fix(ai-review): scope the incoherent-diff bail to mechanical breakage and reclassify evidence-bearing bails

[JSONbored]

Summary

The root-cause fix for the recurring inconclusive-review incident (PRs #8735/#8737; siblings #8794 and #8795 fixed the fallback and copy/classification layers). The bail instruction's "does not cohere with the PR title/description" clause triggered on a valid diff whose title undersold it — title-vs-diff scope mismatch is a reviewable quality signal, not evidence of a stale diff.

Changes

• Prompt — the FAIL-CLOSED bail now targets only mechanically broken diffs (empty / truncated mid-hunk / garbled / contradicting the PR's own changed-file list), with an explicit instruction that a readable diff with scope drift gets reviewed and the mismatch noted, never bailed on.
• Parse-side reclassification — a bail arriving with a substantive valueAssessment rationale (valid magnitude + ≥40 trimmed chars; the confirmed live case carried ~300 chars naming exact call sites) reclassifies into a usable review whose assessment is the fixed public-safe SCOPE_MISMATCH_ASSESSMENT — model text travels only through the existing valueAssessment channel. A bare bail stays null and keeps the deliberate-bail retry break (fix(review): short-circuit the retry loop on a deliberate INCOHERENT_DIFF_ASSESSMENT bail #7518 behavior pinned by the existing #ops-review-burst tests, untouched).
• isIncoherentDiffBail mirrors the reclassification exactly, including toValueAssessment's magnitude validation, honoring its documented "can never disagree with parseModelReview" contract — with a test pinning agreement on the invalid-magnitude edge.

Test plan

• npm run typecheck — clean
• 4 new tests: reclassification (fixed assessment, confidence + rationale preserved), short-rationale bare bail, invalid-magnitude mirror agreement, bail-false for reclassifiable text
• 510 tests green across the five ai-review/selfhost suites; existing bare-bail retry-break tests unchanged
• Changed hunks: 0 uncovered statements/branches

Closes #8789

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	loopover-ui	43c8379	Commit Preview URL Branch Preview URL	Jul 26 2026, 06:28 AM

[github-actions]

Logic backtest

Replayed 0 historical case(s) for linked_issue_scope_mismatch through the base (a8a0912) and head (43c8379) versions of its detection logic (corpus checksum 4f53cda18c2b).

Backtest comparison: linked_issue_scope_mismatch

Verdict: unchanged — no comparable axis moved.

Advisory only — this check never blocks merge (#8105).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.26%. Comparing base (a8a0912) to head (43c8379).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8796      +/-   ##
==========================================
- Coverage   93.81%   92.26%   -1.55%     
==========================================
  Files         797      797              
  Lines       79584    79596      +12     
  Branches    24118    24122       +4     
==========================================
- Hits        74662    73441    -1221     
- Misses       3556     5090    +1534     
+ Partials     1366     1065     -301     

Flag	Coverage Δ
backend	92.93% <100.00%> (-2.16%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/services/ai-review.ts	97.13% <100.00%> (+0.05%)	⬆️

... and 3 files with indirect coverage changes