Code Review with Claude

Two hats: author and reviewer

Claude is a strong author, but it's an equally strong reviewer. Review is where a coding agent quietly saves you the most time: catching the off-by-one, the missing await or the unhandled null before your teammates (or your users) do.

/code-review

The built-in /code-review reviews your current diff, a branch, a pull request number or a path. It looks for correctness bugs and reports findings ranked by severity.

text

/code-review                 # review the current changes
/code-review 482             # review pull request #482
/code-review --fix           # apply the fixes after reviewing

For a deep multi-agent review of a branch in the cloud, /code-review ultra launches a more thorough (and billed) review.

▶Watch it runReviewing a diff

Reviewing a diff

Prompts that produce useful reviews

A vague "review this" gets you vague style comments. Tell Claude what to look for and what to skip:

text

review the diff against main for correctness only: race conditions, error handling,
and edge cases around empty carts. skip style and naming.

If you're checking against a spec, say so, and say "skip style". Reviews get sharper when the reviewer knows the target.

✻

Fresh eyes beat self-review

The session that wrote the code is biased toward believing it works. For important changes, review in a fresh context: run /code-review, start a second session, or ask for a subagent reviewer. A second session makes a great reviewer.

Security reviews

/security-review focuses specifically on vulnerabilities in your pending changes: injection, auth mistakes, secrets in code and unsafe deserialization. Treat it as a smart first pass, not a replacement for your security process.

Review in the pull request

Teams can go further: Claude can review pull requests on GitHub and comment inline. You'll set up GitHub Actions and managed Code Review in Unit 8.

☑Practicesaved on this device

Make a deliberate bug (remove an await, flip a comparison) on a branch
Run /code-review and see if it's caught
Write a focused review prompt that says what to skip
Run /security-review on a change that handles user input

Check your understanding

?Lesson quiz10 XP per correct answer · +25 for a perfect score

QUESTION 1 OF 4

What makes a review prompt produce more useful findings?

Why: Targeted reviews ('correctness only, skip style') find real bugs.

QUESTION 2 OF 4

Why review in a fresh context?

Why: A reviewer that didn't write the code has no stake in it being right.

QUESTION 3 OF 4

Which command focuses on vulnerabilities in pending changes?

Why: /security-review looks specifically for security problems.

QUESTION 4 OF 4

What does /code-review --fix do?

Why: Review first, then apply the fixes automatically.

0 / 4 correct

🎯 By the end of this lesson you'll be able to