Code Reviewer Checklist

Critical Thinking

Before checking items, apply critical thinking:

• Question assumptions: Why was this approach chosen? Is the premise valid?
• Challenge decisions: Is this the best solution, or just the first one that worked?
• Consider alternatives: What trade-offs were made? What was sacrificed?
• Look for hidden issues: What could go wrong that isn't obvious?
• Think long-term: How will this affect maintainability in 6 months?
• Verify claims: If code comments say "this is faster" - is it actually?
• Check edge cases: What happens with null, empty, max values, concurrent access?
• Consider context: Does this make sense given the broader system design?

Focus Areas

1. Architecture & Design

• Does it follow Clean Architecture/DDD?
• Is there proper separation of concerns?
• Is the logic in the right layer?
• Does it introduce unnecessary coupling?
• Is the abstraction level appropriate?

2. Code Quality

• Readability and naming conventions
• DRY (Don't Repeat Yourself) principle
• Function size (less than 50 lines)
• File size (less than 200 lines)
• Complexity (cyclomatic complexity, nesting depth)

3. Correctness & Safety

• Error handling (try-catch, boundary checks)
• Security vulnerabilities (SQLi, XSS, etc.)
• Memory leaks or performance bottlenecks
• Race conditions and thread safety
• Input validation

4. Testing

• Are there sufficient tests?
• Do tests cover edge cases?
• Are tests actually testing behavior, not implementation?
• Can tests fail for the right reasons?

Feedback Style

• Constructive: Explain the reasoning behind suggestions
• Specific: Point to exact lines and provide examples
• Prioritized: Distinguish between critical fixes and minor suggestions
• Actionable: Provide clear steps to fix, not just problems

Review Questions Template

### Critical Questions
1. What problem does this solve? Is it the right problem?
2. What are the assumptions? Are they valid?
3. What could break this? Under what conditions?
4. What's the worst-case scenario if this fails?
5. Is there a simpler way to achieve the same result?