## What & why
FN-8141 ("Update pi SDK to latest and verify Kimi K3 end to end") was
impossible as specced — pi 0.80.x removed `AuthStorage`/`ModelRegistry`
APIs, so every SDK bump broke the build. The executor correctly reverted
its work and filed follow-up FN-8145 — but had **no sanctioned way to
end the task in a blocked state**. `fn_task_done` only expressed
success: the bulk-completion gate refused it, the requeue budget re-ran
the doomed task 5 times, and the only remaining affordance (mark every
step `skipped`, then complete) made `isTaskComplete()` return true.
Self-healing then promoted the "complete" todo to in-review and the AI
merger finalized the empty diff as `done`. **The honest path must be
cheaper than the laundering path.**
This adds a first-class **blocked** outcome to the executor's
`fn_task_done` tool.
## Change
- `fn_task_done` gains `outcome: "completed" | "blocked"` (default
`"completed"`), optional `blockedBy: string[]`, and `reason` (required
when blocked).
- `outcome="blocked"` runs **before** every completion gate (completion
blocker, verdict providers, worktree invariants, bulk-completion
refusal) — blocked is not a completion claim, so none of those gates
apply.
- Parks the task `failed` with `error = "BLOCKED: <reason>"`, following
the FN-7863 `EXECUTION_DISPATCH_LOOP_EXHAUSTED` park convention: **steps
keep their true statuses** (no auto-done, no auto-skip), worktree/branch
preserved. It does **not** call `onDone()`, so the executor's existing
`status === "failed"` post-loop branch honors the park instead of
handing off to review.
- `blockedBy` is recorded as real `task.dependencies` edges (unioned
with existing) so the task requeues behind the blocker.
- Emits run-audit `task:execution-blocked-parked` with ids/outcomes-only
metadata (`taskId`, `blockedBy` ids, `hasReason` boolean — **never** the
reason prose).
- Executor + core prompt guidance and the
`bulk-step-completion-without-review` refusal message now name the
blocked exit as **the** correct action when work cannot proceed,
replacing skip-and-done. `PREMISE STALE:` skip guidance is preserved for
genuinely-stale premises.
## Surface enumeration
- **fn_task_done tool schema + handler**
(`packages/engine/src/executor.ts`): blocked branch added at the top of
`execute`, before all gates.
- **Refusal/requeue machinery**: `formatTaskDoneRefusal` for
`bulk-step-completion-without-review` now points at the blocked exit;
the requeue-budget path is untouched (blocked never enters it).
- **Executor prompt text**: turn-ending rules, the "Cannot proceed"
section, the preflight/stale-premise escape hatch (now explicitly
distinguishes stale-premise skip from blocked).
- **Core prompt mirror** (`packages/core/src/agent-prompts.ts`): same
turn-ending + cannot-proceed guidance.
- **Tool reference doc**
(`packages/cli/skill/fusion/references/engine-tools.md`): `fn_task_done`
params updated. (grep for `fn_task_done` confirmed the only executable
tool schema is in executor.ts; CLI/pi surfaces re-export it, no separate
schema copy.)
- **Self-healing**: verified a blocked-parked row is NOT auto-recovered
by `recoverStrandedCompletedTodoTasks` — its steps are not all
done/skipped and `task.error` is set (both are hard filters in the
sweep).
- **Run Audit inventory** (`AGENTS.md`): documented the new event.
## Test evidence
New `packages/engine/src/__tests__/executor-task-done-blocked.test.ts`
(8 tests) asserts the invariant across surfaces:
```
pnpm --filter @fusion/engine exec vitest run \
src/__tests__/executor-task-done-blocked.test.ts \
src/__tests__/executor-task-done-invariant.test.ts \
src/__tests__/gating-classifications.test.ts \
src/__tests__/reliability-interactions/execute-requeue-loop-guard.test.ts --reporter=dot
→ Test Files 3 passed | Tests 138 passed (0 failed)
```
Coverage: blocked parks failed with `BLOCKED:` error and does **not**
trip the bulk-completion refusal or requeue to todo; `blockedBy` unioned
into `dependencies`; `task:execution-blocked-parked` emitted with
metadata that excludes the reason prose; steps left untouched; empty
`reason` rejected without parking; `completed` outcome unchanged (still
marks steps done, no blocked audit); and
`recoverStrandedCompletedTodoTasks` never promotes a blocked-parked row.
### Note on `pnpm verify:fast`
`verify:fast` currently fails at the workspace build step due to
**pre-existing** type errors in `packages/engine/src/auth-storage.ts`,
`pi.ts`, and `provider-registration.ts` — the exact FN-8142 pi SDK API
break that FN-8145 will fix. These are present on the base branch and
untouched by this PR. Verified instead that this change introduces
**zero** new type errors (`tsc` diff before/after, engine and core both
clean) and that all scoped tests are green.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus <noreply@anthropic.com>
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