---
name: code-review-skill
category: audit
description: Comprehensive code review guidance across frontend, backend, systems, architecture, quality, performance, and security.
---
# Code Review Skill

Transform code reviews from gatekeeping to knowledge sharing through constructive feedback, systematic analysis, and collaborative improvement.

## 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

**Goals of Code Review:**
- Catch bugs and edge cases
- Ensure code maintainability
- Share knowledge across team
- Enforce coding standards
- Improve design and architecture
- Build team culture

**Not the Goals:**
- Show off knowledge
- Nitpick formatting (use linters)
- Block progress unnecessarily
- Rewrite to your preference

### 2. Effective Feedback

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

```markdown
❌ 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

**What to Review:**
- Logic correctness and edge cases
- Security vulnerabilities
- Performance implications
- Test coverage and quality
- Error handling
- Documentation and comments
- API design and naming
- Architectural fit

**What Not to Review Manually:**
- Code formatting (use Prettier, Black, etc.)
- Import organization
- Linting violations
- Simple typos

## Review Process

### Phase 1: Context Gathering (2-3 minutes)

Before diving into code, understand:
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

> For large diffs, pipe the diff through [`scripts/pr-analyzer.py`](scripts/pr-analyzer.py) (`git diff main...HEAD | python scripts/pr-analyzer.py`) to triage complexity and get a suggested review approach before reading.

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

1. **Architecture & Design** - Does the solution fit the problem?
   - For significant changes, consult [Architecture Review Guide](reference/architecture-review-guide.md)
   - Check: SOLID principles, coupling/cohesion, anti-patterns
2. **Performance Assessment** - Are there performance concerns?
   - For performance-critical code, consult [Performance Review Guide](reference/performance-review-guide.md)
   - 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)

For each file, check:
- **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](reference/code-quality-universal.md) 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

Use checklists for consistent reviews. See [Security Review Guide](reference/security-review-guide.md) for comprehensive security checklist.

### Technique 2: The Question Approach

Instead of stating problems, ask questions:

```markdown
❌ "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

Use collaborative language:

```markdown
❌ "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

Use labels to indicate priority:

- 🔴 `[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!

**Severity levels:** 🔴 / 🟡 / 🟢 are the three severity tiers used as the standard across all guides in this skill — 🔴 blocks the merge, 🟡 should be addressed, 🟢 is optional. The remaining markers (💡 / 📚 / 🎉) are non-blocking annotations.

## Language-Specific Guides

根据审查的代码语言，查阅对应的详细指南：

| Language/Framework | Reference File | Key Topics |
|-------------------|----------------|------------|
| **React** | [React Guide](reference/react.md) | Hooks, useEffect, React 19 Actions, RSC, Suspense, TanStack Query v5 |
| **Vue 3** | [Vue Guide](reference/vue.md) | Composition API, 响应性系统, Props/Emits, Watchers, Composables |
| **Angular 17+** | [Angular Guide](reference/angular.md) | Signals, Standalone, RxJS, Zoneless, 模板优化, 测试, 路由守卫, HttpInterceptor |
| **Rust** | [Rust Guide](reference/rust.md) | 所有权/借用, Unsafe 审查, 异步代码, 取消安全性, 错误处理 |
| **TypeScript** | [TypeScript Guide](reference/typescript.md) | 类型安全, async/await, 不可变性, 测试, 模块解析, TS 5.x |
| **Python** | [Python Guide](reference/python.md) | 可变默认参数, 异常处理, 类属性 |
| **Django / DRF** | [Django Guide](reference/django.md) | 安全审查, N+1 查询, Serializer 反模式, ViewSet, 异步视图 |
| **FastAPI** | [FastAPI Guide](reference/fastapi.md) | Depends, Pydantic v2 validation, async correctness, sessions/N+1, auth vs authorization, test-driven verification |
| **Java** | [Java Guide](reference/java.md) | Java 17/21 新特性, Spring Boot 3, 虚拟线程, Stream/Optional |
| **Java 8 / Legacy** | [Java 8 Guide](reference/java8.md) | Java 8, Spring Boot 2, javax.*, Stream/Optional, java.time, CompletableFuture |
| **PHP** | [PHP Guide](reference/php.md) | PHP 8.x type system, PDO, security review, Composer, PHPUnit/PHPStan |
| **Ruby / Rails** | [Ruby Guide](reference/ruby.md) | Ruby semantics, Rails 8, Active Record, Active Job, security, testing |
| **C# / .NET** | [C# Guide](reference/csharp.md) | C# 12 特性, 异步编程, EF Core 性能, ASP.NET Core, LINQ |
| **Go** | [Go Guide](reference/go.md) | 错误处理, goroutine/channel, context, 接口设计 |
| **Kotlin / Android** | [Kotlin Guide](reference/kotlin.md) | 协程, Flow, Jetpack Compose, 空安全, 内存泄漏, 架构模式 |
| **Swift / SwiftUI** | [Swift Guide](reference/swift.md) | Optionals, Swift Concurrency, Sendable/actors, SwiftUI property wrappers, value vs reference types, API design |
| **NestJS** | [NestJS Guide](reference/nestjs.md) | 依赖注入, 分层架构, DTO 验证, Guard/Interceptor, 循环依赖 |
| **Svelte / SvelteKit** | [Svelte Guide](reference/svelte.md) | Runes, Load 函数, Form Actions, Store 迁移, SSR/CSR 边界 |
| **C** | [C Guide](reference/c.md) | 指针/缓冲区, 内存安全, UB, 安全编码, 可移植性, 测试 |
| **C++** | [C++ Guide](reference/cpp.md) | RAII, 智能指针, C++20/23, constexpr, 测试 |
| **Zig** | [Zig Guide](reference/zig.md) | Allocators, error unions, defer/errdefer, comptime, C interop |
| **CSS/Less/Sass** | [CSS Guide](reference/css-less-sass.md) | 变量规范, !important, 性能优化, 响应式, 兼容性 |
| **Qt** | [Qt Guide](reference/qt.md) | 对象模型, 信号/槽, Model/View, QML, Qt6 迁移, 测试 |

## Cross-Cutting Guides

Language-agnostic patterns applicable to all code reviews:

| Topic | Reference File | Key Topics |
|-------|----------------|------------|
| **Architecture Review** | [Architecture Review Guide](reference/architecture-review-guide.md) | SOLID, anti-patterns, coupling/cohesion, dependency direction |
| **Performance Review** | [Performance Review Guide](reference/performance-review-guide.md) | Web Vitals, N+1, algorithm complexity, memory leaks, caching |
| **Security Review** | [Security Review Guide](reference/security-review-guide.md) | SQLi, XSS, CSRF, SSRF, IDOR, 命令注入, 跨语言示例 |
| **Universal Quality** | [Universal Quality Guide](reference/code-quality-universal.md) | Reuse audit, parameter sprawl, leaky abstractions, nested conditionals, stringly-typed code, TOCTOU, no-op updates, redundant state |
| **Common Bugs** | [Common Bugs Checklist](reference/common-bugs-checklist.md) | Language-specific bug patterns, common pitfalls |
| **SQL Injection Prevention** | [SQL Injection Guide](reference/cross-cutting/sql-injection-prevention.md) | Parameterized queries, ORM safety, 6 languages, dynamic identifiers, detection |
| **XSS Prevention** | [XSS Prevention Guide](reference/cross-cutting/xss-prevention.md) | Output encoding, CSP, 5 frameworks, input validation vs encoding, detection |
| **N+1 Queries** | [N+1 Queries Guide](reference/cross-cutting/n-plus-one-queries.md) | Eager loading, batch fetching, DataLoader, 5 languages, detection |
| **Error Handling** | [Error Handling Guide](reference/cross-cutting/error-handling-principles.md) | Fail fast, error hierarchy, 7 languages, anti-patterns, logging |
| **Async & Concurrency** | [Concurrency Guide](reference/cross-cutting/async-concurrency-patterns.md) | Goroutines, async/await, actors, structured concurrency, 7 languages |
| **Review Best Practices** | [Code Review Best Practices](reference/code-review-best-practices.md) | Communication, reviewer mindset, giving feedback, severity labels |

## Additional Resources

- [PR Review Template](assets/pr-review-template.md) - PR 审查评论模板
- [Review Checklist](assets/review-checklist.md) - 快速参考清单