fix(cursor): retire the session when the agent process dies

[ValeraZSD]

When the cursor-agent process dies (crash, OOM, killed from outside), the ACP runtime emits ConnectionTerminated, but CursorAdapter has no case for it and drops it. The session stays in sessions and hasSession stays true, and no session.exited is published, so the thread never goes to stopped. On the next message ProviderCommandReactor sees a live session and reuses it, and every prompt fails straight away with the stored "process exited" error. That lasts until the idle reaper stops the session after 30 minutes, the model/mode/cwd changes, or the server restarts.

Cursor now handles ConnectionTerminated the way Antigravity does, and the way #10607 does for Grok: it marks the session terminated, stops it outside the notification fiber, and emits session.exited with exitKind: "error", so the next message starts a fresh process. The test crashes the mock agent mid-prompt using the same T3_ACP_CRASH_PROMPT hook as #10607 (identical lines, so the two merge cleanly).

Summary by CodeRabbit

• Bug Fixes
  • Cursor sessions are now retired when the agent process terminates unexpectedly and reported as errors. Retired sessions no longer appear in session listings, and further turns on them fail instead of continuing.
• Tests
  • Added coverage for unexpected agent termination and its effects on session status and retries.

[macroscopeapp]

Approvability

Verdict: Approved at ed6473a

Macroscope's review found this PR approvable — This is a narrowly scoped Cursor session-lifecycle bug fix with a regression test: unexpected agent termination now retires the session, reports an error exit, and prevents reuse of the dead process. The other changes are test-only, with no product-default, schema, security, billing, or static-analysis-suppression impact.

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📥 Commits

Reviewing files that changed from the base of the PR and between b2b43be and ed6473a.

📒 Files selected for processing (3)

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

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📝 Walkthrough

Walkthrough

The Cursor adapter now retires sessions when the agent connection terminates, reports an error exit, and excludes terminated sessions from session queries. A mock-agent crash trigger and a test cover this behavior.

Changes

Cursor session termination

Layer / File(s)	Summary
Detect and retire terminated sessions apps/server/src/provider/Layers/CursorAdapter.ts	The adapter marks a session terminated when its connection ends, stops the session, reports an error exit, and excludes it from requireSession, listSessions, and hasSession.
Trigger and test agent termination apps/server/scripts/acp-mock-agent.ts, apps/server/src/provider/Layers/CursorAdapter.test.ts	The mock agent exits when enabled and receives the exact prompt text crash now. The test verifies the error exit event, session removal, and failure of a later sendTurn.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant MockAgent as ACP mock agent
  participant Adapter as CursorAdapter notification loop
  participant Session as Cursor session
  participant Consumer as Event consumer
  MockAgent->>Adapter: ConnectionTerminated notification
  Adapter->>Session: Mark terminated and stop session
  Session->>Consumer: Emit session.exited with error

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Suggested reviewers: maria-rcks

Merge Risk: ⚪ Minimal · up to ed647

The change can proceed through normal checks; no actionable merge-blocking issue was established.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 3 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 describes the main change: retiring the Cursor session when the agent process dies.
Description check	✅ Passed	The description clearly explains what changed and why. It omits the template headings and checklist, but it provides the required change rationale and does not involve UI changes.
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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