code-review

Code Review Skill

Purpose: Enforce automated code reviews as a mandatory guardrail before every commit and deployment. Choose between Claude, OpenAI Codex, Google Gemini, or multiple engines for comprehensive analysis.

---

Review Engine Choice

When running /code-review, users can choose their preferred review engine:

┌─────────────────────────────────────────────────────────────────┐
│  CODE REVIEW - Choose Your Engine                               │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  ○ Claude (default)                                             │
│    Built-in, no extra setup, full conversation context          │
│                                                                 │
│  ○ OpenAI Codex CLI                                             │
│    GPT-5.2-Codex specialized for code review, 88% detection     │
│    Requires: npm install -g @openai/codex                       │
│                                                                 │
│  ○ Google Gemini CLI                                            │
│    Gemini 2.5 Pro with 1M token context, free tier available    │
│    Requires: npm install -g @google/gemini-cli                  │
│                                                                 │
│  ○ Dual Engine (any two)                                        │
│    Run two engines, compare findings, catch more issues         │
│                                                                 │
│  ○ All Three (maximum coverage)                                 │
│    Run Claude + Codex + Gemini for critical/security code       │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

Engine Comparison

Aspect	Claude	Codex	Gemini	Multi-Engine
Setup	None	npm + OpenAI API	npm + Google Account	All setups
Speed	Fast	Fast	Fast	2-3x time
Context	Conversation	Fresh per review	1M tokens	N/A
Detection	Good	88% (best)	63.8% SWE-Bench	Combined
Free Tier	N/A	Limited	1,000/day	Varies
Best for	Quick reviews	High accuracy	Large codebases	Critical code

Set Default Engine

# ~/.claude/settings.toml or project CLAUDE.md
[code-review]
default_engine = "claude"  # Options: claude, codex, gemini, dual, all

Usage Examples

# Use default engine
/code-review

# Explicitly choose engine
/code-review --engine claude
/code-review --engine codex
/code-review --engine gemini

# Dual engine (pick any two)
/code-review --engine claude,codex
/code-review --engine claude,gemini
/code-review --engine codex,gemini

# All three engines
/code-review --engine all

# Quick shortcuts
/code-review              # Uses default
/code-review --codex      # Use Codex
/code-review --gemini     # Use Gemini
/code-review --all        # All three engines

---

Multi-Engine Output

When using multiple engines, findings are compared and deduplicated:

Dual Engine Example

┌─────────────────────────────────────────────────────────────────┐
│  CODE REVIEW RESULTS - DUAL ENGINE (Claude + Codex)             │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  ✅ AGREED (Found by both):                                     │
│  🔴 SQL injection in auth.ts:45                                 │
│  🟡 Missing error handling in api.ts:112                        │
│                                                                 │
│  🔷 CLAUDE ONLY:                                                │
│  🟠 Potential race condition in worker.ts:89                    │
│  🟢 Consider extracting helper function                         │
│                                                                 │
│  🔶 CODEX ONLY:                                                 │
│  🟠 Memory leak - unclosed stream in upload.ts:34               │
│  🟡 N+1 query pattern in orders.ts:156                          │
│                                                                 │
├─────────────────────────────────────────────────────────────────┤
│  SUMMARY                                                        │
│  Agreed: 2 | Claude only: 2 | Codex only: 2                     │
│  Critical: 1 | High: 2 | Medium: 2 | Low: 1                     │
│  Status: ❌ BLOCKED - Fix critical/high issues                  │
└─────────────────────────────────────────────────────────────────┘

Triple Engine Example (All Three)

┌─────────────────────────────────────────────────────────────────┐
│  CODE REVIEW RESULTS - TRIPLE ENGINE                            │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  ✅ UNANIMOUS (All 3 found):                                    │
│  🔴 SQL injection in auth.ts:45                                 │
│                                                                 │
│  ✅ MAJORITY (2 of 3 found):                                    │
│  🟠 Memory leak - unclosed stream in upload.ts:34 (Codex+Gemini)│
│  🟡 Missing error handling in api.ts:112 (Claude+Codex)         │
│                                                                 │
│  🔷 CLAUDE ONLY:                                                │
│  🟠 Potential race condition in worker.ts:89                    │
│                                                                 │
│  🔶 CODEX ONLY:                                                 │
│  🟡 N+1 query pattern in orders.ts:156                          │
│                                                                 │
│  🟢 GEMINI ONLY:                                                │
│  🟡 Consider using batch API for better performance             │
│  🟢 Type could be more specific in types.ts:23                  │
│                                                                 │
├─────────────────────────────────────────────────────────────────┤
│  SUMMARY                                                        │
│  Unanimous: 1 | Majority: 2 | Single: 5                         │
│  Critical: 1 | High: 2 | Medium: 3 | Low: 2                     │
│  Status: ❌ BLOCKED - Fix critical/high issues                  │
└─────────────────────────────────────────────────────────────────┘

When to Use Each Mode

Mode	Use When
Single (Claude)	Quick in-flow reviews, exploration
Single (Codex)	CI/CD automation, high accuracy needed
Single (Gemini)	Large codebases (100+ files), free tier
Dual	Important PRs, pre-merge reviews
Triple (All)	Security-critical code, payment systems, auth

---

Core Philosophy

┌─────────────────────────────────────────────────────────────────┐
│  CODE REVIEW IS NON-NEGOTIABLE                                  │
│  ─────────────────────────────────────────────────────────────  │
│                                                                 │
│  Every commit must pass code review.                            │
│  Every PR must be reviewed before merge.                        │
│  Every deployment must include review sign-off.                 │
│                                                                 │
│  AI catches what humans miss. Humans catch what AI misses.      │
│  Together: fewer bugs, cleaner code, better security.           │
├─────────────────────────────────────────────────────────────────┤
│  INVOKE: /code-review                                           │
│  PLUGIN: code-review@claude-plugins-official                    │
└─────────────────────────────────────────────────────────────────┘

---

When to Run Code Review

Mandatory Review Points

Trigger	Action	Command
Before commit	Review staged changes	/code-review
Before PR	Review all changes vs base	/code-review
Before merge	Final review of PR	/code-review
Before deploy	Review deployment diff	/code-review

Automatic Integration

Run code review automatically before every commit:

┌─────────────────────────────────────────────────────────────────┐
│  COMMIT WORKFLOW                                                │
│  ─────────────────────────────────────────────────────────────  │
│                                                                 │
│  1. Write code                                                  │
│  2. Run tests (TDD - must pass)                                 │
│  3. Run /code-review  ← MANDATORY                               │
│  4. Address critical/high issues                                │
│  5. Commit                                                      │
│  6. Push                                                        │
│                                                                 │
│  Skip step 3? ❌ NO COMMIT ALLOWED                              │
└─────────────────────────────────────────────────────────────────┘

---

Using the Code Review Plugin

Basic Usage

# Review current changes
/code-review

# Review specific files
/code-review src/auth/*.ts

# Review a PR
/code-review --pr 123

# Review with specific focus
/code-review --focus security
/code-review --focus performance
/code-review --focus architecture

Review Categories

The code review plugin analyzes:

Category	What It Checks
Security	Vulnerabilities, injection risks, auth issues, secrets
Performance	N+1 queries, memory leaks, inefficient algorithms
Architecture	Design patterns, SOLID principles, coupling
Code Quality	Readability, complexity, duplication
Best Practices	Language idioms, framework conventions
Testing	Coverage gaps, test quality, edge cases
Documentation	Missing docs, outdated comments

Severity Levels

Level	Action Required	Can Commit?
🔴 Critical	Must fix immediately	❌ NO
🟠 High	Should fix before commit	❌ NO
🟡 Medium	Fix soon, can commit	✅ YES
🟢 Low	Nice to have	✅ YES
ℹ️ Info	Suggestions only	✅ YES

---

Pre-Commit Hook Integration

Install Pre-Commit Hook

#!/bin/bash
# .git/hooks/pre-commit

echo "🔍 Running code review..."

# Run Claude code review on staged files
STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep -E '\.(ts|tsx|js|jsx|py|go|rs)$')

if [ -n "$STAGED_FILES" ]; then
    # Invoke code review (requires claude CLI)
    claude --print "/code-review $STAGED_FILES" > /tmp/code-review-result.txt 2>&1

    # Check for critical/high issues
    if grep -q "🔴\|Critical\|🟠\|High" /tmp/code-review-result.txt; then
        echo "❌ Code review found critical/high issues:"
        cat /tmp/code-review-result.txt
        echo ""
        echo "Fix these issues before committing."
        exit 1
    fi

    echo "✅ Code review passed"
fi

exit 0

Make Hook Executable

chmod +x .git/hooks/pre-commit

---

Codex CLI Setup (For Codex/Both Modes)

If you want to use Codex or Both modes, install the Codex CLI:

# Prerequisites: Node.js 22+
node --version  # Must be 22+

# Install Codex CLI
npm install -g @openai/codex

# Authenticate (choose one):
# Option 1: ChatGPT subscription (Plus, Pro, Team, Enterprise)
codex  # Follow prompts to sign in

# Option 2: API key
export OPENAI_API_KEY=sk-proj-...

Verify Installation

# Check Codex is installed
codex --version

# Test review
codex
> /review

See codex-review.md skill for full Codex documentation.

---

Gemini CLI Setup (For Gemini/Multi-Engine Modes)

If you want to use Gemini or multi-engine modes, install the Gemini CLI:

# Prerequisites: Node.js 20+
node --version  # Must be 20+

# Install Gemini CLI
npm install -g @google/gemini-cli

# Or via Homebrew (macOS)
brew install gemini-cli

# Install Code Review extension
gemini extensions install https://github.com/gemini-cli-extensions/code-review

Authenticate

# Option 1: Google Account (recommended, 1000 req/day free)
gemini  # Follow browser login prompts

# Option 2: API key (100 req/day free)
export GEMINI_API_KEY="your-key-from-aistudio.google.com"

Verify Installation

# Check Gemini is installed
gemini --version

# List extensions
gemini extensions list

# Test review
gemini
> /code-review

See gemini-review.md skill for full Gemini documentation.

---

CI/CD Integration

GitHub Actions - Claude Only

# .github/workflows/code-review.yml
name: Code Review

on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  code-review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Get changed files
        id: changed-files
        run: |
          echo "files=$(git diff --name-only origin/${{ github.base_ref }}...HEAD | tr '\n' ' ')" >> $GITHUB_OUTPUT

      - name: Run Claude Code Review
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
        run: |
          npx @anthropic-ai/claude-code --print "/code-review ${{ steps.changed-files.outputs.files }}" > review.md

      - name: Post Review Comment
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const review = fs.readFileSync('review.md', 'utf8');

            github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: `## 🔍 Claude Code Review\n\n${review}`
            });

      - name: Check for Critical Issues
        run: |
          if grep -q "Critical\|🔴" review.md; then
            echo "❌ Critical issues found"
            exit 1
          fi

GitHub Actions - Codex Only

# .github/workflows/codex-review.yml
name: Codex Code Review

on:
  pull_request:

jobs:
  review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Codex Review
        uses: openai/codex-action@main
        with:
          openai_api_key: ${{ secrets.OPENAI_API_KEY }}
          model: gpt-5.2-codex
          safety_strategy: drop-sudo

GitHub Actions - Both Engines

# .github/workflows/dual-review.yml
name: Dual Code Review

on:
  pull_request:

jobs:
  claude-review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Claude Review
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
        run: |
          npx @anthropic-ai/claude-code --print "/code-review" > claude-review.md

      - uses: actions/upload-artifact@v4
        with:
          name: claude-review
          path: claude-review.md

  codex-review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - uses: actions/setup-node@v4
        with:
          node-version: '22'

      - name: Install Codex
        run: npm install -g @openai/codex

      - name: Codex Review
        env:
          OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
        run: |
          codex exec --full-auto --sandbox read-only \
            --output-last-message codex-review.md \
            "Review this code for bugs, security issues, and quality problems"

      - uses: actions/upload-artifact@v4
        with:
          name: codex-review
          path: codex-review.md

  combine-reviews:
    needs: [claude-review, codex-review]
    runs-on: ubuntu-latest
    steps:
      - uses: actions/download-artifact@v4

      - name: Combine Reviews
        run: |
          echo "## 🔍 Dual Code Review Results" > combined-review.md
          echo "" >> combined-review.md
          echo "### Claude Findings" >> combined-review.md
          cat claude-review/claude-review.md >> combined-review.md
          echo "" >> combined-review.md
          echo "### Codex Findings" >> combined-review.md
          cat codex-review/codex-review.md >> combined-review.md

      - name: Post Combined Review
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const review = fs.readFileSync('combined-review.md', 'utf8');
            github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: review
            });

GitHub Actions - Gemini Only

# .github/workflows/gemini-review.yml
name: Gemini Code Review

on:
  pull_request:
    types: [opened, synchronize]

jobs:
  review:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write

    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'

      - name: Install Gemini CLI
        run: npm install -g @google/gemini-cli

      - name: Run Review
        env:
          GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
        run: |
          # Get diff
          git diff origin/${{ github.base_ref }}...HEAD > diff.txt

          # Run Gemini review
          gemini -p "Review this pull request diff for bugs, security issues, and code quality problems. Be specific about file names and line numbers.

          $(cat diff.txt)" > review.md

      - name: Post Review Comment
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const review = fs.readFileSync('review.md', 'utf8');
            github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: `## 🤖 Gemini Code Review\n\n${review}`
            });

      - name: Check for Critical Issues
        run: |
          if grep -qi "critical\|security vulnerability\|injection" review.md; then
            echo "❌ Critical issues found"
            exit 1
          fi

GitHub Actions - All Three Engines

# .github/workflows/triple-review.yml
name: Triple Engine Code Review

on:
  pull_request:

jobs:
  claude-review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Claude Review
        env:
          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
        run: |
          npx @anthropic-ai/claude-code --print "/code-review" > claude-review.md

      - uses: actions/upload-artifact@v4
        with:
          name: claude-review
          path: claude-review.md

  codex-review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - uses: actions/setup-node@v4
        with:
          node-version: '22'

      - name: Install Codex
        run: npm install -g @openai/codex

      - name: Codex Review
        env:
          OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
        run: |
          codex exec --full-auto --sandbox read-only \
            --output-last-message codex-review.md \
            "Review this code for bugs, security issues, and quality problems"

      - uses: actions/upload-artifact@v4
        with:
          name: codex-review
          path: codex-review.md

  gemini-review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - uses: actions/setup-node@v4
        with:
          node-version: '20'

      - name: Install Gemini CLI
        run: npm install -g @google/gemini-cli

      - name: Gemini Review
        env:
          GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
        run: |
          git diff origin/${{ github.base_ref }}...HEAD > diff.txt
          gemini -p "Review this code diff for bugs, security, and quality issues:
          $(cat diff.txt)" > gemini-review.md

      - uses: actions/upload-artifact@v4
        with:
          name: gemini-review
          path: gemini-review.md

  combine-reviews:
    needs: [claude-review, codex-review, gemini-review]
    runs-on: ubuntu-latest
    steps:
      - uses: actions/download-artifact@v4

      - name: Combine Reviews
        run: |
          echo "## 🔍 Triple Engine Code Review Results" > combined-review.md
          echo "" >> combined-review.md
          echo "### 🟣 Claude Findings" >> combined-review.md
          cat claude-review/claude-review.md >> combined-review.md
          echo "" >> combined-review.md
          echo "---" >> combined-review.md
          echo "### 🟢 Codex Findings" >> combined-review.md
          cat codex-review/codex-review.md >> combined-review.md
          echo "" >> combined-review.md
          echo "---" >> combined-review.md
          echo "### 🔵 Gemini Findings" >> combined-review.md
          cat gemini-review/gemini-review.md >> combined-review.md

      - name: Post Combined Review
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const review = fs.readFileSync('combined-review.md', 'utf8');
            github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: review
            });

      - name: Check Critical Issues
        run: |
          # Fail if any engine found critical issues
          if grep -qi "critical\|🔴" combined-review.md; then
            echo "❌ Critical issues found by at least one engine"
            exit 1
          fi

---

Review Checklist

Before Every Commit

• Run /code-review on staged changes
• No critical (🔴) issues
• No high (🟠) issues
• Security concerns addressed
• Performance issues considered

Before Every PR

• Full code review of all changes
• All critical/high issues resolved
• Tests added for new functionality
• Documentation updated if needed

Before Every Deployment

• Final review of deployment diff
• Security scan passed
• No new vulnerabilities introduced
• Rollback plan documented

---

Common Review Findings

Security Issues (Always Fix)

Issue	Example	Fix
SQL Injection	query = f"SELECT * FROM users WHERE id = {id}"	Use parameterized queries
XSS	innerHTML = userInput	Sanitize or use textContent
Secrets in code	apiKey = "sk-xxx"	Use environment variables
Missing auth	Unprotected endpoints	Add authentication middleware
Insecure crypto	MD5/SHA1 for passwords	Use bcrypt/argon2

Performance Issues (Should Fix)

Issue	Example	Fix
N+1 queries	Loop with individual queries	Use batch/eager loading
Memory leak	Unclosed connections	Use connection pooling
Missing index	Slow queries	Add database indexes
Large payload	Fetching unused fields	Select only needed fields
No pagination	Loading all records	Implement pagination

Code Quality (Nice to Fix)

Issue	Example	Fix
Long function	100+ lines	Extract into smaller functions
Deep nesting	5+ levels	Early returns, extract methods
Magic numbers	if (status === 3)	Use named constants
Duplicate code	Copy-pasted blocks	Extract shared function
Missing types	any everywhere	Add proper TypeScript types

---

Integration with TDD Workflow

┌─────────────────────────────────────────────────────────────────┐
│  TDD + CODE REVIEW WORKFLOW                                     │
│  ─────────────────────────────────────────────────────────────  │
│                                                                 │
│  1. RED: Write failing tests                                    │
│  2. GREEN: Write code to pass tests                             │
│  3. REFACTOR: Clean up code                                     │
│  4. REVIEW: Run /code-review  ← NEW STEP                        │
│  5. FIX: Address critical/high issues                           │
│  6. VALIDATE: Lint + TypeCheck + Coverage                       │
│  7. COMMIT: Only after review passes                            │
│                                                                 │
│  Review catches what tests miss:                                │
│  - Security vulnerabilities                                     │
│  - Performance issues                                           │
│  - Architecture problems                                        │
│  - Code maintainability                                         │
└─────────────────────────────────────────────────────────────────┘

---

Review Response Template

When code review finds issues, respond with:

## Code Review Results

### 🔴 Critical Issues (Must Fix)
1. **SQL Injection in userController.ts:45**
   - Issue: User input directly interpolated into query
   - Fix: Use parameterized query
   - Code: `db.query('SELECT * FROM users WHERE id = $1', [userId])`

### 🟠 High Issues (Should Fix)
1. **Missing authentication on /api/admin endpoints**
   - Issue: Admin routes accessible without auth
   - Fix: Add auth middleware

### 🟡 Medium Issues (Fix Soon)
1. **N+1 query in getOrders function**
   - Consider eager loading or batch query

### 🟢 Low Issues (Nice to Have)
1. **Consider extracting validation logic to separate file**

### ✅ Strengths
- Good test coverage
- Clear function names
- Proper error handling

### 📊 Summary
- Critical: 1 | High: 1 | Medium: 1 | Low: 1
- **Status: ❌ BLOCKED** - Fix critical/high issues before commit

---

Claude Instructions

When to Invoke Code Review

Claude should automatically suggest or run code review:

1. After completing a feature → "Let me run a code review before we commit"
2. Before creating a PR → "Running code review on all changes"
3. When user says "commit" → "First, let me review the changes"
4. After fixing bugs → "Reviewing the fix for any issues"

Review Focus Areas

Prioritize review based on change type:

Change Type	Focus Areas
Auth/Security code	Security, input validation, crypto
Database code	SQL injection, N+1, transactions
API endpoints	Auth, rate limiting, validation
Frontend code	XSS, state management, performance
Infrastructure	Secrets, permissions, logging

---

Quick Reference

Commands

# Basic review
/code-review

# Review specific files
/code-review src/auth.ts src/users.ts

# Review with focus
/code-review --focus security

# Review PR
/code-review --pr 123

Severity Actions

🔴 Critical → STOP. Fix now. No commit.
🟠 High     → STOP. Fix now. No commit.
🟡 Medium   → Note it. Fix soon. Can commit.
🟢 Low      → Optional. Nice to have.
ℹ️ Info     → FYI only.

Workflow

Code → Test → Review → Fix → Commit → Push → PR → Review → Merge → Deploy
              ↑                              ↑                    ↑
           /code-review                /code-review          /code-review