fix(grok): close background tasks when grok reports task completion

[Svyk]

#9139 gave grok monitors and background shells a monitoring pill, but t3 only closed a task when the model polled it with TaskOutput or killed it. grok's monitor tool tells the model not to poll, so when a monitor or shell ended on its own the pill stayed up until the session was stopped or the server restarted. nothing else clears thread background liveness, and the idle reaper skips threads that have it.

grok does report the end itself: a task_completed update carrying a task_snapshot, sent as both _x.ai/task_completed and _x.ai/session/update. this handles that notice and closes only tasks t3 already started.

ordering is the subtle part. ext notification handlers run inline in the single acp read loop, while session updates are applied later by the adapter's event consumer, so a notice can be handled before an earlier start has been applied. waiting on the event stream from inside a handler would block the only reader and deadlock session start and load, so the handler never blocks:

• a notice for a task whose task.started has not been published yet is parked, and the consumer applies it right after it publishes that start. this also guarantees task.completed is never published before task.started.
• closed task ids are remembered (bounded), so a later TaskOutput poll for the same task, which grok often sends after the notice, cannot re-create it.
• notices from other acp sessions are ignored, and only task_completed updates are written to the native log.

already-exited kills stay as #9139 intended; this notice closes those tasks anyway.

verified with 109 focused tests across XAiBackgroundTasks and GrokAdapter through the acp mock agent, covering notice before start, dual delivery, _x.ai/session/update-only delivery, late terminal and running polls, orphan and foreign-session notices, plus server typecheck and scoped lint and formatting. the incident behind this: a thread kept three finished monitors and a finished shell "monitoring" for hours, each with a task_completed notice at the moment it ended.

model: composer-2.5 (implementation), claude-opus-5 (investigation and review); harness: cursor, claude code.

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Summary by CodeRabbit

• Bug Fixes
  • Improved Grok background-task monitoring, including completions received before task startup.
  • Prevented duplicate, orphaned, foreign-session, and missing-session completion notices from generating incorrect task updates.
  • Preserved accurate task status across polling, session updates, and post-turn completions.
  • Prevented closed tasks from being recreated or emitting repeated completion events.
  • Correctly finalized tasks reported as completed even when detailed terminal status information is unavailable.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The PR changes production Grok task lifecycle handling across ACP notifications and event processing, adding stateful ordering, deduplication, and late-poll suppression. Its extensive tests improve confidence, but the runtime coordination is substantial enough to merit focused human review.

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Reviewing files that changed from the base of the PR and between c80df2a and 0a19550.

📒 Files selected for processing (5)

• apps/server/scripts/acp-mock-agent.ts
• apps/server/src/provider/Layers/GrokAdapter.test.ts
• apps/server/src/provider/Layers/GrokAdapter.ts
• apps/server/src/provider/acp/XAiBackgroundTasks.test.ts
• apps/server/src/provider/acp/XAiBackgroundTasks.ts

🚧 Files skipped from review as they are similar to previous changes (5)

• apps/server/src/provider/Layers/GrokAdapter.test.ts
• apps/server/scripts/acp-mock-agent.ts
• apps/server/src/provider/acp/XAiBackgroundTasks.ts
• apps/server/src/provider/Layers/GrokAdapter.ts
• apps/server/src/provider/acp/XAiBackgroundTasks.test.ts

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📝 Walkthrough

Walkthrough

The change adds Grok task completion notice handling. It tracks pending, published, and closed tasks, emits completion events, prevents duplicate task recreation, and adds mock-agent scenarios with unit and live integration coverage.

Changes

Grok task completion lifecycle

Layer / File(s)	Summary
Task lifecycle helpers apps/server/src/provider/acp/XAiBackgroundTasks.ts, apps/server/src/provider/acp/XAiBackgroundTasks.test.ts	The ACP helpers classify completion notices, track pending and closed task IDs, attribute turn IDs, resolve completion status, and emit task.completed events.
Adapter notification wiring apps/server/src/provider/Layers/GrokAdapter.ts	Grok sessions handle _x.ai/task_completed and _x.ai/session/update notifications, park early notices, flush parked notices after task.started, and prevent closed tasks from reopening.
Grok monitor scenarios and integration tests apps/server/scripts/acp-mock-agent.ts, apps/server/src/provider/Layers/GrokAdapter.test.ts	The mock agent adds ordered, duplicate, orphan, foreign-session, polling, session-update, and missing-session scenarios. The live test verifies that a completion notice without sessionId is ignored.

Priority: ⬇️ Low

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant GrokMonitor as Grok monitor
  participant GrokAdapter as GrokAdapter
  participant XAiBackgroundTasks as XAiBackgroundTasks
  participant RuntimeEvents as Runtime task events
  GrokMonitor->>GrokAdapter: Send task completion notification
  GrokAdapter->>XAiBackgroundTasks: Decide notice action
  XAiBackgroundTasks-->>GrokAdapter: Ignore, park, or close
  GrokAdapter->>XAiBackgroundTasks: Build completion events
  XAiBackgroundTasks-->>RuntimeEvents: Emit task.completed

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Merge Risk: ⚪ Minimal · up to 0a195

No concrete merge-blocking risk is established for the completion-notice lifecycle changes.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 42.86% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely states the primary change: closing Grok background tasks when Grok reports task completion.
Description check	✅ Passed	The description clearly explains what changed, why it was needed, the event-ordering approach, scope limits, testing, and verification. It does not use the template headings or checklist, but it conta…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 2

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Inline comments:
In `@apps/server/src/provider/acp/XAiBackgroundTasks.ts`:
- Line 162: Update the status resolution around the running-status guard so
snapshots with completed: true and no explicit terminal status, exit code,
signal, or kill flag fall back to the terminal status "completed" after existing
kill and exit-code handling. Ensure grokTaskCompletedNoticeId and
buildGrokTaskCompletedEvents process these snapshots as terminal and perform
normal cleanup.

In `@apps/server/src/provider/Layers/GrokAdapter.ts`:
- Line 1161: Update the session guard in the handler around the sessionId check
to require an exact match with ctx.acpSessionId, rejecting missing, non-string,
and different values before processing task completion or publishing
task.completed.

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📥 Commits

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📒 Files selected for processing (5)

• apps/server/scripts/acp-mock-agent.ts
• apps/server/src/provider/Layers/GrokAdapter.test.ts
• apps/server/src/provider/Layers/GrokAdapter.ts
• apps/server/src/provider/acp/XAiBackgroundTasks.test.ts
• apps/server/src/provider/acp/XAiBackgroundTasks.ts

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