[Bug]: OpenCode timeout error formatting crashes and skips session recovery

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Summary

When an OpenCode prompt submission and its cleanup abort both time out, openCodeRuntimeErrorDetail throws while formatting the timeout. This replaces the useful timeout error with a TypeError and prevents schedulePromptAdmissionRecovery from running. Repeated follow-up messages fail through the same path.

Steps to reproduce

The observed integration sequence was:

1. Run a thread through the OpenCode provider in the Windows desktop app with a WSL server.
2. The OpenCode event stream disconnects. T3 logs OpenCode connection lost. Reconnecting.
3. Send another message while the OpenCode endpoint is unresponsive.
4. session.promptAsync hits its 10-second timeout.
5. The cleanup session.abort request hits its 1-second timeout.
6. Formatting the cleanup timeout throws before T3 schedules prompt-admission recovery.

The trigger for the original OpenCode connection failure is not established. The error-formatting failure is independently reproducible with the current source:

import { openCodeRuntimeErrorDetail } from "./apps/server/src/provider/opencodeRuntime.ts";

const error = new Error();
Object.defineProperty(error, "message", { value: undefined });
openCodeRuntimeErrorDetail(error);
// TypeError: Cannot read properties of undefined (reading 'trim')

The installed T3 runtime contains an Effect TimeoutError constructor that calls super({ message }), while its timeout implementation calls new TimeoutError() without a message. That produces the error shape above. The worktree's newer Effect dependency supplies a timeout message, so triggering a normal timeout there alone does not reproduce the installed-runtime behavior.

Expected behavior

Report the original submission and cleanup timeouts without throwing from the diagnostic formatter. Execute the intended recovery path so a failed request does not leave subsequent messages failing against stale session state.

Actual behavior

Three follow-up messages at 12:27, 12:32, and 12:49 UTC on September 18 failed after approximately 11 seconds each with the same TypeError. No follow-up user message reached the persisted OpenCode conversation. The T3 thread eventually recorded a stopped session.

Impact

Blocks work completely in the affected thread.

Version or commit

T3 Code desktop 0.0.43-nightly.20260917.1866.

Installed WSL runtime artifact: sha256-92d4c19e9d405a67bd9e5dd39f2dcc4727577472b804acebc679556824c3ed70.

The unsafe formatter is also present in source at commit 19672fcf7b9aac6130133ab26f92c382d529399d and predates that branch's merge.

Environment

Windows desktop, WSL Linux server, OpenCode 1.18.31, provider/model github-copilot/gpt-6-astra.

Logs or stack traces

Relevant trace durations from one failed follow-up:

opencode.session.promptAsync  10002 ms  Interrupted
opencode.session.abort         1001 ms  Interrupted
sendTurn                      11017 ms  Failure

TypeError: Cannot read properties of undefined (reading 'trim')
    at openCodeRuntimeErrorDetail (.../t3:242573:46)
    at Array.<anonymous> (.../t3:245510:18)
    at sendTurn (.../t3:279695:40)
    at sendTurn (definition) (.../t3:245312:20)
    at sendTurn (.../t3:293056:32)
    at sendTurn (definition) (.../t3:279603:19)
    at processTurnStartRequested (.../t3:293229:89)
    at processTurnStartRequested (definition) (.../t3:292880:36)
    at processDomainEvent (.../t3:293258:46)
    at processDomainEvent (definition) (.../t3:293204:29)

Investigation

• apps/server/src/provider/opencodeRuntime.ts assumes cause.message is a string whenever cause instanceof Error:

  if (cause instanceof Error && cause.message.trim().length > 0) return cause.message.trim();
  

• apps/server/src/provider/Layers/OpenCodeAdapter.ts calls the formatter on Cause.squash(cleanupExit.cause) before calling schedulePromptAdmissionRecovery. The formatter's exception skips that recovery call.

• A focused fix should handle missing or non-string error messages and cover the combined prompt-timeout/abort-timeout recovery path in a regression test.

Workaround

No verified workaround for the affected thread yet. The repository changes were committed locally and remained intact.

Start in apps/server/src/provider/opencodeRuntime.ts at openCodeRuntimeErrorDetail and inspect its callers in apps/server/src/provider/Layers/OpenCodeAdapter.ts. Run the existing focused provider tests, then add regression coverage for missing error messages and the combined prompt-timeout/abort-timeout path. Done means timeout details are reported without a TypeError and schedulePromptAdmissionRecovery still runs.