Code review: machine-readable completion signal when no issues are found (👍 reaction has no webhook event)

What variant of Codex are you using?

Web (GitHub integration, automatic code reviews)

What feature would you like to see?

When automatic code review finds issues, Codex submits a PR review, which emits a pull_request_review webhook/Actions event. When it finds nothing, it only replaces its 👀 reaction with 👍 on the PR body. GitHub has no webhook or Actions event for reactions, so this completion signal is invisible to automation.

We gate merges on "Codex finished reviewing the current HEAD" via a required status check. Review submissions and summary comments complete the gate event-driven, but 👍-only outcomes force a scheduled sweep that polls every open PR: clean PRs wait up to a full sweep interval, and the cron runs all day just for this case.

An option to always leave a machine-recognizable completion signal would remove the polling entirely. Any of these would work:

• a setting like "always post a review (or comment) even when there are no findings", or
• always posting/updating the review summary comment (the one with the codex-pull-request-review-summary marker — it currently appears on some PRs but not reliably), or
• a commit status / check run on the reviewed SHA.

Additional information

The 👍 reaction also carries no commit SHA, so consumers must correlate it with push timing to know which HEAD it refers to. Any of the signals above, tied to the reviewed SHA, would solve that as well.

Review the existing GitHub integration paths for pull_request_review events, the codex-pull-request-review-summary marker, and status/check-run handling. Determine which completion signal can be tied to the reviewed SHA and emitted for clean reviews; done means automation can observe clean-review completion without polling.