Field guide / 14 min
Turn changes into reviewable evidence
A coding agent is useful only when its diff, tests, and review survive inspection.
Codex can implement, run checks, show the working-tree diff, and launch a dedicated reviewer. Review scopes are mutually exclusive: uncommitted work, a base-branch comparison, a commit, or custom instructions. The reviewer reports findings without changing the tree.
Verified terminal sequence
- ›
/diff - ›
/review - $
codex review --uncommitted - $
codex review --base main - $
codex review --commit <SHA>
Working principles
Tests prove behavior
Ask for focused regression coverage and the relevant existing checks, not a generic claim that tests pass.
Diff is the artifact
Inspect every changed file, including untracked files and edits that predated the agent.
Review is a separate lens
Use a dedicated reviewer after implementation so correctness and regression risks are examined independently.
Field procedure
- 01
Record the starting state
Know which changes already exist so Codex does not accidentally claim or overwrite them.
- 02
Define verification
Name the focused test and the broader check required before completion.
- 03
Inspect /diff
Compare implementation to the requested scope and reject unrelated cleanup.
- 04
Choose one review target
Use --uncommitted, --base, or --commit; do not combine conflicting scopes.
- 05
Resolve findings deliberately
Confirm evidence, fix real defects, rerun checks, and document any accepted residual risk.
PASS / FAIL
Acceptance checklist
- Starting user changes are preserved.
- Focused and broader checks are recorded.
- Every diff hunk is understood.
- Review findings are resolved or explicitly dispositioned.
WATCH / REJECT
Failure patterns
- Running review before reproducing the requested behavior.
- Treating style-only findings as equal to correctness.
- Letting a fix loop expand into unrelated refactoring.