Code Review

Code Review

Review Order

Always review in this order to catch the most critical issues first:

1. Correctness — Does it do what it's supposed to?
2. Security — Does it introduce vulnerabilities?
3. Performance — Are there obvious bottlenecks?
4. Maintainability — Is it readable and well-structured?
5. Tests — Is the change adequately tested?

Correctness Checklist

• Logic matches the stated requirements
• Edge cases handled (empty input, nulls, boundary values)
• Error paths are handled, not silently swallowed
• No off-by-one errors in loops/slices
• Async code awaited correctly, no race conditions
• State mutations are intentional and isolated

Security Checklist

• No secrets, tokens, or credentials in code
• User input is validated and sanitized before use
• SQL queries use parameterized statements (no string concatenation)
• No eval() or dynamic code execution with user data
• Auth checks happen server-side, not just client-side
• Sensitive data not logged
• Dependencies are not introducing known CVEs

Performance Checklist

• No N+1 query problems (batch or eager-load where needed)
• Large datasets paginated, not loaded entirely into memory
• Expensive operations cached when appropriate
• No unnecessary re-renders (React: check deps arrays)
• Database queries have appropriate indexes

Maintainability Checklist

• Functions and variables have clear, descriptive names
• Functions do one thing (single responsibility)
• No duplication — shared logic is extracted
• No magic numbers or unexplained constants
• Complex logic has a brief comment explaining the why
• Dead code removed

Test Checklist

• New behavior is covered by tests
• Bug fixes have a regression test
• Tests are readable — clear setup, assertion, and test name
• Tests don't depend on external state or execution order
• Edge cases are tested, not just the happy path

Feedback Tone

• Be specific: "This query will N+1 on users.posts — use include: { posts: true }" not "fix the query"
• Distinguish severity: use [blocker], [suggestion], [nit] prefixes
• Explain the why behind concerns, not just what to change
• Acknowledge good decisions: "Good call extracting this into a hook"

Output Format

## Summary
[1-3 sentence overall assessment]

## Blockers
- [blocker] <file>:<line> — <issue and why it matters>

## Suggestions
- [suggestion] <file>:<line> — <improvement and rationale>

## Nits
- [nit] <file>:<line> — <minor style/naming note>

## Positive Notes
- <what was done well>