Merge remote-tracking branch 'origin/develop' into pratik/otel-phase1a-plan-docs

Co-authored-by: Alex Kremer <akremer@ripple.com>

.clang-tidy

@@ -1,159 +1,91 @@
 ---
 Checks: "-*,
-  bugprone-argument-comment,
-  bugprone-assert-side-effect,
-  bugprone-bad-signal-to-kill-thread,
-  bugprone-bool-pointer-implicit-conversion,
-  bugprone-capturing-this-in-member-variable,
-  bugprone-casting-through-void,
-  bugprone-chained-comparison,
-  bugprone-compare-pointer-to-member-virtual-function,
-  bugprone-copy-constructor-init,
-  bugprone-crtp-constructor-accessibility,
-  bugprone-dangling-handle,
-  bugprone-dynamic-static-initializers,
-  bugprone-empty-catch,
-  bugprone-fold-init-type,
-  bugprone-forward-declaration-namespace,
-  bugprone-inaccurate-erase,
-  bugprone-inc-dec-in-conditions,
-  bugprone-incorrect-enable-if,
-  bugprone-incorrect-roundings,
-  bugprone-infinite-loop,
-  bugprone-integer-division,
-  bugprone-lambda-function-name,
-  bugprone-macro-parentheses,
-  bugprone-macro-repeated-side-effects,
-  bugprone-misleading-setter-of-reference,
-  bugprone-misplaced-operator-in-strlen-in-alloc,
-  bugprone-misplaced-pointer-arithmetic-in-alloc,
-  bugprone-misplaced-widening-cast,
-  bugprone-move-forwarding-reference,
-  bugprone-multi-level-implicit-pointer-conversion,
-  bugprone-multiple-new-in-one-expression,
-  bugprone-multiple-statement-macro,
-  bugprone-no-escape,
-  bugprone-non-zero-enum-to-bool-conversion,
-  bugprone-optional-value-conversion,
-  bugprone-parent-virtual-call,
-  bugprone-pointer-arithmetic-on-polymorphic-object,
-  bugprone-posix-return,
-  bugprone-redundant-branch-condition,
-  bugprone-reserved-identifier,
-  bugprone-return-const-ref-from-parameter,
-  bugprone-shared-ptr-array-mismatch,
-  bugprone-signal-handler,
-  bugprone-signed-char-misuse,
-  bugprone-sizeof-container,
-  bugprone-sizeof-expression,
-  bugprone-spuriously-wake-up-functions,
-  bugprone-standalone-empty,
-  bugprone-string-constructor,
-  bugprone-string-integer-assignment,
-  bugprone-string-literal-with-embedded-nul,
-  bugprone-stringview-nullptr,
-  bugprone-suspicious-enum-usage,
-  bugprone-suspicious-include,
-  bugprone-suspicious-memory-comparison,
-  bugprone-suspicious-memset-usage,
-  bugprone-suspicious-missing-comma,
-  bugprone-suspicious-realloc-usage,
-  bugprone-suspicious-semicolon,
-  bugprone-suspicious-string-compare,
-  bugprone-suspicious-stringview-data-usage,
-  bugprone-swapped-arguments,
-  bugprone-switch-missing-default-case,
-  bugprone-terminating-continue,
-  bugprone-throw-keyword-missing,
-  bugprone-too-small-loop-variable,
-  bugprone-unchecked-optional-access,
-  bugprone-undefined-memory-manipulation,
-  bugprone-undelegated-constructor,
-  bugprone-unhandled-exception-at-new,
-  bugprone-unhandled-self-assignment,
-  bugprone-unique-ptr-array-mismatch,
-  bugprone-unsafe-functions,
-  bugprone-unused-local-non-trivial-variable,
-  bugprone-unused-raii,
-  bugprone-unused-return-value,
-  bugprone-use-after-move,
-  bugprone-virtual-near-miss,
-  cppcoreguidelines-init-variables,
-  cppcoreguidelines-misleading-capture-default-by-value,
-  cppcoreguidelines-no-suspend-with-lock,
-  cppcoreguidelines-pro-type-member-init,
-  cppcoreguidelines-pro-type-static-cast-downcast,
-  cppcoreguidelines-rvalue-reference-param-not-moved,
-  cppcoreguidelines-use-default-member-init,
-  cppcoreguidelines-use-enum-class,
-  cppcoreguidelines-virtual-class-destructor,
-  hicpp-ignored-remove-result,
+  bugprone-*,
+  -bugprone-easily-swappable-parameters,
+  -bugprone-exception-escape,
+  -bugprone-implicit-widening-of-multiplication-result,
+  -bugprone-narrowing-conversions,
+  -bugprone-throwing-static-initialization,
+
+  cppcoreguidelines-*,
+  -cppcoreguidelines-avoid-c-arrays,
+  -cppcoreguidelines-avoid-const-or-ref-data-members,
+  -cppcoreguidelines-avoid-do-while,
+  -cppcoreguidelines-avoid-magic-numbers,
+  -cppcoreguidelines-avoid-non-const-global-variables,
+  -cppcoreguidelines-c-copy-assignment-signature,
+  -cppcoreguidelines-interfaces-global-init,
+  -cppcoreguidelines-macro-usage,
+  -cppcoreguidelines-missing-std-forward,
+  -cppcoreguidelines-narrowing-conversions,
+  -cppcoreguidelines-noexcept-move-operations,
+  -cppcoreguidelines-non-private-member-variables-in-classes,
+  -cppcoreguidelines-owning-memory,
+  -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
+  -cppcoreguidelines-pro-bounds-avoid-unchecked-container-access,
+  -cppcoreguidelines-pro-bounds-constant-array-index,
+  -cppcoreguidelines-pro-bounds-pointer-arithmetic,
+  -cppcoreguidelines-pro-type-reinterpret-cast,
+  -cppcoreguidelines-pro-type-union-access,
+  -cppcoreguidelines-special-member-functions,
+
   llvm-namespace-comment,
-  misc-const-correctness,
-  misc-definitions-in-headers,
-  misc-header-include-cycle,
-  misc-include-cleaner,
-  misc-misplaced-const,
-  misc-redundant-expression,
-  misc-static-assert,
-  misc-throw-by-value-catch-by-reference,
-  misc-unused-alias-decls,
-  misc-unused-using-decls,
-  modernize-concat-nested-namespaces,
-  modernize-deprecated-headers,
-  modernize-make-shared,
-  modernize-make-unique,
-  modernize-pass-by-value,
-  modernize-type-traits,
-  modernize-use-designated-initializers,
-  modernize-use-emplace,
-  modernize-use-equals-default,
-  modernize-use-equals-delete,
-  modernize-use-nodiscard,
-  modernize-use-override,
-  modernize-use-ranges,
-  modernize-use-scoped-lock,
-  modernize-use-starts-ends-with,
-  modernize-use-std-numbers,
-  modernize-use-using,
-  performance-faster-string-find,
-  performance-for-range-copy,
-  performance-implicit-conversion-in-loop,
-  performance-inefficient-vector-operation,
-  performance-move-const-arg,
-  performance-move-constructor-init,
-  performance-no-automatic-move,
-  performance-trivially-destructible,
-  readability-ambiguous-smartptr-reset-call,
-  readability-avoid-nested-conditional-operator,
-  readability-avoid-return-with-void-value,
-  readability-braces-around-statements,
-  readability-const-return-type,
-  readability-container-contains,
-  readability-container-size-empty,
-  readability-convert-member-functions-to-static,
-  readability-duplicate-include,
-  readability-else-after-return,
-  readability-enum-initial-value,
-  readability-identifier-naming,
-  readability-implicit-bool-conversion,
-  readability-make-member-function-const,
-  readability-math-missing-parentheses,
-  readability-misleading-indentation,
-  readability-non-const-parameter,
-  readability-redundant-casting,
-  readability-redundant-declaration,
-  readability-redundant-inline-specifier,
-  readability-redundant-member-init,
-  readability-redundant-string-init,
-  readability-reference-to-constructed-temporary,
-  readability-simplify-boolean-expr,
-  readability-static-definition-in-anonymous-namespace,
-  readability-suspicious-call-argument,
-  readability-use-std-min-max
+
+  misc-*,
+  -misc-multiple-inheritance,
+  -misc-no-recursion,
+  -misc-non-private-member-variables-in-classes,
+  -misc-override-with-different-visibility,
+  -misc-unused-parameters,
+  -misc-use-anonymous-namespace,
+  -misc-use-internal-linkage,
+
+  modernize-*,
+  -modernize-avoid-c-arrays,
+  -modernize-avoid-c-style-cast,
+  -modernize-return-braced-init-list,
+  -modernize-use-integer-sign-comparison,
+  -modernize-use-trailing-return-type,
+
+  performance-*,
+  -performance-avoid-endl,
+  -performance-enum-size,
+  -performance-noexcept-move-constructor,
+  -performance-unnecessary-copy-initialization,
+  -performance-unnecessary-value-param,
+
+  readability-*,
+  -readability-avoid-const-params-in-decls,
+  -readability-avoid-unconditional-preprocessor-if,
+  -readability-container-data-pointer,
+  -readability-delete-null-pointer,
+  -readability-function-cognitive-complexity,
+  -readability-function-size,
+  -readability-identifier-length,
+  -readability-inconsistent-declaration-parameter-name,
+  -readability-isolate-declaration,
+  -readability-magic-numbers,
+  -readability-misplaced-array-index,
+  -readability-named-parameter,
+  -readability-operators-representation,
+  -readability-qualified-auto,
+  -readability-redundant-access-specifiers,
+  -readability-redundant-control-flow,
+  -readability-redundant-function-ptr-dereference,
+  -readability-redundant-preprocessor,
+  -readability-redundant-smartptr-get,
+  -readability-redundant-string-cstr,
+  -readability-simplify-subscript-expr,
+  -readability-static-accessed-through-instance,
+  -readability-string-compare,
+  -readability-uniqueptr-delete-release,
+  -readability-uppercase-literal-suffix,
+  -readability-use-anyofallof,
+  -readability-use-concise-preprocessor-directives
   "
 # ---
-# bugprone-narrowing-conversions,                      # this will break a lot of code but we should enable it in the future because it can eliminate a lot of bugs
+# bugprone-narrowing-conversions,                      # This will break a lot of code but we should enable it in the future because it can eliminate a lot of bugs
+# misc-override-with-different-visibility,             # Will be addressed in a future PR, but for now it generates too many warnings
 # readability-inconsistent-declaration-parameter-name, # In this codebase this check will break a lot of arg names
 # readability-static-accessed-through-instance,        # this check is probably unnecessary. It makes the code less readable
 # ---
@@ -162,7 +94,7 @@ CheckOptions:
   bugprone-unsafe-functions.ReportMoreUnsafeFunctions: true
   bugprone-unused-return-value.CheckedReturnTypes: ::std::error_code;::std::error_condition;::std::errc
 
-  misc-include-cleaner.IgnoreHeaders: ".*/(detail|impl)/.*;.*fwd\\.h(pp)?;time.h;stdlib.h;sqlite3.h;netinet/in\\.h;sys/resource\\.h;sys/sysinfo\\.h;linux/sysinfo\\.h;__chrono/.*;bits/.*;_abort\\.h;boost/uuid/uuid_hash.hpp;boost/beast/core/flat_buffer\\.hpp;boost/beast/http/field\\.hpp;boost/beast/http/dynamic_body\\.hpp;boost/beast/http/message\\.hpp;boost/beast/http/read\\.hpp;boost/beast/http/write\\.hpp;openssl/obj_mac\\.h"
+  misc-include-cleaner.IgnoreHeaders: ".*/(detail|impl)/.*;.*fwd\\.h(pp)?;time.h;stdlib.h;sqlite3.h;netinet/in\\.h;sys/resource\\.h;sys/sysinfo\\.h;linux/sysinfo\\.h;__chrono/.*;bits/.*;_abort\\.h;boost/.*;openssl/obj_mac\\.h"
 
   readability-braces-around-statements.ShortStatementLines: 2
   readability-identifier-naming.MacroDefinitionCase: UPPER_CASE

.cspell.config.yaml

@@ -36,9 +36,7 @@ overrides:
       - /'[^']*'/g # single-quoted strings
       - /`[^`]*`/g # backtick strings
 suggestWords:
-  - xprl->xrpl
-  - xprld->xrpld # cspell: disable-line not sure what this problem is....
-  - unsynched->unsynced # cspell: disable-line not sure what this problem is....
+  - unsynched->unsynced
   - synched->synced
   - synch->sync
 words:
@@ -60,12 +58,14 @@ words:
   - autobridging
   - bimap
   - bindir
+  - blindings
   - bookdir
   - Bougalis
   - Britto
   - Btrfs
   - Buildx
   - canonicality
+  - CGNAT
   - changespq
   - checkme
   - choco
@@ -95,6 +95,7 @@ words:
   - daria
   - dcmake
   - dearmor
+  - decryptor
   - dedented
   - deleteme
   - demultiplexer
@@ -106,6 +107,7 @@ words:
   - distro
   - doxyfile
   - dxrpl
+  - elgamal
   - enabled
   - enablerepo
   - endmacro
@@ -119,6 +121,9 @@ words:
   - fmtdur
   - fsanitize
   - funclets
+  - Gamal
+  - gantt
+  - Gantt
   - gcov
   - gcovr
   - ghead
@@ -165,12 +170,11 @@ words:
   - mathbunnyru
   - mcmodel
   - MEMORYSTATUSEX
-  - MPTAMM
-  - MPTDEX
   - Merkle
   - Metafuncton
   - misprediction
   - missingok
+  - MPTAMM
   - mptbalance
   - MPTDEX
   - mptflags
@@ -204,6 +208,7 @@ words:
   - nonxrp
   - noreplace
   - noripple
+  - nostd
   - nostdinc
   - notifempty
   - nudb
@@ -212,10 +217,12 @@ words:
   - Nyffenegger
   - onlatest
   - ostr
+  - otelc
   - pargs
   - partitioner
   - paychan
   - paychans
+  - Pedersen
   - permdex
   - perminute
   - permissioned
@@ -239,6 +246,10 @@ words:
   - Raphson
   - rcflags
   - replayer
+  - rerandomize
+  - rerandomization
+  - rerandomized
+  - rerandomizes
   - rerere
   - retriable
   - RIPD
@@ -255,6 +266,7 @@ words:
   - sahyadri
   - Satoshi
   - scons
+  - Schnorr
   - secp
   - sendq
   - seqit
@@ -285,12 +297,14 @@ words:
   - stvar
   - stvector
   - stxchainattestations
+  - summands
   - superpeer
   - superpeers
   - takergets
   - takerpays
   - ters
   - TMEndpointv2
+  - traceql
   - trixie
   - tx
   - txid
@@ -298,9 +312,11 @@ words:
   - txjson
   - txn
   - txns
+  - txqueue
   - txs
   - ubsan
   - UBSAN
+  - ufdio
   - umant
   - unacquired
   - unambiguity
@@ -345,4 +361,5 @@ words:
   - xrplf
   - xxhash
   - xxhasher
-  - CGNAT
+  - xychart
+  - zpages

.gersemi/definitions.cmake

@@ -48,6 +48,12 @@ endfunction()
 function(add_module parent name)
 endfunction()
 
+function(verify_target_headers target headers_dir)
+endfunction()
+
+function(_verify_add_headers target dir)
+endfunction()
+
 function(setup_protocol_autogen)
 endfunction()
 
@@ -96,3 +102,6 @@ function(verbose_find_path variable name)
         ${ARGN}
     )
 endfunction()
+
+function(patch_nix_binary target)
+endfunction()

.github/actions/setup-conan/action.yml

@@ -9,7 +9,7 @@ inputs:
   remote_url:
     description: "The URL of the Conan endpoint to use."
     required: false
-    default: https://conan.ripplex.io
+    default: https://conan.xrplf.org/repository/conan/
 
 runs:
   using: composite

.github/scripts/levelization/results/loops.txt

@@ -1,9 +1,3 @@
-Loop: test.jtx test.toplevel
-  test.toplevel > test.jtx
-
-Loop: test.jtx test.unit_test
-  test.unit_test ~= test.jtx
-
 Loop: xrpld.app xrpld.overlay
   xrpld.app > xrpld.overlay
 

.github/scripts/levelization/results/ordering.txt

@@ -72,7 +72,6 @@ test.app > xrpl.server
 test.app > xrpl.shamap
 test.app > xrpl.tx
 test.basics > test.jtx
-test.basics > test.unit_test
 test.basics > xrpl.basics
 test.basics > xrpl.core
 test.basics > xrpld.rpc
@@ -83,7 +82,6 @@ test.conditions > xrpl.basics
 test.conditions > xrpl.conditions
 test.consensus > test.csf
 test.consensus > test.jtx
-test.consensus > test.toplevel
 test.consensus > test.unit_test
 test.consensus > xrpl.basics
 test.consensus > xrpld.app
@@ -106,9 +104,9 @@ test.csf > xrpl.basics
 test.csf > xrpld.consensus
 test.csf > xrpl.json
 test.csf > xrpl.ledger
-test.csf > xrpl.protocol
 test.json > test.jtx
 test.json > xrpl.json
+test.jtx > test.unit_test
 test.jtx > xrpl.basics
 test.jtx > xrpl.config
 test.jtx > xrpl.core
@@ -163,9 +161,6 @@ test.protocol > test.unit_test
 test.protocol > xrpl.basics
 test.protocol > xrpl.json
 test.protocol > xrpl.protocol
-test.resource > test.unit_test
-test.resource > xrpl.basics
-test.resource > xrpl.resource
 test.rpc > test.jtx
 test.rpc > xrpl.basics
 test.rpc > xrpl.config
@@ -189,14 +184,6 @@ test.server > xrpld.core
 test.server > xrpl.json
 test.server > xrpl.protocol
 test.server > xrpl.server
-test.shamap > test.unit_test
-test.shamap > xrpl.basics
-test.shamap > xrpl.config
-test.shamap > xrpl.nodestore
-test.shamap > xrpl.protocol
-test.shamap > xrpl.shamap
-test.toplevel > test.csf
-test.toplevel > xrpl.json
 test.unit_test > xrpl.basics
 test.unit_test > xrpl.protocol
 tests.libxrpl > xrpl.basics
@@ -208,6 +195,7 @@ tests.libxrpl > xrpl.net
 tests.libxrpl > xrpl.nodestore
 tests.libxrpl > xrpl.protocol
 tests.libxrpl > xrpl.protocol_autogen
+tests.libxrpl > xrpl.resource
 tests.libxrpl > xrpl.server
 tests.libxrpl > xrpl.shamap
 tests.libxrpl > xrpl.tx
@@ -219,11 +207,14 @@ xrpl.core > xrpl.json
 xrpl.core > xrpl.protocol
 xrpl.json > xrpl.basics
 xrpl.ledger > xrpl.basics
+xrpl.ledger > xrpl.json
+xrpl.ledger > xrpl.nodestore
 xrpl.ledger > xrpl.protocol
 xrpl.ledger > xrpl.shamap
 xrpl.net > xrpl.basics
 xrpl.nodestore > xrpl.basics
 xrpl.nodestore > xrpl.config
+xrpl.nodestore > xrpl.json
 xrpl.nodestore > xrpl.protocol
 xrpl.protocol > xrpl.basics
 xrpl.protocol > xrpl.json
@@ -241,7 +232,6 @@ xrpl.server > xrpl.json
 xrpl.server > xrpl.protocol
 xrpl.server > xrpl.rdb
 xrpl.server > xrpl.resource
-xrpl.server > xrpl.shamap
 xrpl.shamap > xrpl.basics
 xrpl.shamap > xrpl.nodestore
 xrpl.shamap > xrpl.protocol
@@ -296,8 +286,10 @@ xrpld.peerfinder > xrpl.rdb
 xrpld.perflog > xrpl.basics
 xrpld.perflog > xrpl.config
 xrpld.perflog > xrpl.core
+xrpld.perflog > xrpld.app
 xrpld.perflog > xrpld.rpc
 xrpld.perflog > xrpl.json
+xrpld.perflog > xrpl.nodestore
 xrpld.perflog > xrpl.protocol
 xrpld.rpc > xrpl.basics
 xrpld.rpc > xrpl.config
@@ -315,5 +307,6 @@ xrpld.rpc > xrpl.shamap
 xrpld.rpc > xrpl.tx
 xrpld.shamap > xrpl.basics
 xrpld.shamap > xrpld.core
+xrpld.shamap > xrpl.nodestore
 xrpld.shamap > xrpl.protocol
 xrpld.shamap > xrpl.shamap

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

@@ -1,5 +1,5 @@
 {
-  "image_tag": "sha-fe4c8ae",
+  "image_tag": "sha-e29b523",
   "configs": {
     "ubuntu": [
       {

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

@@ -1,6 +1,6 @@
 {
   "platform": "macos/arm64",
-  "runner": ["self-hosted", "macOS", "ARM64", "mac-runner-m1"],
+  "runner": ["self-hosted", "macOS", "ARM64", "macos-26-apple-clang-21"],
   "configs": [
     {
       "build_type": "Release",

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

@@ -1,6 +1,6 @@
 {
   "platform": "windows/amd64",
-  "runner": ["self-hosted", "Windows", "devbox"],
+  "runner": ["self-hosted", "Windows", "dev-box-windows-2026"],
   "configs": [
     { "build_type": "Release" },
     {

.github/workflows/on-pr.yml

@@ -70,6 +70,7 @@ jobs:
             .github/workflows/reusable-upload-recipe.yml
             .clang-tidy
             .codecov.yml
+            bin/check-tools.sh
             cfg/**
             cmake/**
             conan/**
@@ -121,7 +122,6 @@ jobs:
       issues: write
       contents: read
     with:
-      check_only_changed: true
       create_issue_on_failure: false
 
   build-test:
@@ -153,8 +153,8 @@ jobs:
     if: ${{ github.repository == 'XRPLF/rippled' && needs.should-run.outputs.go == 'true' && github.event_name == 'pull_request' && startsWith(github.event.pull_request.base.ref, 'release') }}
     uses: ./.github/workflows/reusable-upload-recipe.yml
     secrets:
-      remote_username: ${{ secrets.CONAN_REMOTE_USERNAME }}
-      remote_password: ${{ secrets.CONAN_REMOTE_PASSWORD }}
+      remote_username: ${{ secrets.NEXUS_REMOTE_USERNAME }}
+      remote_password: ${{ secrets.NEXUS_REMOTE_PASSWORD }}
 
   notify-clio:
     needs: upload-recipe

.github/workflows/on-tag.yml

@@ -20,8 +20,8 @@ jobs:
     if: ${{ github.repository == 'XRPLF/rippled' }}
     uses: ./.github/workflows/reusable-upload-recipe.yml
     secrets:
-      remote_username: ${{ secrets.CONAN_REMOTE_USERNAME }}
-      remote_password: ${{ secrets.CONAN_REMOTE_PASSWORD }}
+      remote_username: ${{ secrets.NEXUS_REMOTE_USERNAME }}
+      remote_password: ${{ secrets.NEXUS_REMOTE_PASSWORD }}
 
   build-test:
     if: ${{ github.repository == 'XRPLF/rippled' }}

.github/workflows/on-trigger.yml

@@ -27,6 +27,7 @@ on:
       - ".github/workflows/reusable-upload-recipe.yml"
       - ".clang-tidy"
       - ".codecov.yml"
+      - "bin/check-tools.sh"
       - "cfg/**"
       - "cmake/**"
       - "conan/**"
@@ -71,7 +72,6 @@ jobs:
       issues: write
       contents: read
     with:
-      check_only_changed: false
       create_issue_on_failure: ${{ github.event_name == 'schedule' }}
 
   build-test:
@@ -97,8 +97,8 @@ jobs:
     if: ${{ github.repository == 'XRPLF/rippled' && github.event_name == 'push' && github.ref == 'refs/heads/develop' }}
     uses: ./.github/workflows/reusable-upload-recipe.yml
     secrets:
-      remote_username: ${{ secrets.CONAN_REMOTE_USERNAME }}
-      remote_password: ${{ secrets.CONAN_REMOTE_PASSWORD }}
+      remote_username: ${{ secrets.NEXUS_REMOTE_USERNAME }}
+      remote_password: ${{ secrets.NEXUS_REMOTE_PASSWORD }}
 
   package:
     needs: build-test

.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@e06d4138c9ec8dceeb7c818645faa38087ea9e3d
+    uses: XRPLF/actions/.github/workflows/pre-commit.yml@1bde119a1ab71305ba5d3716e7a82cea1c7bdede
     with:
       runs_on: ubuntu-latest
       container: '{ "image": "ghcr.io/xrplf/ci/tools-rippled-pre-commit:sha-41ec7c1" }'

.github/workflows/publish-docs.yml

@@ -41,13 +41,13 @@ env:
 jobs:
   build:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-fe4c8ae
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-e29b523
     steps:
       - name: Checkout repository
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@c47daebb2f9db64ffbac71b47d68a661498d5ce8
+        uses: XRPLF/actions/prepare-runner@64ec3cf3b152b4444638f470bbd6df7a7a30c81c
         with:
           enable_ccache: false
 

.github/workflows/reusable-build-test-config.yml

@@ -82,7 +82,7 @@ jobs:
     name: ${{ inputs.config_name }}
     runs-on: ${{ fromJSON(inputs.runs_on) }}
     container: ${{ inputs.image != '' && inputs.image || null }}
-    timeout-minutes: ${{ inputs.sanitizers != '' && 360 || 90 }}
+    timeout-minutes: ${{ inputs.sanitizers != '' && 360 || 180 }}
     env:
       # Use a namespace to keep the objects separate for each configuration.
       CCACHE_NAMESPACE: ${{ inputs.config_name }}
@@ -113,7 +113,7 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@c47daebb2f9db64ffbac71b47d68a661498d5ce8
+        uses: XRPLF/actions/prepare-runner@64ec3cf3b152b4444638f470bbd6df7a7a30c81c
         with:
           enable_ccache: ${{ inputs.ccache_enabled }}
 
@@ -163,7 +163,7 @@ jobs:
           CMAKE_ARGS: ${{ inputs.cmake_args }}
         run: |
           cmake \
-              -G '${{ runner.os == 'Windows' && 'Visual Studio 17 2022' || 'Ninja' }}' \
+              -G '${{ runner.os == 'Windows' && 'Visual Studio 18 2026' || 'Ninja' }}' \
               -DCMAKE_TOOLCHAIN_FILE:FILEPATH=build/generators/conan_toolchain.cmake \
               -DCMAKE_BUILD_TYPE="${BUILD_TYPE}" \
               ${CMAKE_ARGS} \
@@ -227,23 +227,7 @@ jobs:
               --build . \
               --config "${BUILD_TYPE}" \
               --parallel "${BUILD_NPROC}" \
-              --target "${CMAKE_TARGET}" \
-              2>&1 | tee build.log
-
-      # This step is needed to allow running in non-Nix environments
-      - name: Patch binary to use default loader and remove rpath (Linux)
-        if: ${{ runner.os == 'Linux' && env.SANITIZERS_ENABLED == 'false' }}
-        run: |
-          loader="$(/tmp/loader-path.sh)"
-          patchelf --set-interpreter "${loader}" --remove-rpath "${{ env.BUILD_DIR }}/xrpld"
-
-      # We're only running aarch64 Linux builds in Ubuntu-based images, so this is kept simple
-      - name: Install libatomic (Linux aarch64)
-        if: ${{ runner.os == 'Linux' && runner.arch == 'ARM64' }}
-        run: |
-          apt update --yes
-          apt install -y --no-install-recommends \
-              libatomic1
+              --target "${CMAKE_TARGET}"
 
       - name: Show ccache statistics
         if: ${{ inputs.ccache_enabled }}
@@ -341,7 +325,7 @@ jobs:
           LD_PRELOAD="$PRELOAD" ./xrpld --unittest --unittest-jobs "${BUILD_NPROC}" 2>&1 | tee unittest.log
 
       - name: Show test failure summary
-        if: ${{ failure() }}
+        if: ${{ failure() && !inputs.build_only }}
         env:
           WORKING_DIR: ${{ runner.os == 'Windows' && format('{0}\{1}', env.BUILD_DIR, inputs.build_type) || env.BUILD_DIR }}
         run: |
@@ -352,17 +336,13 @@ jobs:
 
           cd "${WORKING_DIR}"
 
-          if [ -f unittest.log ]; then
-              if ! grep -E "failed" unittest.log | grep -vE "^I[0-9]|^[0-9]+> (ERR:|FTL:)"; then
-                  echo "unittest.log present but no failure lines found."
-              fi
-          else
+          if [ ! -f unittest.log ]; then
               echo "unittest.log not found; embedded tests may not have run."
-              if [ -f build.log ]; then
-                  if ! grep -E "error:" build.log; then
-                      echo "build.log present but no compile errors found."
-                  fi
-              fi
+              exit 0
+          fi
+
+          if ! grep -E "failed" unittest.log; then
+              echo "Log present but no failure lines found in unittest.log."
           fi
       - name: Debug failure (Linux)
         if: ${{ failure() && runner.os == 'Linux' && !inputs.build_only }}

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

@@ -3,10 +3,6 @@ name: Run clang-tidy on files
 on:
   workflow_call:
     inputs:
-      check_only_changed:
-        description: "Check only changed files in PR. If false, checks all files in the repository."
-        type: boolean
-        default: false
       create_issue_on_failure:
         description: "Whether to create an issue if the check failed"
         type: boolean
@@ -29,17 +25,16 @@ env:
 
 jobs:
   determine-files:
-    if: ${{ inputs.check_only_changed }}
     permissions:
       contents: read
-    uses: XRPLF/actions/.github/workflows/determine-tidy-files.yml@c7045074aafe9fb92fa537aa4446f81fbfc17e8b
+    uses: XRPLF/actions/.github/workflows/determine-tidy-files.yml@d041ac9f1fa9f07a4ba335eb4c1c82233fb3fef6
 
   run-clang-tidy:
     name: Run clang tidy
     needs: [determine-files]
-    if: ${{ always() && !cancelled() && (!inputs.check_only_changed || needs.determine-files.outputs.cpp_changed_files != '' || needs.determine-files.outputs.clang_tidy_config_changed == 'true') }}
+    if: ${{ needs.determine-files.outputs.cpp_changed_files != '' || needs.determine-files.outputs.need_full_run == 'true' }}
     runs-on: ["self-hosted", "Linux", "X64", "heavy"]
-    container: "ghcr.io/xrplf/xrpld/nix-debian:sha-fe4c8ae"
+    container: "ghcr.io/xrplf/xrpld/nix-debian:sha-e29b523"
     permissions:
       contents: read
       issues: write
@@ -48,7 +43,7 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@c47daebb2f9db64ffbac71b47d68a661498d5ce8
+        uses: XRPLF/actions/prepare-runner@64ec3cf3b152b4444638f470bbd6df7a7a30c81c
         with:
           enable_ccache: false
 
@@ -84,6 +79,7 @@ jobs:
               -Dtests=ON \
               -Dwerr=ON \
               -Dxrpld=ON \
+              -Dverify_headers=ON \
               ..
 
       # clang-tidy needs headers generated from proto files
@@ -96,15 +92,15 @@ jobs:
         id: run_clang_tidy
         continue-on-error: true
         env:
-          TARGETS: ${{ (needs.determine-files.outputs.clang_tidy_config_changed != 'true' && inputs.check_only_changed) && needs.determine-files.outputs.cpp_changed_files || 'src tests' }}
+          TARGETS: ${{ needs.determine-files.outputs.need_full_run != 'true' && needs.determine-files.outputs.cpp_changed_files || 'include src tests' }}
         run: |
           set -o pipefail
           run-clang-tidy -j ${{ steps.nproc.outputs.nproc }} -p "${BUILD_DIR}" -quiet -fix -allow-no-checks ${TARGETS} 2>&1 | tee "${OUTPUT_FILE}"
 
-      - name: Print errors
+      - name: Print filtered clang-tidy errors
         if: ${{ steps.run_clang_tidy.outcome != 'success' }}
         run: |
-          sed '/error\||/!d' "${OUTPUT_FILE}"
+          bin/filter-clang-tidy.py "${OUTPUT_FILE}"
 
       - name: Upload clang-tidy output
         if: ${{ github.event.repository.visibility == 'public' && steps.run_clang_tidy.outcome != 'success' }}
@@ -148,12 +144,12 @@ jobs:
           \`\`\`
           EOF
 
-      - name: Append clang-tidy output to issue body (filter for errors and warnings)
+      - name: Append filtered clang-tidy output to issue body
         if: ${{ steps.run_clang_tidy.outcome != 'success' }}
         run: |
           if [ -f "${OUTPUT_FILE}" ]; then
-              # Extract lines containing 'error:', 'warning:', or 'note:'
-              grep -E '(error:|warning:|note:)' "${OUTPUT_FILE}" >"${FILTERED_OUTPUT_FILE}" || true
+              # Filter to the unique errors with their source context.
+              bin/filter-clang-tidy.py "${OUTPUT_FILE}" >"${FILTERED_OUTPUT_FILE}" || true
 
               # If filtered output is empty, use original (might be a different error format)
               if [ ! -s "${FILTERED_OUTPUT_FILE}" ]; then

.github/workflows/reusable-package.yml

@@ -30,7 +30,7 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
 
       - name: Set up Python
-        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
         with:
           python-version: "3.13"
 
@@ -39,23 +39,8 @@ jobs:
         working-directory: .github/scripts/strategy-matrix
         run: ./generate.py --packaging >>"${GITHUB_OUTPUT}"
 
-  generate-version:
-    runs-on: ubuntu-latest
-    outputs:
-      version: ${{ steps.version.outputs.version }}
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
-        with:
-          sparse-checkout: |
-            .github/actions/generate-version
-            src/libxrpl/protocol/BuildInfo.cpp
-      - name: Generate version
-        id: version
-        uses: ./.github/actions/generate-version
-
   package:
-    needs: [generate-matrix, generate-version]
+    needs: [generate-matrix]
     if: ${{ github.event.repository.visibility == 'public' }}
     strategy:
       fail-fast: false
@@ -82,14 +67,13 @@ jobs:
 
       - name: Build package
         env:
-          PKG_VERSION: ${{ needs.generate-version.outputs.version }}
           PKG_RELEASE: ${{ inputs.pkg_release }}
         run: ./package/build_pkg.sh
 
       - name: Upload package artifact
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
-          name: ${{ matrix.artifact_name }}-pkg-${{ needs.generate-version.outputs.version }}
+          name: ${{ matrix.artifact_name }}-pkg
           path: |
             ${{ env.BUILD_DIR }}/debbuild/*.deb
             ${{ env.BUILD_DIR }}/debbuild/*.ddeb

.github/workflows/reusable-strategy-matrix.yml

@@ -26,7 +26,7 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
 
       - name: Set up Python
-        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6.3.0
         with:
           python-version: "3.13"
 

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

@@ -14,7 +14,7 @@ on:
         description: "The URL of the Conan endpoint to use."
         required: false
         type: string
-        default: https://conan.ripplex.io
+        default: https://conan.xrplf.org/repository/conan/
 
     secrets:
       remote_username:
@@ -40,7 +40,11 @@ defaults:
 jobs:
   upload:
     runs-on: ubuntu-latest
-    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-fe4c8ae
+    container: ghcr.io/xrplf/xrpld/nix-ubuntu:sha-e29b523
+    env:
+      REMOTE_NAME: ${{ inputs.remote_name }}
+      CONAN_LOGIN_USERNAME_XRPLF: ${{ secrets.remote_username }}
+      CONAN_PASSWORD_XRPLF: ${{ secrets.remote_password }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
@@ -56,15 +60,9 @@ jobs:
           remote_url: ${{ inputs.remote_url }}
 
       - name: Log into Conan remote
-        env:
-          REMOTE_NAME: ${{ inputs.remote_name }}
-          REMOTE_USERNAME: ${{ secrets.remote_username }}
-          REMOTE_PASSWORD: ${{ secrets.remote_password }}
-        run: conan remote login "${REMOTE_NAME}" "${REMOTE_USERNAME}" --password "${REMOTE_PASSWORD}"
+        run: conan remote login "${REMOTE_NAME}" "${CONAN_LOGIN_USERNAME_XRPLF}" --password "${CONAN_PASSWORD_XRPLF}"
 
       - name: Upload Conan recipe (version)
-        env:
-          REMOTE_NAME: ${{ inputs.remote_name }}
         run: |
           conan export . --version=${{ steps.version.outputs.version }}
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/${{ steps.version.outputs.version }}
@@ -73,8 +71,6 @@ jobs:
       # 'develop' branch, see on-trigger.yml.
       - name: Upload Conan recipe (develop)
         if: ${{ github.event_name == 'push' }}
-        env:
-          REMOTE_NAME: ${{ inputs.remote_name }}
         run: |
           conan export . --version=develop
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/develop
@@ -83,8 +79,6 @@ jobs:
       # one of the 'release' branches, see on-pr.yml.
       - name: Upload Conan recipe (rc)
         if: ${{ github.event_name == 'pull_request' }}
-        env:
-          REMOTE_NAME: ${{ inputs.remote_name }}
         run: |
           conan export . --version=rc
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/rc
@@ -93,8 +87,6 @@ jobs:
       # release, see on-tag.yml.
       - name: Upload Conan recipe (release)
         if: ${{ startsWith(github.ref, 'refs/tags/') }}
-        env:
-          REMOTE_NAME: ${{ inputs.remote_name }}
         run: |
           conan export . --version=release
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/release

.github/workflows/upload-conan-deps.yml

@@ -34,7 +34,7 @@ on:
 
 env:
   CONAN_REMOTE_NAME: xrplf
-  CONAN_REMOTE_URL: https://conan.ripplex.io
+  CONAN_REMOTE_URL: https://conan.xrplf.org/repository/conan/
   NPROC_SUBTRACT: 2
 
 concurrency:
@@ -68,7 +68,7 @@ jobs:
         uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
 
       - name: Prepare runner
-        uses: XRPLF/actions/prepare-runner@c47daebb2f9db64ffbac71b47d68a661498d5ce8
+        uses: XRPLF/actions/prepare-runner@64ec3cf3b152b4444638f470bbd6df7a7a30c81c
         with:
           enable_ccache: false
 
@@ -108,10 +108,12 @@ jobs:
 
       - name: Log into Conan remote
         if: ${{ github.repository == 'XRPLF/rippled' && (github.event_name == 'push' || github.event_name == 'workflow_dispatch') }}
-        run: conan remote login "${CONAN_REMOTE_NAME}" "${{ secrets.CONAN_REMOTE_USERNAME }}" --password "${{ secrets.CONAN_REMOTE_PASSWORD }}"
+        run: conan remote login "${CONAN_REMOTE_NAME}" "${{ secrets.NEXUS_REMOTE_USERNAME }}" --password "${{ secrets.NEXUS_REMOTE_PASSWORD }}"
 
       - name: Upload Conan packages
         if: ${{ github.repository == 'XRPLF/rippled' && (github.event_name == 'push' || github.event_name == 'workflow_dispatch') }}
         env:
           FORCE_OPTION: ${{ github.event.inputs.force_upload == 'true' && '--force' || '' }}
+          CONAN_LOGIN_USERNAME_XRPLF: ${{ secrets.NEXUS_REMOTE_USERNAME }}
+          CONAN_PASSWORD_XRPLF: ${{ secrets.NEXUS_REMOTE_PASSWORD }}
         run: conan upload "*" --remote="${CONAN_REMOTE_NAME}" --confirm ${FORCE_OPTION}

.pre-commit-config.yaml

@@ -15,6 +15,7 @@ repos:
     hooks:
       - id: check-added-large-files
         args: [--maxkb=400, --enforce-all]
+      - id: check-executables-have-shebangs
       - id: trailing-whitespace
       - id: end-of-file-fixer
       - id: check-merge-conflict
@@ -27,30 +28,37 @@ repos:
         entry: ./bin/pre-commit/clang_tidy_check.py
         language: python
         types_or: [c++, c]
-        exclude: ^include/xrpl/protocol_autogen
-        pass_filenames: false # script determines the staged files itself
+        # .ipp fragments are included by their owning header rather than compiled
+        # as standalone translation units, so they have no compile_commands.json
+        # entry to lint (verify_headers checks them transitively).
+        exclude: '^include/xrpl/protocol_autogen|\.ipp$'
       - id: fix-include-style
         name: fix include style
         entry: ./bin/pre-commit/fix_include_style.py
         language: python
         types_or: [c++, c]
         exclude: ^include/xrpl/protocol_autogen/(transactions|ledger_entries)/
+      - id: fix-pragma-once
+        name: fix missing '#pragma once' declarations in header files
+        language: python
+        entry: ./bin/pre-commit/fix_pragma_once.py
+        files: \.(h|hpp)$
 
   - repo: https://github.com/pre-commit/mirrors-clang-format
     rev: dd18dad857d6133e90bbe478f4f2f22ec0030269 # frozen: v22.1.5
     hooks:
       - id: clang-format
         args: [--style=file]
-        "types_or": [c++, c, proto]
+        types_or: [c++, c, proto]
         exclude: ^include/xrpl/protocol_autogen/(transactions|ledger_entries)/
 
   - repo: https://github.com/BlankSpruce/gersemi-pre-commit
-    rev: faadd6a9d852369ca94f4d15b2404c967ba8cb01 # frozen: 0.27.6
+    rev: e98930bdc210d3387007f9252d8c1694ea7e410f # frozen: 0.27.7
     hooks:
       - id: gersemi
 
   - repo: https://github.com/rbubley/mirrors-prettier
-    rev: 515f543f5718ebfd6ce22e16708bb32c68ff96e1 # frozen: v3.8.3
+    rev: 39e2973981e6d2f9b6c543b0086a2d2393abdc89 # frozen: v3.9.4
     hooks:
       - id: prettier
         args: [--end-of-line=auto]
@@ -80,22 +88,21 @@ repos:
         files: \.md$
 
   - repo: https://github.com/streetsidesoftware/cspell-cli
-    rev: 4643f154907327ee0a2c7038f0296e0dd77d9776 # frozen: v10.0.0
+    rev: ea11f9efc0bec520073405bc30552da887ba71bc # frozen: v10.0.1
     hooks:
-      - id: cspell # Spell check changed files
+      - id: cspell
+        name: check changed files spelling
         exclude: |
           (?x)^(
-              .config/cspell.config.yaml|
+              \.cspell\.config\.yaml|
               include/xrpl/protocol_autogen/(transactions|ledger_entries)/.*
           )$
-      - id: cspell # Spell check the commit message
+      - id: cspell
         name: check commit message spelling
         args:
           - --no-must-find-files
           - --no-progress
           - --no-summary
-          - --files
-          - .git/COMMIT_EDITMSG
         stages: [commit-msg]
 
   - repo: local

BUILD.md

@@ -25,7 +25,7 @@ You can verify that the required tools are installed and runnable with:
 | ----------- | --------------- |
 | GCC         | 15.2            |
 | Clang       | 22              |
-| Apple Clang | 17              |
+| Apple Clang | 21              |
 | MSVC        | 19.44[^windows] |
 
 ## Operating Systems
@@ -101,7 +101,7 @@ More information on customizing Conan can be found in the [Advanced Conan config
 Run the following command to add the `xrplf` remote, which hosts some of our dependencies:
 
 ```bash
-conan remote add --index 0 --force xrplf https://conan.ripplex.io
+conan remote add --index 0 --force xrplf https://conan.xrplf.org/repository/conan/
 ```
 
 ### Set Up Ccache
@@ -317,21 +317,41 @@ See [Sanitizers docs](./docs/build/sanitizers.md) for more details.
 
 ## Options
 
-| Option     | Default Value | Description                                                    |
-| ---------- | ------------- | -------------------------------------------------------------- |
-| `assert`   | OFF           | Force enabling assertions.                                     |
-| `coverage` | OFF           | Prepare the coverage report.                                   |
-| `tests`    | OFF           | Build tests.                                                   |
-| `unity`    | OFF           | Configure a unity build.                                       |
-| `xrpld`    | OFF           | Build the xrpld application, and not just the libxrpl library. |
-| `werr`     | OFF           | Treat compilation warnings as errors                           |
-| `wextra`   | OFF           | Enable additional compilation warnings                         |
+| Option           | Default Value | Description                                                                   |
+| ---------------- | ------------- | ----------------------------------------------------------------------------- |
+| `assert`         | OFF           | Force enabling assertions.                                                    |
+| `coverage`       | OFF           | Prepare the coverage report.                                                  |
+| `tests`          | OFF           | Build tests.                                                                  |
+| `unity`          | OFF           | Configure a unity build.                                                      |
+| `verify_headers` | ON            | Make the `verify-headers` target available to compile each header on its own. |
+| `xrpld`          | OFF           | Build the xrpld application, and not just the libxrpl library.                |
+| `werr`           | OFF           | Treat compilation warnings as errors                                          |
+| `wextra`         | OFF           | Enable additional compilation warnings                                        |
 
 [Unity builds][unity-build] may be faster for the first build (at the cost of much more
 memory) since they concatenate sources into fewer translation units. Non-unity
 builds may be faster for incremental builds, and can be helpful for detecting
 `#include` omissions.
 
+### Verifying headers
+
+The regular build only compiles `.cpp` files, so a header is only ever checked
+through whatever translation unit happens to include it. A header that forgets
+an `#include` is not caught as long as every `.cpp` that uses it includes its
+missing dependency first. The `verify_headers` option (ON by default) adds a
+`verify-headers` target that compiles every header on its own, which fails if a
+header is not self-contained:
+
+```bash
+cmake --build . --target verify-headers
+```
+
+The per-header objects are excluded from the `all` target, so a normal build
+never compiles them; they are built only through `verify-headers`. The generated
+translation units do appear in `compile_commands.json`, so clang-tidy (and
+clangd and IDEs) can lint each header on its own. Pass `-Dverify_headers=OFF` to
+omit them entirely.
+
 ## Troubleshooting
 
 ### Conan

CMakeLists.txt

@@ -57,6 +57,8 @@ if(target)
     )
 endif()
 
+include(PatchNixBinary)
+
 include(XrplSanity)
 include(XrplVersion)
 include(XrplSettings)
@@ -88,6 +90,7 @@ find_package(ed25519 REQUIRED)
 find_package(gRPC REQUIRED)
 find_package(LibArchive REQUIRED)
 find_package(lz4 REQUIRED)
+find_package(mpt-crypto REQUIRED)
 find_package(nudb REQUIRED)
 find_package(OpenSSL REQUIRED)
 find_package(secp256k1 REQUIRED)
@@ -100,6 +103,7 @@ target_link_libraries(
     INTERFACE
         ed25519::ed25519
         lz4::lz4
+        mpt-crypto::mpt-crypto
         OpenSSL::Crypto
         OpenSSL::SSL
         secp256k1::secp256k1

CONTRIBUTING.md

@@ -298,6 +298,46 @@ If you wish to automatically fix whatever clang-tidy finds _and_ is capable of f
 run-clang-tidy -p build -quiet -fix -allow-no-checks src tests
 ```
 
+## Telemetry span attribute naming
+
+OpenTelemetry span attribute keys follow these rules so they stay consistent
+across the code, the OTel collector, Tempo, Grafana dashboards, and docs. The
+constants in the `*SpanNames.h` headers are the single source of truth; every
+other layer must match them. A CI check enforces this end to end.
+
+1. Per-span unique attribute: bare field name — allowed when the field is
+   recorded by a single span/workflow, so the span name already supplies the
+   domain (e.g. `command`, `local`, `version` on `rpc.command` / `tx.process`).
+2. Shared attribute (same concept on more than one span): ONE key, reused
+   verbatim on every span that records it — the span name tells the occurrences
+   apart, so no per-emitter prefix is added. Pick the name by the field's
+   meaning: a property of a domain object keeps that object's bare field name
+   (`ledger_hash`, `ledger_seq`, `tx_hash`, `peer_id`, `full_validation`); a
+   field already qualified by a sub-kind keeps that qualifier on every emitter
+   (`proposal_trusted` on both `consensus.proposal.receive` and
+   `peer.proposal.receive`; `validation_trusted` likewise). Define it once in
+   the base `SpanNames.h` `namespace attr` block and re-export (`using`) it from
+   each domain header, so all emitters share the exact string.
+3. Collision qualifier: `<domain>_<field>` — only when a bare name would collide
+   with a DIFFERENT concept in the shared spanmetrics label space, or with the
+   OTel-reserved `status` key (e.g. `rpc_status`, `grpc_status`,
+   `consensus_phase`, `consensus_round`). This disambiguates distinct concepts
+   that share a word; it is NOT used to tag the same concept with the workflow
+   that emitted it — that is rule 2 (one shared name).
+4. Resource attribute: dotted `xrpl.<subsystem>.<field>` — reserved ONLY for
+   process/network identity set once at startup (`xrpl.network.id`,
+   `xrpl.network.type`). Never use the dotted `xrpl.` form for span attributes.
+5. Span names use `<subsystem>[.<component>]` (dotted). Only attribute _keys_
+   follow rules 1–4.
+
+Standard OpenTelemetry semantic-convention keys keep their canonical dotted
+form (e.g. `service.*` resource attributes, `http.*` span attributes); the
+"no dotted form" rule above applies to xrpl-custom keys, not to OTel-standard
+conventions.
+
+Always reference the `*SpanNames.h` constants — never pass string literals as
+attribute keys or values to `setAttribute`/`addEvent`.
+
 ## Contracts and instrumentation
 
 We are using [Antithesis](https://antithesis.com/) for continuous fuzzing,

OpenTelemetryPlan/00-tracing-fundamentals.md

@@ -0,0 +1,565 @@
+# Distributed Tracing Fundamentals
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Next**: [Architecture Analysis](./01-architecture-analysis.md)
+
+---
+
+## What is Distributed Tracing?
+
+Distributed tracing is a method for tracking data objects as they flow through distributed systems. In a network like XRP Ledger, a single transaction touches multiple independent nodes—each with no shared memory or logging. Distributed tracing connects these dots.
+
+**Without tracing:** You see isolated logs on each node with no way to correlate them.
+
+**With tracing:** You see the complete journey of a transaction or an event across all nodes it touched.
+
+---
+
+## Actors and Actions at a Glance
+
+### Actors
+
+| Who (Plain English)                            | Technical Term  |
+| ---------------------------------------------- | --------------- |
+| A single unit of work being tracked            | Span            |
+| The complete journey of a request              | Trace           |
+| Data that links spans across services          | Trace Context   |
+| Code that creates spans and propagates context | Instrumentation |
+| Service that receives and processes traces     | Collector       |
+| Storage and visualization system               | Backend (Tempo) |
+| Decision logic for which traces to keep        | Sampler         |
+
+### Actions
+
+| What Happens (Plain English)            | Technical Term          |
+| --------------------------------------- | ----------------------- |
+| Start tracking a new operation          | Create a Span           |
+| Connect a child operation to its parent | Set `parent_span_id`    |
+| Group all related operations together   | Share a `trace_id`      |
+| Pass tracking data between services     | Context Propagation     |
+| Decide whether to record a trace        | Sampling (Head or Tail) |
+| Send completed traces to storage        | Export (OTLP)           |
+
+---
+
+## Core Concepts
+
+### 1. Trace
+
+A **trace** represents the entire journey of a request through the system. It has a unique `trace_id` that stays constant across all nodes.
+
+```
+Trace ID: abc123
+├── Node A: received transaction
+├── Node B: relayed transaction
+├── Node C: included in consensus
+└── Node D: applied to ledger
+```
+
+### 2. Span
+
+A **span** represents a single unit of work within a trace. Each span has:
+
+| Attribute        | Description                      | Example                    |
+| ---------------- | -------------------------------- | -------------------------- |
+| `trace_id`       | Identifies the trace             | `event123`                 |
+| `span_id`        | Unique identifier                | `span456`                  |
+| `parent_span_id` | Parent span (if any)             | `p_span123`                |
+| `name`           | Operation name                   | `rpc.submit`               |
+| `start_time`     | When work began (local time)     | `2024-01-15T10:30:00Z`     |
+| `end_time`       | When work completed (local time) | `2024-01-15T10:30:00.050Z` |
+| `attributes`     | Key-value metadata               | `tx_hash=ABC...`           |
+| `status`         | OK, ERROR MSG                    | `OK`                       |
+
+### 3. Trace Context
+
+**Trace context** is the data that propagates between services to link spans together. It contains:
+
+- `trace_id` - The trace this span belongs to
+- `span_id` - The current span (becomes parent for child spans)
+- `trace_flags` - Sampling decisions
+
+---
+
+## How Spans Form a Trace
+
+Spans have parent-child relationships forming a tree structure:
+
+```mermaid
+flowchart TB
+    subgraph trace["Trace: abc123"]
+        A["tx.submit<br/>span_id: 001<br/>50ms"] --> B["tx.validate<br/>span_id: 002<br/>5ms"]
+        A --> C["tx.relay<br/>span_id: 003<br/>10ms"]
+        A --> D["tx.apply<br/>span_id: 004<br/>30ms"]
+        D --> E["ledger.update<br/>span_id: 005<br/>20ms"]
+    end
+
+    style A fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style B fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style C fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style D fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style E fill:#bf360c,stroke:#8c2809,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **tx.submit (blue, root)**: The top-level span representing the entire transaction submission; all other spans are its descendants.
+- **tx.validate, tx.relay, tx.apply (green)**: Direct children of tx.submit, representing the three main stages -- validation, relay to peers, and application to the ledger.
+- **ledger.update (red)**: A grandchild span nested under tx.apply, representing the actual ledger state mutation triggered by applying the transaction.
+- **Arrows (parent to child)**: Each arrow indicates a parent-child span relationship where the parent's completion depends on the child finishing.
+
+The same trace visualized as a **timeline (Gantt chart)**:
+
+```
+Time →   0ms    10ms    20ms    30ms    40ms    50ms
+         ├───────────────────────────────────────────┤
+tx.submit│▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓│
+         ├─────┤
+tx.valid │▓▓▓▓▓│
+         │     ├──────────┤
+tx.relay │     │▓▓▓▓▓▓▓▓▓▓│
+         │               ├────────────────────────────┤
+tx.apply │               │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓│
+         │                         ├──────────────────┤
+ledger   │                         │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓│
+```
+
+---
+
+## Span Relationships
+
+Spans don't always form simple parent-child trees. Distributed tracing defines several relationship types to capture different causal patterns:
+
+### 1. Parent-Child (ChildOf)
+
+The default relationship. The parent span **depends on** or **contains** the child span. The child runs within the scope of the parent.
+
+```
+tx.submit (parent)
+├── tx.validate (child)     ← parent waits for this
+├── tx.relay (child)        ← parent waits for this
+└── tx.apply (child)        ← parent waits for this
+```
+
+**When to use:** Synchronous calls, nested operations, any case where the parent's completion depends on the child.
+
+### 2. Follows-From
+
+A causal relationship where the first span **triggers** the second, but does **not wait** for it. The originator fires and moves on.
+
+```
+Time →
+
+tx.receive [=======]
+                     ↓ triggers (follows-from)
+              tx.relay   [===========]   ← runs independently
+```
+
+**When to use:** Asynchronous jobs, queued work, fire-and-forget patterns. For example, a node receives a transaction and queues it for relay — the relay span _follows from_ the receive span but the receiver doesn't wait for relaying to complete.
+
+> **OpenTracing** defined `FollowsFrom` as a first-class reference type alongside `ChildOf`.
+> **OpenTelemetry** represents this using **Span Links** with descriptive attributes instead (see below).
+
+### 3. Span Links (Cross-Trace and Non-Hierarchical)
+
+Links connect spans that are **causally related but not in a parent-child hierarchy**. Unlike parent-child, links can cross trace boundaries.
+
+```
+Trace A                          Trace B
+──────                           ──────
+batch.schedule                   batch.execute
+├─ item.enqueue (span X)    ┌──► process.item
+├─ item.enqueue (span Y) ───┤    (links to X, Y, Z)
+├─ item.enqueue (span Z)    └──►
+```
+
+**Use cases:**
+
+| Pattern              | Description                                                                 |
+| -------------------- | --------------------------------------------------------------------------- |
+| **Batch processing** | A batch span links back to all individual spans that contributed to it      |
+| **Fan-in**           | An aggregation span links to the multiple producer spans it merges          |
+| **Fan-out**          | Multiple downstream spans link back to the single span that triggered them  |
+| **Async handoff**    | A deferred job links back to the request that queued it (follows-from)      |
+| **Cross-trace**      | Correlating spans across independent traces (e.g., retries, related events) |
+
+**Link structure:** Each link carries the target span's context plus optional attributes:
+
+```
+Link {
+    trace_id:   <target trace>
+    span_id:    <target span>
+    attributes: { "link.description": "triggered by batch scheduler" }
+}
+```
+
+### Relationship Summary
+
+```mermaid
+flowchart LR
+    subgraph parent_child["Parent-Child"]
+        direction TB
+        P["Parent"] --> C["Child"]
+    end
+
+    subgraph follows_from["Follows-From"]
+        direction TB
+        A["Span A"] -.->|triggers| B["Span B"]
+    end
+
+    subgraph links["Span Links"]
+        direction TB
+        X["Span X\n(Trace 1)"] -.-|link| Y["Span Y\n(Trace 2)"]
+    end
+
+    parent_child ~~~ follows_from ~~~ links
+
+    style P fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style C fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style A fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style B fill:#bf360c,stroke:#8c2809,color:#ffffff
+    style X fill:#4a148c,stroke:#38006b,color:#ffffff
+    style Y fill:#4a148c,stroke:#38006b,color:#ffffff
+```
+
+| Relationship     | Same Trace? | Dependency?                | OTel Mechanism    |
+| ---------------- | ----------- | -------------------------- | ----------------- |
+| **Parent-Child** | Yes         | Parent depends on child    | `parent_span_id`  |
+| **Follows-From** | Usually     | Causal but no dependency   | Link + attributes |
+| **Span Link**    | Either      | Correlation, no dependency | Link + attributes |
+
+---
+
+## Trace ID Generation
+
+A `trace_id` is a 128-bit (16-byte) identifier that groups all spans belonging to one logical operation. How it's generated determines how easily you can find and correlate traces later.
+
+### General Approaches
+
+#### 1. Random (W3C Default)
+
+Generate a random 128-bit ID when a trace starts. Standard approach for most services.
+
+```
+trace_id = random_128_bits()
+```
+
+| Pros                        | Cons                                          |
+| --------------------------- | --------------------------------------------- |
+| Simple, standard            | No natural correlation to domain events       |
+| Guaranteed unique per trace | If propagation is lost, trace is broken       |
+| Works with all OTel tooling | "Find trace for TX abc" requires index lookup |
+
+#### 2. Deterministic (Derived from Domain Data)
+
+Compute the trace_id from a hash of a natural identifier. Every node independently derives the **same** trace_id for the same event.
+
+```
+trace_id = SHA-256(domain_identifier)[0:16]   // truncate to 128 bits
+```
+
+| Pros                                                | Cons                                                       |
+| --------------------------------------------------- | ---------------------------------------------------------- |
+| Propagation-resilient — same ID computed everywhere | Same event processed twice (retry) shares trace_id         |
+| Natural search — domain ID maps directly to trace   | Non-standard (tooling assumes random)                      |
+| No coordination needed between nodes                | 256→128 bit truncation (collision risk negligible at ~2⁶⁴) |
+
+#### 3. Hybrid (Deterministic Prefix + Random Suffix)
+
+First 8 bytes derived from domain data, last 8 bytes random.
+
+```
+trace_id = SHA-256(domain_identifier)[0:8] || random_64_bits()
+```
+
+| Pros                                        | Cons                                     |
+| ------------------------------------------- | ---------------------------------------- |
+| Prefix search: "find all traces for TX abc" | Must propagate to maintain full trace_id |
+| Unique per processing instance              | More complex generation logic            |
+| Retries get distinct trace_ids              | Partial correlation only (prefix match)  |
+
+### XRPL Workflow Analysis
+
+XRPL has a unique advantage: its core workflows produce **globally unique 256-bit hashes** that are known on every node. This makes deterministic trace_id generation practical in ways most systems can't achieve.
+
+#### Natural Identifiers by Workflow
+
+| Workflow            | Natural Identifier                | Size       | Known at Start?               | Same on All Nodes?               |
+| ------------------- | --------------------------------- | ---------- | ----------------------------- | -------------------------------- |
+| **Transaction**     | Transaction hash (`tid_`)         | 256-bit    | Yes — computed before signing | Yes — hash of canonical tx data  |
+| **Consensus round** | Previous ledger hash + ledger seq | 256+32 bit | Yes — known when round opens  | Yes — all validators agree       |
+| **Validation**      | Ledger hash being validated       | 256-bit    | Yes — from consensus result   | Yes — same closed ledger         |
+| **Ledger catch-up** | Target ledger hash                | 256-bit    | Yes — we know what to fetch   | Yes — identifies ledger globally |
+
+#### Where These Identifiers Live in Code
+
+```
+Transaction:     STTx::getTransactionID()     → uint256 tid_
+                 TMTransaction::rawTransaction → recompute hash from bytes
+
+Consensus:       ConsensusProposal::prevLedger_ → uint256 (previous ledger hash)
+                 ConsensusProposal::position_   → uint256 (TxSet hash)
+                 LedgerHeader::seq              → uint32_t (ledger sequence)
+
+Validation:      STValidation::getLedgerHash()  → uint256
+                 STValidation::getNodeID()      → NodeID (160-bit)
+
+Ledger fetch:    InboundLedger constructor      → uint256 hash, uint32_t seq
+                 TMGetLedger::ledgerHash        → bytes (uint256)
+```
+
+### Recommended Strategy: Workflow-Scoped Deterministic
+
+Each workflow type derives its trace_id from its natural domain identifier:
+
+```
+Transaction trace:   trace_id = SHA-256("tx"    || tx_hash)[0:16]
+Consensus trace:     trace_id = SHA-256("cons"  || prev_ledger_hash || ledger_seq)[0:16]
+Ledger catch-up:     trace_id = SHA-256("fetch" || target_ledger_hash)[0:16]
+```
+
+The string prefix (`"tx"`, `"cons"`, `"fetch"`) prevents collisions between workflows that might share underlying hashes.
+
+**Why this works for XRPL:**
+
+1. **Propagation-resilient** — Even if a P2P message drops trace context, every node independently computes the same trace_id from the same tx_hash or ledger_hash. Spans still correlate.
+
+2. **Zero-cost search** — "Show me the trace for transaction ABC" becomes a direct lookup: compute `SHA-256("tx" || ABC)[0:16]` and query. No secondary index needed.
+
+3. **Cross-workflow linking via Span Links** — A consensus trace links to individual transaction traces. A validation span links to the consensus trace. This connects the full picture without forcing everything into one giant trace.
+
+### Cross-Workflow Correlation
+
+Each workflow gets its own trace. Span Links tie them together:
+
+```mermaid
+flowchart TB
+    subgraph tx_trace["Transaction Trace"]
+        direction LR
+        Tn["trace_id = f(tx_hash)"]:::note --> T1["tx.receive"] --> T2["tx.validate"] --> T3["tx.relay"]
+    end
+
+    subgraph cons_trace["Consensus Trace"]
+        direction LR
+        Cn["trace_id = f(prev_ledger, seq)"]:::note --> C1["cons.open"] --> C2["cons.propose"] --> C3["cons.accept"]
+    end
+
+    subgraph val_trace["Validation"]
+        direction LR
+        Vn["spans within consensus trace"]:::note --> V1["val.create"] --> V2["val.broadcast"]
+    end
+
+    subgraph fetch_trace["Catch-Up Trace"]
+        direction LR
+        Fn["trace_id = f(ledger_hash)"]:::note --> F1["fetch.request"] --> F2["fetch.receive"] --> F3["fetch.apply"]
+    end
+
+    C1 -.-|"span link\n(tx traces)"| T3
+    C3 --> V1
+    F1 -.-|"span link\n(target ledger)"| C3
+
+    classDef note fill:none,stroke:#888,stroke-dasharray:5 5,color:#333,font-style:italic
+    style T1 fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style T2 fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style T3 fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style C1 fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style C2 fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style C3 fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style V1 fill:#bf360c,stroke:#8c2809,color:#ffffff
+    style V2 fill:#bf360c,stroke:#8c2809,color:#ffffff
+    style F1 fill:#4a148c,stroke:#38006b,color:#ffffff
+    style F2 fill:#4a148c,stroke:#38006b,color:#ffffff
+    style F3 fill:#4a148c,stroke:#38006b,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **Transaction Trace (blue)**: An independent trace whose `trace_id` is deterministically derived from the transaction hash. Contains receive, validate, and relay spans.
+- **Consensus Trace (green)**: An independent trace whose `trace_id` is derived from the previous ledger hash and sequence number. Covers the open, propose, and accept phases.
+- **Validation (red)**: Validation spans live within the consensus trace (not a separate trace). They are created after the accept phase completes.
+- **Catch-Up Trace (purple)**: An independent trace for ledger acquisition, derived from the target ledger hash. Used when a node is behind and fetching missing ledgers.
+- **Dotted arrows (span links)**: Cross-trace correlations. Consensus links to transaction traces it included; catch-up links to the consensus trace that produced the target ledger.
+- **Solid arrow (C3 to V1)**: A parent-child relationship -- validation spans are direct children of the consensus accept span within the same trace.
+
+**How a query flows:**
+
+```
+"Why was TX abc slow?"
+  1. Compute trace_id = SHA-256("tx" || abc)[0:16]
+  2. Find transaction trace → see it was included in consensus round N
+  3. Follow span link → consensus trace for round N
+  4. See which phase was slow (propose? accept?)
+  5. If a node was catching up, follow link → catch-up trace
+```
+
+### Trade-offs to Consider
+
+| Concern                       | Mitigation                                                                                                                    |
+| ----------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
+| **Retries get same trace_id** | Add `attempt` attribute to root span; spans have unique span_ids and timestamps                                               |
+| **256→128 bit truncation**    | Birthday-bound collision at ~2⁶⁴ operations — negligible for XRPL's throughput                                                |
+| **Non-standard generation**   | OTel spec allows any 16-byte non-zero value; tooling works on the hex string                                                  |
+| **Hash computation cost**     | SHA-256 is ~0.3μs per call; XRPL already computes these hashes for other purposes                                             |
+| **Late-binding identifiers**  | Ledger hash isn't known until after consensus — validation spans use ledger_seq as fallback, then link to the consensus trace |
+
+---
+
+## Distributed Traces Across Nodes
+
+In distributed systems like xrpld, traces span **multiple independent nodes**. The trace context must be propagated in network messages:
+
+```mermaid
+sequenceDiagram
+    participant Client
+    participant NodeA as Node A
+    participant NodeB as Node B
+    participant NodeC as Node C
+
+    Client->>NodeA: Submit TX<br/>(no trace context)
+
+    Note over NodeA: Creates new trace<br/>trace_id: abc123<br/>span: tx.receive
+
+    NodeA->>NodeB: Relay TX<br/>(trace_id: abc123, parent: 001)
+
+    Note over NodeB: Creates child span<br/>span: tx.relay<br/>parent_span_id: 001
+
+    NodeA->>NodeC: Relay TX<br/>(trace_id: abc123, parent: 001)
+
+    Note over NodeC: Creates child span<br/>span: tx.relay<br/>parent_span_id: 001
+
+    Note over NodeA,NodeC: All spans share trace_id: abc123<br/>enabling correlation across nodes
+```
+
+**Reading the diagram:**
+
+- **Client**: The external entity that submits a transaction. It does not carry trace context -- the trace originates at the first node.
+- **Node A**: The entry point that creates a new trace (trace_id: abc123) and the root span `tx.receive`. It relays the transaction to peers with trace context attached.
+- **Node B and Node C**: Peer nodes that receive the relayed transaction along with the propagated trace context. Each creates a child span under Node A's span, preserving the same `trace_id`.
+- **Arrows with trace context**: The relay messages carry `trace_id` and `parent_span_id`, allowing each downstream node to link its spans back to the originating span on Node A.
+
+---
+
+## Context Propagation
+
+For traces to work across nodes, **trace context must be propagated** in messages.
+
+### What's in the Context (~26 bytes)
+
+| Field         | Size     | Description                                             |
+| ------------- | -------- | ------------------------------------------------------- |
+| `trace_id`    | 16 bytes | Identifies the entire trace (constant across all nodes) |
+| `span_id`     | 8 bytes  | The sender's current span (becomes parent on receiver)  |
+| `trace_flags` | 1 byte   | Sampling decision (bit 0 = sampled; bits 1-7 reserved)  |
+| `trace_state` | variable | Optional vendor-specific data (typically omitted)       |
+
+### How span_id Changes at Each Hop
+
+Only **one** `span_id` travels in the context - the sender's current span. Each node:
+
+1. Extracts the received `span_id` and uses it as the `parent_span_id`
+2. Creates a **new** `span_id` for its own span
+3. Sends its own `span_id` as the parent when forwarding
+
+```
+Node A                      Node B                      Node C
+──────                      ──────                      ──────
+
+Span AAA                    Span BBB                    Span CCC
+   │                           │                           │
+   ▼                           ▼                           ▼
+Context out:                Context out:                Context out:
+├─ trace_id: abc123         ├─ trace_id: abc123         ├─ trace_id: abc123
+├─ span_id: AAA ──────────► ├─ span_id: BBB ──────────► ├─ span_id: CCC ──────►
+└─ flags: 01                └─ flags: 01                └─ flags: 01
+                               │                           │
+                          parent = AAA               parent = BBB
+```
+
+The `trace_id` stays constant, but `span_id` **changes at every hop** to maintain the parent-child chain.
+
+### Propagation Formats
+
+There are two patterns:
+
+### HTTP/RPC Headers (W3C Trace Context)
+
+```
+traceparent: 00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01
+             │  │                                │                │
+             │  │                                │                └── Flags (sampled)
+             │  │                                └── Parent span ID (16 hex)
+             │  └── Trace ID (32 hex)
+             └── Version
+```
+
+### Protocol Buffers (xrpld P2P messages)
+
+xrpld P2P messages such as `TMTransaction` carry the trace context in two added byte fields alongside the existing payload: `trace_parent` holds the W3C traceparent (`trace_id`, `span_id`, and `trace_flags`), and `trace_state` holds the optional W3C tracestate. Together they propagate the trace across the P2P boundary so a receiving node can attach its spans to the sender's span.
+
+---
+
+## Sampling
+
+Not every trace needs to be recorded. **Sampling** reduces overhead:
+
+### Head Sampling (at trace start)
+
+```
+Request arrives → Random N% chance → Record or skip entire trace
+```
+
+- ✅ Low overhead
+- ❌ May miss interesting traces
+
+> **xrpld note**: xrpld intentionally fixes head sampling at 100% (sample
+> everything) and does not expose a configurable ratio. A per-node ratio
+> would let different nodes make divergent keep/drop decisions for the same
+> distributed trace, producing broken/partial traces. xrpld uses a
+> `ParentBased` sampler so spans with a remote parent honor the upstream
+> decision. Volume reduction is delegated to collector-side tail sampling.
+
+### Tail Sampling (after trace completes)
+
+```
+Trace completes → Collector evaluates:
+                  - Error? → KEEP
+                  - Slow? → KEEP
+                  - Normal? → Sample 10%
+```
+
+- ✅ Never loses important traces
+- ❌ Higher memory usage at collector
+
+---
+
+## Key Benefits for xrpld
+
+| Challenge                          | How Tracing Helps                        |
+| ---------------------------------- | ---------------------------------------- |
+| "Where is my transaction?"         | Follow trace across all nodes it touched |
+| "Why was consensus slow?"          | See timing breakdown of each phase       |
+| "Which node is the bottleneck?"    | Compare span durations across nodes      |
+| "What happened during the outage?" | Correlate errors across the network      |
+
+---
+
+## Glossary
+
+| Term                 | Definition                                                          |
+| -------------------- | ------------------------------------------------------------------- |
+| **Trace**            | Complete journey of a request, identified by `trace_id`             |
+| **Span**             | Single operation within a trace                                     |
+| **Parent-Child**     | Span relationship where the parent depends on the child             |
+| **Follows-From**     | Causal relationship where originator doesn't wait for the result    |
+| **Span Link**        | Non-hierarchical connection between spans, possibly across traces   |
+| **Deterministic ID** | Trace ID derived from domain data (e.g., tx_hash) instead of random |
+| **Context**          | Data propagated between services (`trace_id`, `span_id`, flags)     |
+| **Instrumentation**  | Code that creates spans and propagates context                      |
+| **Collector**        | Service that receives, processes, and exports traces                |
+| **Backend**          | Storage/visualization system (Tempo)                                |
+| **Head Sampling**    | Sampling decision at trace start                                    |
+| **Tail Sampling**    | Sampling decision after trace completes                             |
+
+---
+
+_Next: [Architecture Analysis](./01-architecture-analysis.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/01-architecture-analysis.md

@@ -0,0 +1,467 @@
+# Architecture Analysis
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Design Decisions](./02-design-decisions.md) | [Implementation Strategy](./03-implementation-strategy.md)
+
+---
+
+## 1.1 Current xrpld Architecture Overview
+
+> **WS** = WebSocket | **UNL** = Unique Node List | **TxQ** = Transaction Queue | **StatsD** = Statistics Daemon
+
+The xrpld node software consists of several interconnected components that need instrumentation for distributed tracing:
+
+```mermaid
+flowchart TB
+    subgraph xrpld["xrpld Node"]
+        subgraph services["Core Services"]
+            RPC["RPC Server<br/>(HTTP/WS/gRPC)"]
+            Overlay["Overlay<br/>(P2P Network)"]
+            Consensus["Consensus<br/>(RCLConsensus)"]
+            ValidatorList["ValidatorList<br/>(UNL Mgmt)"]
+        end
+
+        JobQueue["JobQueue<br/>(Thread Pool)"]
+
+        subgraph processing["Processing Layer"]
+            NetworkOPs["NetworkOPs<br/>(Tx Processing)"]
+            LedgerMaster["LedgerMaster<br/>(Ledger Mgmt)"]
+            NodeStore["NodeStore<br/>(Database)"]
+            InboundLedgers["InboundLedgers<br/>(Ledger Sync)"]
+        end
+
+        subgraph appservices["Application Services"]
+            PathFind["PathFinding<br/>(Payment Paths)"]
+            TxQ["TxQ<br/>(Fee Escalation)"]
+            LoadMgr["LoadManager<br/>(Fee/Load)"]
+        end
+
+        subgraph observability["Existing Observability"]
+            PerfLog["PerfLog<br/>(JSON)"]
+            Insight["Insight<br/>(StatsD)"]
+            Logging["Logging<br/>(Journal)"]
+        end
+
+        services --> JobQueue
+        JobQueue --> processing
+        JobQueue --> appservices
+    end
+
+    style xrpld fill:#424242,stroke:#212121,color:#ffffff
+    style services fill:#1565c0,stroke:#0d47a1,color:#ffffff
+    style processing fill:#2e7d32,stroke:#1b5e20,color:#ffffff
+    style appservices fill:#6a1b9a,stroke:#4a148c,color:#ffffff
+    style observability fill:#e65100,stroke:#bf360c,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **Core Services (blue)**: The entry points into xrpld -- RPC Server handles client requests, Overlay manages peer-to-peer networking, Consensus drives agreement, and ValidatorList manages trusted validators.
+- **JobQueue (center)**: The asynchronous thread pool that decouples Core Services from the Processing and Application layers. All work flows through it.
+- **Processing Layer (green)**: Core business logic -- NetworkOPs processes transactions, LedgerMaster manages ledger state, NodeStore handles persistence, and InboundLedgers synchronizes missing data.
+- **Application Services (purple)**: Higher-level features -- PathFinding computes payment routes, TxQ manages fee-based queuing, and LoadManager tracks server load.
+- **Existing Observability (orange)**: The current monitoring stack (PerfLog, Insight, Journal logging) that OpenTelemetry will complement, not replace.
+- **Arrows (Services to JobQueue to layers)**: Work originates at Core Services, is enqueued onto the JobQueue, and dispatched to Processing or Application layers for execution.
+
+---
+
+## 1.1.1 Actors and Actions
+
+### Actors
+
+| Who (Plain English)                       | Technical Term             |
+| ----------------------------------------- | -------------------------- |
+| Network node running XRPL software        | xrpld node                 |
+| External client submitting requests       | RPC Client                 |
+| Network neighbor sharing data             | Peer (PeerImp)             |
+| Request handler for client queries        | RPC Server (ServerHandler) |
+| Command executor for specific RPC methods | RPCHandler                 |
+| Agreement process between nodes           | Consensus (RCLConsensus)   |
+| Transaction processing coordinator        | NetworkOPs                 |
+| Background task scheduler                 | JobQueue                   |
+| Ledger state manager                      | LedgerMaster               |
+| Payment route calculator                  | PathFinding (Pathfinder)   |
+| Transaction waiting room                  | TxQ (Transaction Queue)    |
+| Fee adjustment system                     | LoadManager                |
+| Trusted validator list manager            | ValidatorList              |
+| Protocol upgrade tracker                  | AmendmentTable             |
+| Ledger state hash tree                    | SHAMap                     |
+| Persistent key-value storage              | NodeStore                  |
+
+### Actions
+
+| What Happens (Plain English)                   | Technical Term         |
+| ---------------------------------------------- | ---------------------- |
+| Client sends a request to a node               | `rpc.request`          |
+| Node executes a specific RPC command           | `rpc.command.*`        |
+| Node receives a transaction from a peer        | `tx.receive`           |
+| Node checks if a transaction is valid          | `tx.validate`          |
+| Node forwards a transaction to neighbors       | `tx.relay`             |
+| Nodes agree on which transactions to include   | `consensus.round`      |
+| Consensus progresses through phases            | `consensus.phase.*`    |
+| Node builds a new confirmed ledger             | `ledger.build`         |
+| Node fetches missing ledger data from peers    | `ledger.acquire`       |
+| Node computes payment routes                   | `pathfind.compute`     |
+| Node queues a transaction for later processing | `txq.enqueue`          |
+| Node increases fees due to high load           | `fee.escalate`         |
+| Node fetches the latest trusted validator list | `validator.list.fetch` |
+| Node votes on a protocol amendment             | `amendment.vote`       |
+| Node synchronizes state tree data              | `shamap.sync`          |
+
+---
+
+## 1.2 Key Components for Instrumentation
+
+> **TxQ** = Transaction Queue | **UNL** = Unique Node List
+
+| Component          | Location                                   | Purpose                  | Trace Value                      |
+| ------------------ | ------------------------------------------ | ------------------------ | -------------------------------- |
+| **Overlay**        | `src/xrpld/overlay/`                       | P2P communication        | Message propagation timing       |
+| **PeerImp**        | `src/xrpld/overlay/detail/PeerImp.cpp`     | Individual peer handling | Per-peer latency                 |
+| **RCLConsensus**   | `src/xrpld/app/consensus/RCLConsensus.cpp` | Consensus algorithm      | Round timing, phase analysis     |
+| **NetworkOPs**     | `src/xrpld/app/misc/NetworkOPs.cpp`        | Transaction processing   | Tx lifecycle tracking            |
+| **ServerHandler**  | `src/xrpld/rpc/detail/ServerHandler.cpp`   | RPC entry point          | Request latency                  |
+| **RPCHandler**     | `src/xrpld/rpc/detail/RPCHandler.cpp`      | Command execution        | Per-command timing               |
+| **JobQueue**       | `src/xrpl/core/JobQueue.h`                 | Async task execution     | Queue wait times                 |
+| **PathFinding**    | `src/xrpld/app/paths/`                     | Payment path computation | Path latency, cache hits         |
+| **TxQ**            | `src/xrpld/app/misc/TxQ.cpp`               | Transaction queue/fees   | Queue depth, eviction rates      |
+| **LoadManager**    | `src/xrpld/app/main/LoadManager.cpp`       | Fee escalation/load      | Fee levels, load factors         |
+| **InboundLedgers** | `src/xrpld/app/ledger/InboundLedgers.cpp`  | Ledger acquisition       | Sync time, peer reliability      |
+| **ValidatorList**  | `src/xrpld/app/misc/ValidatorList.cpp`     | UNL management           | List freshness, fetch failures   |
+| **AmendmentTable** | `src/xrpld/app/misc/AmendmentTable.cpp`    | Protocol amendments      | Voting status, activation events |
+| **SHAMap**         | `src/xrpld/shamap/`                        | State hash tree          | Sync speed, missing nodes        |
+
+---
+
+## 1.3 Transaction Flow Diagram
+
+Transaction flow spans multiple nodes in the network. Each node creates linked spans to form a distributed trace:
+
+```mermaid
+sequenceDiagram
+    participant Client
+    participant PeerA as Peer A (Receive)
+    participant PeerB as Peer B (Relay)
+    participant PeerC as Peer C (Validate)
+
+    Client->>PeerA: 1. Submit TX
+
+    rect rgb(230, 245, 255)
+        Note over PeerA: tx.receive SPAN START
+        PeerA->>PeerA: HashRouter Deduplication
+        PeerA->>PeerA: tx.validate (child span)
+    end
+
+    PeerA->>PeerB: 2. Relay TX (with trace ctx)
+
+    rect rgb(230, 245, 255)
+        Note over PeerB: tx.receive (linked span)
+    end
+
+    PeerB->>PeerC: 3. Relay TX
+
+    rect rgb(230, 245, 255)
+        Note over PeerC: tx.receive (linked span)
+        PeerC->>PeerC: tx.process
+    end
+
+    Note over Client,PeerC: DISTRIBUTED TRACE (same trace_id: abc123)
+```
+
+**Reading the diagram:**
+
+- **Client**: The external entity that submits a transaction to Peer A. It has no trace context -- the trace starts at the first node.
+- **Peer A (Receive)**: The entry node that creates the root span `tx.receive`, runs HashRouter deduplication to avoid processing duplicates, and creates a child `tx.validate` span.
+- **Peer A to Peer B arrow**: The relay message carries trace context (trace_id + parent span_id), enabling Peer B to create a linked span under the same trace.
+- **Peer B (Relay)**: Receives the transaction and trace context, creates a `tx.receive` span linked to Peer A's trace, then relays onward.
+- **Peer C (Validate)**: Final hop in this example. Creates a linked `tx.receive` span and runs `tx.process` to fully process the transaction.
+- **Blue rectangles**: Highlight the span boundaries on each node, showing where instrumentation creates and closes spans.
+
+### Trace Structure
+
+```
+trace_id: abc123
+├── span: tx.receive (Peer A)
+│   ├── span: tx.validate
+│   └── span: tx.relay
+├── span: tx.receive (Peer B) [parent: Peer A]
+│   └── span: tx.relay
+└── span: tx.receive (Peer C) [parent: Peer B]
+    └── span: tx.process
+```
+
+---
+
+## 1.4 Consensus Round Flow
+
+Consensus rounds are multi-phase operations that benefit significantly from tracing:
+
+```mermaid
+flowchart TB
+    subgraph round["consensus.round (root span)"]
+        attrs["Attributes:<br/>ledger_seq = 12345678<br/>consensus_mode = proposing<br/>proposers = 35"]
+
+        subgraph open["consensus.phase.open"]
+            open_desc["Duration: ~3s<br/>Waiting for transactions"]
+        end
+
+        subgraph establish["consensus.phase.establish"]
+            est_attrs["proposals_received = 28<br/>disputes_resolved = 3"]
+            est_children["├── consensus.proposal.receive (×28)<br/>├── consensus.proposal.send (×1)<br/>└── consensus.dispute.resolve (×3)"]
+        end
+
+        subgraph accept["consensus.phase.accept"]
+            acc_attrs["transactions_applied = 150<br/>ledger_hash = DEF456..."]
+            acc_children["├── ledger.build<br/>└── ledger.validate"]
+        end
+
+        attrs --> open
+        open --> establish
+        establish --> accept
+    end
+
+    style round fill:#f57f17,stroke:#e65100,color:#ffffff
+    style open fill:#1565c0,stroke:#0d47a1,color:#ffffff
+    style establish fill:#2e7d32,stroke:#1b5e20,color:#ffffff
+    style accept fill:#c2185b,stroke:#880e4f,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **consensus.round (orange, root span)**: The top-level span encompassing the entire consensus round, with attributes like ledger sequence, mode, and proposer count.
+- **consensus.phase.open (blue)**: The first phase where the node waits (~3s) to collect incoming transactions before proposing.
+- **consensus.phase.establish (green)**: The negotiation phase where validators exchange proposals, resolve disputes, and converge on a transaction set. Child spans track each proposal received/sent and each dispute resolved.
+- **consensus.phase.accept (pink)**: The final phase where the agreed transaction set is applied, a new ledger is built, and the ledger is validated. Child spans cover `ledger.build` and `ledger.validate`.
+- **Arrows (open to establish to accept)**: The sequential flow through the three consensus phases. Each phase must complete before the next begins.
+
+---
+
+## 1.5 RPC Request Flow
+
+> **WS** = WebSocket
+
+RPC requests support W3C Trace Context headers for distributed tracing across services:
+
+```mermaid
+flowchart TB
+    subgraph request["rpc.request (root span)"]
+        http["HTTP Request — POST /<br/>traceparent:<br/>00-abc123...-def456...-01"]
+
+        attrs["Attributes:<br/>http.method = POST<br/>net.peer.ip = 192.168.1.100<br/>command = submit"]
+
+        subgraph enqueue["jobqueue.enqueue"]
+            job_attr["job_type = jtCLIENT_RPC"]
+        end
+
+        subgraph command["rpc.command.submit"]
+            cmd_attrs["version = 2<br/>rpc_role = user"]
+            cmd_children["├── tx.deserialize<br/>├── tx.validate_local<br/>└── tx.submit_to_network"]
+        end
+
+        response["Response: 200 OK<br/>Duration: 45ms"]
+
+        http --> attrs
+        attrs --> enqueue
+        enqueue --> command
+        command --> response
+    end
+
+    style request fill:#2e7d32,stroke:#1b5e20,color:#ffffff
+    style enqueue fill:#1565c0,stroke:#0d47a1,color:#ffffff
+    style command fill:#e65100,stroke:#bf360c,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **rpc.request (green, root span)**: The outermost span representing the full RPC request lifecycle, from HTTP receipt to response. Carries the W3C `traceparent` header for distributed tracing.
+- **HTTP Request node**: Shows the incoming POST request with its `traceparent` header and extracted attributes (method, peer IP, command name).
+- **jobqueue.enqueue (blue)**: The span covering the asynchronous handoff from the RPC thread to the JobQueue worker thread. The trace context is preserved across this async boundary.
+- **rpc.command.submit (orange)**: The span for the actual command execution, with child spans for deserialization, local validation, and network submission.
+- **Response node**: The final output with HTTP status and total duration, marking the end of the root span.
+- **Arrows (top to bottom)**: The sequential processing pipeline -- receive request, extract attributes, enqueue job, execute command, return response.
+
+---
+
+## 1.6 Key Trace Points
+
+> **TxQ** = Transaction Queue
+
+The following table identifies priority instrumentation points across the codebase:
+
+| Category        | Span Name              | File                   | Method                  | Priority |
+| --------------- | ---------------------- | ---------------------- | ----------------------- | -------- |
+| **Transaction** | `tx.receive`           | `PeerImp.cpp`          | `handleTransaction()`   | High     |
+| **Transaction** | `tx.validate`          | `NetworkOPs.cpp`       | `processTransaction()`  | High     |
+| **Transaction** | `tx.process`           | `NetworkOPs.cpp`       | `doTransactionSync()`   | High     |
+| **Transaction** | `tx.relay`             | `OverlayImpl.cpp`      | `relay()`               | Medium   |
+| **Consensus**   | `consensus.round`      | `RCLConsensus.cpp`     | `startRound()`          | High     |
+| **Consensus**   | `consensus.phase.*`    | `Consensus.h`          | `timerEntry()`          | High     |
+| **Consensus**   | `consensus.proposal.*` | `RCLConsensus.cpp`     | `peerProposal()`        | Medium   |
+| **RPC**         | `rpc.request`          | `ServerHandler.cpp`    | `onRequest()`           | High     |
+| **RPC**         | `rpc.command.*`        | `RPCHandler.cpp`       | `doCommand()`           | High     |
+| **Peer**        | `peer.connect`         | `OverlayImpl.cpp`      | `onHandoff()`           | Low      |
+| **Peer**        | `peer.message.*`       | `PeerImp.cpp`          | `onMessage()`           | Low      |
+| **Ledger**      | `ledger.acquire`       | `InboundLedgers.cpp`   | `acquire()`             | Medium   |
+| **Ledger**      | `ledger.build`         | `RCLConsensus.cpp`     | `buildLCL()`            | High     |
+| **PathFinding** | `pathfind.request`     | `PathRequest.cpp`      | `doUpdate()`            | High     |
+| **PathFinding** | `pathfind.compute`     | `Pathfinder.cpp`       | `findPaths()`           | High     |
+| **TxQ**         | `txq.enqueue`          | `TxQ.cpp`              | `apply()`               | High     |
+| **TxQ**         | `txq.apply`            | `TxQ.cpp`              | `processClosedLedger()` | High     |
+| **Fee**         | `fee.escalate`         | `LoadManager.cpp`      | `raiseLocalFee()`       | Medium   |
+| **Ledger**      | `ledger.replay`        | `LedgerReplayer.h`     | `replay()`              | Medium   |
+| **Ledger**      | `ledger.delta`         | `LedgerDeltaAcquire.h` | `processData()`         | Medium   |
+| **Validator**   | `validator.list.fetch` | `ValidatorList.cpp`    | `verify()`              | Medium   |
+| **Validator**   | `validator.manifest`   | `Manifest.cpp`         | `applyManifest()`       | Low      |
+| **Amendment**   | `amendment.vote`       | `AmendmentTable.cpp`   | `doVoting()`            | Low      |
+| **SHAMap**      | `shamap.sync`          | `SHAMap.cpp`           | `fetchRoot()`           | Medium   |
+
+---
+
+## 1.7 Instrumentation Priority
+
+> **TxQ** = Transaction Queue
+
+```mermaid
+quadrantChart
+    title Instrumentation Priority Matrix
+    x-axis Low Complexity --> High Complexity
+    y-axis Low Value --> High Value
+    quadrant-1 Implement First
+    quadrant-2 Plan Carefully
+    quadrant-3 Quick Wins
+    quadrant-4 Consider Later
+
+    RPC Tracing: [0.2, 0.92]
+    Transaction Tracing: [0.55, 0.88]
+    Consensus Tracing: [0.78, 0.82]
+    PathFinding: [0.38, 0.75]
+    TxQ and Fees: [0.25, 0.65]
+    Ledger Sync: [0.62, 0.58]
+    Peer Message Tracing: [0.35, 0.25]
+    JobQueue Tracing: [0.2, 0.48]
+    Validator Mgmt: [0.48, 0.42]
+    Amendment Tracking: [0.15, 0.32]
+    SHAMap Operations: [0.72, 0.45]
+```
+
+---
+
+## 1.8 Observable Outcomes
+
+> **TxQ** = Transaction Queue | **UNL** = Unique Node List
+
+After implementing OpenTelemetry, operators and developers will gain visibility into the following:
+
+### 1.8.1 What You Will See: Traces
+
+| Trace Type                 | Description                                                                                 | Example Query in Grafana/Tempo                  |
+| -------------------------- | ------------------------------------------------------------------------------------------- | ----------------------------------------------- |
+| **Transaction Lifecycle**  | Full journey from RPC submission through validation, relay, consensus, and ledger inclusion | `{service.name="xrpld" && tx_hash="ABC123..."}` |
+| **Cross-Node Propagation** | Transaction path across multiple xrpld nodes with timing                                    | `{relay_count > 0}`                             |
+| **Consensus Rounds**       | Complete round with all phases (open, establish, accept)                                    | `{span.name=~"consensus.round.*"}`              |
+| **RPC Request Processing** | Individual command execution with timing breakdown                                          | `{command="account_info"}`                      |
+| **Ledger Acquisition**     | Peer-to-peer ledger data requests and responses                                             | `{span.name="ledger.acquire"}`                  |
+| **PathFinding Latency**    | Path computation time and cache effectiveness for payment RPCs                              | `{span.name="pathfind.compute"}`                |
+| **TxQ Behavior**           | Queue depth, eviction patterns, fee escalation during congestion                            | `{span.name=~"txq.*"}`                          |
+| **Ledger Sync**            | Full acquisition timeline including delta and transaction fetches                           | `{span.name=~"ledger.acquire.*"}`               |
+| **Validator Health**       | UNL fetch success, manifest updates, stale list detection                                   | `{span.name=~"validator.*"}`                    |
+
+### 1.8.2 What You Will See: Metrics (Derived from Traces)
+
+| Metric                        | Description                             | Dashboard Panel             |
+| ----------------------------- | --------------------------------------- | --------------------------- |
+| **RPC Latency (p50/p95/p99)** | Response time distribution per command  | Heatmap by command          |
+| **Transaction Throughput**    | Transactions processed per second       | Time series graph           |
+| **Consensus Round Duration**  | Time to complete consensus phases       | Histogram                   |
+| **Cross-Node Latency**        | Time for transaction to reach N nodes   | Line chart with percentiles |
+| **Error Rate**                | Failed transactions/RPC calls by type   | Stacked bar chart           |
+| **PathFinding Latency**       | Path computation time per currency pair | Heatmap by currency         |
+| **TxQ Depth**                 | Queued transactions over time           | Time series with thresholds |
+| **Fee Escalation Level**      | Current fee multiplier                  | Gauge with alert thresholds |
+| **Ledger Sync Duration**      | Time to acquire missing ledgers         | Histogram                   |
+
+### 1.8.3 Concrete Dashboard Examples
+
+**Transaction Trace View (Tempo):**
+
+```
+┌────────────────────────────────────────────────────────────────────────────────┐
+│ Trace: abc123... (Transaction Submission)                    Duration: 847ms   │
+├────────────────────────────────────────────────────────────────────────────────┤
+│ ├── rpc.request [ServerHandler]                              ████░░░░░░  45ms  │
+│ │   └── rpc.command.submit [RPCHandler]                      ████░░░░░░  42ms  │
+│ │       └── tx.receive [NetworkOPs]                          ███░░░░░░░  35ms  │
+│ │           ├── tx.validate [TxQ]                            █░░░░░░░░░   8ms  │
+│ │           └── tx.relay [Overlay]                           ██░░░░░░░░  15ms  │
+│ │               ├── tx.receive [Node-B]                      █████░░░░░  52ms  │
+│ │               │   └── tx.relay [Node-B]                    ██░░░░░░░░  18ms  │
+│ │               └── tx.receive [Node-C]                      ██████░░░░  65ms  │
+│ └── consensus.round [RCLConsensus]                           ████████░░ 720ms  │
+│     ├── consensus.phase.open                                 ██░░░░░░░░ 180ms  │
+│     ├── consensus.phase.establish                            █████░░░░░ 480ms  │
+│     └── consensus.phase.accept                               █░░░░░░░░░  60ms  │
+└────────────────────────────────────────────────────────────────────────────────┘
+```
+
+**RPC Performance Dashboard Panel:**
+
+```
+┌─────────────────────────────────────────────────────────────┐
+│ RPC Command Latency (Last 1 Hour)                           │
+├─────────────────────────────────────────────────────────────┤
+│ Command          │ p50    │ p95    │ p99    │ Errors │ Rate │
+│──────────────────┼────────┼────────┼────────┼────────┼──────│
+│ account_info     │  12ms  │  45ms  │  89ms  │  0.1%  │ 150/s│
+│ submit           │  35ms  │ 120ms  │ 250ms  │  2.3%  │  45/s│
+│ ledger           │   8ms  │  25ms  │  55ms  │  0.0%  │  80/s│
+│ tx               │  15ms  │  50ms  │ 100ms  │  0.5%  │  60/s│
+│ server_info      │   5ms  │  12ms  │  20ms  │  0.0%  │ 200/s│
+└─────────────────────────────────────────────────────────────┘
+```
+
+**Consensus Health Dashboard Panel:**
+
+```mermaid
+---
+config:
+    xyChart:
+        width: 1200
+        height: 400
+        plotReservedSpacePercent: 50
+        chartOrientation: vertical
+    themeVariables:
+        xyChart:
+            plotColorPalette: "#3498db"
+---
+xychart-beta
+    title "Consensus Round Duration (Last 24 Hours)"
+    x-axis "Time of Day (Hours)" [0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24]
+    y-axis "Duration (seconds)" 1 --> 5
+    line [2.1, 2.4, 2.8, 3.2, 3.8, 4.3, 4.5, 5.0, 4.7, 4.0, 3.2, 2.6, 2.0]
+```
+
+### 1.8.4 Operator Actionable Insights
+
+| Scenario                  | What You'll See                                                              | Action                                           |
+| ------------------------- | ---------------------------------------------------------------------------- | ------------------------------------------------ |
+| **Slow RPC**              | Span showing which phase is slow (parsing, execution, serialization)         | Optimize specific code path                      |
+| **Transaction Stuck**     | Trace stops at validation; error attribute shows reason                      | Fix transaction parameters                       |
+| **Consensus Delay**       | Phase.establish taking too long; proposer attribute shows missing validators | Investigate network connectivity                 |
+| **Memory Spike**          | Large batch of spans correlating with memory increase                        | Tune batch_size or sampling                      |
+| **Network Partition**     | Traces missing cross-node links for specific peer                            | Check peer connectivity                          |
+| **Path Computation Slow** | pathfind.compute span shows high latency; cache miss rate in attributes      | Warm the RippleLineCache, check order book depth |
+| **TxQ Full**              | txq.enqueue spans show evictions; fee.escalate spans increasing              | Monitor fee levels, alert operators              |
+| **Ledger Sync Stalled**   | ledger.acquire spans timing out; peer reliability attributes show issues     | Check peer connectivity, add trusted peers       |
+| **UNL Stale**             | validator.list.fetch spans failing; last_update attribute aging              | Verify validator site URLs, check DNS            |
+
+### 1.8.5 Developer Debugging Workflow
+
+1. **Find Transaction**: Query by `tx_hash` to get full trace
+2. **Identify Bottleneck**: Look at span durations to find slowest component
+3. **Check Attributes**: Review `validity`, `rpc_status` for errors
+4. **Correlate Logs**: Use `trace_id` to find related PerfLog entries
+5. **Compare Nodes**: Filter by `service.instance.id` to compare behavior across nodes
+
+---
+
+_Next: [Design Decisions](./02-design-decisions.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/02-design-decisions.md

@@ -0,0 +1,568 @@
+# Design Decisions
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Architecture Analysis](./01-architecture-analysis.md)
+
+---
+
+## 2.1 OpenTelemetry Components
+
+> **OTLP** = OpenTelemetry Protocol
+
+### 2.1.1 SDK Selection
+
+**Primary Choice**: OpenTelemetry C++ SDK (`opentelemetry-cpp`)
+
+| Component                               | Purpose                | Required                  |
+| --------------------------------------- | ---------------------- | ------------------------- |
+| `opentelemetry-cpp::api`                | Tracing API headers    | Yes                       |
+| `opentelemetry-cpp::sdk`                | SDK implementation     | Yes                       |
+| `opentelemetry-cpp::ext`                | Extensions (exporters) | Yes                       |
+| `opentelemetry-cpp::otlp_http_exporter` | OTLP/HTTP export       | Yes (shipped in Phase 1b) |
+| `opentelemetry-cpp::otlp_grpc_exporter` | OTLP/gRPC export       | Future (not yet wired up) |
+
+### 2.1.2 Instrumentation Strategy
+
+**Manual Instrumentation** (recommended):
+
+| Approach   | Pros                                                            | Cons                                                    |
+| ---------- | --------------------------------------------------------------- | ------------------------------------------------------- |
+| **Manual** | Precise control, optimized placement, xrpld-specific attributes | More development effort                                 |
+| **Auto**   | Less code, automatic coverage                                   | Less control, potential overhead, limited customization |
+
+---
+
+## 2.2 Exporter Configuration
+
+> **OTLP** = OpenTelemetry Protocol
+
+```mermaid
+flowchart TB
+    subgraph nodes["xrpld Nodes"]
+        node1["xrpld<br/>Node 1"]
+        node2["xrpld<br/>Node 2"]
+        node3["xrpld<br/>Node 3"]
+    end
+
+    collector["OpenTelemetry<br/>Collector<br/>(sidecar or standalone)"]
+
+    subgraph backends["Observability Backends"]
+        tempo["Tempo"]
+        elastic["Elastic<br/>APM"]
+    end
+
+    node1 -->|"OTLP/HTTP<br/>:4318"| collector
+    node2 -->|"OTLP/HTTP<br/>:4318"| collector
+    node3 -->|"OTLP/HTTP<br/>:4318"| collector
+
+    collector --> tempo
+    collector --> elastic
+
+    style nodes fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style backends fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style collector fill:#bf360c,stroke:#8c2809,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **xrpld Nodes (blue)**: The source of telemetry data. Each xrpld node exports spans via OTLP/HTTP on port 4318 (the only exporter shipped in Phase 1b).
+- **OpenTelemetry Collector (red)**: The central aggregation point that receives spans from all nodes. Can run as a sidecar (per-node) or standalone (shared). Handles batching, filtering, and routing.
+- **Observability Backends (green)**: The storage and visualization destinations. Tempo is the recommended backend for both development and production, and Elastic APM is an alternative. The Collector routes to one or more backends.
+- **Arrows (nodes to collector to backends)**: The data pipeline -- spans flow from nodes to the Collector over HTTP, then the Collector fans out to the configured backends.
+
+### 2.2.1 OTLP/HTTP (Shipped in Phase 1b)
+
+OTLP/HTTP is the only exporter wired up in Phase 1b. It is configured via
+`OtlpHttpExporterOptions` with the collector traces endpoint
+(`http://localhost:4318/v1/traces` by default) and a JSON content type
+(binary protobuf is also available).
+
+### 2.2.2 OTLP/gRPC (Future Work — Planned Upgrade)
+
+OTLP/gRPC is planned as a future upgrade from the HTTP exporter. The gRPC
+transport offers lower per-span overhead and tighter back-pressure semantics
+than HTTP/JSON, making it attractive for production deployments once the HTTP
+path is validated in earlier phases.
+
+Required to land this upgrade:
+
+1. Add `opentelemetry-cpp::otlp_grpc_exporter` to the Conan recipe (the
+   dependency already exists but is not linked in Phase 1b builds).
+2. Extend `TelemetryConfig.cpp` to parse an `exporter` key (`otlp_http`
+   default, `otlp_grpc` opt-in) and a gRPC endpoint override.
+3. In `Telemetry::start()` branch on the parsed exporter type and construct
+   either `OtlpHttpExporterFactory::Create(httpOpts)` or
+   `OtlpGrpcExporterFactory::Create(grpcOpts)` accordingly.
+4. Update the runbook and dashboards to document the alternate port and TLS
+   settings.
+
+When wired up, the gRPC path will use `OtlpGrpcExporterOptions` configured with
+the collector endpoint (host on port 4317), TLS credentials enabled, and a CA
+certificate path.
+
+Until that work lands, `OtlpGrpcExporterOptions` is **not** used by any code
+path in Phase 1b through Phase 5.
+
+---
+
+## 2.3 Span Naming Conventions
+
+> **TxQ** = Transaction Queue | **UNL** = Unique Node List | **WS** = WebSocket
+
+### 2.3.1 Naming Schema
+
+```
+<component>.<operation>[.<sub-operation>]
+```
+
+**Examples**:
+
+- `tx.receive` - Transaction received from peer
+- `consensus.phase.establish` - Consensus establish phase
+- `rpc.command.server_info` - server_info RPC command
+
+### 2.3.2 Complete Span Catalog
+
+| Span name                      | Description                             |
+| ------------------------------ | --------------------------------------- |
+| `tx.receive`                   | Transaction received from network       |
+| `tx.validate`                  | Transaction signature/format validation |
+| `tx.process`                   | Full transaction processing             |
+| `tx.relay`                     | Transaction relay to peers              |
+| `tx.apply`                     | Apply transaction to ledger             |
+| `consensus.round`              | Complete consensus round                |
+| `consensus.phase.open`         | Open phase - collecting transactions    |
+| `consensus.phase.establish`    | Establish phase - reaching agreement    |
+| `consensus.phase.accept`       | Accept phase - applying consensus       |
+| `consensus.proposal.receive`   | Receive peer proposal                   |
+| `consensus.proposal.send`      | Send our proposal                       |
+| `consensus.validation.receive` | Receive peer validation                 |
+| `consensus.validation.send`    | Send our validation                     |
+| `rpc.request`                  | HTTP/WebSocket request handling         |
+| `rpc.command.*`                | Specific RPC command (dynamic)          |
+| `peer.connect`                 | Peer connection establishment           |
+| `peer.disconnect`              | Peer disconnection                      |
+| `peer.message.send`            | Send protocol message                   |
+| `peer.message.receive`         | Receive protocol message                |
+| `ledger.acquire`               | Ledger acquisition from network         |
+| `ledger.build`                 | Build new ledger                        |
+| `ledger.validate`              | Ledger validation                       |
+| `ledger.close`                 | Close ledger                            |
+| `ledger.replay`                | Ledger replay executed                  |
+| `ledger.delta`                 | Delta-based ledger acquired             |
+| `pathfind.request`             | Path request initiated                  |
+| `pathfind.compute`             | Path computation executed               |
+| `txq.enqueue`                  | Transaction queued                      |
+| `txq.apply`                    | Queued transaction applied              |
+| `fee.escalate`                 | Fee escalation triggered                |
+| `validator.list.fetch`         | UNL list fetched                        |
+| `validator.manifest`           | Manifest update processed               |
+| `amendment.vote`               | Amendment voting executed               |
+| `shamap.sync`                  | State tree synchronization              |
+| `job.enqueue`                  | Job added to queue                      |
+| `job.execute`                  | Job execution                           |
+
+### 2.3.3 Attribute Naming Conventions
+
+Span **names** follow §2.3.1 (dotted `<component>.<operation>`). Span
+**attribute keys** follow the rules below. The constants in the `*SpanNames.h`
+headers are the single source of truth; the collector, Tempo, the Grafana
+dashboards, and the runbook all consume these exact keys, so every layer must
+agree with the code. A CI check enforces this end to end.
+
+1. **Per-span unique attribute** → bare field name, allowed when the field is
+   recorded by a single span/workflow so the span name already supplies the
+   domain (e.g. `command`, `version`, `local` on `rpc.command`).
+2. **Shared attribute (same concept on more than one span)** → ONE key, reused
+   verbatim on every span that records it; the span name tells the occurrences
+   apart, so no per-emitter prefix is added. Name it by the field's meaning: a
+   property of a domain object keeps that object's bare field name (`ledger_hash`,
+   `ledger_seq`, `tx_hash`, `peer_id`, `full_validation`); a field already
+   qualified by a sub-kind keeps that qualifier on every emitter (`proposal_trusted`
+   on both `consensus.proposal.receive` and `peer.proposal.receive`;
+   `validation_trusted` likewise). Defined once in the base `SpanNames.h`
+   `namespace attr` block and re-exported (`using`) by each domain header.
+3. **Collision qualifier** → `<domain>_<field>`, only when a bare name would
+   collide with a DIFFERENT concept in the shared spanmetrics label space or with
+   the OTel-reserved `status` key (e.g. `rpc_status`, `grpc_status`,
+   `consensus_phase`, `consensus_round`, `consensus_mode`). This disambiguates
+   distinct concepts that share a word; it is NOT used to tag the same concept
+   with its emitting workflow — that is rule 2 (one shared name).
+4. **Resource attribute** → dotted `xrpl.<subsystem>.<field>`, reserved ONLY
+   for process/network identity set once at startup (`xrpl.network.id`,
+   `xrpl.network.type`). Span attributes are never dotted in the `xrpl.` form —
+   it blurs the resource/span scope boundary and parses awkwardly in TraceQL.
+5. **Span names** use `<subsystem>[.<component>]` (dotted, per §2.3.1). Only
+   attribute _keys_ follow rules 1–4.
+
+Standard OpenTelemetry semantic-convention keys keep their canonical dotted
+form (e.g. `service.*` resource attributes, `http.*` span attributes); the
+"no dotted form" rule applies to xrpl-custom keys only.
+
+The same rules are recorded in `CONTRIBUTING.md` (the permanent home, since
+`OpenTelemetryPlan/` is removed once the rollout completes). The attribute
+examples in §2.4 below follow these rules.
+
+---
+
+## 2.4 Attribute Schema
+
+> **TxQ** = Transaction Queue | **UNL** = Unique Node List | **OTLP** = OpenTelemetry Protocol
+
+### 2.4.1 Resource Attributes (Set Once at Startup)
+
+Resource attributes identify the process and are set once at startup. They use
+the standard OpenTelemetry semantic conventions plus custom dotted `xrpl.*`
+keys (the dotted form is reserved for resource scope per §2.3.3).
+
+| Key                   | Type / value                                            | Description                    |
+| --------------------- | ------------------------------------------------------- | ------------------------------ |
+| `service.name`        | `"xrpld"`                                               | Standard `SERVICE_NAME`        |
+| `service.version`     | `BuildInfo::getVersionString()`                         | Standard `SERVICE_VERSION`     |
+| `service.instance.id` | node public key (base58)                                | Standard `SERVICE_INSTANCE_ID` |
+| `xrpl.network.id`     | network id (e.g. 0 for mainnet)                         | Network identifier             |
+| `xrpl.network.type`   | `"mainnet"` \| `"testnet"` \| `"devnet"` \| `"unknown"` | Network kind                   |
+| `xrpl.node.type`      | `"validator"` \| `"stock"` \| `"reporting"`             | Node role                      |
+| `xrpl.node.cluster`   | cluster name                                            | Cluster name, if clustered     |
+
+### 2.4.2 Span Attributes by Category
+
+> Span attribute keys use the underscore form from §2.3.3 (shared/qualified
+> keys are `<domain>_<field>`; per-span unique keys are bare). The dotted form
+> is reserved for the resource attributes in §2.4.1 above. This catalog lists
+> the planned attribute set by category; the exact emitted key for each
+> implemented span is defined by the `*SpanNames.h` constants, which are the
+> single source of truth where the two differ.
+
+#### Transaction Attributes
+
+| Key            | Type   | Description                           |
+| -------------- | ------ | ------------------------------------- |
+| `tx_hash`      | string | Transaction hash (hex)                |
+| `tx_type`      | string | `"Payment"`, `"OfferCreate"`, etc.    |
+| `tx_account`   | string | Source account (redacted in prod)     |
+| `tx_sequence`  | int64  | Account sequence number               |
+| `tx_fee`       | int64  | Fee in drops                          |
+| `tx_result`    | string | `"tesSUCCESS"`, `"tecPATH_DRY"`, etc. |
+| `ledger_index` | int64  | Ledger containing transaction         |
+| `relay_count`  | int64  | Peers the transaction was relayed to  |
+| `suppressed`   | bool   | `true` when HashRouter dropped a dup  |
+
+#### Consensus Attributes
+
+| Key                  | Type    | Description                         |
+| -------------------- | ------- | ----------------------------------- |
+| `consensus_round`    | int64   | Round number                        |
+| `consensus_phase`    | string  | `"open"`, `"establish"`, `"accept"` |
+| `consensus_mode`     | string  | `"proposing"`, `"observing"`, etc.  |
+| `proposers`          | int64   | Number of proposers                 |
+| `prev_ledger_prefix` | string  | Previous ledger hash prefix         |
+| `ledger_seq`         | int64   | Ledger sequence                     |
+| `tx_count`           | int64   | Transactions in consensus set       |
+| `round_time_ms`      | float64 | Round duration                      |
+
+#### RPC Attributes
+
+| Key           | Type    | Description                                                                   |
+| ------------- | ------- | ----------------------------------------------------------------------------- |
+| `command`     | string  | Command name (per-span unique on `rpc.command`)                               |
+| `version`     | int64   | API version                                                                   |
+| `rpc_role`    | string  | `"admin"` or `"user"` (qualified — `role` is generic)                         |
+| `params`      | string  | Sanitized parameters (optional)                                               |
+| `rpc_status`  | string  | Response status: `success` \| `error` (qualified — `status` is OTel-reserved) |
+| `duration_ms` | float64 | Request duration in milliseconds                                              |
+
+#### Peer & Message Attributes
+
+| Key                  | Type    | Description                |
+| -------------------- | ------- | -------------------------- |
+| `peer_id`            | string  | Peer public key (base58)   |
+| `peer_address`       | string  | IP:port                    |
+| `peer_latency_ms`    | float64 | Measured latency           |
+| `peer_cluster`       | string  | Cluster name if clustered  |
+| `message_type`       | string  | Protocol message type name |
+| `message_size_bytes` | int64   | Message size               |
+| `message_compressed` | bool    | Whether compressed         |
+
+#### Ledger & Job Attributes
+
+| Key               | Type    | Description           |
+| ----------------- | ------- | --------------------- |
+| `ledger_hash`     | string  | Ledger hash           |
+| `ledger_index`    | int64   | Ledger sequence/index |
+| `close_time`      | int64   | Close time (epoch)    |
+| `ledger_tx_count` | int64   | Transaction count     |
+| `job_type`        | string  | Job type name         |
+| `job_queue_ms`    | float64 | Time spent in queue   |
+| `job_worker`      | int64   | Worker thread ID      |
+
+#### PathFinding Attributes
+
+| Key                        | Type   | Description               |
+| -------------------------- | ------ | ------------------------- |
+| `pathfind_source_currency` | string | Source currency code      |
+| `pathfind_dest_currency`   | string | Destination currency code |
+| `pathfind_path_count`      | int64  | Number of paths found     |
+| `pathfind_cache_hit`       | bool   | RippleLineCache hit       |
+
+#### TxQ Attributes
+
+| Key                   | Type   | Description                 |
+| --------------------- | ------ | --------------------------- |
+| `txq_queue_depth`     | int64  | Current queue depth         |
+| `txq_fee_level`       | int64  | Fee level of transaction    |
+| `txq_eviction_reason` | string | Why transaction was evicted |
+
+#### Fee Attributes
+
+| Key                    | Type  | Description               |
+| ---------------------- | ----- | ------------------------- |
+| `fee_load_factor`      | int64 | Current load factor       |
+| `fee_escalation_level` | int64 | Fee escalation multiplier |
+
+#### Validator Attributes
+
+| Key                      | Type  | Description               |
+| ------------------------ | ----- | ------------------------- |
+| `validator_list_size`    | int64 | UNL size                  |
+| `validator_list_age_sec` | int64 | Seconds since last update |
+
+#### Amendment Attributes
+
+| Key                | Type   | Description                            |
+| ------------------ | ------ | -------------------------------------- |
+| `amendment_name`   | string | Amendment name                         |
+| `amendment_status` | string | `"enabled"`, `"vetoed"`, `"supported"` |
+
+#### SHAMap Attributes
+
+| Key                    | Type    | Description                                   |
+| ---------------------- | ------- | --------------------------------------------- |
+| `shamap_type`          | string  | `"transaction"`, `"state"`, `"account_state"` |
+| `shamap_missing_nodes` | int64   | Number of missing nodes during sync           |
+| `shamap_duration_ms`   | float64 | Sync duration                                 |
+
+### 2.4.3 Data Collection Summary
+
+The following table summarizes what data is collected by category:
+
+| Category        | Attributes Collected                                                                              | Purpose                      |
+| --------------- | ------------------------------------------------------------------------------------------------- | ---------------------------- |
+| **Transaction** | `tx_hash`, `tx_type`, `tx_result`, `tx_fee`, `ledger_index`                                       | Trace transaction lifecycle  |
+| **Consensus**   | `consensus_round`, `consensus_phase`, `consensus_mode`, `proposers`, `round_time_ms`              | Analyze consensus timing     |
+| **RPC**         | `command`, `version`, `rpc_status`, `duration_ms`                                                 | Monitor RPC performance      |
+| **Peer**        | `peer_id` (public key), `peer_latency_ms`, `message_type`, `message_size_bytes`                   | Network topology analysis    |
+| **Ledger**      | `ledger_hash`, `ledger_index`, `close_time`, `ledger_tx_count`                                    | Ledger progression tracking  |
+| **Job**         | `job_type`, `job_queue_ms`, `job_worker`                                                          | JobQueue performance         |
+| **PathFinding** | `pathfind_source_currency`, `pathfind_dest_currency`, `pathfind_path_count`, `pathfind_cache_hit` | Payment path analysis        |
+| **TxQ**         | `txq_queue_depth`, `txq_fee_level`, `txq_eviction_reason`                                         | Queue depth and fee tracking |
+| **Fee**         | `fee_load_factor`, `fee_escalation_level`                                                         | Fee escalation monitoring    |
+| **Validator**   | `validator_list_size`, `validator_list_age_sec`                                                   | UNL health monitoring        |
+| **Amendment**   | `amendment_name`, `amendment_status`                                                              | Protocol upgrade tracking    |
+| **SHAMap**      | `shamap_type`, `shamap_missing_nodes`, `shamap_duration_ms`                                       | State tree sync performance  |
+
+### 2.4.4 Privacy & Sensitive Data Policy
+
+> **PII** = Personally Identifiable Information
+
+OpenTelemetry instrumentation is designed to collect **operational metadata only**, never sensitive content.
+
+#### Data NOT Collected
+
+The following data is explicitly **excluded** from telemetry collection:
+
+| Excluded Data           | Reason                                    |
+| ----------------------- | ----------------------------------------- |
+| **Private Keys**        | Never exposed; not relevant to tracing    |
+| **Account Balances**    | Financial data; privacy sensitive         |
+| **Transaction Amounts** | Financial data; privacy sensitive         |
+| **Raw TX Payloads**     | May contain sensitive memo/data fields    |
+| **Personal Data**       | No PII collected                          |
+| **IP Addresses**        | Configurable; excluded by default in prod |
+
+#### Privacy Protection Mechanisms
+
+| Mechanism                     | Description                                                                                                                             |
+| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
+| **Account Hashing**           | `tx_account` is hashed at collector level before storage                                                                                |
+| **Configurable Redaction**    | Sensitive fields can be excluded via `[telemetry]` config section                                                                       |
+| **Collector Tail Sampling**   | xrpld head sampling is fixed at 1.0 (every span emitted); the collector retains ~10% of non-error traces, reducing stored data exposure |
+| **Local Control**             | Node operators have full control over what gets exported                                                                                |
+| **No Raw Payloads**           | Transaction content is never recorded, only metadata (hash, type, result)                                                               |
+| **Collector-Level Filtering** | Additional redaction/hashing can be configured at OTel Collector                                                                        |
+
+#### Collector-Level Data Protection
+
+The OpenTelemetry Collector can be configured (via an `attributes` processor)
+to hash or redact sensitive attributes before export — for example, hashing
+`tx_account`, deleting `peer_address` to drop IP addresses, and deleting
+`params` to redact request parameters.
+
+#### Configuration Options for Privacy
+
+In `xrpld.cfg`, operators control data collection granularity through the
+`[telemetry]` section. Besides `enabled`, per-component toggles
+(`trace_transactions`, `trace_consensus`, `trace_rpc`, `trace_peer` — the last
+often disabled due to high volume) select which spans are emitted, and
+redaction flags (`redact_account` to hash account addresses, `redact_peer_address`
+to remove peer IP addresses) control SDK-level redaction before export.
+
+> **Note**: The `redact_account` configuration in `xrpld.cfg` controls SDK-level redaction before export, while collector-level filtering (see [Collector-Level Data Protection](#collector-level-data-protection) above) provides an additional defense-in-depth layer. Both can operate independently.
+
+> **Key Principle**: Telemetry collects **operational metadata** (timing, counts, hashes) — never **sensitive content** (keys, balances, amounts, raw payloads).
+
+---
+
+## 2.5 Context Propagation Design
+
+> **WS** = WebSocket
+
+### 2.5.1 Propagation Boundaries
+
+```mermaid
+flowchart TB
+    subgraph http["HTTP/WebSocket (RPC)"]
+        w3c["W3C Trace Context Headers:<br/>traceparent:<br/>00-trace_id-span_id-flags<br/>tracestate: xrpld=..."]
+    end
+
+    subgraph protobuf["Protocol Buffers (P2P)"]
+        proto["message TraceContext {<br/>  bytes trace_id = 1;  // 16 bytes<br/>  bytes span_id = 2;   // 8 bytes<br/>  uint32 trace_flags = 3;<br/>  string trace_state = 4;<br/>}"]
+    end
+
+    subgraph jobqueue["JobQueue (Internal Async)"]
+        job["Context captured at job creation,<br/>restored at execution<br/><br/>class Job {<br/>  otel::context::Context<br/>    traceContext_;<br/>};"]
+    end
+
+    style http fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style protobuf fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style jobqueue fill:#bf360c,stroke:#8c2809,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **HTTP/WebSocket - RPC (blue)**: For client-facing RPC requests, trace context is propagated using the W3C `traceparent` header. This is the standard approach and works with any OTel-compatible client.
+- **Protocol Buffers - P2P (green)**: For peer-to-peer messages between xrpld nodes, trace context is embedded as a protobuf `TraceContext` message carrying trace_id, span_id, flags, and optional trace_state.
+- **JobQueue - Internal Async (red)**: For asynchronous work within a single node, the OTel context is captured when a job is created and restored when the job executes on a worker thread. This bridges the async gap so spans remain linked.
+
+---
+
+## 2.6 Integration with Existing Observability
+
+> **OTLP** = OpenTelemetry Protocol | **WS** = WebSocket
+
+### 2.6.1 Existing Frameworks Comparison
+
+xrpld already has two observability mechanisms. OpenTelemetry complements (not replaces) them:
+
+| Aspect                | PerfLog                       | Beast Insight (StatsD)       | OpenTelemetry             |
+| --------------------- | ----------------------------- | ---------------------------- | ------------------------- |
+| **Type**              | Logging                       | Metrics                      | Distributed Tracing       |
+| **Data**              | JSON log entries              | Counters, gauges, histograms | Spans with context        |
+| **Scope**             | Single node                   | Single node                  | **Cross-node**            |
+| **Output**            | `perf.log` file               | StatsD server                | OTLP Collector            |
+| **Question answered** | "What happened on this node?" | "How many? How fast?"        | "What was the journey?"   |
+| **Correlation**       | By timestamp                  | By metric name               | By `trace_id`             |
+| **Overhead**          | Low (file I/O)                | Low (UDP packets)            | Low-Medium (configurable) |
+
+### 2.6.2 What Each Framework Does Best
+
+#### PerfLog
+
+- **Purpose**: Detailed local event logging for RPC and job execution
+- **Strengths**:
+  - Rich JSON output with timing data
+  - Already integrated in RPC handlers
+  - File-based, no external dependencies
+- **Limitations**:
+  - Single-node only (no cross-node correlation)
+  - No parent-child relationships between events
+  - Manual log parsing required
+
+A PerfLog entry is a JSON object with fields such as `time`, `method`,
+`duration_us`, and `result`.
+
+#### Beast Insight (StatsD)
+
+- **Purpose**: Real-time metrics for monitoring dashboards
+- **Strengths**:
+  - Aggregated metrics (counters, gauges, histograms)
+  - Low overhead (UDP, fire-and-forget)
+  - Good for alerting thresholds
+- **Limitations**:
+  - No request-level detail
+  - No causal relationships
+  - Single-node perspective
+
+In xrpld, Beast Insight is used through `increment` (counters), `gauge`
+(point-in-time values), and `timing` (durations) calls.
+
+#### OpenTelemetry (NEW)
+
+- **Purpose**: Distributed request tracing across nodes
+- **Strengths**:
+  - **Cross-node correlation** via `trace_id`
+  - Parent-child span relationships
+  - Rich attributes per span
+  - Industry standard (CNCF)
+- **Limitations**:
+  - Requires collector infrastructure
+  - Higher complexity than logging
+
+A span is created via `startSpan` (e.g. `"tx.relay"`), annotated with
+attributes such as `tx_hash` and `peer_id`, and is automatically linked to its
+parent through the active context.
+
+### 2.6.3 When to Use Each
+
+| Scenario                                | PerfLog    | StatsD | OpenTelemetry |
+| --------------------------------------- | ---------- | ------ | ------------- |
+| "How many TXs per second?"              | ❌         | ✅     | ✅            |
+| "What's the p99 RPC latency?"           | ❌         | ✅     | ✅            |
+| "Why was this specific TX slow?"        | ⚠️ partial | ❌     | ✅            |
+| "Which node delayed consensus?"         | ❌         | ❌     | ✅            |
+| "What happened on node X at time T?"    | ✅         | ❌     | ✅            |
+| "Show me the TX journey across 5 nodes" | ❌         | ❌     | ✅            |
+
+### 2.6.4 Coexistence Strategy
+
+```mermaid
+flowchart TB
+    subgraph xrpld["xrpld Process"]
+        perflog["PerfLog<br/>(JSON to file)"]
+        insight["Beast Insight<br/>(StatsD)"]
+        otel["OpenTelemetry<br/>(Tracing)"]
+    end
+
+    perflog --> perffile["perf.log"]
+    insight --> statsd["StatsD Server"]
+    otel --> collector["OTLP Collector"]
+
+    perffile --> grafana["Grafana<br/>(Unified UI)"]
+    statsd --> grafana
+    collector --> grafana
+
+    style xrpld fill:#212121,stroke:#0a0a0a,color:#ffffff
+    style grafana fill:#bf360c,stroke:#8c2809,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **xrpld Process (dark gray)**: The single xrpld node running all three observability frameworks side by side. Each framework operates independently with no interference.
+- **PerfLog to perf.log**: PerfLog writes JSON-formatted event logs to a local file. Grafana can ingest these via Loki or a file-based datasource.
+- **Beast Insight to StatsD Server**: Insight sends aggregated metrics (counters, gauges) over UDP to a StatsD server. Grafana reads from StatsD-compatible backends like Graphite or Prometheus (via StatsD exporter).
+- **OpenTelemetry to OTLP Collector**: OTel exports spans over OTLP/HTTP to a Collector, which then forwards to a trace backend (Tempo). (OTLP/gRPC is future work — §2.2.2.)
+- **Grafana (red, unified UI)**: All three data streams converge in Grafana, enabling operators to correlate logs, metrics, and traces in a single dashboard.
+
+### 2.6.5 Correlation with PerfLog
+
+Trace IDs can be correlated with existing PerfLog entries for comprehensive
+debugging. The design is for `RPCHandler.cpp` to start an `rpc.command.<method>`
+span alongside the existing PerfLog `rpcStart`/`rpcFinish`/`rpcError` calls,
+extract the span's `trace_id` (when valid), and eventually stamp it onto the
+PerfLog entry (a planned `setTraceId` hook) so logs and traces share a key. The
+span status is set to OK on success or to error (recording the exception) on
+failure.
+
+---
+
+_Previous: [Architecture Analysis](./01-architecture-analysis.md)_ | _Next: [Implementation Strategy](./03-implementation-strategy.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/03-implementation-strategy.md

@@ -0,0 +1,488 @@
+# Implementation Strategy
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Configuration Reference](./05-configuration-reference.md)
+
+---
+
+## 3.1 Directory Structure
+
+The telemetry implementation follows xrpld's existing code organization pattern:
+
+```
+include/xrpl/
+├── telemetry/
+│   ├── Telemetry.h              # Main telemetry interface
+│   ├── TelemetryConfig.h        # Configuration structures
+│   ├── TraceContext.h           # Context propagation utilities
+│   ├── SpanGuard.h              # RAII span management
+│   └── SpanAttributes.h         # Attribute helper functions
+
+src/libxrpl/
+├── telemetry/
+│   ├── Telemetry.cpp            # Implementation
+│   ├── TelemetryConfig.cpp      # Config parsing
+│   ├── TraceContext.cpp         # Context serialization
+│   └── NullTelemetry.cpp        # No-op implementation
+
+src/xrpld/
+├── telemetry/
+│   ├── TracingInstrumentation.h # Instrumentation macros
+│   └── TracingInstrumentation.cpp
+```
+
+---
+
+## 3.2 Implementation Approach
+
+<div align="center">
+
+```mermaid
+%%{init: {'flowchart': {'nodeSpacing': 20, 'rankSpacing': 30}}}%%
+flowchart TB
+    subgraph phase1["Phase 1: Core"]
+        direction LR
+        sdk["SDK Integration"] ~~~ interface["Telemetry Interface"] ~~~ config["Configuration"]
+    end
+
+    subgraph phase2["Phase 2: RPC"]
+        direction LR
+        http["HTTP Context"] ~~~ rpc["RPC Handlers"]
+    end
+
+    subgraph phase3["Phase 3: P2P"]
+        direction LR
+        proto["Protobuf Context"] ~~~ tx["Transaction Relay"]
+    end
+
+    subgraph phase4["Phase 4: Consensus"]
+        direction LR
+        consensus["Consensus Rounds"] ~~~ proposals["Proposals"]
+    end
+
+    phase1 --> phase2 --> phase3 --> phase4
+
+    style phase1 fill:#1565c0,stroke:#0d47a1,color:#ffffff
+    style phase2 fill:#2e7d32,stroke:#1b5e20,color:#ffffff
+    style phase3 fill:#e65100,stroke:#bf360c,color:#ffffff
+    style phase4 fill:#c2185b,stroke:#880e4f,color:#ffffff
+```
+
+</div>
+
+### Key Principles
+
+1. **Minimal Intrusion**: Instrumentation should not alter existing control flow
+2. **Zero-Cost When Disabled**: Use compile-time flags and no-op implementations
+3. **Backward Compatibility**: Protocol Buffer extensions use high field numbers
+4. **Graceful Degradation**: Tracing failures must not affect node operation
+
+---
+
+## 3.3 Performance Overhead Summary
+
+> **OTLP** = OpenTelemetry Protocol
+
+| Metric        | Overhead   | Notes                                            |
+| ------------- | ---------- | ------------------------------------------------ |
+| CPU           | 1-3%       | Of per-transaction CPU cost (~200μs baseline)    |
+| Memory        | ~10 MB     | SDK statics + batch buffer + worker thread stack |
+| Network       | 10-50 KB/s | Compressed OTLP export to collector              |
+| Latency (p99) | <2%        | With proper sampling configuration               |
+
+---
+
+## 3.4 Detailed CPU Overhead Analysis
+
+### 3.4.1 Per-Operation Costs
+
+> **Note on hardware assumptions**: The costs below are based on the official OTel C++ SDK CI benchmarks
+> (969 runs on GitHub Actions 2-core shared runners). On production server hardware (3+ GHz Xeon),
+> expect costs at the **lower end** of each range (~30-50% improvement over CI hardware).
+
+| Operation             | Time (ns) | Frequency              | Impact     |
+| --------------------- | --------- | ---------------------- | ---------- |
+| Span creation         | 500-1000  | Every traced operation | Low        |
+| Span end              | 100-200   | Every traced operation | Low        |
+| SetAttribute (string) | 80-120    | 3-5 per span           | Low        |
+| SetAttribute (int)    | 40-60     | 2-3 per span           | Negligible |
+| AddEvent              | 100-200   | 0-2 per span           | Low        |
+| Context injection     | 150-250   | Per outgoing message   | Low        |
+| Context extraction    | 100-180   | Per incoming message   | Low        |
+| GetCurrent context    | 10-20     | Thread-local access    | Negligible |
+
+**Source**: Span creation based on OTel C++ SDK `BM_SpanCreation` benchmark (AlwaysOnSampler +
+SimpleSpanProcessor + InMemoryExporter), median ~1,000 ns on CI hardware. AddEvent includes
+timestamp read + string copy + vector push + mutex acquisition. Context injection/extraction
+confirmed by `BM_SpanCreationWithScope` benchmark delta (~160 ns).
+
+### 3.4.2 Transaction Processing Overhead
+
+<div align="center">
+
+```mermaid
+%%{init: {'pie': {'textPosition': 0.75}}}%%
+pie showData
+    "tx.receive (1400ns)" : 1400
+    "tx.validate (1200ns)" : 1200
+    "tx.relay (1200ns)" : 1200
+    "Context inject (200ns)" : 200
+```
+
+**Transaction Tracing Overhead (~4.0μs total)**
+
+</div>
+
+**Overhead percentage**: 4.0 μs / 200 μs (avg tx processing) = **~2.0%**
+
+> **Breakdown**: Each span (tx.receive, tx.validate, tx.relay) costs ~1,000 ns for creation plus
+> ~200-400 ns for 3-5 attribute sets. Context injection is ~200 ns (confirmed by benchmarks).
+> On production hardware, expect ~2.6 μs total (~1.3% overhead) due to faster span creation (~500-600 ns).
+
+### 3.4.3 Consensus Round Overhead
+
+| Operation              | Count | Cost (ns) | Total      |
+| ---------------------- | ----- | --------- | ---------- |
+| consensus.round span   | 1     | ~1200     | ~1.2 μs    |
+| consensus.phase spans  | 3     | ~1100     | ~3.3 μs    |
+| proposal.receive spans | ~20   | ~1100     | ~22 μs     |
+| proposal.send spans    | ~3    | ~1100     | ~3.3 μs    |
+| Context operations     | ~30   | ~200      | ~6 μs      |
+| **TOTAL**              |       |           | **~36 μs** |
+
+> **Why higher**: Each span costs ~1,000 ns creation + ~100-200 ns for 1-2 attributes, totaling ~1,100-1,200 ns.
+> Context operations remain ~200 ns (confirmed by benchmarks). On production hardware, expect ~24 μs total.
+
+**Overhead percentage**: 36 μs / 3s (typical round) = **~0.001%** (negligible)
+
+### 3.4.4 RPC Request Overhead
+
+| Operation        | Cost (ns)    |
+| ---------------- | ------------ |
+| rpc.request span | ~1200        |
+| rpc.command span | ~1100        |
+| Context extract  | ~250         |
+| Context inject   | ~200         |
+| **TOTAL**        | **~2.75 μs** |
+
+> **Why higher**: Each span costs ~1,000 ns creation + ~100-200 ns for attributes (command name,
+> version, role). Context extract/inject costs are confirmed by OTel C++ benchmarks.
+
+- Fast RPC (1ms): 2.75 μs / 1ms = **~0.275%**
+- Slow RPC (100ms): 2.75 μs / 100ms = **~0.003%**
+
+---
+
+## 3.5 Memory Overhead Analysis
+
+> **OTLP** = OpenTelemetry Protocol
+
+### 3.5.1 Static Memory
+
+| Component                            | Size        | Allocated  |
+| ------------------------------------ | ----------- | ---------- |
+| TracerProvider singleton             | ~64 KB      | At startup |
+| BatchSpanProcessor (circular buffer) | ~16 KB      | At startup |
+| BatchSpanProcessor (worker thread)   | ~8 MB       | At startup |
+| OTLP/HTTP exporter (client init)     | ~64 KB      | At startup |
+| Propagator registry                  | ~8 KB       | At startup |
+| **Total static**                     | **~8.1 MB** |            |
+
+> **Why higher than earlier estimate**: The BatchSpanProcessor's circular buffer itself is only ~16 KB
+> (2049 x 8-byte `AtomicUniquePtr` entries), but it spawns a dedicated worker thread whose default
+> stack size on Linux is ~8 MB. The OTLP/HTTP exporter allocates a small client and TLS
+> initialization buffer. The worker thread stack dominates the static footprint.
+
+### 3.5.2 Dynamic Memory
+
+| Component            | Size per unit  | Max units  | Peak            |
+| -------------------- | -------------- | ---------- | --------------- |
+| Active span          | ~500-800 bytes | 1000       | ~500-800 KB     |
+| Queued span (export) | ~500 bytes     | 2048       | ~1 MB           |
+| Attribute storage    | ~80 bytes      | 5 per span | Included        |
+| Context storage      | ~64 bytes      | Per thread | ~6.4 KB         |
+| **Total dynamic**    |                |            | **~1.5-1.8 MB** |
+
+> **Why active spans are larger**: An active `Span` object includes the wrapper (~88 bytes: shared_ptr,
+> mutex, unique_ptr to Recordable) plus `SpanData` (~250 bytes: SpanContext, timestamps, name, status,
+> empty containers) plus attribute storage (~200-500 bytes for 3-5 string attributes in a `std::map`).
+> Source: `sdk/src/trace/span.h` and `sdk/include/opentelemetry/sdk/trace/span_data.h`.
+> Queued spans release the wrapper, keeping only `SpanData` + attributes (~500 bytes).
+
+### 3.5.3 Memory Growth Characteristics
+
+```mermaid
+---
+config:
+    xyChart:
+        width: 700
+        height: 400
+---
+xychart-beta
+    title "Memory Usage vs Span Rate (bounded by queue limit)"
+    x-axis "Spans/second" [0, 200, 400, 600, 800, 1000]
+    y-axis "Memory (MB)" 0 --> 12
+    line [8.5, 9.2, 9.6, 9.9, 10.0, 10.0]
+```
+
+**Notes**:
+
+- Memory increases with span rate but **plateaus at queue capacity** (default 2048 spans)
+- Batch export prevents unbounded growth
+- At queue limit, oldest spans are dropped (not blocked)
+- Maximum memory is bounded: ~8.3 MB static (dominated by worker thread stack) + 2048 queued spans x ~500 bytes (~1 MB) + active spans (~0.8 MB) ≈ **~10 MB ceiling**
+- The worker thread stack (~8 MB) is virtual memory; actual RSS depends on stack usage (typically much less)
+
+> **Measured outcome**: A perf-iac comparison (telemetry compiled-in + enabled vs compiled-out,
+> 9 nodes — validators and client-handlers — under sustained payment load) recorded **no measurable
+> RSS increase over the telemetry-off baseline** (~15 GiB mean / ~18–19 GiB peak on both sides),
+> with no OOM, no swap, and no leak across the run. The ~10 MB ceiling above is therefore a
+> provisioning safety margin (dominated by virtual thread-stack address space), not an expected
+> resident-memory increase. Steady-state cost shows up as throughput (~3–4% at head sampling 1.0),
+> not memory.
+
+### 3.5.4 Performance Data Sources
+
+The overhead estimates in Sections 3.3-3.5 are derived from the following sources:
+
+| Source                                           | What it covers                                        | URL                                                                                                                                        |
+| ------------------------------------------------ | ----------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
+| OTel C++ SDK CI benchmarks (969 runs)            | Span creation, context activation, sampler overhead   | [Benchmark Dashboard](https://open-telemetry.github.io/opentelemetry-cpp/benchmarks/)                                                      |
+| `api/test/trace/span_benchmark.cc`               | API-level span creation (~22 ns no-op)                | [Source](https://github.com/open-telemetry/opentelemetry-cpp/blob/main/api/test/trace/span_benchmark.cc)                                   |
+| `sdk/test/trace/sampler_benchmark.cc`            | SDK span creation with samplers (~1,000 ns AlwaysOn)  | [Source](https://github.com/open-telemetry/opentelemetry-cpp/blob/main/sdk/test/trace/sampler_benchmark.cc)                                |
+| `sdk/include/.../span_data.h`                    | SpanData memory layout (~250 bytes base)              | [Source](https://github.com/open-telemetry/opentelemetry-cpp/blob/main/sdk/include/opentelemetry/sdk/trace/span_data.h)                    |
+| `sdk/src/trace/span.h`                           | Span wrapper memory layout (~88 bytes)                | [Source](https://github.com/open-telemetry/opentelemetry-cpp/blob/main/sdk/src/trace/span.h)                                               |
+| `sdk/include/.../batch_span_processor_options.h` | Default queue size (2048), batch size (512)           | [Source](https://github.com/open-telemetry/opentelemetry-cpp/blob/main/sdk/include/opentelemetry/sdk/trace/batch_span_processor_options.h) |
+| `sdk/include/.../circular_buffer.h`              | CircularBuffer implementation (AtomicUniquePtr array) | [Source](https://github.com/open-telemetry/opentelemetry-cpp/blob/main/sdk/include/opentelemetry/sdk/common/circular_buffer.h)             |
+| OTLP proto definition                            | Serialized span size estimation                       | [Proto](https://github.com/open-telemetry/opentelemetry-proto/blob/main/opentelemetry/proto/trace/v1/trace.proto)                          |
+
+---
+
+## 3.6 Network Overhead Analysis
+
+### 3.6.1 Export Bandwidth
+
+> **Bytes per span**: Estimates use ~500 bytes/span (conservative upper bound). OTLP protobuf analysis
+> shows a typical span with 3-5 string attributes serializes to ~200-300 bytes raw; with gzip
+> compression (~60-70% of raw) and batching (amortized headers), ~350 bytes/span is more realistic.
+> The table uses the conservative estimate for capacity planning.
+
+| Sampling Rate | Spans/sec | Bandwidth | Notes            |
+| ------------- | --------- | --------- | ---------------- |
+| 100%          | ~500      | ~250 KB/s | Development only |
+| 10%           | ~50       | ~25 KB/s  | Staging          |
+| 1%            | ~5        | ~2.5 KB/s | Production       |
+| Error-only    | ~1        | ~0.5 KB/s | Minimal overhead |
+
+### 3.6.2 Trace Context Propagation
+
+| Message Type           | Context Size | Messages/sec | Overhead    |
+| ---------------------- | ------------ | ------------ | ----------- |
+| TMTransaction          | 25 bytes     | ~100         | ~2.5 KB/s   |
+| TMProposeSet           | 25 bytes     | ~10          | ~250 B/s    |
+| TMValidation           | 25 bytes     | ~50          | ~1.25 KB/s  |
+| **Total P2P overhead** |              |              | **~4 KB/s** |
+
+---
+
+## 3.7 Optimization Strategies
+
+### 3.7.1 Sampling Strategies
+
+#### Tail Sampling
+
+```mermaid
+flowchart TD
+    trace["New Trace"]
+
+    trace --> errors{"Is Error?"}
+    errors -->|Yes| sample["SAMPLE"]
+    errors -->|No| consensus{"Is Consensus?"}
+
+    consensus -->|Yes| sample
+    consensus -->|No| slow{"Is Slow?"}
+
+    slow -->|Yes| sample
+    slow -->|No| prob{"Random < 10%?"}
+
+    prob -->|Yes| sample
+    prob -->|No| drop["DROP"]
+
+    style sample fill:#4caf50,stroke:#388e3c,color:#fff
+    style drop fill:#f44336,stroke:#c62828,color:#fff
+```
+
+### 3.7.2 Batch Tuning Recommendations
+
+| Environment        | Batch Size | Batch Delay | Max Queue |
+| ------------------ | ---------- | ----------- | --------- |
+| Low-latency        | 128        | 1000ms      | 512       |
+| High-throughput    | 1024       | 10000ms     | 8192      |
+| Memory-constrained | 256        | 2000ms      | 512       |
+
+### 3.7.3 Conditional Instrumentation
+
+Instrumentation is gated on two levels. A compile-time feature flag (`XRPL_ENABLE_TELEMETRY`) reduces the trace macros to no-ops when telemetry is built out, so disabled builds carry zero cost. At runtime, per-component guards (e.g. `shouldTracePeer()`) skip span creation for components whose tracing is turned off, incurring no overhead beyond a single boolean check.
+
+---
+
+## 3.8 Links to Detailed Documentation
+
+- **[Configuration Reference](./05-configuration-reference.md)**: Configuration options and collector setup
+- **[Implementation Phases](./06-implementation-phases.md)**: Detailed timeline and milestones
+
+---
+
+## 3.9 Code Intrusiveness Assessment
+
+> **TxQ** = Transaction Queue
+
+This section provides a detailed assessment of how intrusive the OpenTelemetry integration is to the existing xrpld codebase.
+
+### 3.9.1 Files Modified Summary
+
+| Component             | Files Modified | Lines Added | Lines Changed | Architectural Impact |
+| --------------------- | -------------- | ----------- | ------------- | -------------------- |
+| **Core Telemetry**    | 11 new files   | ~980        | 0             | None (new module)    |
+| **Application Init**  | 2 files        | ~30         | ~5            | Minimal              |
+| **RPC Layer**         | 3 files        | ~80         | ~20           | Minimal              |
+| **Transaction Relay** | 4 files        | ~120        | ~40           | Low                  |
+| **Consensus**         | 3 files        | ~100        | ~30           | Low-Medium           |
+| **Protocol Buffers**  | 1 file         | ~25         | 0             | Low                  |
+| **CMake/Build**       | 3 files        | ~50         | ~10           | Minimal              |
+| **PathFinding**       | 2              | ~80         | ~5            | Minimal              |
+| **TxQ/Fee**           | 2              | ~60         | ~5            | Minimal              |
+| **Validator/Amend**   | 3              | ~40         | ~5            | Minimal              |
+| **Total**             | **~34 files**  | **~1,670**  | **~120**      | **Low**              |
+
+### 3.9.2 Detailed File Impact
+
+```mermaid
+pie title Code Changes by Component
+    "New Telemetry Module" : 800
+    "Transaction Relay" : 160
+    "Consensus" : 130
+    "RPC Layer" : 100
+    "PathFinding" : 80
+    "TxQ/Fee" : 60
+    "Validator/Amendment" : 40
+    "Application Init" : 35
+    "Protocol Buffers" : 25
+    "Build System" : 60
+```
+
+#### New Files (No Impact on Existing Code)
+
+| File                                             | Lines | Purpose                  |
+| ------------------------------------------------ | ----- | ------------------------ |
+| `include/xrpl/telemetry/Telemetry.h`             | ~160  | Main interface           |
+| `include/xrpl/telemetry/TelemetryConfig.h`       | ~80   | Configuration structures |
+| `include/xrpl/telemetry/TraceContext.h`          | ~80   | Context propagation      |
+| `include/xrpl/telemetry/SpanGuard.h`             | ~120  | RAII wrapper             |
+| `include/xrpl/telemetry/SpanAttributes.h`        | ~60   | Attribute helpers        |
+| `src/libxrpl/telemetry/Telemetry.cpp`            | ~200  | Implementation           |
+| `src/libxrpl/telemetry/TelemetryConfig.cpp`      | ~60   | Config parsing           |
+| `src/libxrpl/telemetry/TraceContext.cpp`         | ~80   | Context serialization    |
+| `src/libxrpl/telemetry/NullTelemetry.cpp`        | ~40   | No-op implementation     |
+| `src/xrpld/telemetry/TracingInstrumentation.h`   | ~60   | Macros                   |
+| `src/xrpld/telemetry/TracingInstrumentation.cpp` | ~40   | Instrumentation impl     |
+
+#### Modified Files (Existing Xrpld Code)
+
+| File                                              | Lines Added | Lines Changed | Risk Level |
+| ------------------------------------------------- | ----------- | ------------- | ---------- |
+| `src/xrpld/app/main/Application.cpp`              | ~15         | ~3            | Low        |
+| `include/xrpl/core/ServiceRegistry.h`             | ~5          | ~2            | Low        |
+| `src/xrpld/rpc/detail/ServerHandler.cpp`          | ~40         | ~10           | Low        |
+| `src/xrpld/rpc/handlers/*.cpp`                    | ~30         | ~8            | Low        |
+| `src/xrpld/overlay/detail/PeerImp.cpp`            | ~60         | ~15           | Medium     |
+| `src/xrpld/overlay/detail/OverlayImpl.cpp`        | ~30         | ~10           | Medium     |
+| `src/xrpld/app/consensus/RCLConsensus.cpp`        | ~50         | ~15           | Medium     |
+| `src/xrpld/app/consensus/RCLConsensusAdaptor.cpp` | ~40         | ~12           | Medium     |
+| `src/xrpld/core/JobQueue.cpp`                     | ~20         | ~5            | Low        |
+| `src/xrpld/app/paths/PathRequest.cpp`             | ~40         | ~3            | Low        |
+| `src/xrpld/app/paths/Pathfinder.cpp`              | ~40         | ~2            | Low        |
+| `src/xrpld/app/misc/TxQ.cpp`                      | ~40         | ~3            | Low        |
+| `src/xrpld/app/main/LoadManager.cpp`              | ~20         | ~2            | Low        |
+| `src/xrpld/app/misc/ValidatorList.cpp`            | ~20         | ~2            | Low        |
+| `src/xrpld/app/misc/AmendmentTable.cpp`           | ~10         | ~2            | Low        |
+| `src/xrpld/app/misc/Manifest.cpp`                 | ~10         | ~1            | Low        |
+| `src/xrpld/shamap/SHAMap.cpp`                     | ~20         | ~3            | Low        |
+| `src/xrpld/overlay/detail/ripple.proto`           | ~25         | 0             | Low        |
+| `CMakeLists.txt`                                  | ~40         | ~8            | Low        |
+| `cmake/FindOpenTelemetry.cmake`                   | ~50         | 0             | None (new) |
+
+### 3.9.3 Risk Assessment by Component
+
+<div align="center">
+
+**Do First** ↖ ↗ **Plan Carefully**
+
+```mermaid
+quadrantChart
+    title Code Intrusiveness Risk Matrix
+    x-axis Low Risk --> High Risk
+    y-axis Low Value --> High Value
+
+    RPC Tracing: [0.2, 0.55]
+    Transaction Relay: [0.55, 0.85]
+    Consensus Tracing: [0.75, 0.92]
+    Peer Message Tracing: [0.85, 0.35]
+    JobQueue Context: [0.3, 0.42]
+    Ledger Acquisition: [0.48, 0.65]
+    PathFinding: [0.38, 0.72]
+    TxQ and Fees: [0.25, 0.62]
+    Validator Mgmt: [0.15, 0.35]
+```
+
+**Optional** ↙ ↘ **Avoid**
+
+</div>
+
+#### Risk Level Definitions
+
+| Risk Level | Definition                                                       | Mitigation                         |
+| ---------- | ---------------------------------------------------------------- | ---------------------------------- |
+| **Low**    | Additive changes only; no modification to existing logic         | Standard code review               |
+| **Medium** | Minor modifications to existing functions; clear boundaries      | Comprehensive unit tests           |
+| **High**   | Changes to core logic or data structures; potential side effects | Integration tests + staged rollout |
+
+### 3.9.4 Architectural Impact Assessment
+
+| Aspect               | Impact  | Justification                                                                    |
+| -------------------- | ------- | -------------------------------------------------------------------------------- |
+| **Data Flow**        | Minimal | Read-only instrumentation; no modification to consensus or transaction data flow |
+| **Threading Model**  | Minimal | Context propagation uses thread-local storage (standard OTel pattern)            |
+| **Memory Model**     | Low     | Bounded queues prevent unbounded growth; RAII ensures cleanup                    |
+| **Network Protocol** | Low     | Optional fields in protobuf (high field numbers); backward compatible            |
+| **Configuration**    | None    | New config section; existing configs unaffected                                  |
+| **Build System**     | Low     | Optional CMake flag; builds work without OpenTelemetry                           |
+| **Dependencies**     | Low     | OpenTelemetry SDK is optional; null implementation when disabled                 |
+
+### 3.9.5 Backward Compatibility
+
+| Compatibility   | Status  | Notes                                                 |
+| --------------- | ------- | ----------------------------------------------------- |
+| **Config File** | ✅ Full | New `[telemetry]` section is optional                 |
+| **Protocol**    | ✅ Full | Optional protobuf fields with high field numbers      |
+| **Build**       | ✅ Full | `XRPL_ENABLE_TELEMETRY=OFF` produces identical binary |
+| **Runtime**     | ✅ Full | `enabled=0` produces zero overhead                    |
+| **API**         | ✅ Full | No changes to public RPC or P2P APIs                  |
+
+### 3.9.6 Rollback Strategy
+
+If issues are discovered after deployment:
+
+1. **Immediate**: Set `enabled=0` in config and restart (zero code change)
+2. **Quick**: Rebuild with `XRPL_ENABLE_TELEMETRY=OFF`
+3. **Complete**: Revert telemetry commits (clean separation makes this easy)
+
+### 3.9.7 Code Change Examples
+
+**Minimal RPC Instrumentation (Low Intrusiveness):** Instrumenting an RPC handler adds roughly 3-4 lines: one macro to start the span and one or two `setAttribute` calls (command name, status). The span ends automatically via RAII, so the existing control flow — process the request, send the result — is untouched.
+
+**Consensus Instrumentation (Medium Intrusiveness):** Consensus is slightly more intrusive because child spans in later phase transitions need the round's context. Beyond the span-start and attribute macros, this requires storing the active context in a new member variable (`currentRoundContext_`) at round start. The existing round logic itself remains unchanged.
+
+---
+
+_Previous: [Design Decisions](./02-design-decisions.md)_ | _Next: [Configuration Reference](./05-configuration-reference.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/05-configuration-reference.md

@@ -0,0 +1,265 @@
+# Configuration Reference
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Implementation Phases](./06-implementation-phases.md)
+
+---
+
+## 5.1 xrpld Configuration
+
+> **OTLP** = OpenTelemetry Protocol | **TxQ** = Transaction Queue
+
+### 5.1.1 Configuration File Section
+
+The authoritative `[telemetry]` example lives in `cfg/xrpld-example.cfg`. Telemetry is disabled by default (`enabled=0`); enabling it turns on distributed tracing for transaction flow, consensus, and RPC calls, with traces exported to an OpenTelemetry Collector over OTLP. Head sampling is intentionally fixed at 1.0 (sample everything) and is not configurable — per-node head-sampling would produce broken/partial distributed traces, so volume reduction is delegated to the collector's tail sampling (see Section 7.4.2). The full option reference follows.
+
+### 5.1.2 Configuration Options Summary
+
+| Option                | Type   | Default                           | Description                                          |
+| --------------------- | ------ | --------------------------------- | ---------------------------------------------------- |
+| `enabled`             | bool   | `false`                           | Enable/disable telemetry                             |
+| `endpoint`            | string | `http://localhost:4318/v1/traces` | OTLP/HTTP collector endpoint                         |
+| `use_tls`             | bool   | `false`                           | Enable TLS for exporter connection                   |
+| `tls_ca_cert`         | string | `""`                              | Path to CA certificate file                          |
+| `batch_size`          | uint   | `512`                             | Spans per export batch                               |
+| `batch_delay_ms`      | uint   | `5000`                            | Max delay before sending batch (ms)                  |
+| `max_queue_size`      | uint   | `2048`                            | Maximum queued spans                                 |
+| `trace_transactions`  | bool   | `true`                            | Enable transaction tracing                           |
+| `trace_consensus`     | bool   | `true`                            | Enable consensus tracing                             |
+| `trace_rpc`           | bool   | `true`                            | Enable RPC tracing                                   |
+| `trace_peer`          | bool   | `true`                            | Enable peer message tracing (high volume)            |
+| `trace_ledger`        | bool   | `true`                            | Enable ledger tracing                                |
+| `service_name`        | string | `"xrpld"`                         | Service name (`service.name`) for traces and metrics |
+| `service_instance_id` | string | `<node_pubkey>`                   | Instance identifier                                  |
+
+**Planned (not yet implemented)**: the following options appear in the design
+documents but are not parsed by `TelemetryConfig.cpp` in Phase 1b and later
+phases. They will be added as the corresponding subsystems are instrumented:
+
+| Option                     | Planned Phase | Purpose                                                                 |
+| -------------------------- | ------------- | ----------------------------------------------------------------------- |
+| `exporter`                 | Future        | Select between OTLP/HTTP and OTLP/gRPC                                  |
+| `trace_pathfind`           | Phase 2       | Path computation tracing toggle                                         |
+| `trace_txq`                | Phase 3       | Transaction queue tracing toggle                                        |
+| `trace_validator`          | Future        | Validator list / manifest update tracing                                |
+| `trace_amendment`          | Future        | Amendment voting tracing                                                |
+| `consensus_trace_strategy` | Phase 4       | Trace ID strategy for consensus rounds (`deterministic` \| `attribute`) |
+
+---
+
+## 5.2 Configuration Parser
+
+> **TxQ** = Transaction Queue
+
+The parser `setup_Telemetry()` in `src/libxrpl/telemetry/TelemetryConfig.cpp` reads the `[telemetry]` `Section` and populates a `Telemetry::Setup` struct, applying the defaults listed in Section 5.1.2 via `section.value_or(...)`. It derives `serviceInstanceId` from the node public key when not overridden, selects the exporter endpoint default by exporter type, and leaves the sampling ratio at its fixed 1.0 default (not read from config — see Section 7.4.2).
+
+---
+
+## 5.3 Application Integration
+
+### 5.3.1 ApplicationImp Changes
+
+> **Deferred identity**: The node public key (`nodeIdentity_`) is not
+> available during `ApplicationImp`'s member initializer list — it is
+> resolved later in `setup()`. The `Telemetry` object is therefore
+> constructed with an empty `serviceInstanceId` and patched via
+> `setServiceInstanceId()` once `setup()` has called `getNodeIdentity()`.
+
+`ApplicationImp` (in `src/xrpld/app/main/Application.cpp`) owns a `std::unique_ptr<telemetry::Telemetry> telemetry_`. It is built in the member initializer list via `make_Telemetry(setup_Telemetry(...))` with an empty `serviceInstanceId`, then patched in `setup()` by calling `setServiceInstanceId()` with the Base58 node public key (unless the user supplied a custom `service_instance_id`). `start()` and `run()` forward to `telemetry_->start()` / `telemetry_->stop()`, and `getTelemetry()` returns the owned instance.
+
+### 5.3.2 ServiceRegistry Interface Addition
+
+`include/xrpl/core/ServiceRegistry.h` gains a pure-virtual `telemetry::Telemetry& getTelemetry()` (with a forward declaration of `telemetry::Telemetry`), giving every component a uniform accessor for the tracing subsystem.
+
+> **Note:** `Application` extends `ServiceRegistry`, so `getTelemetry()` is
+> available on both. Components that hold a `ServiceRegistry&` (e.g.
+> `NetworkOPsImp`) call `registry_.get().getTelemetry()`. Components that
+> still hold an `Application&` (e.g. `ServerHandler`, `PeerImp`,
+> `RCLConsensusAdaptor`) call `app_.getTelemetry()` directly.
+
+---
+
+## 5.4 CMake Integration
+
+> **OTLP** = OpenTelemetry Protocol
+
+### 5.4.1 Find OpenTelemetry Module
+
+A `cmake/FindOpenTelemetry.cmake` module locates the OpenTelemetry C++ SDK. It first tries `find_package(opentelemetry-cpp CONFIG)`, aliasing the imported targets `OpenTelemetry::api`, `OpenTelemetry::sdk`, and `OpenTelemetry::otlp_grpc_exporter`, and falls back to `pkg-config` when no CMake config package is present.
+
+### 5.4.2 CMakeLists.txt Changes
+
+The top-level `CMakeLists.txt` adds an `XRPL_ENABLE_TELEMETRY` option (default `OFF`). When enabled, it runs `find_package(OpenTelemetry REQUIRED)`, defines the `XRPL_ENABLE_TELEMETRY` compile flag, and builds the `xrpl_telemetry` library from the real telemetry sources linked against the OpenTelemetry targets; when disabled, it builds the same target from a no-op `NullTelemetry.cpp` so call sites compile unchanged.
+
+---
+
+## 5.5 OpenTelemetry Collector Configuration
+
+> **OTLP** = OpenTelemetry Protocol | **APM** = Application Performance Monitoring
+
+The authoritative collector config lives in the repo at `docker/telemetry/otel-collector-config.yaml` (with Tempo backend config in `docker/telemetry/tempo.yaml`). The sections below summarize the development and production shapes of that pipeline.
+
+### 5.5.1 Development Configuration
+
+The development collector enables an OTLP receiver on both gRPC (`0.0.0.0:4317`) and HTTP (`0.0.0.0:4318`), a single `batch` processor (1s timeout, batch size 100), and two exporters: a `logging` exporter for console debugging and `otlp/tempo` (insecure) for trace visualization. The single `traces` pipeline wires receiver → batch → both exporters.
+
+### 5.5.2 Production Configuration
+
+The production collector adds TLS on the OTLP gRPC receiver and a richer processor chain: a `memory_limiter` (OOM guard), `batch` (5s timeout, size 512), `tail_sampling`, and an `attributes` processor that hashes sensitive fields (e.g. `tx_account`) and stamps `deployment.environment`. Tail sampling keeps all `ERROR` traces, slow consensus rounds (>5s) and slow RPC requests (>1s), and probabilistically samples the remainder at 10%. Exporters target Grafana Tempo (TLS) and Elastic APM; `health_check` and `zpages` extensions are enabled for operability.
+
+---
+
+## 5.6 Docker Compose Development Environment
+
+> **OTLP** = OpenTelemetry Protocol
+
+The authoritative development stack lives in the repo at `docker/telemetry/docker-compose.yml`. It brings up four services on a shared `xrpld-telemetry` network: an `otel-collector` (otel/opentelemetry-collector-contrib) exposing OTLP gRPC `4317`, OTLP HTTP `4318`, and health check `13133`; `tempo` for trace storage/visualization; `grafana` with provisioned datasources and dashboards (anonymous admin enabled); and an optional `prometheus` for metric correlation.
+
+---
+
+## 5.7 Configuration Architecture
+
+> **OTLP** = OpenTelemetry Protocol
+
+```mermaid
+flowchart TB
+    subgraph config["Configuration Sources"]
+        cfgFile["xrpld.cfg<br/>[telemetry] section"]
+        cmake["CMake<br/>XRPL_ENABLE_TELEMETRY"]
+    end
+
+    subgraph init["Initialization"]
+        parse["setup_Telemetry()"]
+        factory["make_Telemetry()"]
+    end
+
+    subgraph runtime["Runtime Components"]
+        tracer["TracerProvider"]
+        exporter["OTLP Exporter"]
+        processor["BatchProcessor"]
+    end
+
+    subgraph collector["Collector Pipeline"]
+        recv["Receivers"]
+        proc["Processors"]
+        exp["Exporters"]
+    end
+
+    cfgFile --> parse
+    cmake -->|"compile flag"| parse
+    parse --> factory
+    factory --> tracer
+    tracer --> processor
+    processor --> exporter
+    exporter -->|"OTLP"| recv
+    recv --> proc
+    proc --> exp
+
+    style config fill:#e3f2fd,stroke:#1976d2
+    style runtime fill:#e8f5e9,stroke:#388e3c
+    style collector fill:#fff3e0,stroke:#ff9800
+```
+
+**Reading the diagram:**
+
+- **Configuration Sources**: `xrpld.cfg` provides runtime settings (endpoint, per-component trace toggles) while the CMake flag controls whether telemetry is compiled in at all. Head sampling is fixed at 1.0 and is not a config option; volume reduction happens via tail sampling in the collector.
+- **Initialization**: `setup_Telemetry()` parses config values, then `make_Telemetry()` constructs the provider, processor, and exporter objects.
+- **Runtime Components**: The `TracerProvider` creates spans, the `BatchProcessor` buffers them, and the `OTLP Exporter` serializes and sends them over the wire.
+- **OTLP arrow to Collector**: Trace data leaves the xrpld process via OTLP/HTTP and enters the external Collector pipeline. (OTLP/gRPC is future work — see design decisions §2.2.2.)
+- **Collector Pipeline**: `Receivers` ingest OTLP data, `Processors` apply sampling/filtering/enrichment, and `Exporters` forward traces to storage backends (Tempo, etc.).
+
+---
+
+## 5.8 Grafana Integration
+
+> **APM** = Application Performance Monitoring
+
+Step-by-step instructions for integrating xrpld traces with Grafana.
+
+### 5.8.1 Data Source Configuration
+
+#### Tempo (Recommended)
+
+A Tempo datasource (`grafana/provisioning/datasources/tempo.yaml`, provisioned from `docker/telemetry/grafana/`) points at `http://tempo:3200` and enables `tracesToLogs` (linking to Loki on `service.name`/`tx_hash` and mapping `trace_id` → `traceID`), `serviceMap` against Prometheus, the node graph, and Loki search.
+
+#### Elastic APM
+
+Alternatively, an Elasticsearch datasource (`grafana/provisioning/datasources/elastic-apm.yaml`) of type `elasticsearch` points at `http://elasticsearch:9200` against the `apm-*` index, using `@timestamp` as the time field and mapping the log message/level fields.
+
+### 5.8.2 Dashboard Provisioning
+
+A dashboard provider (`grafana/provisioning/dashboards/dashboards.yaml`) loads the `xrpld` dashboard folder from disk (`/var/lib/grafana/dashboards/rippled`), polling for changes every 30s with deletion disabled.
+
+### 5.8.3 Example Dashboard: RPC Performance
+
+An example `xrpld RPC Performance` dashboard (uid `xrpld-rpc-performance`) sourced from Tempo via TraceQL provides four panels: RPC latency by command (heatmap), RPC error rate by command (timeseries), the top 10 slowest RPC commands by average duration (table), and a recent-traces table.
+
+### 5.8.4 Example Dashboard: Transaction Tracing
+
+An example `xrpld Transaction Tracing` dashboard (uid `xrpld-tx-tracing`) over Tempo provides three panels: transaction throughput (`tx.receive` rate, stat), cross-node relay count (average `span.relay_count` on `tx.relay`, timeseries), and a table of transaction validation errors (`tx.validate` with `status.code=error`).
+
+### 5.8.5 TraceQL Query Examples
+
+Common queries for xrpld traces:
+
+```
+# Find all traces for a specific transaction hash
+{resource.service.name="xrpld" && span.tx_hash="ABC123..."}
+
+# Find slow RPC commands (>100ms)
+{resource.service.name="xrpld" && name=~"rpc.command.*"} | duration > 100ms
+
+# Find consensus rounds taking >5 seconds
+{resource.service.name="xrpld" && name="consensus.round"} | duration > 5s
+
+# Find failed transactions with error details
+{resource.service.name="xrpld" && name="tx.validate" && status.code=error}
+
+# Find transactions relayed to many peers
+{resource.service.name="xrpld" && name="tx.relay"} | span.relay_count > 10
+
+# Compare latency across nodes
+{resource.service.name="xrpld" && name="rpc.command.account_info"} | avg(duration) by (resource.service.instance.id)
+```
+
+### 5.8.6 Correlation with PerfLog
+
+To correlate OpenTelemetry traces with existing PerfLog data:
+
+**Step 1: Configure Loki to ingest PerfLog**
+
+Configure a Promtail scrape job (`promtail-config.yaml`) that tails `/var/log/rippled/perf*.log`, parses each JSON line, and promotes `trace_id`, `ledger_seq`, and `tx_hash` to Loki labels.
+
+**Step 2: Add trace_id to PerfLog entries**
+
+Modify PerfLog so its JSON output includes a `trace_id` field whenever a valid span is active: fetch the current span from the OpenTelemetry runtime context, and if its context is valid, render the trace ID as a 32-character lowercase hex string into the log entry.
+
+**Step 3: Configure Grafana trace-to-logs link**
+
+In the Tempo datasource, set the `tracesToLogs` derived field to link to Loki on the `trace_id` and `tx_hash` tags, with `filterByTraceID: true`.
+
+### 5.8.7 Correlation with Insight/StatsD Metrics
+
+To correlate traces with existing Beast Insight metrics:
+
+**Step 1: Export Insight metrics to Prometheus**
+
+Add a Prometheus scrape job (`prometheus.yaml`) named `xrpld-statsd` targeting the StatsD exporter at `statsd-exporter:9102`.
+
+**Step 2: Add exemplars to metrics**
+
+The OpenTelemetry SDK automatically adds exemplars (trace IDs) to metrics when using the Prometheus exporter, linking metric spikes to specific traces.
+
+**Step 3: Configure Grafana metric-to-trace link**
+
+In the Prometheus datasource, set `exemplarTraceIdDestinations` to map the `trace_id` exemplar to the Tempo datasource.
+
+**Step 4: Dashboard panel with exemplars**
+
+Add a timeseries panel over Prometheus (e.g. `histogram_quantile(0.99, rate(xrpld_rpc_duration_seconds_bucket[5m]))`) with `exemplar: true` enabled.
+
+This allows clicking on metric data points to jump directly to the related trace.
+
+---
+
+_Previous: [Implementation Strategy](./03-implementation-strategy.md)_ | _Next: [Implementation Phases](./06-implementation-phases.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/06-implementation-phases.md

@@ -0,0 +1,575 @@
+# Implementation Phases
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Configuration Reference](./05-configuration-reference.md) | [Observability Backends](./07-observability-backends.md)
+
+---
+
+## 6.1 Phase Overview
+
+> **TxQ** = Transaction Queue
+
+```mermaid
+gantt
+    title OpenTelemetry Implementation Timeline
+    dateFormat  YYYY-MM-DD
+    axisFormat  Week %W
+
+    section Phase 1
+    Core Infrastructure        :p1, 2024-01-01, 2w
+    SDK Integration           :p1a, 2024-01-01, 4d
+    Telemetry Interface       :p1b, after p1a, 3d
+    Configuration & CMake     :p1c, after p1b, 3d
+    Unit Tests                :p1d, after p1c, 2d
+    Buffer & Integration      :p1e, after p1d, 2d
+
+    section Phase 2
+    RPC Tracing               :p2, after p1, 2w
+    HTTP Context Extraction   :p2a, after p1, 2d
+    RPC Handler Instrumentation :p2b, after p2a, 4d
+    PathFinding Instrumentation :p2f, after p2b, 2d
+    TxQ Instrumentation       :p2g, after p2f, 2d
+    WebSocket Support         :p2c, after p2g, 2d
+    Integration Tests         :p2d, after p2c, 2d
+    Buffer & Review           :p2e, after p2d, 4d
+
+    section Phase 3
+    Transaction Tracing       :p3, after p2, 2w
+    Protocol Buffer Extension :p3a, after p2, 2d
+    PeerImp Instrumentation   :p3b, after p3a, 3d
+    Fee Escalation Instrumentation :p3f, after p3b, 2d
+    Relay Context Propagation :p3c, after p3f, 3d
+    Multi-node Tests          :p3d, after p3c, 2d
+    Buffer & Review           :p3e, after p3d, 4d
+
+    section Phase 4
+    Consensus Tracing         :p4, after p3, 2w
+    Consensus Round Spans     :p4a, after p3, 3d
+    Proposal Handling         :p4b, after p4a, 3d
+    Validator List & Manifest Tracing :p4f, after p4b, 2d
+    Amendment Voting Tracing  :p4g, after p4f, 2d
+    SHAMap Sync Tracing       :p4h, after p4g, 2d
+    Validation Tests          :p4c, after p4h, 4d
+    Buffer & Review           :p4e, after p4c, 4d
+
+    section Phase 5
+    Documentation & Deploy    :p5, after p4, 1w
+```
+
+---
+
+## 6.2 Phase 1: Core Infrastructure (Weeks 1-2)
+
+**Objective**: Establish foundational telemetry infrastructure
+
+### Tasks
+
+| Task | Description                                           |
+| ---- | ----------------------------------------------------- |
+| 1.1  | Add OpenTelemetry C++ SDK to Conan/CMake              |
+| 1.2  | Implement `Telemetry` interface and factory           |
+| 1.3  | Implement `SpanGuard` RAII wrapper                    |
+| 1.4  | Implement configuration parser                        |
+| 1.5  | Integrate into `ApplicationImp`                       |
+| 1.6  | Add conditional compilation (`XRPL_ENABLE_TELEMETRY`) |
+| 1.7  | Create `NullTelemetry` no-op implementation           |
+| 1.8  | Unit tests for core infrastructure                    |
+
+### Exit Criteria
+
+- [ ] OpenTelemetry SDK compiles and links
+- [ ] Telemetry can be enabled/disabled via config
+- [ ] Basic span creation works
+- [ ] No performance regression when disabled
+- [ ] Unit tests passing
+
+---
+
+## 6.3 Phase 2: RPC Tracing (Weeks 3-4)
+
+> **TxQ** = Transaction Queue
+
+**Objective**: Complete tracing for all RPC operations
+
+### Tasks
+
+| Task | Description                                                                |
+| ---- | -------------------------------------------------------------------------- |
+| 2.1  | Implement W3C Trace Context HTTP header extraction                         |
+| 2.2  | Instrument `ServerHandler::onRequest()`                                    |
+| 2.3  | Instrument `RPCHandler::doCommand()`                                       |
+| 2.4  | Add RPC-specific attributes                                                |
+| 2.5  | Instrument WebSocket handler                                               |
+| 2.6  | PathFinding instrumentation (`pathfind.request`, `pathfind.compute` spans) |
+| 2.7  | TxQ instrumentation (`txq.enqueue`, `txq.apply` spans)                     |
+| 2.8  | Integration tests for RPC tracing                                          |
+| 2.9  | Performance benchmarks                                                     |
+| 2.10 | Documentation                                                              |
+
+### Exit Criteria
+
+- [ ] All RPC commands traced
+- [ ] Trace context propagates from HTTP headers
+- [ ] WebSocket and HTTP both instrumented
+- [ ] <1ms overhead per RPC call
+- [ ] Integration tests passing
+
+---
+
+## 6.4 Phase 3: Transaction Tracing (Weeks 5-6)
+
+**Objective**: Trace transaction lifecycle across network
+
+### Tasks
+
+| Task | Description                                          |
+| ---- | ---------------------------------------------------- |
+| 3.1  | Define `TraceContext` Protocol Buffer message        |
+| 3.2  | Implement protobuf context serialization             |
+| 3.3  | Instrument `PeerImp::handleTransaction()`            |
+| 3.4  | Instrument `NetworkOPs::submitTransaction()`         |
+| 3.5  | Instrument HashRouter integration                    |
+| 3.6  | Fee escalation instrumentation (`fee.escalate` span) |
+| 3.7  | Implement relay context propagation                  |
+| 3.8  | Integration tests (multi-node)                       |
+| 3.9  | Performance benchmarks                               |
+
+### Exit Criteria
+
+- [ ] Transaction traces span across nodes
+- [ ] Trace context in Protocol Buffer messages
+- [ ] HashRouter deduplication visible in traces
+- [ ] Multi-node integration tests passing
+- [ ] <5% overhead on transaction throughput
+
+---
+
+## 6.5 Phase 4: Consensus Tracing (Weeks 7-8)
+
+**Objective**: Full observability into consensus rounds
+
+### Tasks
+
+| Task | Description                                    |
+| ---- | ---------------------------------------------- |
+| 4.1  | Instrument `RCLConsensusAdaptor::startRound()` |
+| 4.2  | Instrument phase transitions                   |
+| 4.3  | Instrument proposal handling                   |
+| 4.4  | Instrument validation handling                 |
+| 4.5  | Add consensus-specific attributes              |
+| 4.6  | Correlate with transaction traces              |
+| 4.7  | Validator list and manifest tracing            |
+| 4.8  | Amendment voting tracing                       |
+| 4.9  | SHAMap sync tracing                            |
+| 4.10 | Multi-validator integration tests              |
+| 4.11 | Performance validation                         |
+
+### Exit Criteria
+
+- [ ] Complete consensus round traces
+- [ ] Phase transitions visible
+- [ ] Proposals and validations traced
+- [ ] No impact on consensus timing
+- [ ] Multi-validator test network validated
+
+### Implementation Status — Phase 4a Plan
+
+Phase 4a (establish-phase gap fill & cross-node correlation) will add:
+
+- **Deterministic trace ID** derived from `previousLedger.id()` so all validators
+  in the same round share the same `trace_id` (switchable via
+  `consensus_trace_strategy` config: `"deterministic"` or `"attribute"`).
+  See [Configuration Reference](./05-configuration-reference.md) for full
+  configuration options.
+- **Round lifecycle spans**: `consensus.round` with round-to-round span links.
+- **Establish phase**: `consensus.establish`, `consensus.update_positions` (with
+  `dispute.resolve` events), `consensus.check` (with threshold tracking).
+- **Mode changes**: `consensus.mode_change` spans.
+- **Validation**: `consensus.validation.send` with span link to round span
+  (thread-safe cross-thread access via `roundSpanContext_` snapshot).
+- **Separation of concerns**: telemetry extracted to private helpers
+  (`startRoundTracing`, `createValidationSpan`, `startEstablishTracing`,
+  `updateEstablishTracing`, `endEstablishTracing`).
+
+The `Phase4_taskList.md` spec document is introduced in the Phase 2 PR (#6424)
+and will contain the full task breakdown and implementation notes.
+
+---
+
+## 6.6 Phase 5: Documentation & Deployment (Week 9)
+
+**Objective**: Production readiness
+
+### Tasks
+
+| Task | Description                   |
+| ---- | ----------------------------- |
+| 5.1  | Operator runbook              |
+| 5.2  | Grafana dashboards            |
+| 5.3  | Alert definitions             |
+| 5.4  | Collector deployment examples |
+| 5.5  | Developer documentation       |
+| 5.6  | Training materials            |
+| 5.7  | Final integration testing     |
+
+---
+
+## 6.7 Risk Assessment
+
+```mermaid
+quadrantChart
+    title Risk Assessment Matrix
+    x-axis Low Impact --> High Impact
+    y-axis Low Likelihood --> High Likelihood
+    quadrant-1 Mitigate Immediately
+    quadrant-2 Plan Mitigation
+    quadrant-3 Accept Risk
+    quadrant-4 Monitor Closely
+
+    SDK Compat: [0.2, 0.18]
+    Protocol Chg: [0.75, 0.72]
+    Perf Overhead: [0.58, 0.42]
+    Context Prop: [0.4, 0.55]
+    Memory Leaks: [0.85, 0.25]
+```
+
+### Risk Details
+
+| Risk                                 | Likelihood | Impact | Mitigation                              |
+| ------------------------------------ | ---------- | ------ | --------------------------------------- |
+| Protocol changes break compatibility | Medium     | High   | Use high field numbers, optional fields |
+| Performance overhead unacceptable    | Medium     | Medium | Sampling, conditional compilation       |
+| Context propagation complexity       | Medium     | Medium | Phased rollout, extensive testing       |
+| SDK compatibility issues             | Low        | Medium | Pin SDK version, fallback to no-op      |
+| Memory leaks in long-running nodes   | Low        | High   | Memory profiling, bounded queues        |
+
+---
+
+## 6.8 Success Metrics
+
+| Metric                   | Target                                                         | Measurement           |
+| ------------------------ | -------------------------------------------------------------- | --------------------- |
+| Trace coverage           | >95% of transaction code paths (independent of sampling ratio) | Sampling verification |
+| CPU overhead             | <3%                                                            | Benchmark tests       |
+| Memory overhead          | <10 MB                                                         | Memory profiling      |
+| Latency impact (p99)     | <2%                                                            | Performance tests     |
+| Trace completeness       | >99% spans with required attrs                                 | Validation script     |
+| Cross-node trace linkage | >90% of multi-hop transactions                                 | Integration tests     |
+
+---
+
+## 6.9 Quick Wins and Crawl-Walk-Run Strategy
+
+> **TxQ** = Transaction Queue
+
+This section outlines a prioritized approach to maximize ROI with minimal initial investment.
+
+### 6.9.1 Crawl-Walk-Run Overview
+
+<div align="center">
+
+```mermaid
+flowchart TB
+    subgraph crawl["🐢 CRAWL (Week 1-2)"]
+        direction LR
+        c1[Core SDK Setup] ~~~ c2[RPC Tracing Only] ~~~ c3[PathFinding + TxQ Tracing] ~~~ c4[Single Node]
+    end
+
+    subgraph walk["🚶 WALK (Week 3-5)"]
+        direction LR
+        w1[Transaction Tracing] ~~~ w2[Fee Escalation Tracing] ~~~ w3[Cross-Node Context] ~~~ w4[Basic Dashboards]
+    end
+
+    subgraph run["🏃 RUN (Week 6-9)"]
+        direction LR
+        r1[Consensus Tracing] ~~~ r2[Validator, Amendment,<br/>SHAMap Tracing] ~~~ r3[Full Correlation] ~~~ r4[Production Deploy]
+    end
+
+    crawl --> walk --> run
+
+    style crawl fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style walk fill:#bf360c,stroke:#8c2809,color:#fff
+    style run fill:#0d47a1,stroke:#082f6a,color:#fff
+    style c1 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style c2 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style c3 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style c4 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style w1 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style w2 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style w3 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style w4 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style r1 fill:#0d47a1,stroke:#082f6a,color:#fff
+    style r2 fill:#0d47a1,stroke:#082f6a,color:#fff
+    style r3 fill:#0d47a1,stroke:#082f6a,color:#fff
+    style r4 fill:#0d47a1,stroke:#082f6a,color:#fff
+```
+
+</div>
+
+**Reading the diagram:**
+
+- **CRAWL (Weeks 1-2)**: Minimal investment -- set up the SDK, instrument RPC and PathFinding/TxQ handlers, and verify on a single node. Delivers immediate latency visibility.
+- **WALK (Weeks 3-5)**: Expand to transaction lifecycle tracing, fee escalation, cross-node context propagation, and basic Grafana dashboards. This is where distributed tracing starts working.
+- **RUN (Weeks 6-9)**: Full consensus instrumentation, validator/amendment/SHAMap tracing, end-to-end correlation, and production deployment with sampling and alerting.
+- **Arrows (crawl → walk → run)**: Each phase builds on the prior one; you cannot skip ahead because later phases depend on infrastructure established earlier.
+
+### 6.9.2 Quick Wins (Immediate Value)
+
+| Quick Win                      | Value  | When to Deploy |
+| ------------------------------ | ------ | -------------- |
+| **RPC Command Tracing**        | High   | Week 2         |
+| **RPC Latency Histograms**     | High   | Week 2         |
+| **Error Rate Dashboard**       | Medium | Week 2         |
+| **Transaction Submit Tracing** | High   | Week 3         |
+| **Consensus Round Duration**   | Medium | Week 6         |
+
+### 6.9.3 CRAWL Phase (Weeks 1-2)
+
+**Goal**: Get basic tracing working with minimal code changes.
+
+**What You Get**:
+
+- RPC request/response traces for all commands
+- Latency breakdown per RPC command
+- PathFinding and TxQ tracing (directly impacts RPC latency)
+- Error visibility with stack traces
+- Basic Grafana dashboard
+
+**Code Changes**: ~15 lines in `ServerHandler.cpp`, ~40 lines in new telemetry module
+
+**Why Start Here**:
+
+- RPC is the lowest-risk, highest-visibility component
+- PathFinding and TxQ are RPC-adjacent and directly affect latency
+- Immediate value for debugging client issues
+- No cross-node complexity
+- Single file modification to existing code
+
+### 6.9.4 WALK Phase (Weeks 3-5)
+
+**Goal**: Add transaction lifecycle tracing across nodes.
+
+**What You Get**:
+
+- End-to-end transaction traces from submit to relay
+- Fee escalation tracing within the transaction pipeline
+- Cross-node correlation (see transaction path)
+- HashRouter deduplication visibility
+- Relay latency metrics
+
+**Code Changes**: ~120 lines across 4 files, plus protobuf extension
+
+**Why Do This Second**:
+
+- Builds on RPC tracing (transactions submitted via RPC)
+- Fee escalation is integral to the transaction processing pipeline
+- Moderate complexity (requires context propagation)
+- High value for debugging transaction issues
+
+### 6.9.5 RUN Phase (Weeks 6-9)
+
+**Goal**: Full observability including consensus.
+
+**What You Get**:
+
+- Complete consensus round visibility
+- Phase transition timing
+- Validator proposal tracking
+- Validator list and manifest tracing
+- Amendment voting tracing
+- SHAMap sync tracing
+- Full end-to-end traces (client → RPC → TX → consensus → ledger)
+
+**Code Changes**: ~100 lines across 3 consensus files, plus validator/amendment/SHAMap modules
+
+**Why Do This Last**:
+
+- Highest complexity (consensus is critical path)
+- Validator, amendment, and SHAMap components are lower priority
+- Requires thorough testing
+- Lower relative value (consensus issues are rarer)
+
+### 6.9.6 ROI Prioritization Matrix
+
+```mermaid
+quadrantChart
+    title Implementation ROI Matrix
+    x-axis Low Effort --> High Effort
+    y-axis Low Value --> High Value
+    quadrant-1 Quick Wins - Do First
+    quadrant-2 Major Projects - Plan Carefully
+    quadrant-3 Nice to Have - Optional
+    quadrant-4 Time Sinks - Avoid
+
+    RPC Tracing: [0.15, 0.92]
+    TX Submit Trace: [0.3, 0.78]
+    TX Relay Trace: [0.5, 0.88]
+    Consensus Trace: [0.72, 0.72]
+    Peer Msg Trace: [0.85, 0.3]
+    Ledger Acquire: [0.55, 0.52]
+```
+
+---
+
+## 6.10 Definition of Done
+
+> **TxQ** = Transaction Queue | **HA** = High Availability
+
+Clear, measurable criteria for each phase.
+
+### 6.10.1 Phase 1: Core Infrastructure
+
+| Criterion       | Measurement                                                | Target                       |
+| --------------- | ---------------------------------------------------------- | ---------------------------- |
+| SDK Integration | `cmake --build` succeeds with `-DXRPL_ENABLE_TELEMETRY=ON` | ✅ Compiles                  |
+| Runtime Toggle  | `enabled=0` produces zero overhead                         | <0.1% CPU difference         |
+| Span Creation   | Unit test creates and exports span                         | Span appears in Tempo        |
+| Configuration   | All config options parsed correctly                        | Config validation tests pass |
+| Documentation   | Developer guide exists                                     | PR approved                  |
+
+**Definition of Done**: All criteria met, PR merged, no regressions in CI.
+
+### 6.10.2 Phase 2: RPC Tracing
+
+| Criterion          | Measurement                        | Target                     |
+| ------------------ | ---------------------------------- | -------------------------- |
+| Coverage           | All RPC commands instrumented      | 100% of commands           |
+| Context Extraction | traceparent header propagates      | Integration test passes    |
+| Attributes         | Command, status, duration recorded | Validation script confirms |
+| Performance        | RPC latency overhead               | <1ms p99                   |
+| Dashboard          | Grafana dashboard deployed         | Screenshot in docs         |
+
+**Definition of Done**: RPC traces visible in Tempo for all commands, dashboard shows latency distribution.
+
+### 6.10.3 Phase 3: Transaction Tracing
+
+| Criterion        | Measurement                     | Target                             |
+| ---------------- | ------------------------------- | ---------------------------------- |
+| Local Trace      | Submit → validate → TxQ traced  | Single-node test passes            |
+| Cross-Node       | Context propagates via protobuf | Multi-node test passes             |
+| Relay Visibility | relay_count attribute correct   | Spot check 100 txs                 |
+| HashRouter       | Deduplication visible in trace  | Duplicate txs show suppressed=true |
+| Performance      | TX throughput overhead          | <5% degradation                    |
+
+**Definition of Done**: Transaction traces span 3+ nodes in test network, performance within bounds.
+
+### 6.10.4 Phase 4: Consensus Tracing
+
+| Criterion            | Measurement                   | Target                    |
+| -------------------- | ----------------------------- | ------------------------- |
+| Round Tracing        | startRound creates root span  | Unit test passes          |
+| Phase Visibility     | All phases have child spans   | Integration test confirms |
+| Proposer Attribution | Proposer ID in attributes     | Spot check 50 rounds      |
+| Timing Accuracy      | Phase durations match PerfLog | <5% variance              |
+| No Consensus Impact  | Round timing unchanged        | Performance test passes   |
+
+**Definition of Done**: Consensus rounds fully traceable, no impact on consensus timing.
+
+### 6.10.5 Phase 5: Production Deployment
+
+| Criterion    | Measurement                  | Target                     |
+| ------------ | ---------------------------- | -------------------------- |
+| Collector HA | Multiple collectors deployed | No single point of failure |
+| Sampling     | Tail sampling configured     | 10% base + errors + slow   |
+| Retention    | Data retained per policy     | 7 days hot, 30 days warm   |
+| Alerting     | Alerts configured            | Error spike, high latency  |
+| Runbook      | Operator documentation       | Approved by ops team       |
+| Training     | Team trained                 | Session completed          |
+
+**Definition of Done**: Telemetry running in production, operators trained, alerts active.
+
+### 6.10.6 Success Metrics Summary
+
+| Phase   | Primary Metric         | Secondary Metric            | Deadline      |
+| ------- | ---------------------- | --------------------------- | ------------- |
+| Phase 1 | SDK compiles and runs  | Zero overhead when disabled | End of Week 2 |
+| Phase 2 | 100% RPC coverage      | <1ms latency overhead       | End of Week 4 |
+| Phase 3 | Cross-node traces work | <5% throughput impact       | End of Week 6 |
+| Phase 4 | Consensus fully traced | No consensus timing impact  | End of Week 8 |
+| Phase 5 | Production deployment  | Operators trained           | End of Week 9 |
+
+---
+
+## 6.11 Recommended Implementation Order
+
+Based on ROI analysis, implement in this exact order:
+
+```mermaid
+flowchart TB
+    subgraph week1["Week 1"]
+        t1[1. OpenTelemetry SDK<br/>Conan/CMake integration]
+        t2[2. Telemetry interface<br/>SpanGuard, config]
+    end
+
+    subgraph week2["Week 2"]
+        t3[3. RPC ServerHandler<br/>instrumentation]
+        t4[4. Basic Tempo setup<br/>for testing]
+    end
+
+    subgraph week3["Week 3"]
+        t5[5. Transaction submit<br/>tracing]
+        t6[6. Grafana dashboard<br/>v1]
+    end
+
+    subgraph week4["Week 4"]
+        t7[7. Protobuf context<br/>extension]
+        t8[8. PeerImp tx.relay<br/>instrumentation]
+    end
+
+    subgraph week5["Week 5"]
+        t9[9. Multi-node<br/>integration tests]
+        t10[10. Performance<br/>benchmarks]
+    end
+
+    subgraph week6_8["Weeks 6-8"]
+        t11[11. Consensus<br/>instrumentation]
+        t12[12. Full integration<br/>testing]
+    end
+
+    subgraph week9["Week 9"]
+        t13[13. Production<br/>deployment]
+        t14[14. Documentation<br/>& training]
+    end
+
+    t1 --> t2 --> t3 --> t4
+    t4 --> t5 --> t6
+    t6 --> t7 --> t8
+    t8 --> t9 --> t10
+    t10 --> t11 --> t12
+    t12 --> t13 --> t14
+
+    style week1 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style week2 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style week3 fill:#bf360c,stroke:#8c2809,color:#fff
+    style week4 fill:#bf360c,stroke:#8c2809,color:#fff
+    style week5 fill:#bf360c,stroke:#8c2809,color:#fff
+    style week6_8 fill:#0d47a1,stroke:#082f6a,color:#fff
+    style week9 fill:#4a148c,stroke:#2e0d57,color:#fff
+    style t1 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style t2 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style t3 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style t4 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style t5 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style t6 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style t7 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style t8 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style t9 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style t10 fill:#ffe0b2,stroke:#ffcc80,color:#1e293b
+    style t11 fill:#0d47a1,stroke:#082f6a,color:#fff
+    style t12 fill:#0d47a1,stroke:#082f6a,color:#fff
+    style t13 fill:#4a148c,stroke:#2e0d57,color:#fff
+    style t14 fill:#4a148c,stroke:#2e0d57,color:#fff
+```
+
+**Reading the diagram:**
+
+- **Week 1 (tasks 1-2)**: Foundation work -- integrate the OpenTelemetry SDK via Conan/CMake and build the `Telemetry` interface with `SpanGuard` and config parsing.
+- **Week 2 (tasks 3-4)**: First observable output -- instrument `ServerHandler` for RPC tracing and stand up Tempo so developers can see traces immediately.
+- **Weeks 3-5 (tasks 5-10)**: Transaction lifecycle -- add submit tracing, build the first Grafana dashboard, extend protobuf for cross-node context, instrument `PeerImp` relay, then validate with multi-node integration tests and performance benchmarks.
+- **Weeks 6-8 (tasks 11-12)**: Consensus deep-dive -- instrument consensus rounds and phases, then run full integration testing across all instrumented paths.
+- **Week 9 (tasks 13-14)**: Go-live -- deploy to production with sampling/alerting configured, and deliver documentation and operator training.
+- **Arrow chain (t1 → ... → t14)**: Strict sequential dependency; each task's output is a prerequisite for the next.
+
+---
+
+_Previous: [Configuration Reference](./05-configuration-reference.md)_ | _Next: [Observability Backends](./07-observability-backends.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/07-observability-backends.md

@@ -0,0 +1,407 @@
+# Observability Backend Recommendations
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Implementation Phases](./06-implementation-phases.md) | [Appendix](./08-appendix.md)
+
+---
+
+## 7.1 Development/Testing Backends
+
+> **OTLP** = OpenTelemetry Protocol
+
+| Backend    | Pros                                | Cons                   | Use Case            |
+| ---------- | ----------------------------------- | ---------------------- | ------------------- |
+| **Tempo**  | Cost-effective, Grafana integration | Requires Grafana stack | Local dev, CI, Prod |
+| **Zipkin** | Simple, lightweight                 | Basic features         | Quick prototyping   |
+
+### Quick Start with Tempo
+
+```bash
+# Start Tempo with OTLP support
+docker run -d --name tempo \
+    -p 3200:3200 \
+    -p 4317:4317 \
+    -p 4318:4318 \
+    grafana/tempo:2.6.1
+```
+
+---
+
+## 7.2 Production Backends
+
+> **APM** = Application Performance Monitoring
+
+| Backend           | Pros                                      | Cons                   | Use Case                    |
+| ----------------- | ----------------------------------------- | ---------------------- | --------------------------- |
+| **Grafana Tempo** | Cost-effective, Grafana integration       | Requires Grafana stack | Most production deployments |
+| **Elastic APM**   | Full observability stack, log correlation | Resource intensive     | Existing Elastic users      |
+| **Honeycomb**     | Excellent query, high cardinality         | SaaS cost              | Deep debugging needs        |
+| **Datadog APM**   | Full platform, easy setup                 | SaaS cost              | Enterprise with budget      |
+
+### Backend Selection Flowchart
+
+```mermaid
+flowchart TD
+    start[Select Backend] --> budget{Budget<br/>Constraints?}
+
+    budget -->|Yes| oss[Open Source]
+    budget -->|No| saas{Prefer<br/>SaaS?}
+
+    oss --> existing{Existing<br/>Stack?}
+    existing -->|Grafana| tempo[Grafana Tempo]
+    existing -->|Elastic| elastic[Elastic APM]
+    existing -->|None| tempo
+
+    saas -->|Yes| enterprise{Enterprise<br/>Support?}
+    saas -->|No| oss
+
+    enterprise -->|Yes| datadog[Datadog APM]
+    enterprise -->|No| honeycomb[Honeycomb]
+
+    tempo --> final[Configure Collector]
+    elastic --> final
+    honeycomb --> final
+    datadog --> final
+
+    style start fill:#0f172a,stroke:#020617,color:#fff
+    style budget fill:#334155,stroke:#1e293b,color:#fff
+    style oss fill:#1e293b,stroke:#0f172a,color:#fff
+    style existing fill:#334155,stroke:#1e293b,color:#fff
+    style saas fill:#334155,stroke:#1e293b,color:#fff
+    style enterprise fill:#334155,stroke:#1e293b,color:#fff
+    style final fill:#0f172a,stroke:#020617,color:#fff
+    style tempo fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style elastic fill:#bf360c,stroke:#8c2809,color:#fff
+    style honeycomb fill:#0d47a1,stroke:#082f6a,color:#fff
+    style datadog fill:#4a148c,stroke:#2e0d57,color:#fff
+```
+
+**Reading the diagram:**
+
+- **Budget Constraints? (Yes)**: Leads to open-source options. If you already run Grafana or Elastic, pick the matching backend; otherwise default to Grafana Tempo.
+- **Budget Constraints? (No) → Prefer SaaS?**: If you want a managed service, choose between Datadog (enterprise support) and Honeycomb (developer-focused). If not, fall back to open-source.
+- **Terminal nodes (Tempo / Elastic / Honeycomb / Datadog)**: Each represents a concrete backend choice, all of which feed into the same final step.
+- **Configure Collector**: Regardless of backend, you always finish by configuring the OTel Collector to export to your chosen destination.
+
+---
+
+## 7.3 Recommended Production Architecture
+
+> **OTLP** = OpenTelemetry Protocol | **APM** = Application Performance Monitoring | **HA** = High Availability
+
+```mermaid
+flowchart TB
+    subgraph validators["Validator Nodes"]
+        v1[xrpld<br/>Validator 1]
+        v2[xrpld<br/>Validator 2]
+    end
+
+    subgraph stock["Stock Nodes"]
+        s1[xrpld<br/>Stock 1]
+        s2[xrpld<br/>Stock 2]
+    end
+
+    subgraph collector["OTel Collector Cluster"]
+        c1[Collector<br/>DC1]
+        c2[Collector<br/>DC2]
+    end
+
+    subgraph backends["Storage Backends"]
+        tempo[(Grafana<br/>Tempo)]
+        elastic[(Elastic<br/>APM)]
+        archive[(S3/GCS<br/>Archive)]
+    end
+
+    subgraph ui["Visualization"]
+        grafana[Grafana<br/>Dashboards]
+    end
+
+    v1 -->|OTLP| c1
+    v2 -->|OTLP| c1
+    s1 -->|OTLP| c2
+    s2 -->|OTLP| c2
+
+    c1 --> tempo
+    c1 --> elastic
+    c2 --> tempo
+    c2 --> archive
+
+    tempo --> grafana
+    elastic --> grafana
+
+    %% Note: simplified single-collector-per-DC topology shown for clarity
+
+    style validators fill:#b71c1c,stroke:#7f1d1d,color:#ffffff
+    style stock fill:#0d47a1,stroke:#082f6a,color:#ffffff
+    style collector fill:#bf360c,stroke:#8c2809,color:#ffffff
+    style backends fill:#1b5e20,stroke:#0d3d14,color:#ffffff
+    style ui fill:#4a148c,stroke:#2e0d57,color:#ffffff
+```
+
+**Reading the diagram:**
+
+- **Validator / Stock Nodes**: All xrpld nodes emit trace data via OTLP. Validators and stock nodes are grouped separately because they may reside in different network zones.
+- **Collector Cluster (DC1, DC2)**: Regional collectors receive OTLP from nodes in their datacenter, apply processing (sampling, enrichment), and fan out to multiple backends. Enrichment includes deployment-tier tagging: each collector stamps `deployment.environment` and (as a fallback) `xrpl.network.type` so one Grafana stack can filter data from many collectors by tier.
+- **Storage Backends**: Tempo and Elastic provide queryable trace storage; S3/GCS Archive provides long-term cold storage for compliance or post-incident analysis.
+- **Grafana Dashboards**: The single visualization layer that queries both Tempo and Elastic, giving operators a unified view of all traces.
+- **Data flow direction**: Nodes → Collectors → Storage → Grafana. Each arrow represents a network hop; minimizing collector-to-backend hops reduces latency.
+
+> **Note**: Production deployments should use multiple collector instances behind a load balancer for high availability. The diagram shows a simplified single-collector topology for clarity.
+
+---
+
+## 7.4 Architecture Considerations
+
+### 7.4.1 Collector Placement
+
+| Strategy      | Description          | Pros                     | Cons                    |
+| ------------- | -------------------- | ------------------------ | ----------------------- |
+| **Sidecar**   | Collector per node   | Isolation, simple config | Resource overhead       |
+| **DaemonSet** | Collector per host   | Shared resources         | Complexity              |
+| **Gateway**   | Central collector(s) | Centralized processing   | Single point of failure |
+
+**Recommendation**: Use **Gateway** pattern with regional collectors for xrpld networks:
+
+- One collector cluster per datacenter/region
+- Tail-based sampling at collector level
+- Multiple export destinations for redundancy
+
+### 7.4.2 Sampling Strategy
+
+```mermaid
+flowchart LR
+    subgraph head["Head Sampling (Node)"]
+        hs[Node-level head sampling<br/>fixed at 100%<br/>not configurable]
+    end
+
+    subgraph tail["Tail Sampling (Collector)"]
+        ts1[Keep all errors]
+        ts2[Keep slow >5s]
+        ts3[Keep 10% rest]
+    end
+
+    head --> tail
+
+    ts1 --> final[Final Traces]
+    ts2 --> final
+    ts3 --> final
+
+    style head fill:#0d47a1,stroke:#082f6a,color:#fff
+    style tail fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style hs fill:#0d47a1,stroke:#082f6a,color:#fff
+    style ts1 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style ts2 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style ts3 fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style final fill:#bf360c,stroke:#8c2809,color:#fff
+```
+
+**Reading the diagram:**
+
+- **Head Sampling (Node)**: xrpld pins head sampling at 100% (sample everything) and does not expose a configurable ratio. This is intentional: a per-node ratio would let different nodes make divergent keep/drop decisions for the same distributed trace, producing broken/partial traces. xrpld uses a `ParentBased` sampler so spans inheriting a remote parent honor the upstream decision. Volume reduction is delegated to the collector's tail sampling.
+- **Tail Sampling (Collector)**: The second filter -- the collector inspects completed traces and applies rules: keep all errors, keep anything slower than 5 seconds, and keep 10% of the remainder.
+- **Arrow head → tail**: All head-sampled traces flow to the collector, where tail sampling further reduces volume while preserving the most valuable data.
+- **Final Traces**: The output after both sampling stages; this is what gets stored and queried. The two-stage approach balances cost with debuggability.
+
+### 7.4.3 Data Retention
+
+| Environment | Hot Storage | Warm Storage | Cold Archive |
+| ----------- | ----------- | ------------ | ------------ |
+| Development | 24 hours    | N/A          | N/A          |
+| Staging     | 7 days      | N/A          | N/A          |
+| Production  | 7 days      | 30 days      | many years   |
+
+---
+
+## 7.5 Integration Checklist
+
+- [ ] Choose primary backend (Tempo recommended for cost/features)
+- [ ] Deploy collector cluster with high availability
+- [ ] Configure tail-based sampling for error/latency traces
+- [ ] Set up Grafana dashboards for trace visualization
+- [ ] Configure alerts for trace anomalies
+- [ ] Establish data retention policies
+- [ ] Test trace correlation with logs and metrics
+
+---
+
+## 7.6 Grafana Dashboard Examples
+
+Pre-built dashboards for xrpld observability.
+
+### 7.6.1 Consensus Health Dashboard
+
+A Tempo-backed dashboard (uid `xrpld-consensus-health`) with four panels, all driven by TraceQL:
+
+- **Consensus Round Duration** (timeseries, ms): average `consensus.round` span duration per node instance, with yellow/red thresholds at 4s/5s.
+- **Phase Duration Breakdown** (barchart): average duration of `consensus.phase.*` spans grouped by span name.
+- **Proposers per Round** (stat): average of the `span.proposers` attribute on `consensus.round` spans.
+- **Recent Slow Rounds (>5s)** (table): `consensus.round` spans filtered to `duration > 5s`.
+
+Each panel's TraceQL query is described inline in its bullet above.
+
+### 7.6.2 Node Overview Dashboard
+
+A Tempo-backed dashboard (uid `xrpld-node-overview`) with four panels:
+
+- **Active Nodes** (stat): count of distinct `resource.service.instance.id` values seen for the `xrpld` service.
+- **Total Transactions (1h)** (stat): count of `tx.receive` spans.
+- **Error Rate** (gauge, percent): ratio of `status.code=error` spans to all spans, with yellow/red thresholds at 1%/5%.
+- **Service Map** (nodeGraph): Tempo-generated service dependency graph.
+
+### 7.6.3 Alert Rules
+
+Grafana provisions three TraceQL-based alert rules (group `xrpld-tracing-alerts`, evaluated every 1m) against the Tempo datasource:
+
+- **Consensus Round Slow** (warning, `for: 5m`): fires when average `consensus.round` duration exceeds 5s.
+
+  ```
+  {resource.service.name="xrpld" && name="consensus.round"} | avg(duration) > 5s
+  ```
+
+- **RPC Error Rate Spike** (critical, `for: 2m`): fires when the error rate across `rpc.command.*` spans exceeds 5%. Error _rate_ is a ratio, so it must divide the error-span rate by the total-span rate — a single TraceQL `rate()` returns spans/second, not a percentage, and would fire on traffic volume alone. This uses span metrics emitted by the collector's `spanmetrics` connector (Prometheus datasource), not a TraceQL query:
+
+  ```
+  sum(rate(traces_spanmetrics_calls_total{service_name="xrpld", span_name=~"rpc.command.*", status_code="STATUS_CODE_ERROR"}[5m]))
+  /
+  sum(rate(traces_spanmetrics_calls_total{service_name="xrpld", span_name=~"rpc.command.*"}[5m]))
+  > 0.05
+  ```
+
+- **Transaction Throughput Drop** (warning, `for: 10m`): fires when the `tx.receive` span rate falls below 10/s.
+
+  ```
+  {resource.service.name="xrpld" && name="tx.receive"} | rate() < 10
+  ```
+
+> **Note**: The Consensus Round Slow and Transaction Throughput Drop rules use TraceQL aggregates (`avg(duration)`, `rate()`), which require Tempo 2.3+ with TraceQL metrics enabled. Verify aggregate query support in your Tempo version before provisioning. The RPC Error Rate Spike rule instead queries Prometheus span metrics (collector `spanmetrics` connector), so it needs that connector enabled in the collector pipeline.
+
+---
+
+## 7.7 PerfLog and Insight Correlation
+
+> **OTLP** = OpenTelemetry Protocol
+
+How to correlate OpenTelemetry traces with existing xrpld observability.
+
+### 7.7.1 Correlation Architecture
+
+```mermaid
+flowchart TB
+    subgraph xrpld["xrpld Node"]
+        otel[OpenTelemetry<br/>Spans]
+        perflog[PerfLog<br/>JSON Logs]
+        insight[Beast Insight<br/>StatsD Metrics]
+    end
+
+    subgraph collectors["Data Collection"]
+        otelc[OTel Collector]
+        promtail[Promtail/Fluentd]
+        statsd[StatsD Exporter]
+    end
+
+    subgraph storage["Storage"]
+        tempo[(Tempo)]
+        loki[(Loki)]
+        prom[(Prometheus)]
+    end
+
+    subgraph grafana["Grafana"]
+        traces[Trace View]
+        logs[Log View]
+        metrics[Metrics View]
+        corr[Correlation<br/>Panel]
+    end
+
+    otel -->|OTLP| otelc --> tempo
+    perflog -->|JSON| promtail --> loki
+    insight -->|StatsD| statsd --> prom
+
+    tempo --> traces
+    loki --> logs
+    prom --> metrics
+
+    traces --> corr
+    logs --> corr
+    metrics --> corr
+
+    style xrpld fill:#0d47a1,stroke:#082f6a,color:#fff
+    style collectors fill:#bf360c,stroke:#8c2809,color:#fff
+    style storage fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style grafana fill:#4a148c,stroke:#2e0d57,color:#fff
+    style otel fill:#0d47a1,stroke:#082f6a,color:#fff
+    style perflog fill:#0d47a1,stroke:#082f6a,color:#fff
+    style insight fill:#0d47a1,stroke:#082f6a,color:#fff
+    style otelc fill:#bf360c,stroke:#8c2809,color:#fff
+    style promtail fill:#bf360c,stroke:#8c2809,color:#fff
+    style statsd fill:#bf360c,stroke:#8c2809,color:#fff
+    style tempo fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style loki fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style prom fill:#1b5e20,stroke:#0d3d14,color:#fff
+    style traces fill:#4a148c,stroke:#2e0d57,color:#fff
+    style logs fill:#4a148c,stroke:#2e0d57,color:#fff
+    style metrics fill:#4a148c,stroke:#2e0d57,color:#fff
+    style corr fill:#4a148c,stroke:#2e0d57,color:#fff
+```
+
+**Reading the diagram:**
+
+- **xrpld Node (three sources)**: A single node emits three independent data streams -- OpenTelemetry spans, PerfLog JSON logs, and Beast Insight StatsD metrics.
+- **Data Collection layer**: Each stream has its own collector -- OTel Collector for spans, Promtail/Fluentd for logs, and a StatsD exporter for metrics. They operate independently.
+- **Storage layer (Tempo, Loki, Prometheus)**: Each data type lands in a purpose-built store optimized for its query patterns (trace search, log grep, metric aggregation).
+- **Grafana Correlation Panel**: The key integration point -- Grafana queries all three stores and links them via shared fields (`trace_id`, `tx_hash`, `ledger_seq`), enabling a single-pane debugging experience.
+
+### 7.7.2 Correlation Fields
+
+| Source      | Field               | Link To       | Purpose                    |
+| ----------- | ------------------- | ------------- | -------------------------- |
+| **Trace**   | `trace_id`          | Logs          | Find log entries for trace |
+| **Trace**   | `tx_hash`           | Logs, Metrics | Find TX-related data       |
+| **Trace**   | `ledger_seq`        | Logs          | Find ledger-related logs   |
+| **PerfLog** | `trace_id` (new)    | Traces        | Jump to trace from log     |
+| **PerfLog** | `ledger_seq`        | Traces        | Find consensus trace       |
+| **Insight** | `exemplar.trace_id` | Traces        | Jump from metric spike     |
+
+### 7.7.3 Example: Debugging a Slow Transaction
+
+**Step 1: Find the trace**
+
+```
+# In Grafana Explore with Tempo
+{resource.service.name="xrpld" && span.tx_hash="ABC123..."}
+```
+
+**Step 2: Get the trace_id from the trace view**
+
+```
+Trace ID: 4bf92f3577b34da6a3ce929d0e0e4736
+```
+
+**Step 3: Find related PerfLog entries**
+
+```
+# In Grafana Explore with Loki
+{job="xrpld"} |= "4bf92f3577b34da6a3ce929d0e0e4736"
+```
+
+**Step 4: Check Insight metrics for the time window**
+
+```
+# In Grafana with Prometheus
+rate(xrpld_tx_applied_total[1m])
+  @ timestamp_from_trace
+```
+
+### 7.7.4 Unified Dashboard Example
+
+A single dashboard (uid `xrpld-unified`) that ties traces, metrics, and logs together across the Tempo, Prometheus, and Loki datasources:
+
+- **Transaction Latency (Traces)** (timeseries, Tempo): `histogram_over_time(duration)` of `tx.receive` spans.
+- **Transaction Rate (Metrics)** (timeseries, Prometheus): `rate(xrpld_tx_received_total[5m])` per instance, with a data link that opens the matching `tx.receive` traces in Tempo.
+- **Recent Logs** (logs, Loki): `{job="xrpld"} | json`.
+- **Trace Search** (table, Tempo): all `xrpld` traces, with per-row data links on `traceID` that jump to the trace in Tempo and to the correlated logs in Loki (`{job="xrpld"} |= "<traceID>"`).
+
+The cross-datasource data links are what make this a single-pane debugging view; the correlation fields they rely on are listed in section 7.7.2.
+
+---
+
+_Previous: [Implementation Phases](./06-implementation-phases.md)_ | _Next: [Appendix](./08-appendix.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/08-appendix.md

@@ -0,0 +1,187 @@
+# Appendix
+
+> **Parent Document**: [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)
+> **Related**: [Observability Backends](./07-observability-backends.md)
+
+---
+
+## 8.1 Glossary
+
+> **OTLP** = OpenTelemetry Protocol | **TxQ** = Transaction Queue
+
+| Term                  | Definition                                                 |
+| --------------------- | ---------------------------------------------------------- |
+| **Span**              | A unit of work with start/end time, name, and attributes   |
+| **Trace**             | A collection of spans representing a complete request flow |
+| **Trace ID**          | 128-bit unique identifier for a trace                      |
+| **Span ID**           | 64-bit unique identifier for a span within a trace         |
+| **Context**           | Carrier for trace/span IDs across boundaries               |
+| **Propagator**        | Component that injects/extracts context                    |
+| **Sampler**           | Decides which traces to record                             |
+| **Exporter**          | Sends spans to backend                                     |
+| **Collector**         | Receives, processes, and forwards telemetry                |
+| **OTLP**              | OpenTelemetry Protocol (wire format)                       |
+| **W3C Trace Context** | Standard HTTP headers for trace propagation                |
+| **Baggage**           | Key-value pairs propagated across service boundaries       |
+| **Resource**          | Entity producing telemetry (service, host, etc.)           |
+| **Instrumentation**   | Code that creates telemetry data                           |
+
+### xrpld-Specific Terms
+
+| Term              | Definition                                                    |
+| ----------------- | ------------------------------------------------------------- |
+| **Overlay**       | P2P network layer managing peer connections                   |
+| **Consensus**     | XRP Ledger consensus algorithm (RCL)                          |
+| **Proposal**      | Validator's suggested transaction set for a ledger            |
+| **Validation**    | Validator's signature on a closed ledger                      |
+| **HashRouter**    | Component for transaction deduplication                       |
+| **JobQueue**      | Thread pool for asynchronous task execution                   |
+| **PerfLog**       | Existing performance logging system in xrpld                  |
+| **Beast Insight** | Existing metrics framework in xrpld                           |
+| **PathFinding**   | Payment path computation engine for cross-currency payments   |
+| **TxQ**           | Transaction queue managing fee-based prioritization           |
+| **LoadManager**   | Dynamic fee escalation based on network load                  |
+| **SHAMap**        | SHA-256 hash-based map (Merkle trie variant) for ledger state |
+
+---
+
+## 8.2 Span Hierarchy Visualization
+
+> **TxQ** = Transaction Queue
+
+```mermaid
+flowchart TB
+    subgraph trace["Trace: Transaction Lifecycle"]
+        rpc["rpc.request<br/>(entry point)"]
+        validate["tx.validate"]
+        relay["tx.relay<br/>(parent span)"]
+
+        subgraph peers["Peer Spans"]
+            p1["peer.send<br/>Peer A"]
+            p2["peer.send<br/>Peer B"]
+            p3["peer.send<br/>Peer C"]
+        end
+
+        subgraph pathfinding["PathFinding Spans"]
+            pathfind["pathfind.request"]
+            pathcomp["pathfind.compute"]
+        end
+
+        consensus["consensus.round"]
+        apply["tx.apply"]
+
+        subgraph txqueue["TxQ Spans"]
+            txq["txq.enqueue"]
+            txqApply["txq.apply"]
+        end
+
+        feeCalc["fee.escalate"]
+    end
+
+    subgraph validators["Validator Spans"]
+        valFetch["validator.list.fetch"]
+        valManifest["validator.manifest"]
+    end
+
+    rpc --> validate
+    rpc --> pathfind
+    pathfind --> pathcomp
+    validate --> relay
+    relay --> p1
+    relay --> p2
+    relay --> p3
+    p1 -.->|"context propagation"| consensus
+    consensus --> apply
+    apply --> txq
+    txq --> txqApply
+    txq --> feeCalc
+
+    style trace fill:#0f172a,stroke:#020617,color:#fff
+    style peers fill:#1e3a8a,stroke:#172554,color:#fff
+    style pathfinding fill:#134e4a,stroke:#0f766e,color:#fff
+    style txqueue fill:#064e3b,stroke:#047857,color:#fff
+    style validators fill:#4c1d95,stroke:#6d28d9,color:#fff
+    style rpc fill:#1d4ed8,stroke:#1e40af,color:#fff
+    style validate fill:#047857,stroke:#064e3b,color:#fff
+    style relay fill:#047857,stroke:#064e3b,color:#fff
+    style p1 fill:#0e7490,stroke:#155e75,color:#fff
+    style p2 fill:#0e7490,stroke:#155e75,color:#fff
+    style p3 fill:#0e7490,stroke:#155e75,color:#fff
+    style consensus fill:#fef3c7,stroke:#fde68a,color:#1e293b
+    style apply fill:#047857,stroke:#064e3b,color:#fff
+    style pathfind fill:#0e7490,stroke:#155e75,color:#fff
+    style pathcomp fill:#0e7490,stroke:#155e75,color:#fff
+    style txq fill:#047857,stroke:#064e3b,color:#fff
+    style txqApply fill:#047857,stroke:#064e3b,color:#fff
+    style feeCalc fill:#047857,stroke:#064e3b,color:#fff
+    style valFetch fill:#6d28d9,stroke:#4c1d95,color:#fff
+    style valManifest fill:#6d28d9,stroke:#4c1d95,color:#fff
+```
+
+**Reading the diagram:**
+
+- **rpc.request (blue, top)**: The entry point — every traced transaction starts as an RPC call; this root span is the parent of all downstream work.
+- **tx.validate and pathfind.request (green/teal, first fork)**: The RPC request fans out into transaction validation and, for cross-currency payments, a PathFinding branch (`pathfind.request` -> `pathfind.compute`).
+- **tx.relay -> Peer Spans (teal, middle)**: After validation, the transaction is relayed to peers A, B, and C in parallel; each `peer.send` is a sibling child span showing fan-out across the network.
+- **context propagation (dashed arrow)**: The dotted line from `peer.send Peer A` to `consensus.round` represents the trace context crossing a node boundary — the receiving validator picks up the same `trace_id` and continues the trace.
+- **consensus.round -> tx.apply -> TxQ Spans (green, lower)**: Once consensus accepts the transaction, it is applied to the ledger; the TxQ spans (`txq.enqueue`, `txq.apply`, `fee.escalate`) capture queue depth and fee escalation behavior.
+- **Validator Spans (purple, detached)**: `validator.list.fetch` and `validator.manifest` are independent workflows for UNL management — they run on their own traces and are linked to consensus via Span Links, not parent-child relationships.
+
+---
+
+## 8.3 References
+
+> **OTLP** = OpenTelemetry Protocol
+
+### OpenTelemetry Resources
+
+1. [OpenTelemetry C++ SDK](https://github.com/open-telemetry/opentelemetry-cpp)
+2. [OpenTelemetry Specification](https://opentelemetry.io/docs/specs/otel/)
+3. [OpenTelemetry Collector](https://opentelemetry.io/docs/collector/)
+4. [OTLP Protocol Specification](https://opentelemetry.io/docs/specs/otlp/)
+
+### Standards
+
+5. [W3C Trace Context](https://www.w3.org/TR/trace-context/)
+6. [W3C Baggage](https://www.w3.org/TR/baggage/)
+7. [Protocol Buffers](https://protobuf.dev/)
+
+### xrpld Resources
+
+8. [xrpld Source Code](https://github.com/XRPLF/rippled)
+9. [XRP Ledger Documentation](https://xrpl.org/docs/)
+10. [xrpld Overlay README](https://github.com/XRPLF/rippled/blob/develop/src/xrpld/overlay/README.md)
+11. [xrpld RPC README](https://github.com/XRPLF/rippled/blob/develop/src/xrpld/rpc/README.md)
+12. [xrpld Consensus README](https://github.com/XRPLF/rippled/blob/develop/src/xrpld/app/consensus/README.md)
+
+---
+
+## 8.4 Version History
+
+| Version | Date       | Author | Changes                                                        |
+| ------- | ---------- | ------ | -------------------------------------------------------------- |
+| 1.0     | 2026-02-12 | -      | Initial implementation plan                                    |
+| 1.1     | 2026-02-13 | -      | Refactored into modular documents                              |
+| 1.2     | 2026-03-24 | -      | Review fixes: accuracy corrections, cross-document consistency |
+
+---
+
+## 8.5 Document Index
+
+### Plan Documents
+
+| Document                                                         | Description                                  |
+| ---------------------------------------------------------------- | -------------------------------------------- |
+| [OpenTelemetryPlan.md](./OpenTelemetryPlan.md)                   | Master overview and executive summary        |
+| [00-tracing-fundamentals.md](./00-tracing-fundamentals.md)       | Distributed tracing concepts and OTel primer |
+| [01-architecture-analysis.md](./01-architecture-analysis.md)     | xrpld architecture and trace points          |
+| [02-design-decisions.md](./02-design-decisions.md)               | SDK selection, exporters, span conventions   |
+| [03-implementation-strategy.md](./03-implementation-strategy.md) | Directory structure, performance analysis    |
+| [05-configuration-reference.md](./05-configuration-reference.md) | xrpld config, CMake, Collector configs       |
+| [06-implementation-phases.md](./06-implementation-phases.md)     | Timeline, tasks, risks, success metrics      |
+| [07-observability-backends.md](./07-observability-backends.md)   | Backend selection and architecture           |
+| [08-appendix.md](./08-appendix.md)                               | Glossary, references, version history        |
+
+---
+
+_Previous: [Observability Backends](./07-observability-backends.md)_ | _Back to: [Overview](./OpenTelemetryPlan.md)_

OpenTelemetryPlan/OpenTelemetryPlan.md

@@ -0,0 +1,199 @@
+# [OpenTelemetry](00-tracing-fundamentals.md) Distributed Tracing Implementation Plan for xrpld
+
+## Executive Summary
+
+> **OTLP** = OpenTelemetry Protocol
+
+This document provides a comprehensive implementation plan for integrating OpenTelemetry distributed tracing into the xrpld XRP Ledger node software. The plan addresses the unique challenges of a decentralized peer-to-peer system where trace context must propagate across network boundaries between independent nodes.
+
+### Key Benefits
+
+- **End-to-end transaction visibility**: Track transactions from submission through consensus to ledger inclusion
+- **Consensus round analysis**: Understand timing and behavior of consensus phases across validators
+- **RPC performance insights**: Identify slow handlers and optimize response times
+- **Network topology understanding**: Visualize message propagation patterns between peers
+- **Incident debugging**: Correlate events across distributed nodes during issues
+
+### Estimated Performance Overhead
+
+| Metric        | Overhead   | Notes                                            |
+| ------------- | ---------- | ------------------------------------------------ |
+| CPU           | 1-3%       | Span creation and attribute setting              |
+| Memory        | <10 MB     | SDK statics + batch buffer + worker thread stack |
+| Network       | 10-50 KB/s | Compressed OTLP export to collector              |
+| Latency (p99) | <2%        | With proper sampling configuration               |
+
+---
+
+## Document Structure
+
+This implementation plan is organized into modular documents for easier navigation:
+
+<div align="center">
+
+```mermaid
+flowchart TB
+    overview["📋 OpenTelemetryPlan.md<br/>(This Document)"]
+
+    subgraph fundamentals["Fundamentals"]
+        fund["00-tracing-fundamentals.md"]
+    end
+
+    subgraph analysis["Analysis & Design"]
+        arch["01-architecture-analysis.md"]
+        design["02-design-decisions.md"]
+    end
+
+    subgraph impl["Implementation"]
+        strategy["03-implementation-strategy.md"]
+        config["05-configuration-reference.md"]
+    end
+
+    subgraph deploy["Deployment & Planning"]
+        phases["06-implementation-phases.md"]
+        backends["07-observability-backends.md"]
+        appendix["08-appendix.md"]
+    end
+
+    overview --> fundamentals
+    overview --> analysis
+    overview --> impl
+    overview --> deploy
+
+    fund --> arch
+    arch --> design
+    design --> strategy
+    strategy --> config
+    config --> phases
+    phases --> backends
+    backends --> appendix
+
+    style overview fill:#1b5e20,stroke:#0d3d14,color:#fff,stroke-width:2px
+    style fundamentals fill:#00695c,stroke:#004d40,color:#fff
+    style fund fill:#00695c,stroke:#004d40,color:#fff
+    style analysis fill:#0d47a1,stroke:#082f6a,color:#fff
+    style impl fill:#bf360c,stroke:#8c2809,color:#fff
+    style deploy fill:#4a148c,stroke:#2e0d57,color:#fff
+    style arch fill:#0d47a1,stroke:#082f6a,color:#fff
+    style design fill:#0d47a1,stroke:#082f6a,color:#fff
+    style strategy fill:#bf360c,stroke:#8c2809,color:#fff
+    style config fill:#bf360c,stroke:#8c2809,color:#fff
+    style phases fill:#4a148c,stroke:#2e0d57,color:#fff
+    style backends fill:#4a148c,stroke:#2e0d57,color:#fff
+    style appendix fill:#4a148c,stroke:#2e0d57,color:#fff
+```
+
+</div>
+
+---
+
+## Table of Contents
+
+| Section | Document                                                   | Description                                                            |
+| ------- | ---------------------------------------------------------- | ---------------------------------------------------------------------- |
+| **0**   | [Tracing Fundamentals](./00-tracing-fundamentals.md)       | Distributed tracing concepts, span relationships, context propagation  |
+| **1**   | [Architecture Analysis](./01-architecture-analysis.md)     | xrpld component analysis, trace points, instrumentation priorities     |
+| **2**   | [Design Decisions](./02-design-decisions.md)               | SDK selection, exporters, span naming, attributes, context propagation |
+| **3**   | [Implementation Strategy](./03-implementation-strategy.md) | Directory structure, key principles, performance optimization          |
+| **5**   | [Configuration Reference](./05-configuration-reference.md) | xrpld config, CMake integration, Collector configurations              |
+| **6**   | [Implementation Phases](./06-implementation-phases.md)     | 5-phase timeline, tasks, risks, success metrics                        |
+| **7**   | [Observability Backends](./07-observability-backends.md)   | Backend selection guide and production architecture                    |
+| **8**   | [Appendix](./08-appendix.md)                               | Glossary, references, version history                                  |
+
+---
+
+## 0. Tracing Fundamentals
+
+This document introduces distributed tracing concepts for readers unfamiliar with the domain. It covers what traces and spans are, how parent-child and follows-from relationships model causality, how context propagates across service boundaries, and how sampling controls data volume. It also maps these concepts to xrpld-specific scenarios like transaction relay and consensus.
+
+➡️ **[Read Tracing Fundamentals](./00-tracing-fundamentals.md)**
+
+---
+
+## 1. Architecture Analysis
+
+> **WS** = WebSocket | **TxQ** = Transaction Queue
+
+The xrpld node consists of several key components that require instrumentation for comprehensive distributed tracing. The main areas include the RPC server (HTTP/WebSocket), Overlay P2P network, Consensus mechanism (RCLConsensus), JobQueue for async task execution, PathFinding, Transaction Queue (TxQ), fee escalation (LoadManager), ledger acquisition, validator management, and existing observability infrastructure (PerfLog, Insight/StatsD, Journal logging).
+
+Key trace points span across transaction submission via RPC, peer-to-peer message propagation, consensus round execution, ledger building, path computation, transaction queue behavior, fee escalation, and validator health. The implementation prioritizes high-value, low-risk components first: RPC handlers provide immediate value with minimal risk, while consensus tracing requires careful implementation to avoid timing impacts.
+
+➡️ **[Read full Architecture Analysis](./01-architecture-analysis.md)**
+
+---
+
+## 2. Design Decisions
+
+> **OTLP** = OpenTelemetry Protocol | **CNCF** = Cloud Native Computing Foundation
+
+The OpenTelemetry C++ SDK is selected for its CNCF backing, active development, and native performance characteristics. Traces are exported via OTLP/HTTP to an OpenTelemetry Collector, which provides flexible routing and sampling. OTLP/gRPC is planned future work (see design decisions §2.2.2).
+
+Span naming follows a hierarchical `<component>.<operation>` convention (e.g., `rpc.submit`, `tx.relay`, `consensus.round`). Context propagation uses W3C Trace Context headers for HTTP and embedded Protocol Buffer fields for P2P messages. The implementation coexists with existing PerfLog and Insight observability systems through correlation IDs.
+
+**Data Collection & Privacy**: Telemetry collects only operational metadata (timing, counts, hashes) — never sensitive content (private keys, balances, amounts, raw payloads). Privacy protection includes account hashing, configurable redaction, sampling, and collector-level filtering. Node operators retain full control over telemetry configuration.
+
+➡️ **[Read full Design Decisions](./02-design-decisions.md)**
+
+---
+
+## 3. Implementation Strategy
+
+The telemetry code is organized under `include/xrpl/telemetry/` for headers and `src/libxrpl/telemetry/` for implementation. Key principles include RAII-based span management via `SpanGuard`, conditional compilation with `XRPL_ENABLE_TELEMETRY`, and minimal runtime overhead through batch processing and efficient sampling.
+
+Performance optimization strategies include head sampling fixed at 100% (intentionally not configurable, so trace keep/drop decisions stay coherent across nodes), tail-based sampling at the collector for errors and slow traces to reduce volume, batch export to reduce network overhead, and conditional instrumentation that compiles to no-ops when disabled.
+
+➡️ **[Read full Implementation Strategy](./03-implementation-strategy.md)**
+
+---
+
+## 5. Configuration Reference
+
+> **OTLP** = OpenTelemetry Protocol | **APM** = Application Performance Monitoring
+
+Configuration is handled through the `[telemetry]` section in `xrpld.cfg` with options for enabling/disabling, exporter selection, endpoint configuration, and component-level filtering. Head sampling is fixed at 1.0 (not operator-configurable); volume reduction is done by tail sampling in the collector. CMake integration includes a `XRPL_ENABLE_TELEMETRY` option for compile-time control.
+
+OpenTelemetry Collector configurations are provided for development and production (with tail-based sampling, Tempo, and Elastic APM). Docker Compose examples enable quick local development environment setup.
+
+➡️ **[View full Configuration Reference](./05-configuration-reference.md)**
+
+---
+
+## 6. Implementation Phases
+
+The implementation spans 9 weeks across 5 phases:
+
+| Phase | Duration  | Focus               | Key Deliverables                                    |
+| ----- | --------- | ------------------- | --------------------------------------------------- |
+| 1     | Weeks 1-2 | Core Infrastructure | SDK integration, Telemetry interface, Configuration |
+| 2     | Weeks 3-4 | RPC Tracing         | HTTP context extraction, Handler instrumentation    |
+| 3     | Weeks 5-6 | Transaction Tracing | Protocol Buffer context, Relay propagation          |
+| 4     | Weeks 7-8 | Consensus Tracing   | Round spans, Proposal/validation tracing            |
+| 5     | Week 9    | Documentation       | Runbook, Dashboards, Training                       |
+
+**Total Effort**: 47 person-days (2 developers working in parallel)
+
+➡️ **[View full Implementation Phases](./06-implementation-phases.md)**
+
+---
+
+## 7. Observability Backends
+
+> **APM** = Application Performance Monitoring | **GCS** = Google Cloud Storage
+
+Grafana Tempo is recommended for all environments due to its cost-effectiveness and Grafana integration, while Elastic APM is ideal for organizations with existing Elastic infrastructure.
+
+The recommended production architecture uses a gateway collector pattern with regional collectors performing tail-based sampling, routing traces to multiple backends (Tempo for primary storage, Elastic for log correlation, S3/GCS for long-term archive).
+
+➡️ **[View Observability Backend Recommendations](./07-observability-backends.md)**
+
+---
+
+## 8. Appendix
+
+The appendix contains a glossary of OpenTelemetry and xrpld-specific terms, references to external documentation and specifications, version history for this implementation plan, and a complete document index.
+
+➡️ **[View Appendix](./08-appendix.md)**
+
+---
+
+_This document provides a comprehensive implementation plan for integrating OpenTelemetry distributed tracing into the xrpld XRP Ledger node software. For detailed information on any section, follow the links to the corresponding sub-documents._

bin/check-tools.sh

@@ -90,16 +90,19 @@ if [ "${os}" = "linux" ] || [ "${os}" = "macos" ]; then
     check perl
     check pkg-config
     check vim
+    check zip
 
     # These tools are present in our Linux CI images and in local development
     # setups, but not in the macOS CI environment. So check them everywhere
     # except when running in CI on macOS.
     if [ "${os}" = "linux" ] || [ -z "${CI:-}" ]; then
         check clang-format
+        check dot
         check doxygen
         check gcovr
         check gh
         check git-cliff
+        check git-lfs
         check gpg
         # pre-commit, or its alternative implementation prek
         check pre-commit sh -c 'pre-commit --version || prek --version'

bin/filter-clang-tidy.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+
+"""
+Reduce run-clang-tidy output to its unique errors.
+
+It does two things:
+
+  1. Filters the raw output down to diagnostics and their source-context lines
+     (the indented "  103 | ..." / "      | ^" lines clang-tidy prints),
+     matching the "path:line:col: error:" diagnostic shape.
+
+  2. Deduplicates. The same diagnostic in a header is reported once per
+     translation unit that includes it, so identical error blocks are collapsed
+     to their first occurrence.
+
+An "error block" is an "error:" line together with the indented context lines
+and any "note:" lines that follow it (up to the next "error:" line). Blocks are
+compared as a whole, so an error stays attached to its own context, and
+first-occurrence order is preserved.
+
+The deduplicated output goes to stdout; a summary of unique error counts per
+check is printed to stderr.
+
+Usage:
+  bin/filter-clang-tidy.py [INPUT_FILE]            # read from file, or
+  run-clang-tidy ... | bin/filter-clang-tidy.py    # read from stdin
+"""
+
+import re
+import sys
+from collections import Counter
+
+# A clang-tidy diagnostic line looks like "path:line:col: error: msg [check]".
+# Matching on that shape (rather than a loose "error" substring) avoids treating
+# progress lines whose paths contain "error" as diagnostics, e.g.
+#   [284/850][0.7s] /nix/.../clang-tidy ... src/.../error.cpp
+DIAG_RE = re.compile(r":\d+:\d+: (?:error|warning|note):")
+ERROR_RE = re.compile(r":\d+:\d+: error:")
+CHECK_RE = re.compile(r" error: .*\[([^\],]+)")
+
+
+def filter_and_dedup(lines: list[str]) -> list[str]:
+    """Keep diagnostics with their context, then drop duplicate error blocks."""
+    blocks: list[str] = []
+    seen: set[str] = set()
+    current: list[str] = []
+
+    def flush() -> None:
+        if not current:
+            return
+        block = "".join(current)
+        if block not in seen:
+            seen.add(block)
+            blocks.append(block)
+
+    for line in lines:
+        # Keep only diagnostics and their indented source-context lines; drop
+        # progress/status output and blank lines.
+        if not (DIAG_RE.search(line) or line[:1] in (" ", "\t")):
+            continue
+        # An "error:" line starts a new block; its context and any following
+        # "note:" lines (and their context) belong to it.
+        if ERROR_RE.search(line):
+            flush()
+            current = []
+        current.append(line)
+    flush()
+
+    return blocks
+
+
+def summarize(blocks: list[str]) -> Counter[str]:
+    """Count unique errors per check name (e.g. "bugprone-branch-clone")."""
+    counts: Counter[str] = Counter()
+    for block in blocks:
+        # The error line is the first line of the block.
+        match = CHECK_RE.search(block.splitlines()[0])
+        if match:
+            counts[match.group(1)] += 1
+    return counts
+
+
+def main() -> int:
+    if len(sys.argv) > 1 and sys.argv[1] != "-":
+        with open(sys.argv[1], encoding="utf-8") as f:
+            lines = f.readlines()
+    else:
+        lines = sys.stdin.readlines()
+
+    blocks = filter_and_dedup(lines)
+    # Blank line between blocks so distinct errors are easy to tell apart.
+    sys.stdout.write("\n".join(blocks))
+
+    print("\nUnique errors per check:", file=sys.stderr)
+    for check, count in summarize(blocks).most_common():
+        print(f"{count:>4} {check}", file=sys.stderr)
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

bin/pre-commit/clang_tidy_check.py

@@ -1,24 +1,27 @@
 #!/usr/bin/env python3
-"""Pre-commit hook that runs clang-tidy on changed files using run-clang-tidy."""
+"""Pre-commit hook that runs clang-tidy on changed files using run-clang-tidy.
+
+The set of files is chosen by pre-commit (see .pre-commit-config.yaml), which
+filters to C/C++ sources and excludes `.ipp` fragments. Headers are linted
+directly: the `verify_headers` build option (ON by default) compiles every
+`.h`/`.hpp` on its own, so each header is the main file of its own
+compile_commands.json entry and run-clang-tidy can analyse it just like a
+`.cpp`.
+"""
 
 from __future__ import annotations
 
-import json
 import os
-import re
 import shutil
 import subprocess
 import sys
-from collections import defaultdict
 from pathlib import Path
 
-HEADER_EXTENSIONS = {".h", ".hpp", ".ipp"}
-SOURCE_EXTENSIONS = {".cpp"}
-INCLUDE_RE = re.compile(r"^\s*#\s*include\s*[<\"]([^>\"]+)[>\"]")
+CLANG_TIDY_VERSION = 22
 
 
 def find_run_clang_tidy() -> str | None:
-    for candidate in ("run-clang-tidy-21", "run-clang-tidy"):
+    for candidate in (f"run-clang-tidy-{CLANG_TIDY_VERSION}", "run-clang-tidy"):
         if path := shutil.which(candidate):
             return path
     return None
@@ -32,142 +35,23 @@ def find_build_dir(repo_root: Path) -> Path | None:
     return None
 
 
-def build_include_graph(build_dir: Path, repo_root: Path) -> tuple[dict, set]:
-    """
-    Scan all files reachable from compile_commands.json and build an inverted include graph.
-
-    Returns:
-        inverted: header_path -> set of files that include it
-        source_files: set of all TU paths from compile_commands.json
-    """
-    with open(build_dir / "compile_commands.json") as f:
-        db = json.load(f)
-
-    source_files = {Path(e["file"]).resolve() for e in db}
-    include_roots = [repo_root / "include", repo_root / "src"]
-    inverted: dict[Path, set[Path]] = defaultdict(set)
-
-    to_scan: set[Path] = set(source_files)
-    scanned: set[Path] = set()
-
-    while to_scan:
-        file = to_scan.pop()
-        if file in scanned or not file.exists():
-            continue
-        scanned.add(file)
-
-        content = file.read_text()
-
-        for line in content.splitlines():
-            m = INCLUDE_RE.match(line)
-            if not m:
-                continue
-            for root in include_roots:
-                candidate = (root / m.group(1)).resolve()
-                if candidate.exists():
-                    inverted[candidate].add(file)
-                    if candidate not in scanned:
-                        to_scan.add(candidate)
-                    break
-
-    return inverted, source_files
-
-
-def find_tus_for_headers(
-    headers: list[Path],
-    inverted: dict[Path, set[Path]],
-    source_files: set[Path],
-) -> set[Path]:
-    """
-    For each header, pick one TU that transitively includes it.
-    Prefers a TU whose stem matches the header's stem, otherwise picks the first found.
-    """
-    result: set[Path] = set()
-
-    for header in headers:
-        preferred: Path | None = None
-        visited: set[Path] = {header}
-        stack: list[Path] = [header]
-
-        while stack:
-            h = stack.pop()
-            for inc in inverted.get(h, ()):
-                if inc in source_files:
-                    if inc.stem == header.stem:
-                        preferred = inc
-                        break
-                    if preferred is None:
-                        preferred = inc
-                if inc not in visited:
-                    visited.add(inc)
-                    stack.append(inc)
-            if preferred is not None and preferred.stem == header.stem:
-                break
-
-        if preferred is not None:
-            result.add(preferred)
-
-    return result
-
-
-def resolve_files(
-    input_files: list[str], build_dir: Path, repo_root: Path
-) -> list[str]:
-    """
-    Split input into source files and headers. Source files are passed through;
-    headers are resolved to the TUs that transitively include them.
-    """
-    sources: list[Path] = []
-    headers: list[Path] = []
-
-    for f in input_files:
-        p = Path(f).resolve()
-        if p.suffix in SOURCE_EXTENSIONS:
-            sources.append(p)
-        elif p.suffix in HEADER_EXTENSIONS:
-            headers.append(p)
-
-    if not headers:
-        return [str(p) for p in sources]
-
-    print(
-        f"Resolving {len(headers)} header(s) to compilation units...", file=sys.stderr
-    )
-    inverted, source_files = build_include_graph(build_dir, repo_root)
-    tus = find_tus_for_headers(headers, inverted, source_files)
-
-    if not tus:
-        print(
-            "Warning: no compilation units found that include the modified headers; "
-            "skipping clang-tidy for headers.",
-            file=sys.stderr,
-        )
-
-    return sorted({str(p) for p in (*sources, *tus)})
-
-
-def staged_files(repo_root: Path) -> list[str]:
-    result = subprocess.run(
-        ["git", "diff", "--staged", "--name-only", "--diff-filter=d"],
-        capture_output=True,
-        text=True,
-        cwd=repo_root,
-    )
-    if result.returncode != 0:
-        print(
-            "clang-tidy check failed: 'git diff --staged' command failed.",
-            file=sys.stderr,
-        )
-        if result.stderr:
-            print(result.stderr, file=sys.stderr)
-        sys.exit(result.returncode or 1)
-    return [str(repo_root / p) for p in result.stdout.splitlines() if p]
-
-
 def main():
     if not os.environ.get("TIDY"):
         return 0
 
+    files = sys.argv[1:]
+    if not files:
+        return 0
+
+    run_clang_tidy = find_run_clang_tidy()
+    if not run_clang_tidy:
+        print(
+            f"clang-tidy check failed: TIDY is enabled but neither "
+            f"'run-clang-tidy-{CLANG_TIDY_VERSION}' nor 'run-clang-tidy' was found in PATH.",
+            file=sys.stderr,
+        )
+        return 1
+
     repo_root = Path(
         subprocess.check_output(
             ["git", "rev-parse", "--show-toplevel"],
@@ -175,19 +59,6 @@ def main():
             text=True,
         ).strip()
     )
-    files = staged_files(repo_root)
-    if not files:
-        return 0
-
-    run_clang_tidy = find_run_clang_tidy()
-    if not run_clang_tidy:
-        print(
-            "clang-tidy check failed: TIDY is enabled but neither "
-            "'run-clang-tidy-21' nor 'run-clang-tidy' was found in PATH.",
-            file=sys.stderr,
-        )
-        return 1
-
     build_dir = find_build_dir(repo_root)
     if not build_dir:
         print(
@@ -197,13 +68,9 @@ def main():
         )
         return 1
 
-    tidy_files = resolve_files(files, build_dir, repo_root)
-    if not tidy_files:
-        return 0
-
     result = subprocess.run(
         [run_clang_tidy, "-quiet", "-p", str(build_dir), "-fix", "-allow-no-checks"]
-        + tidy_files
+        + files
     )
     return result.returncode
 

bin/pre-commit/fix_pragma_once.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+"""
+Adds "#pragma once" to the top of header files that don't already have it.
+
+Usage: ./bin/pre-commit/fix_pragma_once.py <file1> <file2> ...
+"""
+
+import sys
+from pathlib import Path
+
+PRAGMA_ONCE = "#pragma once\n\n"
+
+
+def fix_pragma_once(path: Path) -> bool:
+    original = path.read_text(encoding="utf-8")
+    if PRAGMA_ONCE not in original:
+        path.write_text(PRAGMA_ONCE + original, encoding="utf-8")
+        return False
+    return True
+
+
+def main() -> int:
+    files = [Path(f) for f in sys.argv[1:]]
+    success = True
+
+    for path in files:
+        success &= fix_pragma_once(path)
+
+    return 0 if success else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())

cmake/CompilationEnv.cmake

@@ -56,3 +56,16 @@ elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|arm64|ARM64")
 else()
     message(FATAL_ERROR "Unknown architecture: ${CMAKE_SYSTEM_PROCESSOR}")
 endif()
+
+# --------------------------------------------------------------------
+# Sanitizers
+# --------------------------------------------------------------------
+# SANITIZERS is injected by the Conan toolchain when a sanitizer build is
+# requested (see conan/profiles/sanitizers). The flags are applied to the
+# 'common' target in XrplSanitizers; this flag lets other modules know a
+# sanitizer build is active without depending on that module.
+if(DEFINED SANITIZERS)
+    set(SANITIZERS_ENABLED TRUE)
+else()
+    set(SANITIZERS_ENABLED FALSE)
+endif()

cmake/PatchNixBinary.cmake

@@ -0,0 +1,53 @@
+#[===================================================================[
+   Patch executables to run in non-Nix environments.
+
+   The Nix-based CI image links binaries against an ELF interpreter (loader)
+   that lives in the Nix store, so the resulting binaries don't run elsewhere
+   (including once installed from the .deb package). `patch_nix_binary` adds a
+   POST_BUILD step that resets the interpreter to the system default loader and
+   drops the rpath.
+
+   This is only active inside the Nix-based image, detected by the presence of
+   /tmp/loader-path.sh (shipped by that image, resolves the default loader). It
+   is skipped for sanitizer builds, whose runtime libraries are resolved through
+   the rpath. Everywhere else `patch_nix_binary` is a no-op.
+#]===================================================================]
+
+include_guard(GLOBAL)
+
+include(CompilationEnv)
+
+# Provided by the Nix-based CI image; prints the system default ELF loader path.
+set(_loader_path_script "/tmp/loader-path.sh")
+
+if(is_linux AND NOT SANITIZERS_ENABLED AND EXISTS "${_loader_path_script}")
+    execute_process(
+        COMMAND "${_loader_path_script}"
+        OUTPUT_VARIABLE DEFAULT_LOADER_PATH
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+        COMMAND_ERROR_IS_FATAL ANY
+    )
+    find_program(PATCHELF_COMMAND patchelf REQUIRED)
+    set(PATCH_NIX_BINARIES TRUE)
+    message(
+        STATUS
+        "Binaries will be patched to use loader '${DEFAULT_LOADER_PATH}'"
+    )
+else()
+    set(PATCH_NIX_BINARIES FALSE)
+endif()
+
+function(patch_nix_binary target)
+    if(NOT PATCH_NIX_BINARIES)
+        return()
+    endif()
+    add_custom_command(
+        TARGET ${target}
+        POST_BUILD
+        COMMAND
+            "${PATCHELF_COMMAND}" --set-interpreter "${DEFAULT_LOADER_PATH}"
+            --remove-rpath "$<TARGET_FILE:${target}>"
+        COMMENT "Patching ${target}: set default loader, remove rpath"
+        VERBATIM
+    )
+endfunction()

cmake/XrplCompiler.cmake

@@ -154,6 +154,15 @@ else()
             >
     )
 
+    # On aarch64, libatomic is required for atomic operations. It is not needed on x86_64.
+    # Linking it statically on Linux
+    if(is_arm64 AND is_linux)
+        target_link_options(
+            common
+            INTERFACE -Wl,--push-state -Wl,-Bstatic -latomic -Wl,--pop-state
+        )
+    endif()
+
     # Keep -stdlib=libstdc++ off the compile commands, but preserve it for linking.
     #
     # Conan turns `compiler.libcxx=libstdc++` into `-stdlib=libstdc++` and puts it in

cmake/XrplCore.cmake

@@ -247,6 +247,7 @@ target_link_modules(
 
 if(xrpld)
     add_executable(xrpld)
+    patch_nix_binary(xrpld)
     if(tests)
         target_compile_definitions(xrpld PUBLIC ENABLE_TESTS)
         target_compile_definitions(
@@ -292,4 +293,13 @@ if(xrpld)
             PRIVATE ${CMAKE_SOURCE_DIR}/external/antithesis-sdk
         )
     endif()
+
+    # The xrpld headers are not built with add_module, so verify them against
+    # the executable's own compile environment.
+    if(verify_headers)
+        verify_target_headers(xrpld "${CMAKE_CURRENT_SOURCE_DIR}/src/xrpld")
+        if(tests)
+            verify_target_headers(xrpld "${CMAKE_CURRENT_SOURCE_DIR}/src/test")
+        endif()
+    endif()
 endif()

cmake/XrplPackaging.cmake

@@ -28,7 +28,6 @@ endif()
 set(package_env
     SRC_DIR=${CMAKE_SOURCE_DIR}
     BUILD_DIR=${CMAKE_BINARY_DIR}
-    PKG_VERSION=${xrpld_version}
     PKG_RELEASE=${pkg_release}
 )
 

cmake/XrplSanitizers.cmake

@@ -14,11 +14,9 @@
 include_guard(GLOBAL)
 include(CompilationEnv)
 
-if(NOT DEFINED SANITIZERS)
-    set(SANITIZERS_ENABLED FALSE)
+if(NOT SANITIZERS_ENABLED)
     return()
 endif()
-set(SANITIZERS_ENABLED TRUE)
 
 message(STATUS "=== Configuring Sanitizers ===")
 message(STATUS "  SANITIZERS: ${SANITIZERS}")

cmake/XrplSettings.cmake

@@ -30,6 +30,23 @@ if(tests)
     endif()
 endif()
 
+# Enabled by default so every header is compiled on its own as the main file of
+# its own compile_commands.json entry - this is what lets clang-tidy (and clangd
+# and IDEs) analyse a header's own includes directly. The per-header objects are
+# EXCLUDE_FROM_ALL (see cmake/verify_headers.cmake) and the aggregate target
+# below is not part of `all`, so a normal `cmake --build` never compiles them.
+option(
+    verify_headers
+    "Compile every header on its own to verify it is self-contained."
+    ON
+)
+if(verify_headers)
+    # Aggregate target that builds every per-module header-verification library
+    # created by add_module (see cmake/verify_headers.cmake). Build it with:
+    #   cmake --build . --target verify-headers
+    add_custom_target(verify-headers)
+endif()
+
 option(unity "Creates a build using UNITY support in cmake." OFF)
 if(unity)
     if(NOT is_ci)

cmake/add_module.cmake

@@ -1,4 +1,5 @@
 include(isolate_headers)
+include(verify_headers)
 
 # Create an OBJECT library target named
 #
@@ -37,4 +38,20 @@ function(add_module parent name)
         "${CMAKE_CURRENT_SOURCE_DIR}/src/lib${parent}/${name}"
         PRIVATE
     )
+    # protocol_autogen contains generated headers that are deliberately exempt
+    # from clang-tidy (see ExcludeHeaderFilterRegex in .clang-tidy), so we do not
+    # verify them either.
+    if(
+        verify_headers
+        AND NOT "${parent}/${name}" STREQUAL "xrpl/protocol_autogen"
+    )
+        verify_target_headers(
+            ${target}
+            "${CMAKE_CURRENT_SOURCE_DIR}/include/${parent}/${name}"
+        )
+        verify_target_headers(
+            ${target}
+            "${CMAKE_CURRENT_SOURCE_DIR}/src/lib${parent}/${name}"
+        )
+    endif()
 endfunction()

cmake/verify_headers.cmake

@@ -0,0 +1,84 @@
+# Our normal build only ever compiles `.cpp` files, so a header is only ever
+# checked through whatever translation unit happens to include it. A header that
+# is missing an `#include` is never caught as long as every `.cpp` that uses it
+# includes its missing dependency first. To check a header on its own we compile
+# it directly as a translation unit.
+#
+# Compiling the header itself - rather than a `.cpp` wrapper that includes it -
+# gives two checks at once:
+#   * the compiler fails if the header is not self-contained, i.e. it uses a
+#     declaration that is not available (directly or transitively); and
+#   * the header is the *main file* of its `compile_commands.json` entry, so
+#     clang-tidy's misc-include-cleaner analyses (and can --fix) the header's own
+#     includes - flagging a dependency that is only available transitively, which
+#     a plain compile cannot catch. A wrapper would be the main file instead, and
+#     include-cleaner never looks inside the headers a main file includes.
+#
+# The objects are never linked anywhere; we build them only for these checks.
+
+# Verify that the headers under headers_dir compile on their own, using the
+# compile environment of an existing target so each header is compiled exactly as
+# that target compiles it. This works for both add_module libraries and the xrpld
+# and test binaries: a library's isolated public and private include directories
+# and a binary's `-I src` both live in its INCLUDE_DIRECTORIES, and the modules or
+# libraries it links live in its LINK_LIBRARIES. We copy those usage requirements
+# through generator expressions (rather than linking ${target}, which is
+# impossible for an executable), evaluated at generation time so they capture
+# requirements the caller adds after this runs. The verify library is created
+# once; call this repeatedly to add more header directories.
+#
+# verify_target_headers(target headers_dir)
+function(verify_target_headers target headers_dir)
+    set(verify ${target}.verify)
+    if(NOT TARGET ${verify})
+        add_library(${verify} OBJECT EXCLUDE_FROM_ALL)
+        # A unity build would concatenate the headers into a single translation
+        # unit, where a header missing an include could be satisfied by one that
+        # precedes it in the blob - exactly the bug we want to catch.
+        set_target_properties(${verify} PROPERTIES UNITY_BUILD OFF)
+        target_include_directories(
+            ${verify}
+            PRIVATE $<TARGET_PROPERTY:${target},INCLUDE_DIRECTORIES>
+        )
+        target_compile_definitions(
+            ${verify}
+            PRIVATE $<TARGET_PROPERTY:${target},COMPILE_DEFINITIONS>
+        )
+        target_compile_options(
+            ${verify}
+            PRIVATE $<TARGET_PROPERTY:${target},COMPILE_OPTIONS>
+        )
+        target_link_libraries(
+            ${verify}
+            PRIVATE $<TARGET_PROPERTY:${target},LINK_LIBRARIES>
+        )
+        add_dependencies(verify-headers ${verify})
+    endif()
+    _verify_add_headers(${verify} "${headers_dir}")
+endfunction()
+
+# Add every .h/.hpp under dir to target as a directly-compiled C++ translation
+# unit. .ipp files are inline-implementation fragments included by their owning
+# header (often after a class declaration), so they are not self-contained on
+# their own and are verified transitively when that header is verified.
+function(_verify_add_headers target dir)
+    file(GLOB_RECURSE headers CONFIGURE_DEPENDS "${dir}/*.h" "${dir}/*.hpp")
+    if(NOT headers)
+        return()
+    endif()
+    # `-xc++` forces the header to be compiled as a C++ translation unit; a lone
+    # `.h` is otherwise treated as a header to precompile. `#pragma once` is
+    # harmless (and warns) when the header is the main file, so silence it.
+    # Compiled on its own, a header legitimately defines constants and static or
+    # template functions that nothing in this single translation unit uses (they
+    # exist for the files that include it), so the resulting unused-entity
+    # warnings are expected and must not fail the build under -Werror.
+    set_source_files_properties(
+        ${headers}
+        PROPERTIES
+            LANGUAGE CXX
+            COMPILE_OPTIONS
+                "-xc++;-Wno-pragma-once-outside-header;-Wno-unused-const-variable;-Wno-unused-function"
+    )
+    target_sources(${target} PRIVATE ${headers})
+endfunction()

conan.lock

@@ -1,43 +1,44 @@
 {
     "version": "0.5",
     "requires": [
-        "zlib/1.3.2#1cb806da49011867778ffb6ac7190fcb%1777558780.503",
-        "xxhash/0.8.3#681d36a0a6111fc56e5e45ea182c19cc%1765850149.987",
-        "sqlite3/3.53.0#324ada52333108388a9a6108bfa96734%1776096494.149",
-        "soci/4.0.3#fe32b9ad5eb47e79ab9e45a68f363945%1774450067.231",
-        "snappy/1.1.10#968fef506ff261592ec30c574d4a7809%1765850147.878",
-        "secp256k1/0.7.1#481881709eb0bdd0185a12b912bbe8ad%1770910500.329",
-        "rocksdb/10.5.1#4a197eca381a3e5ae8adf8cffa5aacd0%1765850186.86",
-        "re2/20251105#8579cfd0bda4daf0683f9e3898f964b4%1774398111.888",
-        "protobuf/6.33.5#d96d52ba5baaaa532f47bda866ad87a5%1774467363.12",
-        "openssl/3.6.2#4789bbf131b77d0515d15e094c8f697f%1778071755.506",
-        "nudb/2.0.9#11149c73f8f2baff9a0198fe25971fc7%1775040983.408",
-        "lz4/1.10.0#59fc63cac7f10fbe8e05c7e62c2f3504%1765850143.914",
-        "libiconv/1.17#1e65319e945f2d31941a9d28cc13c058%1765842973.492",
-        "libbacktrace/cci.20210118#a7691bfccd8caaf66309df196790a5a1%1765842973.03",
-        "libarchive/3.8.7#c446109bd1f1d8ba7936c94189bc50e6%1776147552.838",
+        "zlib/1.3.2#1cb806da49011867778ffb6ac7190fcb%1782392402.122708",
+        "xxhash/0.8.3#681d36a0a6111fc56e5e45ea182c19cc%1782392402.420688",
+        "sqlite3/3.53.0#324ada52333108388a9a6108bfa96734%1782392403.185447",
+        "soci/4.0.3#e726491a03468795453f7c83fc924a96%1782392402.679521",
+        "snappy/1.1.10#968fef506ff261592ec30c574d4a7809%1782307151.633168",
+        "secp256k1/0.7.1#b1f450b7f78a36fff75bb6934a356f3a%1782338841.3729",
+        "rocksdb/10.5.1#4a197eca381a3e5ae8adf8cffa5aacd0%1782392413.075713",
+        "re2/20251105#8579cfd0bda4daf0683f9e3898f964b4%1782392402.431897",
+        "protobuf/6.33.5#ff253ead763bd8d9904a52979cd21e81%1782392410.233933",
+        "openssl/3.6.3#1163d4ddc603907084d08a6a0c6e580f%1782307150.583886",
+        "nudb/2.0.9#11149c73f8f2baff9a0198fe25971fc7%1782392402.297166",
+        "mpt-crypto/0.4.0-rc2#a580f2f9ad0e795de696aa62d54fb9af%1782425834.488828",
+        "lz4/1.10.0#982d9b673900f665a1da109e09c17cab%1782392402.164188",
+        "libiconv/1.17#9923bc6dc6f106646d6967e0039a5ada%1782392792.775744",
+        "libbacktrace/cci.20210118#a7691bfccd8caaf66309df196790a5a1%1782392402.420732",
+        "libarchive/3.8.7#c446109bd1f1d8ba7936c94189bc50e6%1782392403.066892",
         "jemalloc/5.3.1#1fc58d55316041f10fbc1e8a2eae632a%1776700028.228",
-        "gtest/1.17.0#5224b3b3ff3b4ce1133cbdd27d53ee7d%1768312129.152",
-        "grpc/1.78.1#b1a9e74b145cc471bed4dc64dc6eb2c1%1774467387.342",
-        "ed25519/2015.03#ae761bdc52730a843f0809bdf6c1b1f6%1765850143.772",
-        "date/3.0.4#862e11e80030356b53c2c38599ceb32b%1765850143.772",
-        "c-ares/1.34.6#545240bb1c40e2cacd4362d6b8967650%1774439234.681",
-        "bzip2/1.0.8#c470882369c2d95c5c77e970c0c7e321%1765850143.837",
-        "boost/1.91.0#ea540ca2133d831b560036aa24dece3c%1778050991.9",
-        "abseil/20250127.0#bb0baf1f362bc4a725a24eddd419b8f7%1774365460.196"
+        "gtest/1.17.0#5224b3b3ff3b4ce1133cbdd27d53ee7d%1782392402.791979",
+        "grpc/1.81.1#5217e6ef0544c42b46f4af35d5e7f649%1782307148.845616",
+        "ed25519/2015.03#ae761bdc52730a843f0809bdf6c1b1f6%1782307148.15562",
+        "date/3.0.4#862e11e80030356b53c2c38599ceb32b%1782392402.538492",
+        "c-ares/1.34.6#545240bb1c40e2cacd4362d6b8967650%1782392402.681654",
+        "bzip2/1.0.8#c470882369c2d95c5c77e970c0c7e321%1782392402.296732",
+        "boost/1.91.0#ea540ca2133d831b560036aa24dece3c%1782392419.475605",
+        "abseil/20250127.0#bb0baf1f362bc4a725a24eddd419b8f7%1782307147.395833"
     ],
     "build_requires": [
-        "zlib/1.3.2#1cb806da49011867778ffb6ac7190fcb%1777558780.503",
-        "strawberryperl/5.32.1.1#8d114504d172cfea8ea1662d09b6333e%1774447376.964",
-        "protobuf/6.33.5#d96d52ba5baaaa532f47bda866ad87a5%1774467363.12",
-        "nasm/2.16.01#31e26f2ee3c4346ecd347911bd126904%1765850144.707",
+        "zlib/1.3.2#1cb806da49011867778ffb6ac7190fcb%1782392402.122708",
+        "strawberryperl/5.32.1.1#8d114504d172cfea8ea1662d09b6333e%1782395692.540639",
+        "protobuf/6.33.5#ff253ead763bd8d9904a52979cd21e81%1782392410.233933",
+        "nasm/2.16.01#31e26f2ee3c4346ecd347911bd126904%1782395690.33162",
         "msys2/cci.latest#d22fe7b2808f5fd34d0a7923ace9c54f%1770657326.649",
-        "m4/1.4.19#4523e4347b55cd26ae918bd5770cab9a%1778062762.471",
-        "cmake/4.3.0#b939a42e98f593fb34d3a8c5cc860359%1774439249.183",
-        "b2/5.4.2#ffd6084a119587e70f11cd45d1a386e2%1774439233.447",
+        "m4/1.4.19#34c4bbc3eeebe98ca6edf2f52d602e7d%1777282960.259",
+        "cmake/4.3.3#840cf00ea09777e05c2050a50a82c722%1782392418.696091",
+        "b2/5.4.2#ffd6084a119587e70f11cd45d1a386e2%1782392402.624226",
         "automake/1.16.5#b91b7c384c3deaa9d535be02da14d04f%1755524470.56",
         "autoconf/2.71#51077f068e61700d65bb05541ea1e4b0%1731054366.86",
-        "abseil/20250127.0#bb0baf1f362bc4a725a24eddd419b8f7%1774365460.196"
+        "abseil/20250127.0#bb0baf1f362bc4a725a24eddd419b8f7%1782307147.395833"
     ],
     "python_requires": [],
     "overrides": {
@@ -57,7 +58,7 @@
             "boost/1.91.0"
         ],
         "lz4/[>=1.9.4 <2]": [
-            "lz4/1.10.0#59fc63cac7f10fbe8e05c7e62c2f3504"
+            "lz4/1.10.0#982d9b673900f665a1da109e09c17cab"
         ]
     },
     "config_requires": []

conan/lockfile/regenerate.sh

@@ -14,7 +14,7 @@ export CONAN_HOME="$TEMP_DIR"
 # Ensure that the xrplf remote is the first to be consulted, so any recipes we
 # patched are used. We also add it there to not created huge diff when the
 # official Conan Center Index is updated.
-conan remote add --force --index 0 xrplf https://conan.ripplex.io
+conan remote add --force --index 0 xrplf https://conan.xrplf.org/repository/conan/
 
 # Delete any existing lockfile.
 rm -f conan.lock

conan/profiles/default

@@ -10,16 +10,18 @@
 os={{ os }}
 arch={{ arch }}
 build_type=Debug
-compiler={{compiler}}
+compiler={{ compiler }}
 compiler.version={{ compiler_version }}
 compiler.cppstd=23
 {% if os == "Windows" %}
 compiler.runtime=static
 {% else %}
-compiler.libcxx={{detect_api.detect_libcxx(compiler, version, compiler_exe)}}
+compiler.libcxx={{ detect_api.detect_libcxx(compiler, version, compiler_exe) }}
 {% endif %}
 
 [conf]
-{% if compiler == "gcc" and compiler_version < 13 %}
-tools.build:cxxflags+=['-Wno-restrict']
-{% endif %}
+{# By default, Conan tries to reuse binaries built with different cppstd versions. #}
+{# We want to avoid that to improve reproduceability, so we add the cppstd version to the package ID. #}
+{# More info: https://docs.conan.io/2/reference/extensions/binary_compatibility.html #}
+user.package:cppstd_version=23
+tools.info.package_id:confs+=["user.package:cppstd_version"]

conan/profiles/sanitizers

@@ -87,15 +87,15 @@ include(default)
 {% endif %}
 
 [conf]
-tools.build:defines+={{defines}}
-tools.build:cxxflags+={{sanitizer_compiler_flags}}
-tools.build:sharedlinkflags+={{sanitizer_linker_flags}}
-tools.build:exelinkflags+={{sanitizer_linker_flags}}
+tools.build:defines+={{ defines }}
+tools.build:cxxflags+={{ sanitizer_compiler_flags }}
+tools.build:sharedlinkflags+={{ sanitizer_linker_flags }}
+tools.build:exelinkflags+={{ sanitizer_linker_flags }}
 
 tools.info.package_id:confs+=["tools.build:cxxflags", "tools.build:exelinkflags", "tools.build:sharedlinkflags", "tools.build:defines"]
 
 # &: means "apply only to the consumer/root package"
-&:tools.cmake.cmaketoolchain:extra_variables={"SANITIZERS": "{{sanitizers}}", "SANITIZERS_COMPILER_FLAGS": "{{sanitizer_compiler_flags | join(' ')}}", "SANITIZERS_LINKER_FLAGS": "{{sanitizer_linker_flags | join(' ')}}"}
+&:tools.cmake.cmaketoolchain:extra_variables={"SANITIZERS": "{{ sanitizers }}", "SANITIZERS_COMPILER_FLAGS": "{{ sanitizer_compiler_flags | join(' ') }}", "SANITIZERS_LINKER_FLAGS": "{{ sanitizer_linker_flags | join(' ') }}"}
 
 [options]
 {% if enable_asan %}

conanfile.py

@@ -28,11 +28,10 @@ class Xrpl(ConanFile):
 
     requires = [
         "ed25519/2015.03",
-        "grpc/1.78.1",
+        "grpc/1.81.1",
         "libarchive/3.8.7",
         "nudb/2.0.9",
-        "openssl/3.6.2",
-        "secp256k1/0.7.1",
+        "openssl/3.6.3",
         "soci/4.0.3",
         "zlib/1.3.2",
     ]
@@ -132,13 +131,15 @@ class Xrpl(ConanFile):
     def requirements(self):
         self.requires("boost/1.91.0", force=True, transitive_headers=True)
         self.requires("date/3.0.4", transitive_headers=True)
-        self.requires("lz4/1.10.0", force=True)
-        self.requires("protobuf/6.33.5", force=True)
-        self.requires("sqlite3/3.53.0", force=True)
         if self.options.jemalloc:
             self.requires("jemalloc/5.3.1")
+        self.requires("lz4/1.10.0", force=True)
+        self.requires("mpt-crypto/0.4.0-rc2", transitive_headers=True)
+        self.requires("protobuf/6.33.5", force=True)
         if self.options.rocksdb:
             self.requires("rocksdb/10.5.1")
+        self.requires("secp256k1/0.7.1", transitive_headers=True)
+        self.requires("sqlite3/3.53.0", force=True)
         self.requires("xxhash/0.8.3", transitive_headers=True)
 
     exports_sources = (
@@ -208,6 +209,7 @@ class Xrpl(ConanFile):
             "grpc::grpc++",
             "libarchive::libarchive",
             "lz4::lz4",
+            "mpt-crypto::mpt-crypto",
             "nudb::nudb",
             "openssl::crypto",
             "protobuf::libprotobuf",

docs/0001-negative-unl/README.md

@@ -288,7 +288,7 @@ components with non-trivial changes are colored green.
     validated.
 
 ![Sequence diagram](./negativeUNL_highLevel_sequence.png?raw=true "Negative UNL
- Changes")
+Changes")
 
 ## Roads Not Taken
 

docs/build/advanced_conan.md

@@ -34,7 +34,7 @@ higher index than the default Conan Center remote, so it is consulted first. You
 can do this by running:
 
 ```bash
-conan remote add --index 0 --force xrplf https://conan.ripplex.io
+conan remote add --index 0 --force xrplf https://conan.xrplf.org/repository/conan/
 ```
 
 Alternatively, you can pull our recipes from the repository and export them locally:

include/xrpl/basics/Buffer.h

@@ -6,6 +6,7 @@
 #include <cstdint>
 #include <cstring>
 #include <memory>
+#include <utility>
 
 namespace xrpl {
 

include/xrpl/basics/CompressionAlgorithms.h

@@ -5,6 +5,7 @@
 #include <lz4.h>
 
 #include <algorithm>
+#include <cstddef>
 #include <cstdint>
 #include <stdexcept>
 #include <vector>

include/xrpl/basics/DecayingSample.h

@@ -2,6 +2,7 @@
 
 #include <chrono>
 #include <cmath>
+#include <cstddef>
 
 namespace xrpl {
 
@@ -12,8 +13,8 @@ template <int Window, typename Clock>
 class DecayingSample
 {
 public:
-    using value_type = typename Clock::duration::rep;
-    using time_point = typename Clock::time_point;
+    using value_type = Clock::duration::rep;
+    using time_point = Clock::time_point;
 
     DecayingSample() = delete;
 
@@ -93,7 +94,7 @@ template <int HalfLife, class Clock>
 class DecayWindow
 {
 public:
-    using time_point = typename Clock::time_point;
+    using time_point = Clock::time_point;
 
     explicit DecayWindow(time_point now) : when_(now)
     {

include/xrpl/basics/FileUtilities.h

@@ -3,7 +3,9 @@
 #include <boost/filesystem.hpp>
 #include <boost/system/error_code.hpp>
 
+#include <cstddef>
 #include <optional>
+#include <string>
 
 namespace xrpl {
 

include/xrpl/basics/IntrusivePointer.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <concepts>
+#include <cstddef>
 #include <cstdint>
 #include <type_traits>
 #include <utility>

include/xrpl/basics/IntrusivePointer.ipp

@@ -641,6 +641,9 @@ template <class T>
 T*
 SharedWeakUnion<T>::unsafeGetRawPtr() const
 {
+    // tp_ packs a raw pointer together with a strength bit; recovering the
+    // pointer inherently requires an integer-to-pointer cast.
+    // NOLINTNEXTLINE(performance-no-int-to-ptr)
     return reinterpret_cast<T*>(tp_ & kPtrMask);
 }
 

include/xrpl/basics/IntrusiveRefCounts.h

@@ -3,6 +3,7 @@
 #include <xrpl/beast/utility/instrumentation.h>
 
 #include <atomic>
+#include <cstddef>
 #include <cstdint>
 
 namespace xrpl {

include/xrpl/basics/Log.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <xrpl/basics/UnorderedContainers.h>
 #include <xrpl/beast/utility/Journal.h>
 
 #include <boost/beast/core/string.hpp>
@@ -11,7 +10,9 @@
 #include <memory>
 #include <mutex>
 #include <optional>
+#include <string>
 #include <utility>
+#include <vector>
 
 namespace xrpl {
 
@@ -206,8 +207,7 @@ private:
 #ifndef JLOG
 #define JLOG(x) \
     if (!(x))   \
-    {           \
-    }           \
+        ;       \
     else        \
         x
 #endif

include/xrpl/basics/Number.h

@@ -2,7 +2,9 @@
 
 #include <xrpl/beast/utility/instrumentation.h>
 
+#include <algorithm>
 #include <array>
+#include <cstddef>
 #include <cstdint>
 #include <functional>
 #include <limits>
@@ -11,7 +13,9 @@
 #include <set>
 #include <stdexcept>
 #include <string>
+#include <type_traits>
 #include <unordered_map>
+#include <utility>
 
 namespace xrpl {
 

include/xrpl/basics/RangeSet.h

@@ -6,6 +6,7 @@
 #include <boost/icl/closed_interval.hpp>
 #include <boost/icl/interval_set.hpp>
 
+#include <functional>
 #include <optional>
 #include <string>
 #include <vector>

include/xrpl/basics/Resolver.h

@@ -3,6 +3,7 @@
 #include <xrpl/beast/net/IPEndpoint.h>
 
 #include <functional>
+#include <string>
 #include <vector>
 
 namespace xrpl {

include/xrpl/basics/ResolverAsio.h

@@ -5,6 +5,8 @@
 
 #include <boost/asio/io_context.hpp>
 
+#include <memory>
+
 namespace xrpl {
 
 class ResolverAsio : public Resolver

include/xrpl/basics/SHAMapHash.h

@@ -3,7 +3,9 @@
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/partitioned_unordered_map.h>
 
+#include <cstddef>
 #include <ostream>
+#include <string>
 
 namespace xrpl {
 

include/xrpl/basics/SharedWeakCachePointer.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <concepts>
+#include <cstddef>
 #include <memory>
 #include <variant>
 

include/xrpl/basics/SlabAllocator.h

@@ -15,6 +15,7 @@
 #include <cstdint>
 #include <cstring>
 #include <mutex>
+#include <stdexcept>
 #include <vector>
 
 #if BOOST_OS_LINUX

include/xrpl/basics/Slice.h

@@ -211,15 +211,17 @@ operator<<(Stream& s, Slice const& v)
 }
 
 template <class T, std::size_t N>
-std::enable_if_t<std::is_same_v<T, char> || std::is_same_v<T, unsigned char>, Slice>
+Slice
 makeSlice(std::array<T, N> const& a)
+    requires(std::is_same_v<T, char> || std::is_same_v<T, unsigned char>)
 {
     return Slice(a.data(), a.size());
 }
 
 template <class T, class Alloc>
-std::enable_if_t<std::is_same_v<T, char> || std::is_same_v<T, unsigned char>, Slice>
+Slice
 makeSlice(std::vector<T, Alloc> const& v)
+    requires(std::is_same_v<T, char> || std::is_same_v<T, unsigned char>)
 {
     return Slice(v.data(), v.size());
 }

include/xrpl/basics/StringUtilities.h

@@ -1,18 +1,19 @@
 #pragma once
 
 #include <xrpl/basics/Blob.h>
-#include <xrpl/basics/strHex.h>
 
 #include <boost/format.hpp>
 #include <boost/utility/string_view.hpp>
 
 #include <array>
 #include <concepts>
+#include <cstddef>
 #include <cstdint>
 #include <optional>
 #include <string>
 #include <string_view>
 #include <type_traits>
+#include <utility>
 
 namespace xrpl {
 

include/xrpl/basics/TaggedCache.h

@@ -1,22 +1,46 @@
 #pragma once
 
-#include <xrpl/basics/IntrusivePointer.h>
-#include <xrpl/basics/Log.h>
-#include <xrpl/basics/SharedWeakCachePointer.ipp>
+#include <xrpl/basics/SharedWeakCachePointer.h>
+#include <xrpl/basics/SharedWeakCachePointer.ipp>  // IWYU pragma: keep
 #include <xrpl/basics/UnorderedContainers.h>
 #include <xrpl/basics/hardened_hash.h>
 #include <xrpl/beast/clock/abstract_clock.h>
-#include <xrpl/beast/insight/Insight.h>
+#include <xrpl/beast/insight/Collector.h>
+#include <xrpl/beast/insight/Gauge.h>
+#include <xrpl/beast/insight/Hook.h>
+#include <xrpl/beast/insight/NullCollector.h>
+#include <xrpl/beast/utility/Journal.h>
 
 #include <atomic>
+#include <chrono>
+#include <cstddef>
+#include <cstdint>
 #include <functional>
+#include <memory>
 #include <mutex>
+#include <string>
 #include <thread>
 #include <type_traits>
 #include <vector>
 
 namespace xrpl {
 
+namespace detail {
+
+// Replace-policy tags selecting how TaggedCache::canonicalizeImpl resolves a
+// collision when the key already exists (defined in TaggedCache.ipp):
+//   - ReplaceCached: always replace the cached value with `data`. `data` is
+//     never written back and may be const.
+//   - ReplaceClient: keep the cached value and write it back into `data` (the
+//     client's pointer), which must therefore be writable.
+//   - ReplaceDynamically: call the supplied callback to decide per call; `data`
+//     is written back when the cached value is kept, so it must be writable.
+struct ReplaceCached;
+struct ReplaceClient;
+struct ReplaceDynamically;
+
+}  // namespace detail
+
 /** Map/cache combination.
     This class implements a cache and a map. The cache keeps objects alive
     in the map. The map allows multiple code paths that reference objects
@@ -96,6 +120,32 @@ public:
     bool
     del(key_type const& key, bool valid);
 
+private:
+    // Selects the `data` parameter type of canonicalizeImpl from the replace
+    // policy: const for detail::ReplaceCached (never written back), otherwise
+    // writable.
+    template <typename Policy>
+    using CanonicalizeClientPointerType = std::conditional_t<
+        std::is_same_v<detail::ReplaceCached, Policy>,
+        SharedPointerType const&,
+        SharedPointerType&>;
+
+    /** Shared implementation of the canonicalize family.
+
+        `policy` selects how a collision is resolved when `key` already exists:
+        detail::ReplaceCached, detail::ReplaceClient or
+        detail::ReplaceDynamically. For ReplaceDynamically `replaceCallback` is
+        invoked with the existing strong pointer and returns whether to replace
+        the cached value with `data`; for the tag policies it is unused.
+    */
+    template <class Policy, class Callback = std::nullptr_t>
+    bool
+    canonicalizeImpl(
+        key_type const& key,
+        CanonicalizeClientPointerType<Policy> data,
+        Policy policy,
+        Callback&& replaceCallback = nullptr);
+
 public:
     /** Replace aliased objects with originals.
 
@@ -104,19 +154,52 @@ public:
         This routine eliminates the duplicate and performs a replacement
         on the callers shared pointer if needed.
 
+        `replaceCallback` is a callable taking the existing strong pointer and
+        returning whether to replace the cached value with `data` (true) or to
+        keep the cached value and write it back into `data` (false). Because the
+        write-back case mutates `data`, `data` must be writable.
+
         @param key The key corresponding to the object
         @param data A shared pointer to the data corresponding to the object.
-        @param replace Function that decides if cache should be replaced
+        @param replaceCallback A callable (existing strong pointer -> bool).
 
-        @return `true` If the key already existed.
-    */
-    template <class R>
+        @return `true` if an existing live entry was found and used; `false` if a new entry was
+                inserted or an expired tracked entry was re-cached.
+    **/
+    template <class Callback>
     bool
-    canonicalize(key_type const& key, SharedPointerType& data, R&& replaceCallback);
+    canonicalize(key_type const& key, SharedPointerType& data, Callback&& replaceCallback);
 
+    /** Insert/update the canonical entry for `key`, always replacing the
+        cached value with `data`.
+
+        If an entry already exists for `key`, the cached value is unconditionally
+        replaced with `data`; otherwise `data` is inserted. `data` is never
+        written back, so it may be const.
+
+        @param key The key corresponding to the object.
+        @param data A shared pointer to the data corresponding to the object.
+
+        @return `true` if an existing live entry was found and used; `false` if a new entry was
+                inserted or an expired tracked entry was re-cached.
+    **/
     bool
     canonicalizeReplaceCache(key_type const& key, SharedPointerType const& data);
 
+    /** Insert the canonical entry for `key`, keeping any existing cached value.
+
+        If an entry already exists for `key`, the cached value is kept and
+        written back into `data` so the caller ends up with the canonical
+        object; otherwise `data` is inserted. Because `data` may be overwritten
+        it must be writable.
+
+        @param key The key corresponding to the object.
+        @param data A shared pointer to the data corresponding to the object;
+                    updated to the canonical value when one already exists.
+
+        @return `true` if an existing live entry was found and used; `false` if a new entry was
+                inserted or an expired tracked entry was re-cached.
+    **/
     bool
     canonicalizeReplaceClient(key_type const& key, SharedPointerType& data);
 
@@ -129,11 +212,13 @@ public:
     */
     template <class ReturnType = bool>
     auto
-    insert(key_type const& key, T const& value) -> std::enable_if_t<!IsKeyCache, ReturnType>;
+    insert(key_type const& key, T const& value) -> ReturnType
+        requires(!IsKeyCache);
 
     template <class ReturnType = bool>
     auto
-    insert(key_type const& key) -> std::enable_if_t<IsKeyCache, ReturnType>;
+    insert(key_type const& key) -> ReturnType
+        requires IsKeyCache;
 
     // VFALCO NOTE It looks like this returns a copy of the data in
     //             the output parameter 'data'. This could be expensive.
@@ -262,7 +347,7 @@ private:
     sweepHelper(
         clock_type::time_point const& whenExpire,
         [[maybe_unused]] clock_type::time_point const& now,
-        typename KeyValueCacheType::map_type& partition,
+        KeyValueCacheType::map_type& partition,
         SweptPointersVector& stuffToSweep,
         std::atomic<int>& allRemovals,
         std::scoped_lock<std::recursive_mutex> const&);
@@ -271,7 +356,7 @@ private:
     sweepHelper(
         clock_type::time_point const& whenExpire,
         clock_type::time_point const& now,
-        typename KeyOnlyCacheType::map_type& partition,
+        KeyOnlyCacheType::map_type& partition,
         SweptPointersVector&,
         std::atomic<int>& allRemovals,
         std::scoped_lock<std::recursive_mutex> const&);

include/xrpl/basics/TaggedCache.ipp

@@ -1,10 +1,35 @@
 #pragma once
 
 #include <xrpl/basics/IntrusivePointer.ipp>
+#include <xrpl/basics/Log.h>  // IWYU pragma: keep
 #include <xrpl/basics/TaggedCache.h>
 
 namespace xrpl {
 
+namespace detail {
+
+// Replace-policy tags selecting how TaggedCache::canonicalizeImpl resolves a
+// collision when the key already exists:
+//   - ReplaceCached: always replace the cached value with `data`. `data` is
+//     never written back and may be const.
+//   - ReplaceClient: keep the cached value and write it back into `data` (the
+//     client's pointer), which must therefore be writable.
+//   - ReplaceDynamically: call the supplied callback to decide per call; `data`
+//     is written back when the cached value is kept, so it must be writable.
+struct ReplaceCached
+{
+};
+
+struct ReplaceClient
+{
+};
+
+struct ReplaceDynamically
+{
+};
+
+}  // namespace detail
+
 template <
     class Key,
     class T,
@@ -32,7 +57,10 @@ inline TaggedCache<
         beast::insight::Collector::ptr const& collector)
     : journal_(journal)
     , clock_(clock)
-    , stats_(name, std::bind(&TaggedCache::collectMetrics, this), collector)
+    , stats_(
+          name,
+          [this] { collectMetrics(); },
+          collector)
     , name_(name)
     , targetSize_(size)
     , targetAge_(expiration)
@@ -300,13 +328,29 @@ template <
     class Hash,
     class KeyEqual,
     class Mutex>
-template <class R>
+template <class Policy, class Callback>
 inline bool
 TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash, KeyEqual, Mutex>::
-    canonicalize(key_type const& key, SharedPointerType& data, R&& replaceCallback)
+    canonicalizeImpl(
+        key_type const& key,
+        CanonicalizeClientPointerType<Policy> data,
+        [[maybe_unused]] Policy policy,
+        [[maybe_unused]] Callback&& replaceCallback)
 {
     // Return canonical value, store if needed, refresh in cache
     // Return values: true=we had the data already
+
+    // `Policy` is one of:
+    //   - detail::ReplaceCached: always replace the cached value with `data`;
+    //     `data` is never written back and may be const.
+    //   - detail::ReplaceClient: keep the cached value and write it back into
+    //     `data` (the client's pointer), which must therefore be writable.
+    //   - detail::ReplaceDynamically: call `replaceCallback` to decide at run
+    //     time; `data` must be writable.
+    // For the latter two the write-back below requires a mutable `data`, so
+    // passing a const argument is a compile error.
+    constexpr bool replaceCached = std::is_same_v<Policy, detail::ReplaceCached>;
+
     std::scoped_lock const lock(mutex_);
 
     auto cit = cache_.find(key);
@@ -324,13 +368,14 @@ TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash,
     Entry& entry = cit->second;
     entry.touch(clock_.now());
 
-    auto shouldReplace = [&] {
-        if constexpr (std::is_invocable_r_v<bool, R>)
+    auto shouldReplaceCached = [&] {
+        if constexpr (replaceCached)
         {
-            // The reason for this extra complexity is for intrusive
-            // strong/weak combo getting a strong is relatively expensive
-            // and not needed for many cases.
-            return replaceCallback();
+            return true;
+        }
+        else if constexpr (std::is_same_v<Policy, detail::ReplaceClient>)
+        {
+            return false;
         }
         else
         {
@@ -340,11 +385,11 @@ TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash,
 
     if (entry.isCached())
     {
-        if (shouldReplace())
+        if (shouldReplaceCached())
         {
             entry.ptr = data;
         }
-        else
+        else if constexpr (!replaceCached)
         {
             data = entry.ptr.getStrong();
         }
@@ -356,11 +401,11 @@ TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash,
 
     if (cachedData)
     {
-        if (shouldReplace())
+        if (shouldReplaceCached())
         {
             entry.ptr = data;
         }
-        else
+        else if constexpr (!replaceCached)
         {
             entry.ptr.convertToStrong();
             data = cachedData;
@@ -376,6 +421,24 @@ TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash,
     return false;
 }
 
+template <
+    class Key,
+    class T,
+    bool IsKeyCache,
+    class SharedWeakUnionPointer,
+    class SharedPointerType,
+    class Hash,
+    class KeyEqual,
+    class Mutex>
+template <class Callback>
+inline bool
+TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash, KeyEqual, Mutex>::
+    canonicalize(key_type const& key, SharedPointerType& data, Callback&& replaceCallback)
+{
+    return canonicalizeImpl(
+        key, data, detail::ReplaceDynamically{}, std::forward<Callback>(replaceCallback));
+}
+
 template <
     class Key,
     class T,
@@ -389,7 +452,7 @@ inline bool
 TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash, KeyEqual, Mutex>::
     canonicalizeReplaceCache(key_type const& key, SharedPointerType const& data)
 {
-    return canonicalize(key, const_cast<SharedPointerType&>(data), []() { return true; });
+    return canonicalizeImpl(key, data, detail::ReplaceCached{});
 }
 
 template <
@@ -405,7 +468,7 @@ inline bool
 TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash, KeyEqual, Mutex>::
     canonicalizeReplaceClient(key_type const& key, SharedPointerType& data)
 {
-    return canonicalize(key, data, []() { return false; });
+    return canonicalizeImpl(key, data, detail::ReplaceClient{});
 }
 
 template <
@@ -440,7 +503,8 @@ template <
 template <class ReturnType>
 inline auto
 TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash, KeyEqual, Mutex>::
-    insert(key_type const& key, T const& value) -> std::enable_if_t<!IsKeyCache, ReturnType>
+    insert(key_type const& key, T const& value) -> ReturnType
+    requires(!IsKeyCache)
 {
     static_assert(
         std::is_same_v<std::shared_ptr<T>, SharedPointerType> ||
@@ -470,7 +534,8 @@ template <
 template <class ReturnType>
 inline auto
 TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash, KeyEqual, Mutex>::
-    insert(key_type const& key) -> std::enable_if_t<IsKeyCache, ReturnType>
+    insert(key_type const& key) -> ReturnType
+    requires IsKeyCache
 {
     std::scoped_lock const lock(mutex_);
     clock_type::time_point const now(clock_.now());
@@ -676,7 +741,7 @@ TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash,
     sweepHelper(
         clock_type::time_point const& whenExpire,
         [[maybe_unused]] clock_type::time_point const& now,
-        typename KeyValueCacheType::map_type& partition,
+        KeyValueCacheType::map_type& partition,
         SweptPointersVector& stuffToSweep,
         std::atomic<int>& allRemovals,
         std::scoped_lock<std::recursive_mutex> const&)
@@ -756,7 +821,7 @@ TaggedCache<Key, T, IsKeyCache, SharedWeakUnionPointer, SharedPointerType, Hash,
     sweepHelper(
         clock_type::time_point const& whenExpire,
         clock_type::time_point const& now,
-        typename KeyOnlyCacheType::map_type& partition,
+        KeyOnlyCacheType::map_type& partition,
         SweptPointersVector&,
         std::atomic<int>& allRemovals,
         std::scoped_lock<std::recursive_mutex> const&)

include/xrpl/basics/ToString.h

@@ -12,8 +12,9 @@ namespace xrpl {
  */
 
 template <class T>
-std::enable_if_t<std::is_arithmetic_v<T>, std::string>
+std::string
 to_string(T t)  // NOLINT(readability-identifier-naming)
+    requires(std::is_arithmetic_v<T>)
 {
     return std::to_string(t);
 }

include/xrpl/basics/UnorderedContainers.h

@@ -2,12 +2,14 @@
 
 #include <xrpl/basics/hardened_hash.h>
 #include <xrpl/basics/partitioned_unordered_map.h>
-#include <xrpl/beast/hash/hash_append.h>
 #include <xrpl/beast/hash/uhash.h>
 #include <xrpl/beast/hash/xxhasher.h>
 
+#include <functional>
+#include <memory>
 #include <unordered_map>
 #include <unordered_set>
+#include <utility>
 
 /**
  * Use hash_* containers for keys that do not need a cryptographically secure

include/xrpl/basics/base64.h

@@ -34,6 +34,7 @@
 
 #pragma once
 
+#include <cstddef>
 #include <cstdint>
 #include <string>
 #include <string_view>

include/xrpl/basics/base_uint.h

@@ -10,6 +10,7 @@
 #include <xrpl/basics/hardened_hash.h>
 #include <xrpl/basics/partitioned_unordered_map.h>
 #include <xrpl/basics/strHex.h>
+#include <xrpl/beast/hash/hash_append.h>
 #include <xrpl/beast/utility/Zero.h>
 #include <xrpl/beast/utility/instrumentation.h>
 
@@ -18,8 +19,17 @@
 
 #include <algorithm>
 #include <array>
+#include <compare>
+#include <cstddef>
+#include <cstdint>
 #include <cstring>
 #include <expected>
+#include <iterator>
+#include <optional>
+#include <ostream>
+#include <stdexcept>
+#include <string>
+#include <string_view>
 #include <type_traits>
 
 namespace xrpl {
@@ -87,7 +97,7 @@ public:
     //
 
     static constexpr std::size_t kBytes = Bits / 8;
-    static_assert(sizeof(data_) == kBytes, "");
+    static_assert(sizeof(data_) == kBytes);
 
     using size_type = std::size_t;
     using difference_type = std::ptrdiff_t;
@@ -270,12 +280,11 @@ public:
     {
     }
 
-    template <
-        class Container,
-        class = std::enable_if_t<
-            detail::IsContiguousContainer<Container>::value &&
-            std::is_trivially_copyable_v<typename Container::value_type>>>
+    template <class Container>
     explicit BaseUInt(Container const& c)
+        requires(
+            detail::IsContiguousContainer<Container>::value &&
+            std::is_trivially_copyable_v<typename Container::value_type>)
     {
         // Use AlwaysFalseT so the static_assert condition is dependent
         // and only triggers when this constructor template is instantiated.
@@ -285,13 +294,12 @@ public:
             "Use base_uint::fromRaw instead.");
     }
 
-    template <
-        class Container,
-        class = std::enable_if_t<
-            detail::IsContiguousContainer<Container>::value &&
-            std::is_trivially_copyable_v<typename Container::value_type>>>
+    template <class Container>
     static BaseUInt
     fromRaw(Container const& c)
+        requires(
+            detail::IsContiguousContainer<Container>::value &&
+            std::is_trivially_copyable_v<typename Container::value_type>)
     {
         BaseUInt result;
         XRPL_ASSERT(
@@ -302,11 +310,11 @@ public:
     }
 
     template <class Container>
-    std::enable_if_t<
-        detail::IsContiguousContainer<Container>::value &&
-            std::is_trivially_copyable_v<typename Container::value_type>,
-        BaseUInt&>
+    BaseUInt&
     operator=(Container const& c)
+        requires(
+            detail::IsContiguousContainer<Container>::value &&
+            std::is_trivially_copyable_v<typename Container::value_type>)
     {
         XRPL_ASSERT(
             c.size() * sizeof(typename Container::value_type) == size(),

include/xrpl/basics/chrono.h

@@ -10,6 +10,7 @@
 #include <cstdint>
 #include <ratio>
 #include <string>
+#include <type_traits>
 
 namespace xrpl {
 

include/xrpl/basics/comparators.h

@@ -1,54 +0,0 @@
-#pragma once
-
-#include <functional>
-
-namespace xrpl {
-
-#ifdef _MSC_VER
-
-/*
- * MSVC 2019 version 16.9.0 added [[nodiscard]] to the std comparison
- * operator() functions. boost::bimap checks that the comparator is a
- * BinaryFunction, in part by calling the function and ignoring the value.
- * These two things don't play well together. These wrapper classes simply
- * strip [[nodiscard]] from operator() for use in boost::bimap.
- *
- * See also:
- *  https://www.boost.org/doc/libs/1_75_0/libs/bimap/doc/html/boost_bimap/the_tutorial/controlling_collection_types.html
- */
-
-template <class T = void>
-struct less
-{
-    using result_type = bool;
-
-    constexpr bool
-    operator()(T const& left, T const& right) const
-    {
-        return std::less<T>()(left, right);
-    }
-};
-
-template <class T = void>
-struct equal_to
-{
-    using result_type = bool;
-
-    constexpr bool
-    operator()(T const& left, T const& right) const
-    {
-        return std::equal_to<T>()(left, right);
-    }
-};
-
-#else
-
-template <class T = void>
-using less = std::less<T>;
-
-template <class T = void>
-using equal_to = std::equal_to<T>;
-
-#endif
-
-}  // namespace xrpl

include/xrpl/basics/hardened_hash.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <xrpl/beast/hash/hash_append.h>
 #include <xrpl/beast/hash/xxhasher.h>
 
 #include <cstdint>
@@ -75,7 +74,7 @@ private:
     detail::seed_pair seeds_{detail::makeSeedPair<>()};
 
 public:
-    using result_type = typename HashAlgorithm::result_type;
+    using result_type = HashAlgorithm::result_type;
 
     HardenedHash() = default;
 

include/xrpl/basics/join.h

@@ -1,7 +1,9 @@
 #pragma once
 
+#include <cstddef>
 #include <string>
 #include <string_view>
+#include <utility>
 
 namespace xrpl {
 

include/xrpl/basics/make_SSLContext.h

@@ -2,6 +2,7 @@
 
 #include <boost/asio/ssl/context.hpp>
 
+#include <memory>
 #include <string>
 
 namespace xrpl {

include/xrpl/basics/partitioned_unordered_map.h

@@ -3,7 +3,10 @@
 #include <xrpl/beast/hash/uhash.h>
 #include <xrpl/beast/utility/instrumentation.h>
 
+#include <cstddef>
 #include <functional>
+#include <iterator>
+#include <memory>
 #include <optional>
 #include <string>
 #include <thread>
@@ -57,8 +60,8 @@ public:
     {
         using iterator_category = std::forward_iterator_tag;
         partition_map_type* map{nullptr};
-        typename partition_map_type::iterator ait{};
-        typename map_type::iterator mit;
+        partition_map_type::iterator ait{};
+        map_type::iterator mit;
 
         Iterator() = default;
 
@@ -126,8 +129,8 @@ public:
         using iterator_category = std::forward_iterator_tag;
 
         partition_map_type* map{nullptr};
-        typename partition_map_type::iterator ait{};
-        typename map_type::iterator mit;
+        partition_map_type::iterator ait{};
+        map_type::iterator mit;
 
         ConstIterator() = default;
 
@@ -135,11 +138,8 @@ public:
         {
         }
 
-        ConstIterator(Iterator const& orig)
+        ConstIterator(Iterator const& orig) : map(orig.map), ait(orig.ait), mit(orig.mit)
         {
-            map = orig.map;
-            ait = orig.ait;
-            mit = orig.mit;
         }
 
         const_reference
@@ -228,11 +228,11 @@ private:
 
 public:
     PartitionedUnorderedMap(std::optional<std::size_t> partitions = std::nullopt)
-    {
         // Set partitions to the number of hardware threads if the parameter
         // is either empty or set to 0.
-        partitions_ =
-            partitions && (*partitions != 0u) ? *partitions : std::thread::hardware_concurrency();
+        : partitions_(
+              partitions && (*partitions != 0u) ? *partitions : std::thread::hardware_concurrency())
+    {
         map_.resize(partitions_);
         XRPL_ASSERT(
             partitions_,

include/xrpl/basics/random.h

@@ -3,7 +3,6 @@
 #include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/beast/xor_shift_engine.h>
 
-#include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <mutex>
@@ -29,6 +28,7 @@ static_assert(
 namespace detail {
 
 // Determines if a type can be called like an Engine
+// NOLINTNEXTLINE(readability-redundant-typename): typename required by MSVC
 template <class Engine, class Result = typename Engine::result_type>
 using is_engine = std::is_invocable_r<Result, Engine>;
 }  // namespace detail
@@ -91,8 +91,9 @@ defaultPrng()
 */
 /** @{ */
 template <class Engine, class Integral>
-std::enable_if_t<std::is_integral_v<Integral> && detail::is_engine<Engine>::value, Integral>
+Integral
 randInt(Engine& engine, Integral min, Integral max)
+    requires(std::is_integral_v<Integral> && detail::is_engine<Engine>::value)
 {
     XRPL_ASSERT(max > min, "xrpl::randInt : max over min inputs");
 
@@ -103,36 +104,41 @@ randInt(Engine& engine, Integral min, Integral max)
 }
 
 template <class Integral>
-std::enable_if_t<std::is_integral_v<Integral>, Integral>
+Integral
 randInt(Integral min, Integral max)
+    requires(std::is_integral_v<Integral>)
 {
     return randInt(defaultPrng(), min, max);
 }
 
 template <class Engine, class Integral>
-std::enable_if_t<std::is_integral_v<Integral> && detail::is_engine<Engine>::value, Integral>
+Integral
 randInt(Engine& engine, Integral max)
+    requires(std::is_integral_v<Integral> && detail::is_engine<Engine>::value)
 {
     return randInt(engine, Integral(0), max);
 }
 
 template <class Integral>
-std::enable_if_t<std::is_integral_v<Integral>, Integral>
+Integral
 randInt(Integral max)
+    requires(std::is_integral_v<Integral>)
 {
     return randInt(defaultPrng(), max);
 }
 
 template <class Integral, class Engine>
-std::enable_if_t<std::is_integral_v<Integral> && detail::is_engine<Engine>::value, Integral>
+Integral
 randInt(Engine& engine)
+    requires(std::is_integral_v<Integral> && detail::is_engine<Engine>::value)
 {
     return randInt(engine, std::numeric_limits<Integral>::max());
 }
 
 template <class Integral = int>
-std::enable_if_t<std::is_integral_v<Integral>, Integral>
+Integral
 randInt()
+    requires(std::is_integral_v<Integral>)
 {
     return randInt(defaultPrng(), std::numeric_limits<Integral>::max());
 }
@@ -141,19 +147,20 @@ randInt()
 /** Return a random byte */
 /** @{ */
 template <class Byte, class Engine>
-std::enable_if_t<
-    (std::is_same_v<Byte, unsigned char> || std::is_same_v<Byte, std::uint8_t>) &&
-        detail::is_engine<Engine>::value,
-    Byte>
+Byte
 randByte(Engine& engine)
+    requires(
+        (std::is_same_v<Byte, unsigned char> || std::is_same_v<Byte, std::uint8_t>) &&
+        detail::is_engine<Engine>::value)
 {
     return static_cast<Byte>(randInt<Engine, std::uint32_t>(
         engine, std::numeric_limits<Byte>::min(), std::numeric_limits<Byte>::max()));
 }
 
 template <class Byte = std::uint8_t>
-std::enable_if_t<(std::is_same_v<Byte, unsigned char> || std::is_same_v<Byte, std::uint8_t>), Byte>
+Byte
 randByte()
+    requires(std::is_same_v<Byte, unsigned char> || std::is_same_v<Byte, std::uint8_t>)
 {
     return randByte<Byte>(defaultPrng());
 }

include/xrpl/basics/safe_cast.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/beast/utility/instrumentation.h>  // IWYU pragma: keep
 
 #include <type_traits>
 
@@ -17,8 +17,9 @@ concept SafeToCast = (std::is_integral_v<Src> && std::is_integral_v<Dest>) &&
                                                      : sizeof(Dest) >= sizeof(Src));
 
 template <class Dest, class Src>
-constexpr std::enable_if_t<std::is_integral_v<Dest> && std::is_integral_v<Src>, Dest>
+constexpr Dest
 safeCast(Src s) noexcept
+    requires(std::is_integral_v<Dest> && std::is_integral_v<Src>)
 {
     static_assert(
         std::is_signed_v<Dest> || std::is_unsigned_v<Src>, "Cannot cast signed to unsigned");
@@ -30,15 +31,17 @@ safeCast(Src s) noexcept
 }
 
 template <class Dest, class Src>
-constexpr std::enable_if_t<std::is_enum_v<Dest> && std::is_integral_v<Src>, Dest>
+constexpr Dest
 safeCast(Src s) noexcept
+    requires(std::is_enum_v<Dest> && std::is_integral_v<Src>)
 {
     return static_cast<Dest>(safeCast<std::underlying_type_t<Dest>>(s));
 }
 
 template <class Dest, class Src>
-constexpr std::enable_if_t<std::is_integral_v<Dest> && std::is_enum_v<Src>, Dest>
+constexpr Dest
 safeCast(Src s) noexcept
+    requires(std::is_integral_v<Dest> && std::is_enum_v<Src>)
 {
     return safeCast<Dest>(static_cast<std::underlying_type_t<Src>>(s));
 }
@@ -48,8 +51,9 @@ safeCast(Src s) noexcept
 // underlying types become safe, it can be converted to a safe_cast.
 
 template <class Dest, class Src>
-constexpr std::enable_if_t<std::is_integral_v<Dest> && std::is_integral_v<Src>, Dest>
+constexpr Dest
 unsafeCast(Src s) noexcept
+    requires(std::is_integral_v<Dest> && std::is_integral_v<Src>)
 {
     static_assert(
         !SafeToCast<Src, Dest>,
@@ -59,15 +63,17 @@ unsafeCast(Src s) noexcept
 }
 
 template <class Dest, class Src>
-constexpr std::enable_if_t<std::is_enum_v<Dest> && std::is_integral_v<Src>, Dest>
+constexpr Dest
 unsafeCast(Src s) noexcept
+    requires(std::is_enum_v<Dest> && std::is_integral_v<Src>)
 {
     return static_cast<Dest>(unsafeCast<std::underlying_type_t<Dest>>(s));
 }
 
 template <class Dest, class Src>
-constexpr std::enable_if_t<std::is_integral_v<Dest> && std::is_enum_v<Src>, Dest>
+constexpr Dest
 unsafeCast(Src s) noexcept
+    requires(std::is_integral_v<Dest> && std::is_enum_v<Src>)
 {
     return unsafeCast<Dest>(static_cast<std::underlying_type_t<Src>>(s));
 }

include/xrpl/basics/scope.h

@@ -46,11 +46,9 @@ public:
     operator=(ScopeExit&&) = delete;
 
     template <class EFP>
-    explicit ScopeExit(
-        EFP&& f,
-        std::enable_if_t<
-            !std::is_same_v<std::remove_cv_t<EFP>, ScopeExit> &&
-            std::is_constructible_v<EF, EFP>>* = 0) noexcept
+    explicit ScopeExit(EFP&& f) noexcept
+        requires(
+            !std::is_same_v<std::remove_cv_t<EFP>, ScopeExit> && std::is_constructible_v<EF, EFP>)
         : exitFunction_{std::forward<EFP>(f)}
     {
         static_assert(std::is_nothrow_constructible_v<EF, decltype(std::forward<EFP>(f))>);
@@ -93,11 +91,9 @@ public:
     operator=(ScopeFail&&) = delete;
 
     template <class EFP>
-    explicit ScopeFail(
-        EFP&& f,
-        std::enable_if_t<
-            !std::is_same_v<std::remove_cv_t<EFP>, ScopeFail> &&
-            std::is_constructible_v<EF, EFP>>* = 0) noexcept
+    explicit ScopeFail(EFP&& f) noexcept
+        requires(
+            !std::is_same_v<std::remove_cv_t<EFP>, ScopeFail> && std::is_constructible_v<EF, EFP>)
         : exitFunction_{std::forward<EFP>(f)}
     {
         static_assert(std::is_nothrow_constructible_v<EF, decltype(std::forward<EFP>(f))>);
@@ -140,12 +136,11 @@ public:
     operator=(ScopeSuccess&&) = delete;
 
     template <class EFP>
-    explicit ScopeSuccess(
-        EFP&& f,
-        std::enable_if_t<
+    explicit ScopeSuccess(EFP&& f) noexcept(
+        std::is_nothrow_constructible_v<EF, EFP> || std::is_nothrow_constructible_v<EF, EFP&>)
+        requires(
             !std::is_same_v<std::remove_cv_t<EFP>, ScopeSuccess> &&
-            std::is_constructible_v<EF, EFP>>* =
-            0) noexcept(std::is_nothrow_constructible_v<EF, EFP> || std::is_nothrow_constructible_v<EF, EFP&>)
+            std::is_constructible_v<EF, EFP>)
         : exitFunction_{std::forward<EFP>(f)}
     {
     }

include/xrpl/basics/strHex.h

@@ -3,6 +3,9 @@
 #include <boost/algorithm/hex.hpp>
 #include <boost/endian/conversion.hpp>
 
+#include <iterator>
+#include <string>
+
 namespace xrpl {
 
 template <class FwdIt>

include/xrpl/basics/tagged_integer.h

@@ -7,6 +7,7 @@
 #include <boost/operators.hpp>
 
 #include <iostream>
+#include <string>
 #include <type_traits>
 
 namespace xrpl {
@@ -42,10 +43,10 @@ public:
 
     TaggedInteger() = default;
 
-    template <
-        class OtherInt,
-        class = std::enable_if_t<std::is_integral_v<OtherInt> && sizeof(OtherInt) <= sizeof(Int)>>
-    explicit constexpr TaggedInteger(OtherInt value) noexcept : value_(value)
+    template <class OtherInt>
+    explicit constexpr TaggedInteger(OtherInt value) noexcept
+        requires(std::is_integral_v<OtherInt> && sizeof(OtherInt) <= sizeof(Int))
+        : value_(value)
     {
         static_assert(sizeof(TaggedInteger) == sizeof(Int), "tagged_integer is adding padding");
     }

include/xrpl/beast/asio/io_latency_probe.h

@@ -8,6 +8,7 @@
 
 #include <chrono>
 #include <condition_variable>
+#include <cstddef>
 #include <mutex>
 #include <stdexcept>
 
@@ -18,8 +19,8 @@ template <class Clock>
 class IOLatencyProbe
 {
 private:
-    using duration = typename Clock::duration;
-    using time_point = typename Clock::time_point;
+    using duration = Clock::duration;
+    using time_point = Clock::time_point;
 
     std::recursive_mutex mutex_;
     std::condition_variable_any cond_;

include/xrpl/beast/clock/abstract_clock.h

@@ -34,10 +34,10 @@ template <class Clock>
 class AbstractClock
 {
 public:
-    using rep = typename Clock::rep;
-    using period = typename Clock::period;
-    using duration = typename Clock::duration;
-    using time_point = typename Clock::time_point;
+    using rep = Clock::rep;
+    using period = Clock::period;
+    using duration = Clock::duration;
+    using time_point = Clock::time_point;
     using clock_type = Clock;
 
     static bool const is_steady = Clock::is_steady;  // NOLINT(readability-identifier-naming)

include/xrpl/beast/clock/basic_seconds_clock.h

@@ -20,10 +20,10 @@ public:
 
     explicit BasicSecondsClock() = default;
 
-    using rep = typename Clock::rep;
-    using period = typename Clock::period;
-    using duration = typename Clock::duration;
-    using time_point = typename Clock::time_point;
+    using rep = Clock::rep;
+    using period = Clock::period;
+    using duration = Clock::duration;
+    using time_point = Clock::time_point;
 
     static bool const is_steady =  // NOLINT(readability-identifier-naming)
         Clock::is_steady;

include/xrpl/beast/container/aged_container_utility.h

@@ -3,14 +3,15 @@
 #include <xrpl/beast/container/aged_container.h>
 
 #include <chrono>
-#include <type_traits>
+#include <cstddef>
 
 namespace beast {
 
 /** Expire aged container items past the specified age. */
 template <class AgedContainer, class Rep, class Period>
-std::enable_if_t<IsAgedContainer<AgedContainer>::value, std::size_t>
+std::size_t
 expire(AgedContainer& c, std::chrono::duration<Rep, Period> const& age)
+    requires(IsAgedContainer<AgedContainer>::value)
 {
     std::size_t n(0);
     auto const expired(c.clock().now() - age);

include/xrpl/beast/container/aged_map.h

@@ -5,6 +5,7 @@
 #include <chrono>
 #include <functional>
 #include <memory>
+#include <utility>
 
 namespace beast {
 

include/xrpl/beast/container/aged_multimap.h

@@ -5,6 +5,7 @@
 #include <chrono>
 #include <functional>
 #include <memory>
+#include <utility>
 
 namespace beast {
 

include/xrpl/beast/container/aged_unordered_map.h

@@ -5,6 +5,7 @@
 #include <chrono>
 #include <functional>
 #include <memory>
+#include <utility>
 
 namespace beast {
 

include/xrpl/beast/container/aged_unordered_multimap.h

@@ -5,6 +5,7 @@
 #include <chrono>
 #include <functional>
 #include <memory>
+#include <utility>
 
 namespace beast {
 

include/xrpl/beast/container/detail/aged_container_iterator.h

@@ -16,34 +16,33 @@ template <bool IsConst, class Iterator>
 class AgedContainerIterator
 {
 public:
-    using iterator_category = typename std::iterator_traits<Iterator>::iterator_category;
+    using iterator_category = std::iterator_traits<Iterator>::iterator_category;
     using value_type = std::conditional_t<
         IsConst,
         typename Iterator::value_type::Stashed::value_type const,
         typename Iterator::value_type::Stashed::value_type>;
-    using difference_type = typename std::iterator_traits<Iterator>::difference_type;
+    using difference_type = std::iterator_traits<Iterator>::difference_type;
     using pointer = value_type*;
     using reference = value_type&;
-    using time_point = typename Iterator::value_type::Stashed::time_point;
+    using time_point = Iterator::value_type::Stashed::time_point;
 
     AgedContainerIterator() = default;
 
     // Disable constructing a const_iterator from a non-const_iterator.
     // Converting between reverse and non-reverse iterators should be explicit.
-    template <
-        bool OtherIsConst,
-        class OtherIterator,
-        class = std::enable_if_t<
-            (!OtherIsConst || IsConst) &&
-            !static_cast<bool>(std::is_same_v<Iterator, OtherIterator>)>>
+    template <bool OtherIsConst, class OtherIterator>
     explicit AgedContainerIterator(AgedContainerIterator<OtherIsConst, OtherIterator> const& other)
+        requires(
+            (!OtherIsConst || IsConst) &&
+            !static_cast<bool>(std::is_same_v<Iterator, OtherIterator>))
         : iter_(other.iter_)
     {
     }
 
     // Disable constructing a const_iterator from a non-const_iterator.
-    template <bool OtherIsConst, class = std::enable_if_t<!OtherIsConst || IsConst>>
+    template <bool OtherIsConst>
     AgedContainerIterator(AgedContainerIterator<OtherIsConst, Iterator> const& other)
+        requires(!OtherIsConst || IsConst)
         : iter_(other.iter_)
     {
     }
@@ -52,7 +51,8 @@ public:
     template <bool OtherIsConst, class OtherIterator>
     auto
     operator=(AgedContainerIterator<OtherIsConst, OtherIterator> const& other)
-        -> std::enable_if_t<!OtherIsConst || IsConst, AgedContainerIterator&>
+        -> AgedContainerIterator&
+        requires(!OtherIsConst || IsConst)
     {
         iter_ = other.iter_;
         return *this;

include/xrpl/beast/container/detail/aged_ordered_container.h

@@ -11,9 +11,14 @@
 #include <boost/version.hpp>
 
 #include <algorithm>
+#include <chrono>
+#include <cstddef>
+#include <cstdint>
 #include <functional>
 #include <initializer_list>
 #include <memory>
+#include <stdexcept>
+#include <tuple>
 #include <type_traits>
 #include <utility>
 
@@ -62,8 +67,8 @@ class AgedOrderedContainer
 {
 public:
     using clock_type = AbstractClock<Clock>;
-    using time_point = typename clock_type::time_point;
-    using duration = typename clock_type::duration;
+    using time_point = clock_type::time_point;
+    using duration = clock_type::duration;
     using key_type = Key;
     using mapped_type = T;
     using value_type = std::conditional_t<IsMap, std::pair<Key const, T>, Key>;
@@ -94,8 +99,8 @@ private:
         {
             explicit Stashed() = default;
 
-            using value_type = typename AgedOrderedContainer::value_type;
-            using time_point = typename AgedOrderedContainer::time_point;
+            using value_type = AgedOrderedContainer::value_type;
+            using time_point = AgedOrderedContainer::time_point;
         };
 
         Element(time_point const& when, value_type const& value) : value(value), when(when)
@@ -106,10 +111,9 @@ private:
         {
         }
 
-        template <
-            class... Args,
-            class = std::enable_if_t<std::is_constructible_v<value_type, Args...>>>
+        template <class... Args>
         Element(time_point const& when, Args&&... args)
+            requires(std::is_constructible_v<value_type, Args...>)
             : value(std::forward<Args>(args)...), when(when)
         {
         }
@@ -192,8 +196,8 @@ private:
         }
     };
 
-    using list_type = typename boost::intrusive::
-        make_list<Element, boost::intrusive::constant_time_size<false>>::type;
+    using list_type =
+        boost::intrusive::make_list<Element, boost::intrusive::constant_time_size<false>>::type;
 
     using cont_type = std::conditional_t<
         IsMulti,
@@ -206,8 +210,7 @@ private:
             boost::intrusive::constant_time_size<true>,
             boost::intrusive::compare<KeyValueCompare>>::type>;
 
-    using ElementAllocator =
-        typename std::allocator_traits<Allocator>::template rebind_alloc<Element>;
+    using ElementAllocator = std::allocator_traits<Allocator>::template rebind_alloc<Element>;
 
     using ElementAllocatorTraits = std::allocator_traits<ElementAllocator>;
 
@@ -356,6 +359,7 @@ private:
     deleteElement(Element const* p)
     {
         ElementAllocatorTraits::destroy(config_.alloc(), p);
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast)
         ElementAllocatorTraits::deallocate(config_.alloc(), const_cast<Element*>(p), 1);
     }
 
@@ -373,8 +377,8 @@ public:
     using allocator_type = Allocator;
     using reference = value_type&;
     using const_reference = value_type const&;
-    using pointer = typename std::allocator_traits<Allocator>::pointer;
-    using const_pointer = typename std::allocator_traits<Allocator>::const_pointer;
+    using pointer = std::allocator_traits<Allocator>::pointer;
+    using const_pointer = std::allocator_traits<Allocator>::const_pointer;
 
     // A set iterator (IsMap==false) is always const
     // because the elements of a set are immutable.
@@ -604,35 +608,25 @@ public:
     //
     //--------------------------------------------------------------------------
 
-    template <
-        class K,
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
+    template <class K, bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     std::conditional_t<IsMap, T, void*>&
-    at(K const& k);
+    at(K const& k)
+        requires(MaybeMap && !MaybeMulti);
 
-    template <
-        class K,
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
-    typename std::conditional<IsMap, T, void*>::type const&
-    at(K const& k) const;
+    template <class K, bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
+    std::conditional<IsMap, T, void*>::type const&
+    at(K const& k) const
+        requires(MaybeMap && !MaybeMulti);
 
-    template <
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
+    template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     std::conditional_t<IsMap, T, void*>&
-    operator[](Key const& key);
+    operator[](Key const& key)
+        requires(MaybeMap && !MaybeMulti);
 
-    template <
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
+    template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     std::conditional_t<IsMap, T, void*>&
-    operator[](Key&& key);
+    operator[](Key&& key)
+        requires(MaybeMap && !MaybeMulti);
 
     //--------------------------------------------------------------------------
     //
@@ -766,35 +760,40 @@ public:
     // map, set
     template <bool MaybeMulti = IsMulti>
     auto
-    insert(value_type const& value) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    insert(value_type const& value) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
     auto
-    insert(value_type const& value) -> std::enable_if_t<MaybeMulti, iterator>;
+    insert(value_type const& value) -> iterator
+        requires MaybeMulti;
 
     // set
     template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     auto
-    insert(value_type&& value)
-        -> std::enable_if_t<!MaybeMulti && !MaybeMap, std::pair<iterator, bool>>;
+    insert(value_type&& value) -> std::pair<iterator, bool>
+        requires(!MaybeMulti && !MaybeMap);
 
     // multiset
     template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     auto
-    insert(value_type&& value) -> std::enable_if_t<MaybeMulti && !MaybeMap, iterator>;
+    insert(value_type&& value) -> iterator
+        requires(MaybeMulti && !MaybeMap);
 
     //---
 
     // map, set
     template <bool MaybeMulti = IsMulti>
     auto
-    insert(const_iterator hint, value_type const& value) -> std::enable_if_t<!MaybeMulti, iterator>;
+    insert(const_iterator hint, value_type const& value) -> iterator
+        requires(!MaybeMulti);
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
-    std::enable_if_t<MaybeMulti, iterator>
+    iterator
     insert(const_iterator /*hint*/, value_type const& value)
+        requires MaybeMulti
     {
         // VFALCO TODO Figure out how to utilize 'hint'
         return insert(value);
@@ -803,12 +802,14 @@ public:
     // map, set
     template <bool MaybeMulti = IsMulti>
     auto
-    insert(const_iterator hint, value_type&& value) -> std::enable_if_t<!MaybeMulti, iterator>;
+    insert(const_iterator hint, value_type&& value) -> iterator
+        requires(!MaybeMulti);
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
-    std::enable_if_t<MaybeMulti, iterator>
+    iterator
     insert(const_iterator /*hint*/, value_type&& value)
+        requires MaybeMulti
     {
         // VFALCO TODO Figure out how to utilize 'hint'
         return insert(std::move(value));
@@ -816,20 +817,18 @@ public:
 
     // map, multimap
     template <class P, bool MaybeMap = IsMap>
-    std::enable_if_t<
-        MaybeMap && std::is_constructible_v<value_type, P&&>,
-        std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>>
+    std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>
     insert(P&& value)
+        requires(MaybeMap && std::is_constructible_v<value_type, P &&>)
     {
         return emplace(std::forward<P>(value));
     }
 
     // map, multimap
     template <class P, bool MaybeMap = IsMap>
-    std::enable_if_t<
-        MaybeMap && std::is_constructible_v<value_type, P&&>,
-        std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>>
+    std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>
     insert(const_iterator hint, P&& value)
+        requires(MaybeMap && std::is_constructible_v<value_type, P &&>)
     {
         return emplaceHint(hint, std::forward<P>(value));
     }
@@ -851,46 +850,45 @@ public:
     // map, set
     template <bool MaybeMulti = IsMulti, class... Args>
     auto
-    emplace(Args&&... args) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    emplace(Args&&... args) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multiset, multimap
     template <bool MaybeMulti = IsMulti, class... Args>
     auto
-    emplace(Args&&... args) -> std::enable_if_t<MaybeMulti, iterator>;
+    emplace(Args&&... args) -> iterator
+        requires MaybeMulti;
 
     // map, set
     template <bool MaybeMulti = IsMulti, class... Args>
     auto
-    emplaceHint(const_iterator hint, Args&&... args)
-        -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    emplaceHint(const_iterator hint, Args&&... args) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multiset, multimap
     template <bool MaybeMulti = IsMulti, class... Args>
-    std::enable_if_t<MaybeMulti, iterator>
+    iterator
     emplaceHint(const_iterator /*hint*/, Args&&... args)
+        requires MaybeMulti
     {
         // VFALCO TODO Figure out how to utilize 'hint'
         return emplace<MaybeMulti>(std::forward<Args>(args)...);
     }
 
-    // enable_if prevents erase (reverse_iterator pos) from compiling
-    template <
-        bool IsConst,
-        class Iterator,
-        class = std::enable_if_t<!IsBoostReverseIterator<Iterator>::value>>
+    // The constraint prevents erase (reverse_iterator pos) from compiling
+    template <bool IsConst, class Iterator>
     beast::detail::AgedContainerIterator<false, Iterator>
-    erase(beast::detail::AgedContainerIterator<IsConst, Iterator> pos);
+    erase(beast::detail::AgedContainerIterator<IsConst, Iterator> pos)
+        requires(!IsBoostReverseIterator<Iterator>::value);
 
-    // enable_if prevents erase (reverse_iterator first, reverse_iterator last)
+    // The constraint prevents erase (reverse_iterator first, reverse_iterator last)
     // from compiling
-    template <
-        bool IsConst,
-        class Iterator,
-        class = std::enable_if_t<!IsBoostReverseIterator<Iterator>::value>>
+    template <bool IsConst, class Iterator>
     beast::detail::AgedContainerIterator<false, Iterator>
     erase(
         beast::detail::AgedContainerIterator<IsConst, Iterator> first,
-        beast::detail::AgedContainerIterator<IsConst, Iterator> last);
+        beast::detail::AgedContainerIterator<IsConst, Iterator> last)
+        requires(!IsBoostReverseIterator<Iterator>::value);
 
     template <class K>
     auto
@@ -901,13 +899,11 @@ public:
 
     //--------------------------------------------------------------------------
 
-    // enable_if prevents touch (reverse_iterator pos) from compiling
-    template <
-        bool IsConst,
-        class Iterator,
-        class = std::enable_if_t<!IsBoostReverseIterator<Iterator>::value>>
+    // The constraint prevents touch (reverse_iterator pos) from compiling
+    template <bool IsConst, class Iterator>
     void
     touch(beast::detail::AgedContainerIterator<IsConst, Iterator> pos)
+        requires(!IsBoostReverseIterator<Iterator>::value)
     {
         touch(pos, clock().now());
     }
@@ -1138,25 +1134,25 @@ public:
     }
 
 private:
-    // enable_if prevents erase (reverse_iterator pos, now) from compiling
-    template <
-        bool IsConst,
-        class Iterator,
-        class = std::enable_if_t<!IsBoostReverseIterator<Iterator>::value>>
+    // The constraint prevents erase (reverse_iterator pos, now) from compiling
+    template <bool IsConst, class Iterator>
     void
     touch(
         beast::detail::AgedContainerIterator<IsConst, Iterator> pos,
-        typename clock_type::time_point const& now);
+        clock_type::time_point const& now)
+        requires(!IsBoostReverseIterator<Iterator>::value);
 
     template <
         bool MaybePropagate = std::allocator_traits<Allocator>::propagate_on_container_swap::value>
-    std::enable_if_t<MaybePropagate>
-    swapData(AgedOrderedContainer& other) noexcept;
+    void
+    swapData(AgedOrderedContainer& other) noexcept
+        requires MaybePropagate;
 
     template <
         bool MaybePropagate = std::allocator_traits<Allocator>::propagate_on_container_swap::value>
-    std::enable_if_t<!MaybePropagate>
-    swapData(AgedOrderedContainer& other) noexcept;
+    void
+    swapData(AgedOrderedContainer& other) noexcept
+        requires(!MaybePropagate);
 
 private:
     ConfigT config_;
@@ -1248,12 +1244,7 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::AgedOrd
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::AgedOrderedContainer(
     AgedOrderedContainer const& other)
-    : config_(other.config_)
-#if BOOST_VERSION >= 108000
-    , cont_(other.cont_.get_comp())
-#else
-    , cont_(other.cont_.comp())
-#endif
+    : config_(other.config_), cont_(other.cont_.get_comp())
 {
     insert(other.cbegin(), other.cend());
 }
@@ -1262,12 +1253,7 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::AgedOrderedContainer(
     AgedOrderedContainer const& other,
     Allocator const& alloc)
-    : config_(other.config_, alloc)
-#if BOOST_VERSION >= 108000
-    , cont_(other.cont_.get_comp())
-#else
-    , cont_(other.cont_.comp())
-#endif
+    : config_(other.config_, alloc), cont_(other.cont_.get_comp())
 {
     insert(other.cbegin(), other.cend());
 }
@@ -1284,13 +1270,7 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::AgedOrderedContainer(
     AgedOrderedContainer&& other,  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
     Allocator const& alloc)
-    : config_(std::move(other.config_), alloc)
-#if BOOST_VERSION >= 108000
-    , cont_(std::move(other.cont_.get_comp()))
-#else
-    , cont_(std::move(other.cont_.comp()))
-#endif
-
+    : config_(std::move(other.config_), alloc), cont_(std::move(other.cont_.get_comp()))
 {
     insert(other.cbegin(), other.cend());
     other.clear();
@@ -1381,9 +1361,10 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::operato
 //------------------------------------------------------------------------------
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <class K, bool MaybeMulti, bool MaybeMap, class>
+template <class K, bool MaybeMulti, bool MaybeMap>
 std::conditional_t<IsMap, T, void*>&
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::at(K const& k)
+    requires(MaybeMap && !MaybeMulti)
 {
     auto const iter(cont_.find(k, std::cref(config_.keyCompare())));
     if (iter == cont_.end())
@@ -1392,9 +1373,10 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::at(K co
 }
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <class K, bool MaybeMulti, bool MaybeMap, class>
-typename std::conditional<IsMap, T, void*>::type const&
+template <class K, bool MaybeMulti, bool MaybeMap>
+std::conditional<IsMap, T, void*>::type const&
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::at(K const& k) const
+    requires(MaybeMap && !MaybeMulti)
 {
     auto const iter(cont_.find(k, std::cref(config_.keyCompare())));
     if (iter == cont_.end())
@@ -1403,9 +1385,10 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::at(K co
 }
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <bool MaybeMulti, bool MaybeMap, class>
+template <bool MaybeMulti, bool MaybeMap>
 std::conditional_t<IsMap, T, void*>&
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::operator[](Key const& key)
+    requires(MaybeMap && !MaybeMulti)
 {
     typename cont_type::insert_commit_data d;
     auto const result(cont_.insert_check(key, std::cref(config_.keyCompare()), d));
@@ -1421,9 +1404,10 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::operato
 }
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <bool MaybeMulti, bool MaybeMap, class>
+template <bool MaybeMulti, bool MaybeMap>
 std::conditional_t<IsMap, T, void*>&
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::operator[](Key&& key)
+    requires(MaybeMap && !MaybeMulti)
 {
     typename cont_type::insert_commit_data d;
     auto const result(cont_.insert_check(key, std::cref(config_.keyCompare()), d));
@@ -1457,7 +1441,8 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 template <bool MaybeMulti>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::insert(
-    value_type const& value) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    value_type const& value) -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     typename cont_type::insert_commit_data d;
     auto const result(cont_.insert_check(extract(value), std::cref(config_.keyCompare()), d));
@@ -1476,7 +1461,8 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 template <bool MaybeMulti>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::insert(
-    value_type const& value) -> std::enable_if_t<MaybeMulti, iterator>
+    value_type const& value) -> iterator
+    requires MaybeMulti
 {
     auto const before(cont_.upper_bound(extract(value), std::cref(config_.keyCompare())));
     Element* const p(newElement(value));
@@ -1490,7 +1476,8 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 template <bool MaybeMulti, bool MaybeMap>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::insert(value_type&& value)
-    -> std::enable_if_t<!MaybeMulti && !MaybeMap, std::pair<iterator, bool>>
+    -> std::pair<iterator, bool>
+    requires(!MaybeMulti && !MaybeMap)
 {
     typename cont_type::insert_commit_data d;
     auto const result(cont_.insert_check(extract(value), std::cref(config_.keyCompare()), d));
@@ -1509,7 +1496,8 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 template <bool MaybeMulti, bool MaybeMap>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::insert(value_type&& value)
-    -> std::enable_if_t<MaybeMulti && !MaybeMap, iterator>
+    -> iterator
+    requires(MaybeMulti && !MaybeMap)
 {
     auto const before(cont_.upper_bound(extract(value), std::cref(config_.keyCompare())));
     Element* const p(newElement(std::move(value)));
@@ -1526,7 +1514,8 @@ template <bool MaybeMulti>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::insert(
     const_iterator hint,
-    value_type const& value) -> std::enable_if_t<!MaybeMulti, iterator>
+    value_type const& value) -> iterator
+    requires(!MaybeMulti)
 {
     typename cont_type::insert_commit_data d;
     auto const result(
@@ -1547,7 +1536,8 @@ template <bool MaybeMulti>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::insert(
     const_iterator hint,
-    value_type&& value) -> std::enable_if_t<!MaybeMulti, iterator>
+    value_type&& value) -> iterator
+    requires(!MaybeMulti)
 {
     typename cont_type::insert_commit_data d;
     auto const result(
@@ -1567,7 +1557,8 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 template <bool MaybeMulti, class... Args>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::emplace(Args&&... args)
-    -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     // VFALCO NOTE Its unfortunate that we need to
     //             construct element here
@@ -1589,7 +1580,8 @@ template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compa
 template <bool MaybeMulti, class... Args>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::emplace(Args&&... args)
-    -> std::enable_if_t<MaybeMulti, iterator>
+    -> iterator
+    requires MaybeMulti
 {
     Element* const p(newElement(std::forward<Args>(args)...));
     auto const before(cont_.upper_bound(extract(p->value), std::cref(config_.keyCompare())));
@@ -1604,7 +1596,8 @@ template <bool MaybeMulti, class... Args>
 auto
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::emplaceHint(
     const_iterator hint,
-    Args&&... args) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    Args&&... args) -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     // VFALCO NOTE Its unfortunate that we need to
     //             construct element here
@@ -1623,21 +1616,23 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::emplace
 }
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <bool IsConst, class Iterator, class>
+template <bool IsConst, class Iterator>
 beast::detail::AgedContainerIterator<false, Iterator>
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::erase(
     beast::detail::AgedContainerIterator<IsConst, Iterator> pos)
+    requires(!IsBoostReverseIterator<Iterator>::value)
 {
     unlinkAndDeleteElement(&*((pos++).iterator()));
     return beast::detail::AgedContainerIterator<false, Iterator>(pos.iterator());
 }
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <bool IsConst, class Iterator, class>
+template <bool IsConst, class Iterator>
 beast::detail::AgedContainerIterator<false, Iterator>
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::erase(
     beast::detail::AgedContainerIterator<IsConst, Iterator> first,
     beast::detail::AgedContainerIterator<IsConst, Iterator> last)
+    requires(!IsBoostReverseIterator<Iterator>::value)
 {
     for (; first != last;)
         unlinkAndDeleteElement(&*((first++).iterator()));
@@ -1732,7 +1727,7 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::operato
         cend(),
         other.cbegin(),
         other.cend(),
-        [&eq, &other](value_type const& lhs, typename Other::value_type const& rhs) {
+        [&eq, &other](value_type const& lhs, Other::value_type const& rhs) {
             return eq(extract(lhs), other.extract(rhs));
         });
 }
@@ -1740,11 +1735,12 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::operato
 //------------------------------------------------------------------------------
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
-template <bool IsConst, class Iterator, class>
+template <bool IsConst, class Iterator>
 void
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::touch(
     beast::detail::AgedContainerIterator<IsConst, Iterator> pos,
-    typename clock_type::time_point const& now)
+    clock_type::time_point const& now)
+    requires(!IsBoostReverseIterator<Iterator>::value)
 {
     auto& e(*pos.iterator());
     e.when = now;
@@ -1754,9 +1750,10 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::touch(
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
 template <bool MaybePropagate>
-std::enable_if_t<MaybePropagate>
+void
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::swapData(
     AgedOrderedContainer& other) noexcept
+    requires MaybePropagate
 {
     std::swap(config_.keyCompare(), other.config_.keyCompare());
     std::swap(config_.alloc(), other.config_.alloc());
@@ -1765,9 +1762,10 @@ AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::swapDat
 
 template <bool IsMulti, bool IsMap, class Key, class T, class Clock, class Compare, class Allocator>
 template <bool MaybePropagate>
-std::enable_if_t<!MaybePropagate>
+void
 AgedOrderedContainer<IsMulti, IsMap, Key, T, Clock, Compare, Allocator>::swapData(
     AgedOrderedContainer& other) noexcept
+    requires(!MaybePropagate)
 {
     std::swap(config_.keyCompare(), other.config_.keyCompare());
     std::swap(config_.clock, other.config_.clock);

include/xrpl/beast/container/detail/aged_unordered_container.h

@@ -10,13 +10,19 @@
 #include <boost/intrusive/unordered_set.hpp>
 
 #include <algorithm>
+#include <chrono>
 #include <cmath>
+#include <cstddef>
+#include <cstdint>
 #include <functional>
 #include <initializer_list>
 #include <iterator>
 #include <memory>
+#include <stdexcept>
+#include <tuple>
 #include <type_traits>
 #include <utility>
+#include <vector>
 
 /*
 
@@ -67,8 +73,8 @@ class AgedUnorderedContainer
 {
 public:
     using clock_type = AbstractClock<Clock>;
-    using time_point = typename clock_type::time_point;
-    using duration = typename clock_type::duration;
+    using time_point = clock_type::time_point;
+    using duration = clock_type::duration;
     using key_type = Key;
     using mapped_type = T;
     using value_type = std::conditional_t<IsMap, std::pair<Key const, T>, Key>;
@@ -99,8 +105,8 @@ private:
         {
             explicit Stashed() = default;
 
-            using value_type = typename AgedUnorderedContainer::value_type;
-            using time_point = typename AgedUnorderedContainer::time_point;
+            using value_type = AgedUnorderedContainer::value_type;
+            using time_point = AgedUnorderedContainer::time_point;
         };
 
         Element(time_point const& when, value_type const& value) : value(value), when(when)
@@ -111,10 +117,9 @@ private:
         {
         }
 
-        template <
-            class... Args,
-            class = std::enable_if_t<std::is_constructible_v<value_type, Args...>>>
+        template <class... Args>
         Element(time_point const& when, Args&&... args)
+            requires(std::is_constructible_v<value_type, Args...>)
             : value(std::forward<Args>(args)...), when(when)
         {
         }
@@ -201,8 +206,8 @@ private:
         }
     };
 
-    using list_type = typename boost::intrusive::
-        make_list<Element, boost::intrusive::constant_time_size<false>>::type;
+    using list_type =
+        boost::intrusive::make_list<Element, boost::intrusive::constant_time_size<false>>::type;
 
     using cont_type = std::conditional_t<
         IsMulti,
@@ -219,16 +224,14 @@ private:
             boost::intrusive::equal<KeyValueEqual>,
             boost::intrusive::cache_begin<true>>::type>;
 
-    using bucket_type = typename cont_type::bucket_type;
-    using bucket_traits = typename cont_type::bucket_traits;
+    using bucket_type = cont_type::bucket_type;
+    using bucket_traits = cont_type::bucket_traits;
 
-    using ElementAllocator =
-        typename std::allocator_traits<Allocator>::template rebind_alloc<Element>;
+    using ElementAllocator = std::allocator_traits<Allocator>::template rebind_alloc<Element>;
 
     using ElementAllocatorTraits = std::allocator_traits<ElementAllocator>;
 
-    using BucketAllocator =
-        typename std::allocator_traits<Allocator>::template rebind_alloc<Element>;
+    using BucketAllocator = std::allocator_traits<Allocator>::template rebind_alloc<Element>;
 
     using BucketAllocatorTraits = std::allocator_traits<BucketAllocator>;
 
@@ -525,6 +528,7 @@ private:
     deleteElement(Element const* p)
     {
         ElementAllocatorTraits::destroy(config_.alloc(), p);
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast)
         ElementAllocatorTraits::deallocate(config_.alloc(), const_cast<Element*>(p), 1);
     }
 
@@ -542,8 +546,8 @@ public:
     using allocator_type = Allocator;
     using reference = value_type&;
     using const_reference = value_type const&;
-    using pointer = typename std::allocator_traits<Allocator>::pointer;
-    using const_pointer = typename std::allocator_traits<Allocator>::const_pointer;
+    using pointer = std::allocator_traits<Allocator>::pointer;
+    using const_pointer = std::allocator_traits<Allocator>::const_pointer;
 
     // A set iterator (IsMap==false) is always const
     // because the elements of a set are immutable.
@@ -837,35 +841,25 @@ public:
     //
     //--------------------------------------------------------------------------
 
-    template <
-        class K,
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
+    template <class K, bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     std::conditional_t<IsMap, T, void*>&
-    at(K const& k);
+    at(K const& k)
+        requires(MaybeMap && !MaybeMulti);
 
-    template <
-        class K,
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
-    typename std::conditional<IsMap, T, void*>::type const&
-    at(K const& k) const;
+    template <class K, bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
+    std::conditional<IsMap, T, void*>::type const&
+    at(K const& k) const
+        requires(MaybeMap && !MaybeMulti);
 
-    template <
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
+    template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     std::conditional_t<IsMap, T, void*>&
-    operator[](Key const& key);
+    operator[](Key const& key)
+        requires(MaybeMap && !MaybeMulti);
 
-    template <
-        bool MaybeMulti = IsMulti,
-        bool MaybeMap = IsMap,
-        class = std::enable_if_t<MaybeMap && !MaybeMulti>>
+    template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     std::conditional_t<IsMap, T, void*>&
-    operator[](Key&& key);
+    operator[](Key&& key)
+        requires(MaybeMap && !MaybeMulti);
 
     //--------------------------------------------------------------------------
     //
@@ -963,28 +957,32 @@ public:
     // map, set
     template <bool MaybeMulti = IsMulti>
     auto
-    insert(value_type const& value) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    insert(value_type const& value) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
     auto
-    insert(value_type const& value) -> std::enable_if_t<MaybeMulti, iterator>;
+    insert(value_type const& value) -> iterator
+        requires MaybeMulti;
 
     // map, set
     template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     auto
-    insert(value_type&& value)
-        -> std::enable_if_t<!MaybeMulti && !MaybeMap, std::pair<iterator, bool>>;
+    insert(value_type&& value) -> std::pair<iterator, bool>
+        requires(!MaybeMulti && !MaybeMap);
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti, bool MaybeMap = IsMap>
     auto
-    insert(value_type&& value) -> std::enable_if_t<MaybeMulti && !MaybeMap, iterator>;
+    insert(value_type&& value) -> iterator
+        requires(MaybeMulti && !MaybeMap);
 
     // map, set
     template <bool MaybeMulti = IsMulti>
-    std::enable_if_t<!MaybeMulti, iterator>
+    iterator
     insert(const_iterator /*hint*/, value_type const& value)
+        requires(!MaybeMulti)
     {
         // Hint is ignored but we provide the interface so
         // callers may use ordered and unordered interchangeably.
@@ -993,8 +991,9 @@ public:
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
-    std::enable_if_t<MaybeMulti, iterator>
+    iterator
     insert(const_iterator /*hint*/, value_type const& value)
+        requires MaybeMulti
     {
         // VFALCO TODO The hint could be used to let
         //             the client order equal ranges
@@ -1003,8 +1002,9 @@ public:
 
     // map, set
     template <bool MaybeMulti = IsMulti>
-    std::enable_if_t<!MaybeMulti, iterator>
+    iterator
     insert(const_iterator /*hint*/, value_type&& value)
+        requires(!MaybeMulti)
     {
         // Hint is ignored but we provide the interface so
         // callers may use ordered and unordered interchangeably.
@@ -1013,8 +1013,9 @@ public:
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
-    std::enable_if_t<MaybeMulti, iterator>
+    iterator
     insert(const_iterator /*hint*/, value_type&& value)
+        requires MaybeMulti
     {
         // VFALCO TODO The hint could be used to let
         //             the client order equal ranges
@@ -1023,20 +1024,18 @@ public:
 
     // map, multimap
     template <class P, bool MaybeMap = IsMap>
-    std::enable_if_t<
-        MaybeMap && std::is_constructible_v<value_type, P&&>,
-        std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>>
+    std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>
     insert(P&& value)
+        requires(MaybeMap && std::is_constructible_v<value_type, P &&>)
     {
         return emplace(std::forward<P>(value));
     }
 
     // map, multimap
     template <class P, bool MaybeMap = IsMap>
-    std::enable_if_t<
-        MaybeMap && std::is_constructible_v<value_type, P&&>,
-        std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>>
+    std::conditional_t<IsMulti, iterator, std::pair<iterator, bool>>
     insert(const_iterator hint, P&& value)
+        requires(MaybeMap && std::is_constructible_v<value_type, P &&>)
     {
         return emplaceHint(hint, std::forward<P>(value));
     }
@@ -1057,23 +1056,26 @@ public:
     // set, map
     template <bool MaybeMulti = IsMulti, class... Args>
     auto
-    emplace(Args&&... args) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    emplace(Args&&... args) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multiset, multimap
     template <bool MaybeMulti = IsMulti, class... Args>
     auto
-    emplace(Args&&... args) -> std::enable_if_t<MaybeMulti, iterator>;
+    emplace(Args&&... args) -> iterator
+        requires MaybeMulti;
 
     // set, map
     template <bool MaybeMulti = IsMulti, class... Args>
     auto
-    emplaceHint(const_iterator /*hint*/, Args&&... args)
-        -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    emplaceHint(const_iterator /*hint*/, Args&&... args) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multiset, multimap
     template <bool MaybeMulti = IsMulti, class... Args>
-    std::enable_if_t<MaybeMulti, iterator>
+    iterator
     emplaceHint(const_iterator /*hint*/, Args&&... args)
+        requires MaybeMulti
     {
         // VFALCO TODO The hint could be used for multi, to let
         //             the client order equal ranges
@@ -1304,7 +1306,7 @@ public:
         class OtherHash,
         class OtherAllocator,
         bool MaybeMulti = IsMulti>
-    std::enable_if_t<!MaybeMulti, bool>
+    bool
     operator==(AgedUnorderedContainer<
                false,
                OtherIsMap,
@@ -1313,7 +1315,8 @@ public:
                OtherDuration,
                OtherHash,
                KeyEqual,
-               OtherAllocator> const& other) const;
+               OtherAllocator> const& other) const
+        requires(!MaybeMulti);
 
     template <
         bool OtherIsMap,
@@ -1323,7 +1326,7 @@ public:
         class OtherHash,
         class OtherAllocator,
         bool MaybeMulti = IsMulti>
-    std::enable_if_t<MaybeMulti, bool>
+    bool
     operator==(AgedUnorderedContainer<
                true,
                OtherIsMap,
@@ -1332,7 +1335,8 @@ public:
                OtherDuration,
                OtherHash,
                KeyEqual,
-               OtherAllocator> const& other) const;
+               OtherAllocator> const& other) const
+        requires MaybeMulti;
 
     template <
         bool OtherIsMulti,
@@ -1377,13 +1381,14 @@ private:
     // map, set
     template <bool MaybeMulti = IsMulti>
     auto
-    insertUnchecked(value_type const& value)
-        -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>;
+    insertUnchecked(value_type const& value) -> std::pair<iterator, bool>
+        requires(!MaybeMulti);
 
     // multimap, multiset
     template <bool MaybeMulti = IsMulti>
     auto
-    insertUnchecked(value_type const& value) -> std::enable_if_t<MaybeMulti, iterator>;
+    insertUnchecked(value_type const& value) -> iterator
+        requires MaybeMulti;
 
     template <class InputIt>
     void
@@ -1414,7 +1419,7 @@ private:
     void
     touch(
         beast::detail::AgedContainerIterator<IsConst, Iterator> pos,
-        typename clock_type::time_point const& now)
+        clock_type::time_point const& now)
     {
         auto& e(*pos.iterator());
         e.when = now;
@@ -1424,8 +1429,9 @@ private:
 
     template <
         bool MaybePropagate = std::allocator_traits<Allocator>::propagate_on_container_swap::value>
-    std::enable_if_t<MaybePropagate>
+    void
     swapData(AgedUnorderedContainer& other) noexcept
+        requires MaybePropagate
     {
         std::swap(config_.hashFunction(), other.config_.hashFunction());
         std::swap(config_.keyEq(), other.config_.keyEq());
@@ -1435,8 +1441,9 @@ private:
 
     template <
         bool MaybePropagate = std::allocator_traits<Allocator>::propagate_on_container_swap::value>
-    std::enable_if_t<!MaybePropagate>
+    void
     swapData(AgedUnorderedContainer& other) noexcept
+        requires(!MaybePropagate)
     {
         std::swap(config_.hashFunction(), other.config_.hashFunction());
         std::swap(config_.keyEq(), other.config_.keyEq());
@@ -2090,9 +2097,10 @@ template <
     class Hash,
     class KeyEqual,
     class Allocator>
-template <class K, bool MaybeMulti, bool MaybeMap, class>
+template <class K, bool MaybeMulti, bool MaybeMap>
 std::conditional_t<IsMap, T, void*>&
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::at(K const& k)
+    requires(MaybeMap && !MaybeMulti)
 {
     auto const iter(
         cont_.find(k, std::cref(config_.hashFunction()), std::cref(config_.keyValueEqual())));
@@ -2110,10 +2118,11 @@ template <
     class Hash,
     class KeyEqual,
     class Allocator>
-template <class K, bool MaybeMulti, bool MaybeMap, class>
-typename std::conditional<IsMap, T, void*>::type const&
+template <class K, bool MaybeMulti, bool MaybeMap>
+std::conditional<IsMap, T, void*>::type const&
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::at(
     K const& k) const
+    requires(MaybeMap && !MaybeMulti)
 {
     auto const iter(
         cont_.find(k, std::cref(config_.hashFunction()), std::cref(config_.keyValueEqual())));
@@ -2131,10 +2140,11 @@ template <
     class Hash,
     class KeyEqual,
     class Allocator>
-template <bool MaybeMulti, bool MaybeMap, class>
+template <bool MaybeMulti, bool MaybeMap>
 std::conditional_t<IsMap, T, void*>&
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator[](
     Key const& key)
+    requires(MaybeMap && !MaybeMulti)
 {
     maybeRehash(1);
     typename cont_type::insert_commit_data d;
@@ -2160,10 +2170,11 @@ template <
     class Hash,
     class KeyEqual,
     class Allocator>
-template <bool MaybeMulti, bool MaybeMap, class>
+template <bool MaybeMulti, bool MaybeMap>
 std::conditional_t<IsMap, T, void*>&
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator[](
     Key&& key)
+    requires(MaybeMap && !MaybeMulti)
 {
     maybeRehash(1);
     typename cont_type::insert_commit_data d;
@@ -2216,7 +2227,8 @@ template <
 template <bool MaybeMulti>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
-    value_type const& value) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    value_type const& value) -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     maybeRehash(1);
     typename cont_type::insert_commit_data d;
@@ -2245,7 +2257,8 @@ template <
 template <bool MaybeMulti>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
-    value_type const& value) -> std::enable_if_t<MaybeMulti, iterator>
+    value_type const& value) -> iterator
+    requires MaybeMulti
 {
     maybeRehash(1);
     Element* const p(newElement(value));
@@ -2267,7 +2280,8 @@ template <
 template <bool MaybeMulti, bool MaybeMap>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
-    value_type&& value) -> std::enable_if_t<!MaybeMulti && !MaybeMap, std::pair<iterator, bool>>
+    value_type&& value) -> std::pair<iterator, bool>
+    requires(!MaybeMulti && !MaybeMap)
 {
     maybeRehash(1);
     typename cont_type::insert_commit_data d;
@@ -2296,7 +2310,8 @@ template <
 template <bool MaybeMulti, bool MaybeMap>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
-    value_type&& value) -> std::enable_if_t<MaybeMulti && !MaybeMap, iterator>
+    value_type&& value) -> iterator
+    requires(MaybeMulti && !MaybeMap)
 {
     maybeRehash(1);
     Element* const p(newElement(std::move(value)));
@@ -2305,7 +2320,6 @@ AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>
     return iterator(iter);
 }
 
-#if 1  // Use insert() instead of insert_check() insert_commit()
 // set, map
 template <
     bool IsMulti,
@@ -2319,7 +2333,8 @@ template <
 template <bool MaybeMulti, class... Args>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace(
-    Args&&... args) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    Args&&... args) -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     maybeRehash(1);
     // VFALCO NOTE Its unfortunate that we need to
@@ -2334,42 +2349,6 @@ AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>
     deleteElement(p);
     return std::make_pair(iterator(result.first), false);
 }
-#else   // As original, use insert_check() / insert_commit () pair.
-// set, map
-template <
-    bool IsMulti,
-    bool IsMap,
-    class Key,
-    class T,
-    class Clock,
-    class Hash,
-    class KeyEqual,
-    class Allocator>
-template <bool maybe_multi, class... Args>
-auto
-AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace(
-    Args&&... args) -> typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type
-{
-    maybe_rehash(1);
-    // VFALCO NOTE Its unfortunate that we need to
-    //             construct element here
-    element* const p(new_element(std::forward<Args>(args)...));
-    typename cont_type::insert_commit_data d;
-    auto const result(m_cont.insert_check(
-        extract(p->value),
-        std::cref(m_config.hashFunction()),
-        std::cref(m_config.keyValueEqual()),
-        d));
-    if (result.second)
-    {
-        auto const iter(m_cont.insert_commit(*p, d));
-        chronological.list.push_back(*p);
-        return std::make_pair(iterator(iter), true);
-    }
-    delete_element(p);
-    return std::make_pair(iterator(result.first), false);
-}
-#endif  // 0
 
 // multiset, multimap
 template <
@@ -2384,7 +2363,8 @@ template <
 template <bool MaybeMulti, class... Args>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace(
-    Args&&... args) -> std::enable_if_t<MaybeMulti, iterator>
+    Args&&... args) -> iterator
+    requires MaybeMulti
 {
     maybeRehash(1);
     Element* const p(newElement(std::forward<Args>(args)...));
@@ -2407,7 +2387,8 @@ template <bool MaybeMulti, class... Args>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplaceHint(
     const_iterator /*hint*/,
-    Args&&... args) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    Args&&... args) -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     maybeRehash(1);
     // VFALCO NOTE Its unfortunate that we need to
@@ -2558,7 +2539,7 @@ template <
     class OtherHash,
     class OtherAllocator,
     bool MaybeMulti>
-std::enable_if_t<!MaybeMulti, bool>
+bool
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator==(
     AgedUnorderedContainer<
         false,
@@ -2569,6 +2550,7 @@ AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>
         OtherHash,
         KeyEqual,
         OtherAllocator> const& other) const
+    requires(!MaybeMulti)
 {
     if (size() != other.size())
         return false;
@@ -2598,7 +2580,7 @@ template <
     class OtherHash,
     class OtherAllocator,
     bool MaybeMulti>
-std::enable_if_t<MaybeMulti, bool>
+bool
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator==(
     AgedUnorderedContainer<
         true,
@@ -2609,6 +2591,7 @@ AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>
         OtherHash,
         KeyEqual,
         OtherAllocator> const& other) const
+    requires MaybeMulti
 {
     if (size() != other.size())
         return false;
@@ -2645,7 +2628,8 @@ template <
 template <bool MaybeMulti>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insertUnchecked(
-    value_type const& value) -> std::enable_if_t<!MaybeMulti, std::pair<iterator, bool>>
+    value_type const& value) -> std::pair<iterator, bool>
+    requires(!MaybeMulti)
 {
     typename cont_type::insert_commit_data d;
     auto const result(cont_.insert_check(
@@ -2673,7 +2657,8 @@ template <
 template <bool MaybeMulti>
 auto
 AgedUnorderedContainer<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insertUnchecked(
-    value_type const& value) -> std::enable_if_t<MaybeMulti, iterator>
+    value_type const& value) -> iterator
+    requires MaybeMulti
 {
     Element* const p(newElement(value));
     chronological.list_.push_back(*p);

include/xrpl/beast/core/CurrentThreadName.h

@@ -6,6 +6,7 @@
 
 #include <boost/predef.h>
 
+#include <cstddef>
 #include <string>
 #include <string_view>
 

include/xrpl/beast/core/LexicalCast.h

@@ -5,11 +5,12 @@
 #include <boost/core/detail/string_view.hpp>
 
 #include <algorithm>
-#include <cerrno>
+#include <cctype>
 #include <charconv>
-#include <cstdlib>
 #include <iterator>
 #include <string>
+#include <string_view>
+#include <system_error>
 #include <type_traits>
 #include <typeinfo>
 
@@ -28,16 +29,18 @@ struct LexicalCast<std::string, In>
     explicit LexicalCast() = default;
 
     template <class Arithmetic = In>
-    std::enable_if_t<std::is_arithmetic_v<Arithmetic>, bool>
+    bool
     operator()(std::string& out, Arithmetic in)
+        requires(std::is_arithmetic_v<Arithmetic>)
     {
         out = std::to_string(in);
         return true;
     }
 
     template <class Enumeration = In>
-    std::enable_if_t<std::is_enum_v<Enumeration>, bool>
+    bool
     operator()(std::string& out, Enumeration in)
+        requires(std::is_enum_v<Enumeration>)
     {
         out = std::to_string(static_cast<std::underlying_type_t<Enumeration>>(in));
         return true;
@@ -55,8 +58,9 @@ struct LexicalCast<Out, std::string_view>
         "beast::LexicalCast can only be used with integral types");
 
     template <class Integral = Out>
-    std::enable_if_t<std::is_integral_v<Integral> && !std::is_same_v<Integral, bool>, bool>
+    bool
     operator()(Integral& out, std::string_view in) const
+        requires(std::is_integral_v<Integral> && !std::is_same_v<Integral, bool>)
     {
         auto first = in.data();
         auto last = in.data() + in.size();