Two follow-ups to FN-8004. Both were found by watching FN-8004's *own*
merge livelock for 40 minutes — it turned out to be blocked by the very
class of bug it was filed to fix.
## 1. AI merge rejections lost their reasons
The reviewer prompt said **both** of these:
> "**End with a single decision line**: `REVIEW_VERDICT:
approve|reject`"
> "**Then list each concrete reason as a bullet.**"
Those are impossible to satisfy at once. Reviewers obeyed "End with" and
wrote their reasoning *above* the verdict — but `extractRejectReasons`
only scanned lines *after* it. So every such rejection collapsed to the
placeholder `reviewer rejected the merge without a stated reason`, and
that placeholder was then handed to the corrective re-merge pass **as
its instruction**. The pass got no actionable feedback and just
re-rolled the merge.
The evidence, from FN-8004's own merge — the pattern repeated across
*both* attempts:
| | Attempt A | Attempt B |
|---|---|---|
| review pass 1 | rejected, no reason (03:46) | rejected, no reason
(03:57) |
| corrective pass | 1/3 | 1/3 |
| review pass 2 | **approved** `a3a3cc6a8` (03:49) | approved |
A reviewer that rejects and then approves identical content isn't
objecting — the reason was being thrown away. Each wasted cycle cost ~7
minutes, stretching the merge past main's ~8-minute churn window so
every attempt lost to a concurrent advance and rebuilt. **The livelock
was caused by the lost-reason bug.**
Fix: the parser recovers reasons from either side of the verdict (inline
→ after → before, nearest-first so the closing argument leads, capped at
8 so a long transcript can't flood the corrective prompt), skipping
severity/verdict/markdown scaffolding. The prompt ordering is now
unambiguous — reasons first, verdict last, nothing after it.
## 2. An orphaned merge-active stamp was un-retryable by hand
The Retry gate refused **every** merge-active status (`Task is not in a
retryable state (current status: landing)`), while self-healing cleared
stale stamps automatically minutes later. So a merger killed mid-flight
— crash, engine restart, operator SIGTERM — blocked the operator's own
escape hatch at exactly the moment they'd reach for it. FN-8004 hit
this: a killed merge left `landing` stamped and Retry 400'd for the full
sweep delay.
`isStaleMergeActiveStatus` now lives in the leaf
`merge-active-status.ts`, shared by `recoverStaleMergingStatus` and the
Retry gate — so **the manual path can never be stricter than the
automatic one**. This is the same one-concept-two-definitions bug as
FN-8004's transient classifier, which is why it's worth fixing
structurally rather than adding another special case.
A live merge stays protected by two independent signals: it holds the
in-process lease **and** refreshes `updatedAt` each phase. Staleness
fails closed on an unparseable timestamp.
One subtlety worth reviewing: the bypass feeds `isInReviewRetry` rather
than only the gate. A bare gate bypass would fall through to the generic
branch and move fully-executed work to `todo`, **re-running finished
work** — a bug this fix could easily have introduced.
## Verification
- Gate green (294 + 122 + 63) · lint clean · engine + dashboard
typecheck clean · `verify:fast` PASS
- 70 merger-suite tests green; all 7 pre-existing verdict-parser tests
still pass (backward compatible — none of them covered the verdict-last
layout, which is exactly why this shipped)
- **The route regression test was confirmed non-vacuous**: neutralizing
the fix fails the two "now retryable" cases while the three
live-merge-protection cases still pass, proving they guard real behavior
rather than the new code.
- Regression tests assert the invariant across every surface per *Fix
the Invariant, Not the Repro*: all five `ACTIVE_MERGE_STATUSES` (a
merger can die in any phase, not just the reported `landing`), both
live-merge signals, boundary conditions, fail-closed paths, and that
pre-existing retry paths are unchanged. Test files carry the required
`## Symptom Verification` and `## Surface Enumeration` sections.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* AI merge rejections now reliably include concrete, correctly ordered
reasons, even when provided before the verdict line.
* Manual retry can recover tasks stuck in stale merge-processing states.
* Retry is still blocked for tasks tied to active merge activity or
recently updated/advancing merges.
* Existing failed-merge retry behavior remains unchanged.
* **Reliability**
* Improved shared handling of “orphaned” merge-active detection across
the engine and dashboard.
* **Tests**
* Added/expanded coverage for merge-active staleness, retry eligibility,
and verdict/reason parsing.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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