ci: classify Bun epoll faults as runtime crashes

[Wibias]

Summary

• Classify Bun 1.3.14's Linux EEXIST: file already exists, epoll_ctl failure from internal WriteStream setup as a Bun runtime crash even when Bun exits with status 1.
• Route that narrow signature through the singleton recovery path added in ci: isolate Bun test shards into fresh-process batches #1469 instead of treating it as an assertion/test failure and aborting the shard.
• Keep ordinary exit-1 assertion failures fail-fast. The new detector requires the Bun "Unhandled error between tests" marker, the exact epoll_ctl error, and an internal:fs/streams WriteStream frame.

This addresses the runtime failure seen in the Linux test shard for #1457, where the existing #1469 fallback was skipped because the Bun runtime fault exited with status 1.

Verification

• bash -n scripts/ci/run-bun-test-batches.sh — pass.
• Replayed the exact captured failure log against the classifier: current dev detector does not classify the exit-1 epoll_ctl fault as runtime; patched detector does.
• End-to-end fake-Bun probe against the full batch helper:
  • exact internal epoll_ctl runtime signature on a two-file batch -> classified as runtime, singleton recovery runs, both singleton processes pass, helper exits 0;
  • ordinary assertion failure with exit 1 -> no singleton retry, helper exits 1;
  • EEXIST ... epoll_ctl without Bun's internal WriteStream frame -> no singleton retry, helper exits 1.
• Reconstructed the pre-change script byte-for-byte and verified its Git blob SHA matched dev (6031deb91f78ca7d93f087719c5c460ec9f9ee95) before applying the 10-line patch.
• Full bun run typecheck / bun run test were not executable in the current tool environment because it does not have a Bun binary. Repository CI should provide the Bun-native validation.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed. No user-facing behavior changed, so no docs update is needed.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults. This changes only failure classification in the bounded CI test helper; it does not change credentials, permissions, workflows, or external inputs.

Summary by CodeRabbit

• Bug Fixes
  • Improved detection of Bun runtime crashes by requiring specific crash indicators in test logs.
  • Reduced the risk of incorrectly classifying unrelated status-1 test failures as runtime crashes.

[github-actions]

✅ Deterministic PR hygiene checks passed.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: f31e20ac-5638-4227-ac54-148b4301c034

📥 Commits

Reviewing files that changed from the base of the PR and between 9ef7df8 and 33e2c24.

📒 Files selected for processing (1)

• scripts/ci/run-bun-test-batches.sh

---

📝 Walkthrough

Walkthrough

The CI helper now classifies a status-1 Bun failure as a runtime crash only when the log contains the required epoll EEXIST, unhandled-error, and internal WriteStream signatures.

Changes

Bun crash detection

Layer / File(s)	Summary
Match Bun epoll crash signature scripts/ci/run-bun-test-batches.sh:70-79	is_bun_runtime_crash now requires exit status 1 and matching epoll EEXIST, unhandled-error, and internal WriteStream log signatures before returning a runtime-crash classification.

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

Possibly related PRs

• lidge-jun/opencodex#1469: Introduces the is_bun_runtime_crash helper that this change refines.

Suggested reviewers: ingwannu, lidge-jun

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main CI change: classifying Bun epoll faults as runtime crashes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/ci-bun-epoll-runtime-detection

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}