Code Review Excellence

When to Use This Skill

• Reviewing pull requests and code changes
• Establishing code review standards for teams
• Mentoring junior developers through reviews
• Conducting architecture reviews
• Creating review checklists and guidelines
• Improving team collaboration
• Reducing code review cycle time
• Maintaining code quality standards

Core Principles

1. The Review Mindset

• Catch bugs and edge cases
• Ensure code maintainability
• Share knowledge across team
• Enforce coding standards
• Improve design and architecture
• Build team culture

• Show off knowledge
• Nitpick formatting (use linters)
• Block progress unnecessarily
• Rewrite to your preference

2. Effective Feedback

• Specific and actionable
• Educational, not judgmental
• Focused on the code, not the person
• Balanced (praise good work too)
• Prioritized (critical vs nice-to-have)

❌ Bad: "This is wrong."
✅ Good: "This could cause a race condition when multiple users
         access simultaneously. Consider using a mutex here."

❌ Bad: "Why didn't you use X pattern?"
✅ Good: "Have you considered the Repository pattern? It would
         make this easier to test. Here's an example: [link]"

❌ Bad: "Rename this variable."
✅ Good: "[nit] Consider `userCount` instead of `uc` for
         clarity. Not blocking if you prefer to keep it."

3. Review Scope

• Logic correctness and edge cases
• Security vulnerabilities
• Performance implications
• Test coverage and quality
• Error handling
• Documentation and comments
• API design and naming
• Architectural fit

• Code formatting (use Prettier, Black, etc.)
• Import organization
• Linting violations
• Simple typos

Review Process

Phase 1: Context Gathering (2-3 minutes)

1. Read PR description and linked issue
2. Check PR size (>400 lines? Ask to split)
3. Review CI/CD status (tests passing?)
4. Understand the business requirement
5. Note any relevant architectural decisions

Phase 2: High-Level Review (5-10 minutes)

1. Architecture & Design - Does the solution fit the problem?
   • For significant changes, consult Architecture Review Guide
   • Check: SOLID principles, coupling/cohesion, anti-patterns
2. Performance Assessment - Are there performance concerns?
   • For performance-critical code, consult Performance Review Guide
   • Check: Algorithm complexity, N+1 queries, memory usage
3. File Organization - Are new files in the right places?
4. Testing Strategy - Are there tests covering edge cases?

Phase 3: Line-by-Line Review (10-20 minutes)

• Logic & Correctness - Edge cases, off-by-one, null checks, race conditions
• Security - Input validation, injection risks, XSS, sensitive data
• Performance - N+1 queries, unnecessary loops, memory leaks
• Maintainability - Clear names, single responsibility, comments
• Reuse - Before accepting new code, search for existing utilities/helpers that could replace it. Check adjacent files and shared modules for similar patterns. See Universal Quality Guide for anti-patterns like parameter sprawl, leaky abstractions, nested conditionals, stringly-typed code, TOCTOU, and no-op updates.

Phase 4: Summary & Decision (2-3 minutes)

1. Summarize key concerns
2. Highlight what you liked
3. Make clear decision:
   • ✅ Approve
   • 💬 Comment (minor suggestions)
   • 🔄 Request Changes (must address)
4. Offer to pair if complex

Review Techniques

Technique 1: The Checklist Method

Technique 2: The Question Approach

❌ "This will fail if the list is empty."
✅ "What happens if `items` is an empty array?"

❌ "You need error handling here."
✅ "How should this behave if the API call fails?"

Technique 3: Suggest, Don't Command

❌ "You must change this to use async/await"
✅ "Suggestion: async/await might make this more readable. What do you think?"

❌ "Extract this into a function"
✅ "This logic appears in 3 places. Would it make sense to extract it?"

Technique 4: Differentiate Severity

• 🔴

  [blocking]

  - Must fix before merge
• 🟡

  [important]

  - Should fix, discuss if disagree
• 🟢

  [nit]

  - Nice to have, not blocking
• 💡

  [suggestion]

  - Alternative approach to consider
• 📚

  [learning]

  - Educational comment, no action needed
• 🎉

  [praise]

  - Good work, keep it up!

Language-Specific Guides

Cross-Cutting Guides

Additional Resources

• Architecture Review Guide - 架构设计审查指南（SOLID、反模式、耦合度）
• Performance Review Guide - 性能审查指南（Web Vitals、N+1、复杂度）
• Common Bugs Checklist - 按语言分类的常见错误清单
• Security Review Guide - 安全审查指南
• Code Review Best Practices - 代码审查最佳实践
• PR Review Template - PR 审查评论模板
• Review Checklist - 快速参考清单