Third root-cause fix in the FN-5475 sweep. When `aiMergeTask` /
`recoverNoOpReviewTasks` classified a task as `proven-no-op` or
`no-changes-finalized`, both call sites moved the task to Done while
clearing `modifiedFiles: []` — silently destroying the audit trail when the
work product was uncommitted in the worktree, squashed against the wrong
branch, or dropped by reuse-handoff churn. This was the load-bearing site
of the FN-5490 / FN-5517 / FN-5526 / FN-5540 lost-work patterns.
Both call sites now check `task.modifiedFiles.length` before finalizing as
no-op. If the task claims work was done but no commit landed, the task is
moved back to `todo` with progress preserved and a new
`task:finalize-lost-work-blocked` audit event is emitted. The next
executor run re-attempts the work; the operator sees the audit event in
the timeline.
The post-hoc `reconcileDoneTaskIntegrity` path is intentionally NOT gated
— it cleans up already-Done tasks (legacy state) and is out-of-scope for
prevention. 9 lost-work tasks already in this state at sweep time are
cataloged in docs/incidents/2026-05-23-lost-work-tasks.md for fresh
re-spec.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Follow-up to 1983dac6e addressing nine findings from a code review of the
FN-5345/FN-5377 engine fixes. Includes a real bug fix (commit-message bypass
of the amend detection), two reliability invariant restorations (FN-4811 +
FN-4954 in the new D3 reuse-fallback path), a resource-leak cleanup, plus
test/audit/taxonomy polish.
HIGH
- D3 reuse-fallback now respects FN-4811 active-session safety: matches whose
path is currently owned by a different task in activeSessionRegistry are
skipped, never silently rebound. Skipped owners are recorded in audit
metadata for forensics.
- D3 reuse-fallback now respects FN-4954 pool-lease bookkeeping: when
recycleWorktrees=true AND a worktree pool is attached, the direct-reuse
shortcut is bypassed and the existing acquireTaskWorktree path is used so
WorktreePool.acquire/.release stays consistent. Without this guard the
new path could trip PoolDoubleLeaseError.
- prepare-commit-msg amend detection tokenizes the parent command line and
stops at the first message-supplying flag (-m/-F/--message/--file/=variants)
so a commit message containing the substring '--amend' cannot bypass the
guard. New regression test in prepare-commit-msg-empty-guard.real-git.test.ts.
MEDIUM
- Early empty-own-diff fast-path extracted into tryEarlyEmptyOwnDiffFinalize()
helper. Removes the exception-as-control-flow sentinel ('skip-early-fast-path:
not-reuse-mode') in favor of a plain if (eligible) { try { ... } catch {} }
block.
- Fast-path best-effort cleans up the stranded fusion/<id> worktree and branch
before completeTask(), so empty-own-diff residuals do not accumulate in
.worktrees/ or the branch namespace. FN-4811 guard ensures we never remove
a foreign-owned worktree.
- Two new audit subtypes in run-audit.ts replace the prior overloading of
merge:reuse-fallback-new-worktree:
- merge:reuse-fallback-pruned-stale-registration
- merge:reuse-fallback-reused-existing-registration
merge:reuse-fallback-new-worktree is now reserved for actual new-worktree
creation. Local emitReuseHandoffAuditEvent type union updated to match.
- New direct classifier test in merger-finalize-unproven.real-git.test.ts
('classifies proven-no-op for empty-own-diff branches') covers the new
branch in classifyOwnedLandedEvidence that self-healing and post-handoff
paths also depend on.
LOW
- Alpine/busybox ps fallback: prepare-commit-msg hook reads /proc/$PPID/cmdline
if 'ps -o args=' returns empty (busybox ps often lacks '-o args=' support).
- New backstop test variant 'FN-5345: empty-own-diff fast-path fires even
when branch is registered to two worktrees' reproduces the actual FN-5345
production wedge geometry where fusion/<id> was double-registered to two
worktrees.
Tests
- Full @fusion/engine suite: 448 files / 5881 tests / 9 skipped, all green
- pnpm lint green, pnpm build green
Implements the `mergeIntegrationWorktree` setting (FN-5279) that allows tasks to reuse their own worktree as the integration root instead of spawning a separate one. Steps 1–2 added the settings schema, types, and SettingsModal surface with documentation; Step 3 wired an integration-root resolver th
Fusion-Task-Id: FN-5279
