fix(ci): flaky unit tests — prompt-during-run and hook timeout

[terisuke]

Summary

Two unit tests fail intermittently in CI (GitHub Actions Linux runner), causing unit (linux) job to report failure. These are pre-existing flakes unrelated to any recent PR changes.

Failing Tests

1. prompt submitted during an active run is included in the next LLM input

• Location: Likely in test/session/ or test/prompt/
• Failure mode: Timing-dependent — test expects a prompt submitted during an active LLM run to be queued and included in the next input. Race condition between prompt submission and run completion.
• Frequency: Fails consistently in CI, may pass locally due to faster I/O
• Root cause hypothesis: Non-deterministic timing in async prompt submission pipeline. Test lacks explicit synchronization barrier.
• Suggested fix: Add explicit waitFor/flush before assertion, or mock the timing to remove non-determinism.

2. hook.execute > runHook > timeout returns pass

• Location: Likely in test/hook/
• Failure mode: Takes 5000.98ms — just barely exceeds the 5000ms timeout threshold
• Frequency: Fails in CI where runners are slower, passes locally
• Root cause hypothesis: The timeout boundary is too tight for CI environments. The test expects the hook to resolve within exactly 5000ms but CI jitter pushes it over.
• Suggested fix: Either increase the timeout threshold by a small margin (e.g., 5100ms) or use a more generous timeout in CI environments via process.env.CI detection.

Impact

• These failures are non-blocking for PRs that don't touch session/hook code
• unit results (linux) secondary job also reports failure as a consequence
• Developers may waste time investigating false positives

Evidence

CI logs from PR #117-#120 (all show identical failures):

(fail) prompt submitted during an active run is included in the next LLM input [283.00ms]
(fail) hook.execute > runHook > timeout returns pass [5000.98ms]

Suggested Actions

• Investigate and fix the timing issue in prompt-during-run test
• Adjust hook timeout test to account for CI jitter
• Consider adding @flaky tag or retry annotation as interim measure
• Check if these are known upstream issues (anomalyco/opencode)

Ref

Observed across PRs #117, #118, #119, #120 (2026-04-06)

[terisuke]

PR #127 investigation results

Hook timeout test — FIXED

• Root cause: sleep 10 + 200ms kill timeout overhead exceeded test harness limit
• Fix: increased test timeout from 5s → 15s
• CI result: now passes consistently

Prompt-during-run test — PRE-EXISTING RACE CONDITION

• Root cause: NOT a timeout issue. Test fails at ~300-400ms (well within 10s limit)
• The test expects prompt.prompt() to properly queue while a held LLM call is active
• Effect.sleep(50) barriers and increased polling intervals did not resolve it
• This is a genuine race condition in the upstream session prompt pipeline
• The test's llm.wait(1) + immediate second prompt submission creates a window where the session state may not be consistent
• CI shows fail_on_failure: false — this is informational, not a PR blocker

Recommendation

• The hook timeout fix is complete and should be merged
• The prompt-during-run flake needs a deeper fix in packages/opencode/src/session/prompt.ts (synchronization barrier between concurrent prompt submissions)
• This is upstream test code — consider filing upstream or accepting as known flake

[terisuke]

Root cause identified: NOT a flaky test. CI runner downgrade from blacksmith-4vcpu to ubuntu-latest (2 shared vCPU) causes timing-sensitive tests to fail. Superseded by #129 which tracks the proper fix.

Hook timeout fix included in PR #127 (5s → 15s). Prompt-during-run race needs runner restoration (Option A in #129) or deeper synchronization fix.