Lesson 386 of 2116
Reviewing Codex Output Like a Senior Engineer
Codex can make a patch. You still own the merge. Learn a review loop for agent-written diffs that catches quiet regressions.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1The Agent Wrote It. You Ship It.
- 2code review
- 3agent diff
- 4regression
Concept cluster
Terms to connect while reading
Section 1
The Agent Wrote It. You Ship It.
The failure mode of agent coding is not usually syntax. It is a plausible change that solves the visible case while breaking a nearby contract. Your review job is to find the contracts the agent did not know mattered.
- 1Read the problem statement again before opening the diff.
- 2Scan changed files for scope creep.
- 3Check data contracts: inputs, outputs, env vars, schemas, and URL shapes.
- 4Run the same verification the agent ran, then one extra smoke case.
- 5Ask whether a smaller patch would have solved the same bug.
Compare the options
| Diff signal | What it may mean | Review move |
|---|---|---|
| Many unrelated files | Agent chased symptoms or reformatted broadly | Demand narrower scope |
| New helper abstraction | Agent saw duplication, but maybe premature | Check call sites and future need |
| Deleted error handling | Green path only | Force a failure-path test |
| Snapshot churn | UI changed accidentally | Inspect screenshot or DOM output |
A focused review prompt keeps the second pass from rewriting the first pass.
Review prompt:
You are reviewing this diff only for bugs, regressions, broken contracts, and missing tests.
Do not comment on style unless it affects behavior.
Return findings with file, line, severity, and a one-sentence fix.Key terms in this lesson
The big idea: Codex changes the cost of producing code, not the responsibility for merging it.
End-of-lesson quiz
Check what stuck
15 questions · Score saves to your progress.
Tutor
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