## What & why
FN-8141 laundered a failed task into `done`. The executor correctly
parked the task `failed` ("task parked failed during no-fn_task_done
retry" / "fn_task_done refusal retry budget exhausted"), the pause-abort
machinery bounced it to `todo`, and ~12 minutes later
`recoverStrandedCompletedTodoTasks` promoted it to `in-review` because
every step was done/skipped — overriding the honest failure park. From
there the AI merger found an empty diff and finalized it as a no-op
`done`, with no reviewer ever seeing it.
Existing exclusions (`task.error`,
`evaluateNoCommitsNoOpFinalize().blocked`, active statuses, refreshing
review state) all missed it because the failure provenance lived **only
in the durable task log** by the time the promoter ran — status/error
had been cleared by the pause-abort bounce.
This PR restores the invariant: **a stranded-completed promoter must not
promote a task whose most recent execution lifecycle ended in a
failure/refusal park.**
## Change
- New pure, unit-testable evaluator
`evaluateCompletedPromotionFailureProvenance(task)` in `@fusion/core`
(next to `no-commits-finalize-guard.ts`). It scans the task-log **tail**
(bounded to 250 entries) and lets the **most-recent execution-outcome
marker** decide: a failure/refusal park → `{ blocked: true, reason:
"failure-provenance" }`; a fresh clean completion (`Task marked done by
agent` / `All steps complete — implicit fn_task_done`) that appears more
recently supersedes an earlier park; zero failure markers → not blocked.
Recency is by construction, so a failure that predates a newer clean
execution is never reached.
- Both self-healing sweeps (`recoverCompletedTasks` stuck-in-progress
**and** `recoverStrandedCompletedTodoTasks` stranded-todo) fetch the
full task for candidates that already cleared the cheap slim filters
(slim listings strip `log`) and skip when blocked, emitting a
**deduped** `task:reconcile-stranded-completed-no-action` run-audit
event (ids/outcomes-only: `taskId`, `reason`, `sweep`, `marker?`).
- Defense-in-depth: the shared executor `recoverCompletedTask`
chokepoint — which the sweeps AND the executor's own
unpause/`resumeOrphaned` fast-paths all funnel through — also refuses a
provenance-blocked promotion, so no route can launder a failed park.
**Escape hatch (documented in FNXC comments):** an operator
retrying/moving the task starts a fresh execution whose clean-completion
marker supersedes the failure park, clearing the block with no code
change.
## Surface enumeration
- `recoverCompletedTasks` (stuck-in-progress sweep, self-healing.ts) —
guarded + audited.
- `recoverStrandedCompletedTodoTasks` (stranded-todo sweep,
self-healing.ts) — guarded + audited. FN-8141 shows both columns can
launder.
- `recoverCompletedTask` executor callback (the route both sweeps +
unpause + `resumeOrphaned` share) — verified it did **not** check
log-based provenance; added the guard there as the final chokepoint.
## Test evidence
Pure-evaluator unit tests (`@fusion/core`) — marker detection,
most-recent-outcome recency, supersede-by-clean-completion,
empty/missing log, tail-scan bound:
```
pnpm --filter @fusion/core exec vitest run src/__tests__/completed-promotion-failure-provenance.test.ts
Test Files 1 passed (1) Tests 9 passed (9)
```
Self-healing integration tests (`@fusion/engine`) — FN-8141-shaped todo
(3 done + 2 skipped + refusal-exhaust/park marker) is NOT promoted and
emits the no-action event exactly once (deduped across a second cycle);
same task after a fresh clean execution IS promoted; stuck-in-progress
variant covered:
```
pnpm --filter @fusion/engine exec vitest run src/__tests__/self-healing.test.ts -t "recoverCompletedTasks|recoverStrandedCompletedTodoTasks|FN-8141"
Test Files 1 passed (1) Tests 14 passed | 382 skipped (396)
```
`@fusion/core` builds clean. My engine changes add **zero** new type
errors (verified: all 13 engine build errors are the pre-existing pi-SDK
cluster in `auth-storage.ts`/`pi.ts`/`provider-registration.ts`, none in
`self-healing.ts`/`run-audit.ts`/`executor.ts`/the new file).
## Known environmental blocker
`pnpm verify:fast` cannot go green on this branch: the `@fusion/engine`
build is **already broken at baseline** (confirmed by stashing all my
changes) by the pi 0.80.x SDK migration errors
(`ModelRegistry`/`AuthStorage`/`ModelRuntime`) — the exact FN-8145
upstream breakage described in the FN-8141 incident. That is out of
scope for this task and independent of this diff. Likewise, the 22
pre-existing
`restart.integration.test.ts`/`executor-fast-mode-workflows.test.ts`
failures are identical with and without my changes.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus <noreply@anthropic.com>
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