fix(server): OpenCode stop no longer hangs when a turn is interrupted before submission

[SunkenInTime]

Fixes #11889

What Changed

OpenCodeAdapter.sendTurn now settles promptAdmission.submissionSettled in an Effect.ensuring finalizer on the admission body, so the deferred resolves no matter how the body exits.

context.promptSemaphore.withPermit(
  Effect.gen(function* () { /* unchanged */ }).pipe(
    Effect.ensuring(/* Deferred.succeed(context.promptAdmission?.submissionSettled) */),
  ),
);

Test: stopSession completes after sendTurn is interrupted before the prompt is submitted gates the Clock so sendTurn is parked right after it publishes the admission (in updateProviderSession's nowIso), interrupts it there, then asserts stopSession finishes and the session is gone. It hangs indefinitely without the fix and passes with it.

Why

sendTurn publishes context.promptAdmission and only settles submissionSettled later — at the early-cancel check or in the forked prompt fiber's onExit. Between those points there are yield points (updateProviderSession, emit). If the caller fiber is interrupted in that window (e.g. the turn start is torn down while a thread is being deleted), the deferred is never settled. stopSession → stopOpenCodeContext → cancelPendingOpenCodePrompt then waits on it forever.

That hang sits inside the thread-deletion worker. ws.ts fences every thread.create on ThreadDeletionReactor.drainThrough, so one stuck OpenCode teardown stops every new chat until the server restarts — the symptom reported in #11889. Settling the deferred on every exit path is the smallest change that removes the pin; the deletion fence itself is left as designed.

Reproduce

This is a fiber-interruption race, so there is no deterministic UI or screenshot repro. The regression test is the reproduction:

1. Check out main, apply only the test from this PR.
2. vp test run apps/server/src/provider/Layers/OpenCodeAdapter.test.ts -t "interrupted before the prompt is submitted" — the test never completes (stopSession blocks on submissionSettled).
3. Apply the adapter change — the test passes (111 passed).

In-app the symptom is: delete an OpenCode thread whose turn was being started, then every subsequent "New chat" spins until restart.

UI Changes

Not applicable (server-only; no deterministic UI reproduction).

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes (N/A)
• I included a video for animation/interaction changes

Verified with vp test run apps/server/src/provider/Layers/OpenCodeAdapter.test.ts (111 passed), server tsc --noEmit, and vp lint on the two touched files.

Written by Claude (Devin harness).

Summary by CodeRabbit

• Bug Fixes

  • Fixed an issue where stopping a session could become stuck if an in-progress message submission was interrupted.
  • Session stopping now completes reliably regardless of whether a pending submission succeeds, fails, or is canceled.

• Tests

  • Added coverage for stopping sessions while a message submission is paused before being sent.

[macroscopeapp]

Approvability

Verdict: Approved at 8b9b3c9

Macroscope's review found this PR approvable — This is a small, self-contained server bug fix that settles the pending OpenCode admission during interrupted turns, preventing teardown hangs. A targeted regression test covers the race, with no product-default, schema, deployment, security, or static-analysis changes.

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📒 Files selected for processing (2)

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

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📝 Walkthrough

Walkthrough

sendTurn now settles prompt submission state when it completes, including interruption. A regression test interrupts a pre-submit send and verifies that stopSession completes and removes the session.

Changes

OpenCode shutdown

Layer / File(s)	Summary
Prompt submission settlement and regression coverage apps/server/src/provider/Layers/OpenCodeAdapter.ts, apps/server/src/provider/Layers/OpenCodeAdapter.test.ts	sendTurn settles submissionSettled in an Effect.ensuring finalizer. The test uses a gated clock, interrupts a pre-submit send, and verifies successful session shutdown and session removal.

Priority: ➖ Normal

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

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: t3dotgg

Merge Risk: ⚪ Minimal · up to 8b9b3

No concrete merge-blocking risk remains; the interrupted-send shutdown fix is mergeable after normal checks.

🚥 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 identifies the OpenCode server hang and its fix when a turn is interrupted before submission.
Description check	✅ Passed	The description includes the change, cause, rationale, reproduction steps, test coverage, UI applicability, and validation results. It is small in scope and matches the required template.
Linked Issues check	✅ Passed	Issue #11889 requires teardown to complete when prompt admission is interrupted and to avoid the deletion barrier blocking later chats. The PR wraps the sendTurn prompt-admission body in `Effect.ens…
Out of Scope Changes check	✅ Passed	The changes are limited to apps/server/src/provider/Layers/OpenCodeAdapter.ts and its test. The production change fixes the prompt-admission teardown state from issue #11889. The test directly cover…

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[shivamhwp]

Note: GPT-6 on behalf of shivam (@shivamhwp).

This fixes the interrupted-send cancellation race behind #11889. The remaining gap is that ThreadDeletionReactor.drainThrough still waits for all deletions, so cleanup stuck for another reason can block unrelated new chats.

Could we make that wait specific to the thread being created? Reusing the same thread ID should still wait for its previous cleanup, while unrelated chats should proceed. Add regression coverage for both behaviors.

This could be a separate follow-up PR to keep your cancellation fix focused.