fix(server): drop Codex sessions whose runtime exited

[stephenjason89]

Fixes #10798

Problem

When a Codex App Server process dies mid-turn, CodexSessionRuntime emits session/exited. The adapter maps it to a canonical session.exited and offers it to the runtime event queue — and then leaves the dead session sitting in its sessions map.

Nothing else removes it. Only stopSessionInternal deletes, and that runs solely from an explicit stopSession/stopAll. So after the process is gone:

• hasSession(threadId) still returns true, because the entry exists and stopped is still false
• listSessions() still returns it, because it filters only on stopped
• the session scope is never closed, leaking the runtime's client, queues, and stderr fibers

Startup reconciliation trusts listSessions() to decide which persisted bindings are still live, and ProviderSessionReaper permanently skips sessions holding an activeTurnId. A dead runtime retained in the map evades both, so the thread stays running with its activeTurnId set and the UI shows "Working" indefinitely. I hit this on a loop that sat at "Working" for 7+ hours with no process behind it.

Every other adapter already deletes on this path, each guarded on map identity: ClaudeAdapter.ts:4143, OpenCodeAdapter.ts:963, AntigravityAdapter.ts:437, CursorAdapter.ts:478, GrokAdapter.ts:936. CodexAdapter was the only one missing it.

Fix

One branch in the adapter's runtime-event consumer: when a forwarded batch contains session.exited, drop that session and release its scope.

• The event is forwarded first, so ingestion behavior is unchanged.
• exited?.scope === sessionScope guards map identity, so a replacement session already started for the same thread is untouched — same guard the other adapters use.
• The map delete is synchronous, so hasSession/listSessions are correct the moment the event lands.
• stopSessionInternal is forked into the adapter scope because it interrupts the event fiber and closes the session scope that fiber runs in. Running it inline would make the consumer interrupt itself mid-teardown.

Tests

New case in CodexAdapter.test.ts, using the existing scoped fake runtime: start a session, emit session/exited, assert the event is still forwarded, then assert the session is gone, listSessions() excludes it, and the runtime was closed and its scope released.

Without the fix it fails on hasSession returning true.

vp test run src/provider/Layers/CodexAdapter.test.ts      53 passed
+ CodexSessionRuntime.test.ts, ClaudeAdapter.test.ts     219 passed
vp run typecheck (apps/server)                           clean
vp lint / vp fmt --check (both files)                    clean

Scope

Deliberately narrow. This does not touch ingestion, projections, or the reaper, so it does not overlap #9391, #7854, or #8859 — those all work downstream of the adapter and none of them stop listSessions() from advertising a dead runtime. It is also distinct from #4713, which covers a live provider that never sends a terminal event; here the provider is dead and did send one.

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Written with GPT-5.6 Sol in T3 Code, on the Codex harness.

Summary by CodeRabbit

• Bug Fixes

  • Sessions are now removed from active tracking when their runtime exits, including during startup.
  • Runtime resources are closed and session cleanup completes reliably after an exit.
  • Prevents exited sessions from being treated as active during recovery and cleanup.
  • Preserves replacement sessions started on the same thread when an earlier session exits.

• Tests

  • Added regression coverage for session exits during startup, replacement sessions, runtime shutdown, and cleanup.

[macroscopeapp]

Approvability

Verdict: Would Approve

Macroscope's review found this PR approvable — This is a narrow, well-tested fix that cleans up Codex sessions after runtime exit without changing other session paths. A remaining High-severity correctness finding identifies a race that could remove a replacement session and must be handled by the independent correctness gate.

Not approved because:

• 1 blocking correctness issue found at or above your repo's Minimum Blocking Severity

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• apps/server/src/provider/Layers/CodexAdapter.test.ts
• apps/server/src/provider/Layers/CodexAdapter.ts

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📝 Walkthrough

Walkthrough

The Codex adapter now removes sessions when the runtime emits session.exited. It performs asynchronous teardown in the adapter scope and tests replacement-session behavior during startup.

Changes

Codex exited-session cleanup

Layer / File(s)	Summary
Adapter lifecycle cleanup apps/server/src/provider/Layers/CodexAdapter.ts	The adapter registers sessions before startup, removes the matching session after session.exited, and runs stopSessionInternal in the adapter scope. Teardown preserves replacement sessions.
Startup exit test support and coverage apps/server/src/provider/Layers/CodexAdapter.test.ts	The fake runtime can emit session/exited during startup. The scoped lifecycle test verifies removal, one-time runtime closure, scope release, and replacement-session preservation.

Priority: ➖ Normal — Schedule the Codex session cleanup because exited runtimes could remain falsely active, leak resources, and leave the UI stuck showing “Working.”

Estimated code review effort: 2 (Simple) | ~10 minutes

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 31efc

Exited Codex runtimes are now removed from active session state and cleaned up without affecting replacement sessions, preventing stale working status and leaked session resources.

Suggested reviewers: t3dotgg, maria-rcks

🚥 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 1 functions across 2 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 primary change: removing Codex sessions after their runtime exits.
Description check	✅ Passed	The description clearly explains the problem, fix, tests, and scope. It does not use the template headings or include the checklist, but it provides the required substantive information and is mostly …
Linked Issues check	✅ Passed	The changes satisfy issue #10798. They forward the exit event, remove the matching session using scope identity, release its scope, and add regression coverage for event forwarding, session removal, l…
Out of Scope Changes check	✅ Passed	The changes are limited to Codex adapter lifecycle handling and its regression test. They match the linked issue and do not modify unrelated ingestion, projection, reaper, or UI behavior.

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Actionable comments posted: 1

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Inline comments:
In `@apps/server/src/provider/Layers/CodexAdapter.ts`:
- Around line 2446-2449: Update startSession to register the session before
invoking runtime.start(), ensuring session.exited events consumed by the event
fiber can find and clean up the session. Remove the registration on startup
failure, and add a regression case covering start() emitting session/exited.

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• apps/server/src/provider/Layers/CodexAdapter.test.ts
• apps/server/src/provider/Layers/CodexAdapter.ts

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