Even with FN-5627's merger TOCTOU fix + transient-failure self-healing
sweep + safety-fallback auto-prerebase landed, the merger can still hit
transient failure classes (lease handoff races, brief same-SHA non-FF
advances) for tasks whose branches are particularly out-of-sync. The
self-healing sweep auto-recovers them within bounded budget \u2014 but each
individual failure cycle was firing a ntfy alarm before the recovery
cleared the failed state, producing user-facing alarm spam for tasks
that were never actually stuck.
Two layers of fix:
1. NotificationService.handleTaskUpdated now classifies task.error via
the new shared classifyTransientMergeError helper before scheduling
the deferred failure notification. Transient classes
(lease-handoff-target-not-queued, spurious-concurrent-advance-same-sha)
get logged as suppressed and never schedule a ntfy timer.
2. Defense-in-depth: fireDeferredFailureNotification re-classifies the
error at dispatch time, so a failure scheduled before the suppression
landed on a newer cycle still suppresses if the error matches a
transient class.
The classifier itself moved from self-healing.ts to a new logger-free
transient-merge-error-classifier.ts module so consumers in
NotificationService don't pull createLogger through the import chain and
break test mocks of ../logger.js (per project-memory rule about new
modules using createLogger). self-healing.ts re-exports the symbol for
backward compatibility.
Log prefix for the recovery actions also changed from
'[FN-5627] Auto-recovering...' to 'Auto-recovered:' so that
NotificationService.maybeSuppressTransientFailedNotification's existing
/^Auto-recovered:/ log-prefix check cancels any already-scheduled failure
notification when the sweep runs mid-grace-window.
Tests (3 new):
- transient lease-handoff-target-not-queued failure NOT notified
- transient spurious-concurrent-advance-same-sha failure NOT notified
- genuine different-SHAs concurrent-advance still notifies (control)
Engine suite: 6166 tests pass.
Fusion-Task-Id: FN-5627
e75c4dae28