeLengthLength(int length);
+
+    /**
+     * Appends the length header for a field of the given length.
+     *
+     * The field's own data is not written; the caller appends it next.
+     *
+     * @param length Field length in bytes.
+     * @return Offset within this Serializer at which the header was written.
+     * @throws std::overflow_error if length is negative, or above
+     * kMaxValueOfLengthFor3ByteHeader.
+     */
     int
     addEncoded(int length);
 };
@@ -390,9 +558,15 @@ public:
     void
     getFieldID(int& type, int& name);
 
-    // Returns the size of the VL if the
-    // next object is a VL. Advances the iterator
-    // to the beginning of the VL.
+    /**
+     * Reads the length header at the read position and steps past it.
+     *
+     * @return Field length in bytes. The iterator is left on the first byte of
+     * the field data.
+     * @throws std::overflow_error if the header states a length the encoder could
+     * not have written.
+     * @throws std::runtime_error if the data runs out before the header does.
+     */
     int
     getVLDataLength();
 

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)

include/xrpl/protocol/detail/STVar.h

@@ -34,10 +34,11 @@ concept ValidConstructSTArgs =
 // and includes a small-object allocation optimization.
 class STVar
 {
-private:
+public:
     // The largest "small object" we can accommodate
     static constexpr std::size_t kMaxSize = 72;
 
+private:
     alignas(std::max_align_t) std::byte d_[kMaxSize] = {};
     STBase* p_ = nullptr;
 

include/xrpl/protocol/detail/features.macro

@@ -18,7 +18,7 @@
 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)

include/xrpl/tx/ApplyContext.h

@@ -8,6 +8,7 @@
 #include <xrpl/ledger/ApplyViewImpl.h>
 #include <xrpl/ledger/OpenView.h>
 #include <xrpl/ledger/RawView.h>
+#include <xrpl/protocol/Book.h>
 #include <xrpl/protocol/STAmount.h>
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/TER.h>
@@ -129,6 +130,14 @@ public:
         view_->rawDestroyXRP(fee);
     }
 
+    /**
+     * Registers a newly-created order book directory with the shared,
+     * process-wide OrderBookDB, unless this transaction is being applied
+     * under TapDryRun.
+     */
+    void
+    addOrderBook(Book const& book);
+
     ApplyViewContext
     getApplyViewContext()
     {

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

include/xrpl/tx/applySteps.h

@@ -12,6 +12,7 @@
 #include <xrpl/protocol/XRPAmount.h>
 
 #include <cstdint>
+#include <expected>
 #include <optional>
 #include <utility>
 
@@ -393,16 +394,21 @@ preclaim(PreflightResult const& preflightResult, ServiceRegistry& registry, Open
  *
  * No validation is done or implied by this function.
  *
- * Caller is responsible for handling any exceptions.
- * Since none should be thrown, that will usually
- * mean terminating.
- *
+ * Callers do not expect this function to throw; exceptions from a transactor's
+ * `calculateBaseFee` are caught and reported as an error instead.
  * @param view The current open ledger.
  * @param tx The transaction to be checked.
  *
- * @return The base fee.
+ * @return The base fee on success. Returns `std::unexpected(temUNKNOWN)` if the transaction
+ * type is not recognized, and `std::unexpected(tefEXCEPTION)` if the transactor's
+ * `calculateBaseFee` threw.
+ *
+ * @note Failure is reported as an error rather than a fee of zero because a
+ * zero (or default) fee would pass checkFee and let the transaction be
+ * applied for less than it owes. Callers that only need a fee hint may fall
+ * back to a default; callers deciding whether to apply should reject.
  */
-XRPAmount
+[[nodiscard]] std::expected<XRPAmount, TER>
 calculateBaseFee(ReadView const& view, STTx const& tx);
 
 /**

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_;

include/xrpl/tx/invariants/LoanInvariant.h

@@ -15,9 +15,35 @@ 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: neither `PrincipalOutstanding` nor
+ *          `TotalValueOutstanding` increases, and at least one of them
+ *          strictly decreases;
+ *          `PaymentRemaining` strictly decreases;
+ *          `NextPaymentDueDate` advances by N * `PaymentInterval`, N > 0.
+ *       `PaymentRemaining == 0` after: pinned by checks 1 and 5b.
  *
  */
 class ValidLoan
@@ -25,6 +51,9 @@ 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

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:
     /**

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;

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);

package/Dockerfile

@@ -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

package/README.md

@@ -10,10 +10,13 @@ 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.in, lintian-overrides.in, rules, copyright, docs, links, source/format).
+                    The `.in` files are templates rendered by `build_pkg.py`; `docs` and `links` are staged under the package name
   shared/
     xrpld.service       systemd unit file (used by both RPM and DEB)
     xrpld.sysusers      sysusers.d config (used by both RPM and DEB)
@@ -23,46 +26,109 @@ package/
 
 ## Prerequisites
 
-Packaging targets and their container images are declared in
-[`.github/scripts/strategy-matrix/linux.json`](../.github/scripts/strategy-matrix/linux.json)
-under `package_configs`, one entry per distro. Today only `linux/amd64` is
-emitted. Each entry pins its full container image in an `image` field; to move
-to a new image, edit that field and both CI and local builds pick it up. The
-entry also declares the format that image builds in a `package_type` field,
-which CI passes to `build_pkg.py` as `--package-type`; the two have to stay in
-step.
+Packaging is declared on the build configs themselves, in
+[`.github/scripts/strategy-matrix/linux.json`](../.github/scripts/strategy-matrix/linux.json):
+a config that is also packaged carries a `package` map, so its binaries and its
+packaging job cannot drift apart. Today only `linux/amd64` is emitted. The map
+pins the full container image in `image` — edit that field to move to a new
+image and both CI and local builds pick it up — and names the format that image
+builds in `type`, which CI passes to `build_pkg.py` as `--package-type`; the two
+have to stay in step. An optional `variant` names a flavour of the package (see
+[Package variants](#package-variants)), and CI passes it as `--variant`.
 
-| Package type | Image (`package_configs.<distro>[].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`:
+To print the full packaging matrix (artifact names, images and package names)
+for the current `linux.json`:
 
 ```bash
 ./.github/scripts/strategy-matrix/generate.py --packaging
 ```
 
+## Package variants
+
+A config whose binaries are not the plain release build cannot be packaged as
+`xrpld`: both would carry the same name and version, so whichever published last
+would win. It is packaged as a **variant** instead — `variant: "assert"` in its
+`package` map, which CI passes to `build_pkg.py` as `--variant assert`,
+producing `xrpld-assert`. What the build option itself does is a build concern,
+not a packaging one; see the options table in [`BUILD.md`](../BUILD.md).
+
+A variant ships the same paths as `xrpld` — `/usr/bin/xrpld`, `/etc/xrpld`,
+`xrpld.service`, `/etc/logrotate.d/xrpld` — differing only in the per-package
+documentation directory, so it declares itself a stand-in for the plain package
+rather than something installable next to it: `Conflicts`, `Replaces` and a
+versioned `Provides: xrpld` on Debian, `Conflicts` and `Provides` on RPM.
+Neither format declares `Obsoletes`, so `apt upgrade` and `dnf upgrade` keep an
+installed flavour on its own flavour, and switching is always explicit:
+
+```bash
+apt-get install xrpld-assert # apt removes the plain package itself
+dnf swap xrpld xrpld-VARIANT # 'dnf install' alone stops at the conflict
+```
+
+Only the DEB packages carry a variant today — `xrpld-assert` comes from the
+`debian` config alone, there being no call for an assert build on RHEL-based
+distributions — but the RPM side works the same way if one is added.
+
+A switch is a removal plus an installation rather than an upgrade, so unlike a
+version upgrade it stops the service: Debian's scriptlets start it again, while
+on RPM the operator runs `systemctl start xrpld`. Configuration survives either
+way, being conffiles on Debian and `%config(noreplace)` on RPM.
+
+`dnf` installs the replacement before erasing the old flavour, whose `%preun`
+would leave `xrpld.service` disabled, so `%postun` re-applies the preset when
+the unit file outlives the erase — which, since rpm keeps a file another
+installed package owns, happens only during a swap. The cost is that a
+deliberate `systemctl disable` is not carried across an RPM switch.
+
+The alternative is an `xrpld-common` package owning the unit, the sysusers and
+tmpfiles snippets and the configuration, required by both flavours at an exact
+version: nothing is erased mid-swap, so no scriptlet has to detect one. It is
+not worth it for a single variant — it moves files out of the production
+package, and a sanitizer flavour would likely need its own unit anyway, putting
+the lifecycle back where it is now.
+
+Adding a variant is the flavour in `VARIANTS` in `build_pkg.py`, which is the
+list `--variant` accepts, plus a config in `linux.json` with the CMake arguments
+and a `package` map naming it, for one format or for both: `generate.py
+--packaging` emits the package names per format, and the `test-install-deb` and
+`test-install-rpm` jobs install what their own format produced.
+
+Operators switch between the flavours as described in
+[`docs/install.md`](../docs/install.md#optional-the-assert-enabled-build).
+
 ## Building packages
 
 ### 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
-`package_configs` in `linux.json` (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 its
-`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:
 
-The binaries come from the `debian` and `rhel` build configurations in
-`linux.json`'s `configs` section, which pass `-Dvalidator_keys=ON` so that the
+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-deb` and `test-install-rpm` call
+   [`reusable-package-test-install.yml`](../.github/workflows/reusable-package-test-install.yml)
+   with their format's package names and distro images, installing each package
+   in the container of every distro that format targets and running 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
 build job produces `validator-keys` next to `xrpld` and uploads it as the
-`validator-keys-<config name>` artifact. The packaging entry for a distro names
-both artifacts (`xrpld_artifact_name` and `validator_keys_artifact_name`), so a
-packaged configuration must keep `-Dvalidator_keys=ON`.
+`validator-keys-<config name>` artifact. The packaging matrix names both
+artifacts (`xrpld_artifact_name` and `validator_keys_artifact_name`) after that
+same config, so a packaged config must keep `-Dvalidator_keys=ON`. Those configs
+are not `minimal`, so `on-pr.yml` only packages once a PR runs the full matrix.
 
 `validator-keys` is fetched from an exact commit pinned in
 [`cmake/XrplValidatorKeys.cmake`](../cmake/XrplValidatorKeys.cmake), so a given
@@ -75,10 +141,10 @@ With `xrpld` and `validator-keys` binaries already built at `build/xrpld` and
 The image tag is derived from `linux.json` so you don't need to hardcode a SHA.
 
 ```bash
-# From the repo root. Each distro's container image is the `image` field of its
-# package_configs entry in linux.json. Example for the rpm-producing image (use
-# .package_configs.debian[0].image and --package-type deb for the other one):
-IMAGE=$(jq -r '.package_configs.rhel[0].image' .github/scripts/strategy-matrix/linux.json)
+# From the repo root. Each distro's container image is the `package.image` field
+# of its config in linux.json. Example for the rpm-producing image (use
+# .configs.debian[0].package.image and --package-type deb for the other one):
+IMAGE=$(jq -r '.configs.rhel[0].package.image' .github/scripts/strategy-matrix/linux.json)
 
 PKG_RELEASE=1
 
@@ -91,11 +157,13 @@ 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
 ```
 
+Add `--variant assert` to package binaries built with `-Dassert=ON`; the package
+is then named `xrpld-assert`.
+
 ### Via CMake (host-side target)
 
 If you run CMake configure on a host that has `rpmbuild` or `dpkg-buildpackage`
@@ -125,6 +193,9 @@ The package version is not a CMake input on this path: `build_pkg.py` derives it
 from the just-built `xrpld` binary's `xrpld --version` output. The package
 release defaults to 1 and is overridable with `-Dpkg_release=N`.
 
+`-Dassert=ON` passes `--variant assert`, so such a build packages as
+`xrpld-assert` without anything else being asked for.
+
 ## Publishing packages
 
 Packages are published to the XRPLF repositories on Sonatype Nexus at
@@ -139,6 +210,9 @@ the event, and `publish_pkg.py` maps that channel to its repositories:
 | push to `develop`        | `xrpld --version` | `develop` | `deb-develop`  | `rpm-develop-hosted`  |
 | tag, non-public codebase | _any_             | `private` | `deb-private`  | `rpm-private-hosted`  |
 
+A variant is published to the same channel under its own name, so
+`xrpld-assert` never overwrites `xrpld`.
+
 Only a tag names a channel — do not extend that to `develop`, where
 `BuildInfo.cpp`'s `versionString` moves through `-bN`, `-rcN` and even the final
 version during a release cycle, which would send develop builds into `stable`.
@@ -146,22 +220,28 @@ 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 the install tests, 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:
 
 - Each apt-hosted repository needs a distribution (ours use `any`) and a PGP
   signing keypair configured in Nexus, which rejects one created without a
   keypair. Nexus signs the apt metadata with it, never the packages.
-- Hosted yum repositories cannot be signed by Nexus, so each `rpm-<channel>-hosted`
+- yum-hosted repositories cannot be signed by Nexus, so each `rpm-<channel>-hosted`
   repository sits behind a `rpm-<channel>` yum group repository whose metadata
   Nexus signs. Uploads go to the hosted repository; clients point at the group
   and verify the metadata with `repo_gpgcheck=1`. Nexus never signs the RPMs
@@ -175,6 +255,12 @@ 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
@@ -187,6 +273,9 @@ 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.
@@ -221,6 +310,19 @@ pre-release ordering convention, so RPM filenames/NVRs begin with forms like
 `xrpld-3.2.0~b1-...` and `xrpld-3.2.0~rc1-...` instead of encoding
 pre-releases with an older `0.<release>.<suffix>` RPM `Release` value.
 
+`--variant` is the flavour of the package, empty by default and accepting only
+the flavours in `VARIANTS`; see [Package variants](#package-variants). The RPM
+path passes it to the spec as the `pkg_variant` macro, which suffixes `Name` and
+adds the `Conflicts`/`Provides` pair. Debian control files have no conditionals, so the DEB path renders
+`debian/control.in` and `debian/lintian-overrides.in` instead, substituting
+`@PKG@` with the package name and `@VARIANT_FIELDS@` with the
+`Conflicts`/`Replaces`/`Provides` block, empty for the plain package; a token
+with no value fails the build rather than reaching dpkg. The files debhelper
+keys by package name (`docs`, `links`, and the units) are staged under that same
+name. The paths inside the package are unchanged either way, so `debian/rules`
+reads its package name from `dh_listpackages` and names the unit, sysusers,
+tmpfiles and logrotate files with `--name xrpld`.
+
 The package format is `--package-type`, either `deb` or `rpm`. It is required,
 so a job never silently builds the wrong format for the image it runs in; the
 matching build tool still has to be on PATH.
@@ -263,38 +365,51 @@ service restart.
 1. Creates a staging source tree at `debbuild/source/` inside the build directory.
 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.
+3. Stages `package/debian/` into `debbuild/source/debian/`: the `.in` templates
+   are rendered, and the files debhelper keys by package name (`docs`, `links`,
+   `lintian-overrides`) are staged under the name being built.
+4. Copies shared service/sysusers/tmpfiles/logrotate into `debian/` as
+   `<package>.xrpld.*`, which `dh_installsystemd`, `dh_installsysusers`,
+   `dh_installtmpfiles` and `dh_installlogrotate` read because `debian/rules`
+   passes them `--name xrpld`.
 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.

package/build_pkg.py

@@ -19,7 +19,15 @@ 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]+)(\+.*)?$")
+PRE_RELEASE = re.compile(r"^(b|rc)(0|[1-9][0-9]*)(\+.*)?$")
+
+# The package name a variant suffixes, and the name every variant keeps for its
+# on-disk paths (/usr/bin/xrpld, /etc/xrpld, xrpld.service).
+BASE_NAME = "xrpld"
+
+# The flavours that can be built, '' being the plain xrpld package. A variant
+# needs a config in linux.json to be built by CI; see package/README.md.
+VARIANTS = ("", "assert")
 
 # Files both packaging systems consume, staged under the same names.
 STAGED_FROM_BUILD = ("xrpld", "validator-keys", "validator-keys-LICENSE")
@@ -31,6 +39,18 @@ STAGED_FROM_SRC = {
 }
 STAGED_UNITS = ("xrpld.service", "xrpld.sysusers", "xrpld.tmpfiles", "xrpld.logrotate")
 
+# debian/ files debhelper keys by package name, staged as '<package>.<name>'.
+DEBIAN_PKG_FILES = ("docs", "links")
+
+# Debian control files have no conditionals, so what makes a variant replace the
+# plain package is rendered into control.in rather than written there.
+DEB_VARIANT_FIELDS = """\
+Conflicts: xrpld
+Replaces: xrpld
+Provides: xrpld (= ${binary:Version})"""
+
+TOKEN = re.compile(r"@[A-Z_]+@")
+
 
 def run(*command: object, cwd: Path | None = None) -> None:
     """Echo a command and run it."""
@@ -75,6 +95,28 @@ def package_version(reported: str) -> str:
     return version
 
 
+def render(template: Path, dest: Path, values: dict[str, str]) -> None:
+    """Write template to dest with its @TOKEN@ placeholders substituted.
+
+    A token left without a value fails the build rather than reaching dpkg.
+    """
+    text = template.read_text()
+    for token, value in values.items():
+        text = text.replace(f"@{token}@", value)
+
+    missing = sorted(set(TOKEN.findall(text)))
+    assert not missing, f"{template}: no value for {', '.join(missing)}"
+
+    # An empty value at the end of a stanza would otherwise leave a blank line,
+    # which is what ends a stanza.
+    dest.write_text(text.rstrip("\n") + "\n")
+
+
+def package_name(variant: str) -> str:
+    """The binary package name for a variant: '' -> xrpld, 'assert' -> xrpld-assert."""
+    return f"{BASE_NAME}-{variant}" if variant else BASE_NAME
+
+
 def read_version(xrpld: Path) -> str:
     """Read the version from the binary that is about to be packaged."""
     fields = capture(xrpld, "--version").partition("\n")[0].split()
@@ -133,11 +175,20 @@ 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, *, prefix: str = "") -> None:
+    """Copy the systemd, sysusers, tmpfiles and logrotate files into dest.
+
+    Each format wants them somewhere else: rpmbuild reads them from SOURCES by
+    path, debhelper from debian/ by package name -- hence 'prefix', which makes
+    the copies 'xrpld-assert.xrpld.service' and so on.
+    """
     for name in STAGED_UNITS:
-        shutil.copy2(SRC_DIR / "package" / "shared" / name, dest / name)
+        shutil.copy2(SRC_DIR / "package" / "shared" / name, dest / f"{prefix}{name}")
 
 
-def build_rpm(build_dir: Path, *, version: str, pkg_release: str) -> None:
+def build_rpm(build_dir: Path, *, version: str, pkg_release: str, variant: str) -> None:
     """Stage the spec and its sources, then build the binary RPMs."""
     topdir = build_dir / "rpmbuild"
     for name in ("BUILD", "BUILDROOT", "RPMS", "SOURCES", "SPECS", "SRPMS"):
@@ -146,6 +197,10 @@ 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")
+
+    # The spec defaults it to nothing, so a plain build is unchanged.
+    variant_defines = ["--define", f"pkg_variant {variant}"] if variant else []
 
     run(
         "rpmbuild",
@@ -159,10 +214,29 @@ def build_rpm(build_dir: Path, *, version: str, pkg_release: str) -> None:
         # The image tracks the newest distro, but the packages target el9.
         "--define",
         "dist .el9",
+        *variant_defines,
         spec,
     )
 
 
+def stage_debian(dest: Path, name: str) -> None:
+    """Stage the debian directory for the package name being built."""
+    source = SRC_DIR / "package" / "debian"
+    shutil.copytree(
+        source, dest, ignore=shutil.ignore_patterns("*.in", *DEBIAN_PKG_FILES)
+    )
+
+    values = {
+        "PKG": name,
+        "VARIANT_FIELDS": "" if name == BASE_NAME else DEB_VARIANT_FIELDS,
+    }
+    render(source / "control.in", dest / "control", values)
+    render(source / "lintian-overrides.in", dest / f"{name}.lintian-overrides", values)
+
+    for suffix in DEBIAN_PKG_FILES:
+        shutil.copy2(source / suffix, dest / f"{name}.{suffix}")
+
+
 def build_deb(
     build_dir: Path,
     *,
@@ -171,30 +245,29 @@ def build_deb(
     pkg_release: str,
     channel: str,
     epoch: int,
+    name: str,
 ) -> None:
     """Stage the debian directory and its sources, then build the binary DEBs."""
     staging = build_dir / "debbuild" / "source"
     stage_common(build_dir, staging)
-    shutil.copytree(SRC_DIR / "package" / "debian", staging / "debian")
+    stage_debian(staging / "debian", name)
 
-    # debhelper picks these up from debian/ automatically.
-    for name in STAGED_UNITS:
-        shutil.copy2(staging / name, staging / "debian" / name)
+    # Prefixed whether it is a variant's name or not: debian/rules names them
+    # explicitly either way.
+    stage_units(staging / "debian", prefix=f"{name}.")
 
     date = datetime.fromtimestamp(epoch, timezone.utc).strftime(
         "%a, %d %b %Y %H:%M:%S %z"
     )
     # The leading spaces are significant to dpkg.
     changelog = textwrap.dedent(f"""\
-        xrpld ({version}-{pkg_release}) {channel}; urgency=medium
+        {name} ({version}-{pkg_release}) {channel}; urgency=medium
           * Release {reported}.
 
          -- XRPL Foundation <contact@xrplf.org>  {date}
         """)
     (staging / "debian" / "changelog").write_text(changelog)
 
-    (staging / "debian" / "rules").chmod(0o755)
-
     run("dpkg-buildpackage", "-b", "--no-sign", "-d", cwd=staging)
 
 
@@ -217,6 +290,14 @@ def main() -> None:
         default="1",
         help="package release iteration (default: %(default)s)",
     )
+    parser.add_argument(
+        "--variant",
+        default="",
+        choices=VARIANTS,
+        help="the flavour of the package to build: 'assert' produces "
+        "xrpld-assert, which ships the same paths as xrpld and replaces it "
+        "(default: the plain xrpld package)",
+    )
     parser.add_argument(
         "--channel",
         required=True,
@@ -228,6 +309,8 @@ def main() -> None:
     build_dir: Path = args.build_dir.resolve()
     pkg_release: str = args.pkg_release
     channel: str = args.channel
+    variant: str = args.variant
+    name = package_name(variant)
 
     assert build_dir.is_dir(), (
         f"build directory not found: {build_dir}. Build the binaries before "
@@ -247,6 +330,8 @@ def main() -> None:
     for tree in ("debbuild", "rpmbuild"):
         shutil.rmtree(build_dir / tree, ignore_errors=True)
 
+    print(f"Building {package_type} {name} {version}-{pkg_release}", flush=True)
+
     if package_type == "deb":
         build_deb(
             build_dir,
@@ -255,9 +340,10 @@ def main() -> None:
             pkg_release=pkg_release,
             channel=channel,
             epoch=epoch,
+            name=name,
         )
     else:
-        build_rpm(build_dir, version=version, pkg_release=pkg_release)
+        build_rpm(build_dir, version=version, pkg_release=pkg_release, variant=variant)
 
 
 if __name__ == "__main__":

package/debian/control.in

@@ -1,18 +1,17 @@
-Source: xrpld
+Source: @PKG@
 Section: net
 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
 Vcs-Git: https://github.com/XRPLF/rippled.git
 Vcs-Browser: https://github.com/XRPLF/rippled
 
-Package: xrpld
-Section: net
-Priority: optional
+Package: @PKG@
 Architecture: any
 Depends:
  ${shlibs:Depends},
@@ -23,3 +22,4 @@ Description: XRP Ledger daemon
  transactions, and maintains the ledger database.
  This package also includes the validator-keys tool for validator key
  management.
+@VARIANT_FIELDS@

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.

package/debian/docs

@@ -1,2 +1,3 @@
 README.md
+LICENSE.md
 validator-keys-LICENSE

package/debian/links

@@ -0,0 +1,3 @@
+# Legacy compatibility for pre-FHS package layouts.
+# TODO: remove after rippled fully deprecated.
+usr/bin/xrpld          usr/local/bin/rippled

package/debian/lintian-overrides.in

@@ -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/links after rippled fully deprecated.
+@PKG@: dir-in-usr-local [usr/local/bin/]
+@PKG@: file-in-usr-local [usr/local/bin/rippled]
+@PKG@: file-in-unusual-dir [usr/local/bin/rippled]

package/debian/rules

@@ -2,25 +2,76 @@
 
 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
+
+# The binary package's name, which a variant build changes to e.g. xrpld-assert,
+# and the directory debhelper expects its files staged in.
+PKG := $(firstword $(shell dh_listpackages))
+PKG_DIR = debian/$(PKG)
+
+# The base name, which every package ships under whatever it is called itself.
+BASE_NAME = xrpld
+
+# What build_pkg.py stages beside this directory, each installed under its own
+# name. The binaries are also the ones checked against LIBC_MIN below.
+BINARIES = $(BASE_NAME) validator-keys
+CONFIGS = $(BASE_NAME).cfg validators.txt
+
 %:
 	dh $@
 
 override_dh_auto_configure override_dh_auto_build override_dh_auto_test:
 	@:
 
+# The unit, sysusers, tmpfiles and logrotate files are named after the daemon
+# rather than after the package, so a variant still ships xrpld.service and
+# /etc/logrotate.d/xrpld. debhelper only reads debian/$(PKG).$(BASE_NAME).* when told
+# the name.
 override_dh_installsystemd:
-	dh_installsystemd --no-stop-on-upgrade xrpld.service
+	dh_installsystemd --no-stop-on-upgrade --name $(BASE_NAME)
 
+# 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
+	dh_installsysusers --name $(BASE_NAME)
 
 override_dh_installsysusers:
 
+override_dh_installtmpfiles:
+	dh_installtmpfiles --name $(BASE_NAME)
+
+override_dh_installlogrotate:
+	dh_installlogrotate --name $(BASE_NAME)
+
 override_dh_install:
-	install -D -m 0755 xrpld            debian/xrpld/usr/bin/xrpld
-	install -D -m 0755 validator-keys   debian/xrpld/usr/bin/validator-keys
-	install -D -m 0644 xrpld.cfg        debian/xrpld/etc/xrpld/xrpld.cfg
-	install -D -m 0644 validators.txt   debian/xrpld/etc/xrpld/validators.txt
+	for binary in $(BINARIES); do \
+		install -D -m 0755 "$$binary" "$(PKG_DIR)/usr/bin/$$binary"; \
+	done
+	for config in $(CONFIGS); do \
+		install -D -m 0644 "$$config" "$(PKG_DIR)/etc/$(BASE_NAME)/$$config"; \
+	done
+
+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 $(BINARIES); 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 (>= $(LIBC_MIN))/' debian/$(PKG).substvars
 
 override_dh_dwz:
 	@:

package/debian/xrpld.links

@@ -1,2 +0,0 @@
-# Legacy compat symlinks (remove next major release)
-usr/bin/xrpld          usr/local/bin/rippled

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

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("*")

package/rpm/xrpld.spec

@@ -6,10 +6,14 @@
 %{error:pkg_release must be defined}
 %endif
 
-Name:     xrpld
+# The base name, which every package ships under. A variant build
+# (build_pkg.py --variant) only suffixes the package name, e.g. xrpld-assert.
+%global base_name xrpld
+
+Name:     %{base_name}%{?pkg_variant:-%{pkg_variant}}
 Version:  %{pkg_version}
 Release:  %{pkg_release}%{?dist}
-Summary:  XRP Ledger daemon
+Summary:  XRP Ledger daemon%{?pkg_variant: (%{pkg_variant} build)}
 
 License:  ISC
 URL:      https://github.com/XRPLF/rippled
@@ -17,6 +21,17 @@ URL:      https://github.com/XRPLF/rippled
 ExclusiveArch: x86_64 aarch64
 BuildRequires: systemd-rpm-macros
 
+# A variant owns the same paths, so it stands in for the plain package.
+%if "%{?pkg_variant}" != ""
+Conflicts: %{base_name}
+Provides:  %{base_name} = %{version}-%{release}
+%endif
+
+# 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 +40,13 @@ 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
@@ -44,22 +62,22 @@ management.
 :
 
 %install
-install -Dm0755 %{_sourcedir}/xrpld                %{buildroot}%{_bindir}/%{name}
+install -Dm0755 %{_sourcedir}/xrpld                %{buildroot}%{_bindir}/%{base_name}
 install -Dm0755 %{_sourcedir}/validator-keys       %{buildroot}%{_bindir}/validator-keys
-install -Dm0644 %{_sourcedir}/xrpld.cfg            %{buildroot}%{_sysconfdir}/%{name}/xrpld.cfg
-install -Dm0644 %{_sourcedir}/validators.txt       %{buildroot}%{_sysconfdir}/%{name}/validators.txt
+install -Dm0644 %{_sourcedir}/xrpld.cfg            %{buildroot}%{_sysconfdir}/%{base_name}/xrpld.cfg
+install -Dm0644 %{_sourcedir}/validators.txt       %{buildroot}%{_sysconfdir}/%{base_name}/validators.txt
 
 # systemd units, sysusers, tmpfiles, preset
 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
-cat >%{buildroot}%{_presetdir}/50-xrpld.preset <<'EOF'
+install -d %{buildroot}%{_presetdir}
+cat >%{buildroot}%{_presetdir}/50-%{base_name}.preset <<'EOF'
 enable xrpld.service
 EOF
 
 # Logrotate config
-install -Dm0644 %{_sourcedir}/xrpld.logrotate      %{buildroot}%{_sysconfdir}/logrotate.d/%{name}
+install -Dm0644 %{_sourcedir}/xrpld.logrotate      %{buildroot}%{_sysconfdir}/logrotate.d/%{base_name}
 
 # Docs
 install -Dm0644 %{_sourcedir}/LICENSE.md %{buildroot}%{_docdir}/%{name}/LICENSE.md
@@ -70,13 +88,13 @@ install -Dm0644 %{_sourcedir}/validator-keys-LICENSE %{buildroot}%{_docdir}/%{na
 # Legacy compatibility for pre-FHS package layouts.
 # TODO: remove after rippled fully deprecated.
 install -d %{buildroot}/usr/local/bin
-ln -s %{_bindir}/%{name} %{buildroot}/usr/local/bin/rippled
+ln -s %{_bindir}/%{base_name} %{buildroot}/usr/local/bin/rippled
 
 %pre
-%sysusers_create_package %{name} %{_sourcedir}/xrpld.sysusers
+%sysusers_create_package %{base_name} %{_sourcedir}/xrpld.sysusers
 
 %post
-systemd-tmpfiles --create %{_tmpfilesdir}/xrpld.conf || :
+%tmpfiles_create_package %{base_name} %{_sourcedir}/xrpld.tmpfiles
 %systemd_post xrpld.service
 
 %preun
@@ -84,24 +102,32 @@ systemd-tmpfiles --create %{_tmpfilesdir}/xrpld.conf || :
 
 %postun
 %systemd_postun xrpld.service
+# A flavour swap installs the replacement before erasing this package, so the
+# %%preun above has just disabled a unit the replacement still owns. rpm keeps a
+# file that another installed package owns, so the unit outliving our own erase
+# means exactly that; a plain erase takes it with us and re-presets nothing.
+if [ $1 -eq 0 ] && [ -f %{_unitdir}/xrpld.service ]; then
+    systemctl preset xrpld.service >/dev/null 2>&1 || :
+fi
 
 %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}/%{base_name}
 
-%{_bindir}/%{name}
+%{_bindir}/%{base_name}
 %{_bindir}/validator-keys
 
-%config(noreplace) %{_sysconfdir}/%{name}/xrpld.cfg
-%config(noreplace) %{_sysconfdir}/%{name}/validators.txt
-%config(noreplace) %{_sysconfdir}/logrotate.d/%{name}
+%config(noreplace) %{_sysconfdir}/%{base_name}/xrpld.cfg
+%config(noreplace) %{_sysconfdir}/%{base_name}/validators.txt
+%config(noreplace) %{_sysconfdir}/logrotate.d/%{base_name}
 
 
 %{_unitdir}/xrpld.service
-%{_presetdir}/50-xrpld.preset
+%attr(0644,root,root) %{_presetdir}/50-%{base_name}.preset
 %{_sysusersdir}/xrpld.conf
 %{_tmpfilesdir}/xrpld.conf
 %ghost %dir /var/lib/xrpld

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

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}"

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
     {

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);

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>

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)
 {

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());

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.

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,

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)
 {

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"
     // clang-format on
     ;
 

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(),

src/libxrpl/protocol/NFTSyntheticSerializer.cpp

@@ -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

src/libxrpl/protocol/STPathSet.cpp

@@ -1,6 +1,8 @@
 #include <xrpl/protocol/STPathSet.h>
 
+#include <xrpl/basics/CountedObject.h>
 #include <xrpl/basics/Log.h>
+#include <xrpl/basics/UnorderedContainers.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/contract.h>
 #include <xrpl/beast/hash/uhash.h>
@@ -11,10 +13,12 @@
 #include <xrpl/protocol/STBase.h>
 #include <xrpl/protocol/Serializer.h>
 #include <xrpl/protocol/UintTypes.h>
+#include <xrpl/protocol/detail/STVar.h>
 #include <xrpl/protocol/jss.h>
 
 #include <algorithm>
 #include <cstddef>
+#include <memory>
 #include <stdexcept>
 #include <utility>
 #include <vector>
@@ -31,6 +35,11 @@ STPathElement::getHash(STPathElement const& element)
     // NIKB NOTE: This doesn't have to be a secure hash as speed is more
     //            important. We don't even really need to fully hash the whole
     //            base_uint here, as a few bytes would do for our use.
+    //
+    // The note above is only true because the result of this function reaches
+    // nothing but STPathElement::operator==, where it is a fast-reject
+    // prefilter ahead of the field comparisons that decide the answer.  Do not
+    // use it to key a container.
 
     for (auto const x : element.getAccountID())
         hashAccount += (hashAccount * 257) ^ x;
@@ -51,10 +60,49 @@ STPathElement::getHash(STPathElement const& element)
     return (hashAccount ^ hashCurrency ^ hashIssuer);
 }
 
-[[nodiscard]] size_t
-STPathElement::getHash() const
+// For guidance on deciding which option to pursue:
+// 1. Try to decrease the size of the STPathSet first.  For instance, if a std::optional was
+//    injected into the type, could you get the same functionality using a std::unique_ptr instead?
+// 2. If the size of the STPathSet is already as small as it can be, then consider what the cost
+//    of increasing STVar::kMaxSize would be on all the other STVar types.  Each of those types
+//    will carry the additional cost of accommodating the larger STPathSet in their SBO.
+// 3. If the cost of increasing STVar::kMaxSize is too high, then heap allocate the STPathSet and
+//    remove this static_assert.
+static_assert(
+    sizeof(STPathSet) <= detail::STVar::kMaxSize,
+    "STPathSet is too large to fit in STVar's small object optimization. Please verify if it "
+    "should, if the kMaxSize should be increased, or if STPathSet should be stored on the heap "
+    "instead of in STVar.");
+
+STPathSet::STPathSet(DeduplicationTag) : seen_{std::make_unique<hardened_hash_set<STPath>>()}
 {
-    return STPathElement::getHash(*this);
+}
+
+STPathSet::STPathSet(STPathSet const& other)
+    : STBase{other}
+    , CountedObject<STPathSet>{other}
+    , value_{other.value_}
+    , seen_{
+          other.seen_ != nullptr ? std::make_unique<hardened_hash_set<STPath>>(*other.seen_)
+                                 : nullptr}
+{
+}
+
+STPathSet&
+STPathSet::operator=(STPathSet const& other)
+{
+    if (this == &other)
+    {
+        return *this;
+    }
+    auto newSeen = other.seen_ != nullptr
+        ? std::make_unique<hardened_hash_set<STPath>>(*other.seen_)
+        : nullptr;
+    STBase::operator=(other);
+    CountedObject<STPathSet>::operator=(other);
+    value_ = other.value_;
+    seen_ = std::move(newSeen);
+    return *this;
 }
 
 STPathSet::STPathSet(SerialIter& sit, SField const& name) : STBase(name)
@@ -72,7 +120,8 @@ STPathSet::STPathSet(SerialIter& sit, SField const& name) : STBase(name)
                 Throw<std::runtime_error>("empty path");
             }
 
-            pushBack(path);
+            // Move rather than converting the vector to an STPath by copy.
+            value_.emplace_back(std::move(path));
             path.clear();
 
             if (iType == STPathElement::TypeNone)
@@ -132,16 +181,10 @@ STPathSet::move(std::size_t n, void* buf)
 bool
 STPathSet::assembleAdd(STPath const& base, STPathElement const& tail)
 {  // assemble base+tail and add it to the set if it's not a duplicate
+    XRPL_ASSERT(seen_ != nullptr, "xrpl::STPathSet::assembleAdd : DeduplicationTag");
     STPath combined = base;
     combined.pushBack(tail);
-
-    if (!seenHashes_.insert(combined).second)
-    {
-        return false;
-    }
-
-    value_.push_back(std::move(combined));
-    return true;
+    return appendUnique([&](auto& value) { value.push_back(std::move(combined)); });
 }
 
 bool

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

src/libxrpl/protocol/STValidation.cpp

@@ -1,6 +1,7 @@
 #include <xrpl/protocol/STValidation.h>
 
 #include <xrpl/basics/Blob.h>
+#include <xrpl/basics/Log.h>
 #include <xrpl/basics/Slice.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/chrono.h>
@@ -15,6 +16,7 @@
 #include <xrpl/protocol/Serializer.h>
 
 #include <cstddef>
+#include <exception>
 #include <utility>
 
 namespace xrpl {
@@ -104,11 +106,42 @@ STValidation::isValid() const noexcept
             publicKeyType(getSignerPublic()) == KeyType::Secp256k1,
             "xrpl::STValidation::isValid : valid key type");
 
-        valid_ = verifyDigest(
-            getSignerPublic(),
-            getSigningHash(),
-            makeSlice(getFieldVL(sfSignature)),
-            (getFlags() & kVfFullyCanonicalSig) != 0u);
+        // Log that the signature was never checked, so an operator does not
+        // read this as a bad key. The log is guarded because it can throw too.
+        auto reportUncheckable = [this](char const* reason) noexcept {
+            try
+            {
+                JLOG(debugLog().error())
+                    << "Cannot check the signature of the validation for ledger " << getLedgerHash()
+                    << ": " << reason;
+            }
+            catch (...)  // NOLINT(bugprone-empty-catch)
+            {
+                // Nothing can be reported when reporting is what failed.
+            }
+        };
+
+        // The signing hash re-serializes the fields, which can fail. This
+        // function is noexcept, so report the validation as invalid instead of
+        // throwing. valid_ stays unset, so a later call checks again.
+        try
+        {
+            valid_ = verifyDigest(
+                getSignerPublic(),
+                getSigningHash(),
+                makeSlice(getFieldVL(sfSignature)),
+                (getFlags() & kVfFullyCanonicalSig) != 0u);
+        }
+        catch (std::exception const& e)
+        {
+            reportUncheckable(e.what());
+            return false;
+        }
+        catch (...)
+        {
+            reportUncheckable("unknown exception");
+            return false;
+        }
     }
 
     return valid_.value();

src/libxrpl/protocol/Serializer.cpp

@@ -143,10 +143,10 @@ Serializer::addFieldID(int type, int name)
 }
 
 int
-Serializer::add8(unsigned char byte)
+Serializer::add8(unsigned char byteValue)
 {
     int const ret = data_.size();
-    data_.push_back(byte);
+    data_.push_back(byteValue);
     return ret;
 }
 
@@ -210,109 +210,138 @@ Serializer::addVL(void const* ptr, int len)
 int
 Serializer::addEncoded(int length)
 {
-    std::array<std::uint8_t, 4> bytes{};
+    // Without this, a negative length would fall into the 1 byte case below and
+    // be cast to a first byte no header uses. A size too big for int arrives
+    // here negative as well, since callers pass sizes through this parameter.
+    if (length < kMinValueOfLengthFor1ByteHeader)
+        Throw<std::overflow_error>("addEncoded: length is negative or did not fit in an int");
+
+    std::array<std::byte, kMaxNumberOfBytesInHeader> bytes{};
     int numBytes = 0;
 
-    if (length <= 192)
+    if (length <= kMaxValueOfLengthFor1ByteHeader)
     {
-        bytes[0] = static_cast<unsigned char>(length);
+        bytes[0] = static_cast<std::byte>(length);
         numBytes = 1;
     }
-    else if (length <= 12480)
+    else if (length <= kMaxValueOfLengthFor2ByteHeader)
     {
-        length -= 193;
-        bytes[0] = 193 + static_cast<unsigned char>(length >> 8);
-        bytes[1] = static_cast<unsigned char>(length & 0xff);
+        // Count from the smallest length a 2 byte header covers.
+        int const offset = length - kMinValueOfLengthFor2ByteHeader;
+        bytes[0] = static_cast<std::byte>(
+            kMinValueOfFirstByteFor2ByteHeader + (offset / kNumberOfValuesInOneByte));
+        bytes[1] = static_cast<std::byte>(offset % kNumberOfValuesInOneByte);
         numBytes = 2;
     }
-    else if (length <= 918744)
+    else if (length <= kMaxValueOfLengthFor3ByteHeader)
     {
-        length -= 12481;
-        bytes[0] = 241 + static_cast<unsigned char>(length >> 16);
-        bytes[1] = static_cast<unsigned char>((length >> 8) & 0xff);
-        bytes[2] = static_cast<unsigned char>(length & 0xff);
+        int const offset = length - kMinValueOfLengthFor3ByteHeader;
+        bytes[0] = static_cast<std::byte>(
+            kMinValueOfFirstByteFor3ByteHeader + (offset / kNumberOfValuesInTwoBytes));
+        bytes[1] =
+            static_cast<std::byte>((offset / kNumberOfValuesInOneByte) % kNumberOfValuesInOneByte);
+        bytes[2] = static_cast<std::byte>(offset % kNumberOfValuesInOneByte);
         numBytes = 3;
     }
     else
     {
-        Throw<std::overflow_error>("lenlen");
+        Throw<std::overflow_error>("addEncoded: length is too large to encode");
     }
 
-    return addRaw(&bytes[0], numBytes);
+    return addRaw(bytes.data(), numBytes);
 }
 
 int
 Serializer::encodeLengthLength(int length)
 {
-    if (length < 0)
-        Throw<std::overflow_error>("len<0");
+    if (length < kMinValueOfLengthFor1ByteHeader)
+    {
+        Throw<std::overflow_error>(
+            "encodeLengthLength: length is negative or did not fit in an int");
+    }
 
-    if (length <= 192)
+    if (length <= kMaxValueOfLengthFor1ByteHeader)
         return 1;
 
-    if (length <= 12480)
+    if (length <= kMaxValueOfLengthFor2ByteHeader)
         return 2;
 
-    if (length <= 918744)
+    if (length <= kMaxValueOfLengthFor3ByteHeader)
         return 3;
 
-    Throw<std::overflow_error>("len>918744");
-    return 0;  // Silence compiler warning.
+    Throw<std::overflow_error>("encodeLengthLength: length is too large to encode");
 }
 
 int
-Serializer::decodeLengthLength(int b1)
+Serializer::decodeLengthLength(std::byte firstByte)
 {
-    if (b1 < 0)
-        Throw<std::overflow_error>("b1<0");
+    int const firstByteValue = std::to_integer<int>(firstByte);
 
-    if (b1 <= 192)
+    if (firstByteValue <= kMaxValueOfFirstByteFor1ByteHeader)
         return 1;
 
-    if (b1 <= 240)
+    if (firstByteValue <= kMaxValueOfFirstByteFor2ByteHeader)
         return 2;
 
-    if (b1 <= 254)
+    if (firstByteValue <= kMaxValueOfFirstByteFor3ByteHeader)
         return 3;
 
-    Throw<std::overflow_error>("b1>254");
-    return 0;  // Silence compiler warning.
+    Throw<std::overflow_error>("decodeLengthLength: first byte does not start any header");
 }
 
 int
-Serializer::decodeVLLength(int b1)
+Serializer::decodeVLLength(std::byte firstByte)
 {
-    if (b1 < 0)
-        Throw<std::overflow_error>("b1<0");
+    int const length = std::to_integer<int>(firstByte);
 
-    if (b1 > 254)
-        Throw<std::overflow_error>("b1>254");
+    // A bigger value means a longer header, so it is not a length by itself.
+    if (length > kMaxValueOfLengthFor1ByteHeader)
+        Throw<std::overflow_error>("decodeVLLength 1 byte: first byte is not a length");
 
-    return b1;
+    return length;
 }
 
 int
-Serializer::decodeVLLength(int b1, int b2)
+Serializer::decodeVLLength(std::byte firstByte, std::byte secondByte)
 {
-    if (b1 < 193)
-        Throw<std::overflow_error>("b1<193");
+    int const firstByteValue = std::to_integer<int>(firstByte);
 
-    if (b1 > 240)
-        Throw<std::overflow_error>("b1>240");
+    if (firstByteValue < kMinValueOfFirstByteFor2ByteHeader)
+        Throw<std::overflow_error>("decodeVLLength 2 byte: first byte is below the range");
 
-    return 193 + ((b1 - 193) * 256) + b2;
+    if (firstByteValue > kMaxValueOfFirstByteFor2ByteHeader)
+        Throw<std::overflow_error>("decodeVLLength 2 byte: first byte is above the range");
+
+    // Both bytes are bounded by their own type, and the first one is bounded to
+    // the 2 byte range above, so this cannot leave the range the header covers.
+    return kMinValueOfLengthFor2ByteHeader +
+        ((firstByteValue - kMinValueOfFirstByteFor2ByteHeader) * kNumberOfValuesInOneByte) +
+        std::to_integer<int>(secondByte);
 }
 
 int
-Serializer::decodeVLLength(int b1, int b2, int b3)
+Serializer::decodeVLLength(std::byte firstByte, std::byte secondByte, std::byte thirdByte)
 {
-    if (b1 < 241)
-        Throw<std::overflow_error>("b1<241");
+    int const firstByteValue = std::to_integer<int>(firstByte);
 
-    if (b1 > 254)
-        Throw<std::overflow_error>("b1>254");
+    if (firstByteValue < kMinValueOfFirstByteFor3ByteHeader)
+        Throw<std::overflow_error>("decodeVLLength 3 byte: first byte is below the range");
 
-    return 12481 + ((b1 - 241) * 65536) + (b2 * 256) + b3;
+    if (firstByteValue > kMaxValueOfFirstByteFor3ByteHeader)
+        Throw<std::overflow_error>("decodeVLLength 3 byte: first byte is above the range");
+
+    int const length = kMinValueOfLengthFor3ByteHeader +
+        ((firstByteValue - kMinValueOfFirstByteFor3ByteHeader) * kNumberOfValuesInTwoBytes) +
+        (std::to_integer<int>(secondByte) * kNumberOfValuesInOneByte) +
+        std::to_integer<int>(thirdByte);
+
+    // A 3 byte header reaches further than kMaxValueOfLengthFor3ByteHeader, which
+    // is as far as the encoder goes. Refuse the rest, so every length accepted
+    // here is one that can be written back.
+    if (length > kMaxValueOfLengthFor3ByteHeader)
+        Throw<std::overflow_error>("decodeVLLength 3 byte: length is too large to re-encode");
+
+    return length;
 }
 
 //------------------------------------------------------------------------------
@@ -471,24 +500,24 @@ SerialIter::getRaw(int size)
 int
 SerialIter::getVLDataLength()
 {
-    int const b1 = get8();
+    std::byte const firstByte{get8()};
     int datLen = 0;
-    int const lenLen = Serializer::decodeLengthLength(b1);
+    int const lenLen = Serializer::decodeLengthLength(firstByte);
     if (lenLen == 1)
     {
-        datLen = Serializer::decodeVLLength(b1);
+        datLen = Serializer::decodeVLLength(firstByte);
     }
     else if (lenLen == 2)
     {
-        int const b2 = get8();
-        datLen = Serializer::decodeVLLength(b1, b2);
+        std::byte const secondByte{get8()};
+        datLen = Serializer::decodeVLLength(firstByte, secondByte);
     }
     else
     {
         XRPL_ASSERT(lenLen == 3, "xrpl::SerialIter::getVLDataLength : lenLen is 3");
-        int const b2 = get8();
-        int const b3 = get8();
-        datLen = Serializer::decodeVLLength(b1, b2, b3);
+        std::byte const secondByte{get8()};
+        std::byte const thirdByte{get8()};
+        datLen = Serializer::decodeVLLength(firstByte, secondByte, thirdByte);
     }
     return datLen;
 }

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;
 }

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

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.

src/libxrpl/tx/ApplyContext.cpp

@@ -6,6 +6,8 @@
 #include <xrpl/core/ServiceRegistry.h>
 #include <xrpl/ledger/ApplyView.h>
 #include <xrpl/ledger/OpenView.h>
+#include <xrpl/ledger/OrderBookDB.h>
+#include <xrpl/protocol/Book.h>
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/TER.h>
 #include <xrpl/protocol/TxMeta.h>
@@ -54,6 +56,13 @@ ApplyContext::apply(TER ter)
     return view_->apply(base_, tx, ter, parentBatchId_, (flags_ & TapDryRun) != 0u, journal);
 }
 
+void
+ApplyContext::addOrderBook(Book const& book)
+{
+    if ((flags_ & TapDryRun) == TapNone)
+        registry.get().getOrderBookDB().addOrderBook(book);
+}
+
 std::size_t
 ApplyContext::size()
 {

src/libxrpl/tx/CLAUDE.md

@@ -0,0 +1 @@
+AGENTS.md

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);
             }
         }
@@ -1437,8 +1437,7 @@ 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))
         {
@@ -1447,11 +1446,6 @@ 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)
         {
@@ -1529,7 +1523,7 @@ 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:

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

src/libxrpl/tx/applySteps.cpp

@@ -17,6 +17,7 @@
 
 #include <cstdint>
 #include <exception>
+#include <expected>
 #include <memory>
 #include <optional>
 #include <utility>
@@ -195,7 +196,12 @@ invokePreclaim(PreclaimContext const& ctx)
                     }())
                     return preSigResult;
 
-                if (TER const result = T::checkFee(ctx, calculateBaseFee(ctx.view, ctx.tx)))
+                // We can't check the fee if we can't compute it, so reject.
+                auto const baseFee = calculateBaseFee(ctx.view, ctx.tx);
+                if (!baseFee)
+                    return baseFee.error();
+
+                if (TER const result = T::checkFee(ctx, *baseFee))
                     return result;
             }
 
@@ -223,13 +229,12 @@ invokePreclaim(PreclaimContext const& ctx)
  *
  * @param view The ledger view to use for fee calculation.
  * @param tx The transaction for which the base fee is to be calculated.
- * @return The calculated base fee as an XRPAmount.
+ * @return The calculated base fee. Returns `std::unexpected(temUNKNOWN)` if the transaction
+ * type is not recognized, and `std::unexpected(tefEXCEPTION)` if the transactor's
+ * `calculateBaseFee` threw.
  *
- * @throws std::exception If an error occurs during fee calculation, including
- * but not limited to unknown transaction types or internal errors, the function
- * logs an error and returns an XRPAmount of zero.
  */
-static XRPAmount
+static std::expected<XRPAmount, TER>
 invokeCalculateBaseFee(ReadView const& view, STTx const& tx)
 {
     try
@@ -238,13 +243,25 @@ invokeCalculateBaseFee(ReadView const& view, STTx const& tx)
             return T::calculateBaseFee(view, tx);
         });
     }
-    catch (UnknownTxnType const& e)
+    catch (UnknownTxnType const&)
     {
         // LCOV_EXCL_START
         UNREACHABLE("xrpl::invoke_calculateBaseFee : unknown transaction type");
-        return XRPAmount{0};
+        return std::unexpected(temUNKNOWN);
         // LCOV_EXCL_STOP
     }
+    catch (std::exception const& e)
+    {
+        JLOG(debugLog().error()) << "calculateBaseFee: " << tx.getTransactionID()
+                                 << " threw an exception: " << e.what();
+        return std::unexpected(tefEXCEPTION);
+    }
+    catch (...)
+    {
+        JLOG(debugLog().error()) << "calculateBaseFee: " << tx.getTransactionID()
+                                 << " threw an unknown exception";
+        return std::unexpected(tefEXCEPTION);
+    }
 }
 
 TxConsequences::TxConsequences(NotTEC pfResult)
@@ -416,7 +433,7 @@ preclaim(PreflightResult const& preflightResult, ServiceRegistry& registry, Open
     }
 }
 
-XRPAmount
+std::expected<XRPAmount, TER>
 calculateBaseFee(ReadView const& view, STTx const& tx)
 {
     return invokeCalculateBaseFee(view, tx);
@@ -441,13 +458,26 @@ doApply(PreclaimResult const& preclaimResult, ServiceRegistry& registry, OpenVie
     {
         if (!preclaimResult.likelyToClaimFee)
             return {preclaimResult.ter, false};
+
+        // For any tx with a real account, preclaim already computed this fee
+        // successfully against this same view.
+        auto const baseFee = calculateBaseFee(view, preclaimResult.tx);
+        if (!baseFee)
+        {
+            // LCOV_EXCL_START
+            JLOG(preclaimResult.j.error())
+                << "apply: could not compute base fee: " << transToken(baseFee.error());
+            return {tefINTERNAL, false};
+            // LCOV_EXCL_STOP
+        }
+
         ApplyContext ctx(
             registry,
             view,
             preclaimResult.parentBatchId,
             preclaimResult.tx,
             preclaimResult.ter,
-            calculateBaseFee(view, preclaimResult.tx),
+            *baseFee,
             preclaimResult.flags,
             preclaimResult.j);
         return invokeApply(ctx);

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:

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.

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 +151,146 @@ 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.
+            //
+            // PrincipalOutstanding may stay put on a non-final pay: at integer
+            // scale, fixCleanup3_2_0 rounds principal up so a fractional
+            // amortization step does not reduce it. Interest (TVO) still falls.
+            // Neither balance may grow: a payment never adds to what is owed,
+            // since late-payment penalties are charged in the same transaction
+            // rather than tracked in TotalValueOutstanding.
+            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 not increase "
+                                           "PrincipalOutstanding on a non-full-repayment";
+                        return false;
+                    }
+                    if (after->at(sfTotalValueOutstanding) > before->at(sfTotalValueOutstanding))
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: loan pay must not increase "
+                                           "TotalValueOutstanding on a non-full-repayment";
+                        return false;
+                    }
+                    if (after->at(sfPrincipalOutstanding) == before->at(sfPrincipalOutstanding) &&
+                        after->at(sfTotalValueOutstanding) == before->at(sfTotalValueOutstanding))
+                    {
+                        JLOG(j.fatal()) << "Invariant failed: loan pay must decrease "
+                                           "PrincipalOutstanding or TotalValueOutstanding "
+                                           "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;
 }

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 "
@@ -307,27 +299,46 @@ ValidMPTIssuance::finalize(
                     return false;
                 }
             }
-            else if (lendingProtocolEnabled && (mptokensCreated_ + mptokensDeleted_) > 1)
+            else
             {
-                JLOG(j.fatal()) << "Invariant failed: MPT authorize succeeded "
-                                   "but created/deleted bad number mptokens";
-                return false;
-            }
-            else if (submittedByIssuer && (mptokensCreated_ > 0 || mptokensDeleted_ > 0))
-            {
-                JLOG(j.fatal()) << "Invariant failed: MPT authorize submitted by issuer "
-                                   "succeeded but created/deleted mptokens";
-                return false;
-            }
-            else if (
-                !submittedByIssuer && hasPrivilege(tx, Privilege::MustAuthorizeMpt) &&
-                (mptokensCreated_ + mptokensDeleted_ != 1))
-            {
-                // if the holder submitted this tx, then a mptoken must be
-                // either created or deleted.
-                JLOG(j.fatal()) << "Invariant failed: MPT authorize submitted by holder "
-                                   "succeeded but created/deleted bad number of mptokens";
-                return false;
+                // Cap on MPToken creates and deletes while featureLendingProtocol is enabled.
+                // - LoanSet: at most two creates and no deletes.
+                // - VaultWithdraw: at most one create and one delete.
+                // - Other MayAuthorizeMpt types: created + deleted <= 1.
+                // - MustAuthorizeMpt still requires exactly one create or delete below.
+                auto const mptokensExceedAuthorizeCap = [&] {
+                    if (!lendingProtocolEnabled)
+                        return false;
+                    if (rules.enabled(fixCleanup3_4_0))
+                    {
+                        if (txnType == ttLOAN_SET)
+                            return mptokensDeleted_ != 0 || mptokensCreated_ > 2;
+                        if (txnType == ttVAULT_WITHDRAW)
+                            return mptokensCreated_ > 1 || mptokensDeleted_ > 1;
+                    }
+                    return (mptokensCreated_ + mptokensDeleted_) > 1;
+                };
+                if (mptokensExceedAuthorizeCap())
+                {
+                    JLOG(j.fatal()) << "Invariant failed: MPT authorize succeeded "
+                                       "but created/deleted bad number mptokens";
+                    return false;
+                }
+                if (submittedByIssuer && (mptokensCreated_ > 0 || mptokensDeleted_ > 0))
+                {
+                    JLOG(j.fatal()) << "Invariant failed: MPT authorize submitted by issuer "
+                                       "succeeded but created/deleted mptokens";
+                    return false;
+                }
+                if (!submittedByIssuer && hasPrivilege(tx, Privilege::MustAuthorizeMpt) &&
+                    (mptokensCreated_ + mptokensDeleted_ != 1))
+                {
+                    // if the holder submitted this tx, then a mptoken must be
+                    // either created or deleted.
+                    JLOG(j.fatal()) << "Invariant failed: MPT authorize submitted by holder "
+                                       "succeeded but created/deleted bad number of mptokens";
+                    return false;
+                }
             }
 
             return true;
@@ -832,6 +843,14 @@ 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 +863,19 @@ 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);

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;

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