Code Reviewer

A comprehensive code review skill that analyzes pull requests and code changes for quality, security, maintainability, and best practices.

When This Skill Activates

This skill activates when you:

• Ask for a code review
• Request a PR review
• Mention reviewing changes
• Say "review this" or "check this code"

Review Process

Phase 1: Context Gathering

1. Get changed files

   git diff main...HEAD --name-only
   git log main...HEAD --oneline
   

2. Get the diff

   git diff main...HEAD
   

3. Understand project context

   • Read relevant documentation
   • Check existing patterns in similar files
   • Identify project-specific conventions

Phase 2: Analysis Categories

1. Correctness

• Logic is sound and matches requirements
• Edge cases are handled
• Error handling is appropriate
• No obvious bugs or typos

2. Security

• No hardcoded secrets or credentials
• Input validation and sanitization
• SQL injection prevention
• XSS prevention (for frontend)
• Authentication/authorization checks
• Safe handling of user data

3. Performance

• No N+1 queries
• Appropriate caching
• Efficient algorithms
• No unnecessary computations
• Memory efficiency

4. Code Quality

• Follows DRY principle
• Follows KISS principle
• Appropriate abstractions
• Clear naming conventions
• Proper typing (if TypeScript)
• No commented-out code

5. Testing

• Tests cover new functionality
• Tests cover edge cases
• Test assertions are meaningful
• No brittle tests

6. Documentation

• Complex logic is explained
• Public APIs have documentation
• JSDoc/TSDoc for functions
• README updated if needed

7. Maintainability

• Code is readable
• Consistent style
• Modular design
• Separation of concerns

Phase 3: Output Format

Use this structured format for review feedback:

# Code Review

## Summary
Brief overview of the changes (2-3 sentences).

## Issues by Severity

### Critical
Must fix before merge.

- [ ] **Issue Title**: Description with file:line reference

### High
Should fix before merge unless there's a good reason.

- [ ] **Issue Title**: Description with file:line reference

### Medium
Consider fixing, can be done in follow-up.

- [ ] **Issue Title**: Description with file:line reference

### Low
Nice to have improvements.

- [ ] **Issue Title**: Description with file:line reference

## Positive Highlights
What was done well in this PR.

## Suggestions
Optional improvements that don't require immediate action.

## Approval Status
- [ ] Approved
- [ ] Approved with suggestions
- [ ] Request changes

Common Issues to Check

Security Issues

Issue	Pattern	Recommendation
Hardcoded secrets	const API_KEY = "sk-"	Use environment variables
SQL injection	\"SELECT * FROM...\" + user_input	Use parameterized queries
XSS vulnerability	innerHTML = user_input	Sanitize or use textContent
Missing auth check	New endpoint without @RequireAuth	Add authentication middleware

Performance Issues

Issue	Pattern	Recommendation
N+1 query	Loop with database call	Use eager loading or batch queries
Unnecessary re-render	Missing dependencies in useEffect	Fix dependency array
Memory leak	Event listener not removed	Add cleanup in useEffect return
Inefficient loop	Nested loops O(n²)	Consider hash map or different algorithm

Code Quality Issues

Issue	Pattern	Recommendation
Duplicate code	Similar blocks repeated	Extract to function
Magic number	if (status === 5)	Use named constant
Long function	Function >50 lines	Split into smaller functions
Complex condition	`a && b

Testing Issues

Issue	Pattern	Recommendation
No tests	New feature without test file	Add unit tests
Untested edge case	Test only covers happy path	Add edge case tests
Brittle test	Test relies on implementation details	Test behavior, not implementation
Missing assertion	Test doesn't assert anything	Add proper assertions

Language-Specific Guidelines

TypeScript

• Use unknown instead of any for untyped values
• Prefer interface for public APIs, type for unions
• Use strict mode settings
• Avoid as assertions when possible

React

• Follow Hooks rules
• Use useCallback/useMemo appropriately (not prematurely)
• Prefer function components
• Use proper key props in lists
• Avoid prop drilling with Context

Python

• Follow PEP 8 style guide
• Use type hints
• Use f-strings for formatting
• Prefer list comprehensions over map/filter
• Use context managers for resources

Go

• Handle errors explicitly
• Use named returns for clarity
• Keep goroutines simple
• Use channels for communication
• Avoid package-level state

Before Approving

Confirm the following:

• All critical issues are addressed
• Tests pass locally
• No merge conflicts
• Commit messages are clear
• Documentation is updated
• Breaking changes are documented

Scripts

Run the review checklist script:

python scripts/review_checklist.py <pr-number>

References

• references/checklist.md - Complete review checklist
• references/security.md - Security review guidelines
• references/patterns.md - Common patterns and anti-patterns