diag(noalias): the last six contracts of the audit; waterFillRecallShares takes the buffer form (309 → 301)

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Follow-up to #200 (the macro) and #201 (the first 15 guards): the six rows of the audit's apply list that were waiting on #200 to be on main or on files other lanes owned.

row	file	symbol	guard	why
A1	src/recall.h	waterFillRecallShares	VERIFY_NO_ALIAS_BUF( demand, alloc )	reads demand[i] while writing alloc[i] in one loop and never resizes either, so the buffer promise holds from the top of the body — the tree's only codegen row: 309 → 301 instructions at -O3 -DNDEBUG -march=native -ffast-math -mllvm -basic-aa-separate-storage (re-measured on main 7800768, matches the audit)
D5	src/notes.h	splitNoteTail	VERIFY_NO_ALIAS3( text, sha, branch )	three same-type out-strings written in sequence; passing one twice is a silent wrong answer
D6	src/quality.h	takeAckNamedToken	VERIFY_NO_ALIAS( reason, valueOut )	valueOut is assigned from a substring of reason, then reason is erased
E1	src/quality.h	computeDelta	null-safe VERIFY_TEXT( a == nullptr || a != b, … )	both out-pointers default to nullptr, so the object form would dereference null

D5, D6 and E1 (and C3, B3 below) take the object form: the check runs in debug; in release the macro leaves the separate_storage promise on the two objects, which the optimizer reads on clang 18+ by default, on LLVM 17 / AppleClang 16 only with the CMake-added flag and for scalar accesses, and never on GCC or clang before 17. For these sites it measured no codegen change, so there is no performance claim beyond the A1 row above.

Second commit (cf69220), after #210 freed the files: C3 src/graph.h markCandidateFilesIncludingDecl (VERIFY_NO_ALIAS3( isDecl, isCand, proven ) — proven[] written while isDecl[]/isCand[] are read) and B3 src/verbs_quality.h partitionByScope (VERIFY_NO_ALIAS( regs, outOfScope ) — push_back into outOfScope while iterating regs). Both --edit-check unchanged, incompatible="0"; quality-delta shows two ambient short-horizon-churn rows, gating="0". With these, all 21 rows of the audit's apply list are in the tree. The branch merged main 69a9efa for them (clean).

Verification (worktree from main 7800768): cmake --build build -j clean; --edit-check on all four (./src/quality.h:computeDelta qualified — the bare name is ambiguous with a test fixture): status="unchanged" incompatible="0"; test/noaliascheck.sh ALL PASS (nine arms); test/manifestcheck.sh 0 FAIL rows; test/versioncheck.sh ALL PASS; determinism byte-identical and xmllint --noout clean on test/fixture; docs/limits_build.py --check and docs/gatecount_build.py --root . --check clean (609). src/recall.h gains #include "infra/Diagnostics.h" (it had no path to the macro before).

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📝 Summary

Summary by CodeRabbit

• Bug Fixes

  • Added safeguards to detect overlapping input and output data before processing.
  • Improved protection against unsafe behavior when the same data is provided for multiple roles.

• Tests

  • Expanded validation across note parsing, recall allocation, quality analysis, candidate tracking, and scope partitioning.
  • Documented additional no-alias contracts, bringing entry-point coverage to 21 functions.

Walkthrough

The change adds no-alias assertions at six function entry points. The assertions cover buffers, vectors, references, and output pointers. The changelog records the completed 21-function audit.

Changes

No-alias contract coverage

Layer / File(s)	Summary
Buffer and partition alias guards src/recall.h, src/graph.h, src/verbs_quality.h	waterFillRecallShares, markCandidateFilesIncludingDecl, and partitionByScope now verify distinct input and output buffers before processing.
Parsing and output alias guards src/notes.h, src/quality.h	splitNoteTail, takeAckNamedToken, and computeDelta now verify distinct outputs.
Audit documentation CHANGELOG.md	The changelog documents the six added guards and the completed 21-function audit.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 93432

No merge-blocking risk was identified in the supplied review context.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 63.64% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 11 functions across 5 files. (1 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the final six no-alias contracts and the measured waterFillRecallShares change.
Description check	✅ Passed	The description directly explains all six guards, their rationale, verification results, and completion of the audit.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 63.64% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 11 functions across 5 files. (1 skipped: 1 unsupported.)

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In `@CHANGELOG.md`:
- Line 125: Update the changelog heading near the listed aliasing contracts to
say “Six more” instead of “Four more,” preserving the remaining wording and
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