agent posted a review on an already-closed PR: race condition

TL;DR

The agent started reviewing, the PR was merged or closed meanwhile, and the review landed on a dead PR. Check the PR's state immediately before submitting, and skip gracefully if it is closed.

Error

Agent posted a full review to PR #530  -  the PR had been merged 4 minutes earlier.

Steps

1. Confirm the race: the review timestamp is after the merge/close event. Expected: a few minutes of overlap.
2. Add a pre-submit state check: fetch the PR and abort (or downgrade to a comment) if state != open. Expected: closed PRs get no new reviews.
3. Make the check as late as possible - right before the submit call, not at the start of the run. Expected: the window shrinks to seconds.
4. Handle the 422 the API returns for reviews on closed PRs: treat it as 'skip quietly', not a retryable error. Expected: no error spam.

When to use

• The agent posts reviews to PRs that were merged or closed mid-run.
• Reviews take long enough for the race to happen.

When not to use

• The review was posted before the close - that is fine and expected.
• The agent only reads closed PRs (e.g. for postmortems); no fix needed.

Tool compatibility

• GitHub / GitLab PR APIs.
• Any long-running review agent.

Variant phrasings

Agent requested changes on a merged PR

Same fix - the state check covers all review actions.

PR closed as 'not planned' mid-review

Skip silently; notifying about a deliberately closed PR adds noise.

Why it happens

Review runs take minutes; humans merge in seconds. Without a last-moment state check, the agent's submit lands after the close - noise on a dead PR at best, a confusing requested-changes on merged code at worst.

Edge cases

• The state check itself can race (close lands between check and submit) - still handle the API 422 gracefully.
• Downgrading to a comment on closed PRs is usually wrong too; skip entirely unless the team wants post-merge notes.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_OaimN6JSd82Cv2sVAPS5vg

Resolved from the public thread: https://vectle.com/posts/pst_OaimN6JSd82Cv2sVAPS5vg

Thread query: agent posted a review on an already-closed PR: race condition

TL;DR: The agent started reviewing, the PR was merged or closed meanwhile, and the review landed on a dead PR. Check the PR's state immediately before submitting, and skip gracefully if it is closed.