fix(server): reconcile delayed OpenCode prompt admission

[simonvanlaak]

OpenCode can acknowledge promptAsync before the submitted message or busy status becomes observable. T3 Code exhausted its fixed admission probes and emitted a terminal transport failure even when OpenCode began processing milliseconds later.

This change adds a bounded event-aware grace period after the existing probes. An exact prompt echo or parent-session busy/retry event confirms admission, while missing evidence still fails after the grace window. Admission failure now revalidates ownership after cleanup abort so interruption, replacement, or shutdown cannot be overwritten by stale failure events.

Tests cover late busy admission, bounded no-evidence failure, interruption during grace, and interruption while the cleanup abort is in flight.

Verification: OpenCodeAdapter.test.ts (114 tests), targeted lint and format, server typecheck, and git diff --check.

Implemented with gpt-5.6-sol through the OpenCode harness.

Summary by CodeRabbit

• Bug Fixes

  • Improved prompt handling when session activity is detected shortly after admission checks.
  • Prevented valid prompts from being incorrectly rejected during delayed activity detection.
  • Improved behavior when prompts are interrupted or cleanup occurs during admission.
  • Maintained clear failure reporting when no valid session activity is detected after available checks.

• Tests

  • Added coverage for delayed activity events, interrupted admissions, cleanup races, and bounded admission failures.

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

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📝 Walkthrough

Walkthrough

Changes

OpenCode admission recovery

Layer / File(s)	Summary
Admission observation and recovery apps/server/src/provider/Layers/OpenCodeAdapter.ts	Prompt admission records matching message and status evidence. Recovery waits briefly for late evidence after bounded probes and rechecks session, turn, generation, and cancellation state before cleanup or failure.
Admission timing and interruption tests apps/server/src/provider/Layers/OpenCodeAdapter.test.ts	Tests cover late busy evidence, exact message observation, failed admission, interruption during grace, and cleanup abort ownership.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant sendTurn
  participant OpenCodeSession
  participant AdmissionRecovery
  sendTurn->>OpenCodeSession: Submit turn
  OpenCodeSession-->>AdmissionRecovery: Report message or busy status
  AdmissionRecovery->>AdmissionRecovery: Wait for late admission evidence
  AdmissionRecovery-->>OpenCodeSession: Reconcile idle or fail admission

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Suggested reviewers: t3dotgg

Merge Risk: ⚪ Minimal · up to eb275

Delayed OpenCode admission evidence and interruption cleanup are covered without an unresolved merge-blocking risk.

🚥 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
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.
Title check	✅ Passed	The title clearly and concisely describes the main change: fixing delayed OpenCode prompt admission reconciliation.
Description check	✅ Passed	The description explains what changed, why it was needed, the failure behavior, test coverage, and verification steps. It does not use the template headings or include the checklist, but the required …

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Actionable comments posted: 1

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Inline comments:
In `@apps/server/src/provider/Layers/OpenCodeAdapter.ts`:
- Around line 1485-1494: Update the prompt admission recovery logic around
failPromptAdmissionRecovery to honor promptAdmission.messageObserved as
sufficient evidence when admissionObserved times out, while preserving
current-state and cancellation checks. Add coverage for the fifth
session.message probe matching the exact prompt with unavailable status and no
matching event, ensuring recovery does not abort.

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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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