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
Three engine-level fixes for the in-review wedge class identified via FN-5345
(verification-only task with empty handoff commit + drifted worktree mapping
escalating to 'merge-deadlock-detected: verified content not on main' after
FN-4999 completion-handoff-limbo recovery exhausts).
D1 — prepare-commit-msg empty-commit guard
Fusion task worktrees install a prepare-commit-msg hook that refuses
'git commit --allow-empty' and other zero-staged-diff commits. Amend
(detected via $2==commit source arg or '--amend' in 'ps -o args= -p $PPID')
and merge/squash/cherry-pick/revert/rebase ceremonies are allowed.
D5 — early empty-own-diff fast-path in aiMergeTask
In reuse-task-worktree integration mode, BEFORE any reuse-handoff acquisition,
detect branches with own_commit_count >= 1 but zero net diff vs merge-base
(git diff --quiet <mergeBase>..<branch>) and finalize as no-op with
mergeDetails.noOpMerge=true + task:auto-recover-finalize-already-on-main
audit (reason: empty-own-diff-early-fast-path). cwd-main integration mode
is unchanged. classifyOwnedLandedEvidence also detects empty-own-diff so
self-healing and post-handoff finalize paths benefit too.
D3 — reuse-fallback consults existing branch registration
Before creating a fresh worktree in merger's reacquireReuseIntegrationWorktree,
consult 'git worktree list --porcelain' for existing registrations of
fusion/<id>. Reuse extant usable registrations directly. Prune stale
registrations first. Eliminates FN-5083-class double-registration where
'git worktree add -f' on an already-registered branch produced two worktrees
both claiming the branch and wedged the next handoff gate.
Tests
- New real-git backstop: prepare-commit-msg-empty-guard.real-git.test.ts
- New reliability interaction backstop in merge-reuse-task-worktree.test.ts
('FN-5345: empty-own-diff branch auto-finalizes via early fast-path')
- commit-msg-trailer.real-git.test.ts updated to use real commits (it was
relying on --allow-empty, which the new guard now refuses)
- Full @fusion/engine suite: 448 files / 5879 tests / 9 skipped, all green
- pnpm lint green, pnpm build green
