Codex as the second pair of eyes
Codex's pipe-friendly nature makes it a natural code reviewer. git diff main...HEAD | codex exec reviews a PR diff in seconds. --ask-for-approval never --sandbox read-only guarantees no edits — pure review. Combine with --output-format json for downstream parsing in CI.
Two review depths to know: (1) diff review — Codex sees only the patch, fast and tight, good for "obvious bug" detection; (2) diff-in-context review — Codex reads the full file plus the diff, slower but catches issues a patch alone won't (e.g., the patch is fine, but the function it sits in is now redundant).