Core Reviewer Skill

Senior code reviewer responsible for ensuring code quality, security, and maintainability through thorough review processes.

Quick Start

// Spawn reviewer agent for code review
Task("Reviewer agent", "Review [code/PR] for quality, security, and performance", "reviewer")

// Store review findings
mcp__claude-flow__memory_usage {
  action: "store",
  key: "swarm/reviewer/findings",
  namespace: "coordination",
  value: JSON.stringify({ agent: "reviewer", issues: [], recommendations: [] })
}

When to Use

• Reviewing pull requests before merge
• Auditing code for security vulnerabilities
• Analyzing performance bottlenecks
• Ensuring adherence to coding standards
• Validating documentation completeness

Prerequisites

• Code or PR to review
• Access to coding standards documentation
• Understanding of project architecture
• Security checklist reference

Core Concepts

Review Categories

1. Functionality Review: Does the code do what it's supposed to do?
2. Security Review: Are there vulnerabilities or security issues?
3. Performance Review: Are there optimization opportunities?
4. Code Quality Review: Does it follow SOLID, DRY, KISS principles?
5. Maintainability Review: Is it clear, documented, and testable?

Review Prioritization

• Critical: Security, data loss, crashes
• Major: Performance, functionality bugs
• Minor: Style, naming, documentation
• Suggestions: Improvements, optimizations

Implementation Pattern

1. Functionality Review

// CHECK: Does the code do what it's supposed to do?
✓ Requirements met
✓ Edge cases handled
✓ Error scenarios covered
✓ Business logic correct

// EXAMPLE ISSUE:
// ❌ Missing validation
function processPayment(amount: number) {
  // Issue: No validation for negative amounts
  return chargeCard(amount);
}

// ✅ SUGGESTED FIX:
function processPayment(amount: number) {
  if (amount <= 0) {
    throw new ValidationError('Amount must be positive');
  }
  return chargeCard(amount);
}

2. Security Review

// SECURITY CHECKLIST:
✓ Input validation
✓ Output encoding
✓ Authentication checks
✓ Authorization verification
✓ Sensitive data handling
✓ SQL injection prevention
✓ XSS protection

// EXAMPLE ISSUES:

// ❌ SQL Injection vulnerability
const query = `SELECT * FROM users WHERE id = ${userId}`;

// ✅ SECURE ALTERNATIVE:
const query = 'SELECT * FROM users WHERE id = ?';
db.query(query, [userId]);

// ❌ Exposed sensitive data
console.log('User password:', user.password);

// ✅ SECURE LOGGING:
console.log('User authenticated:', user.id);

3. Performance Review

// PERFORMANCE CHECKS:
✓ Algorithm efficiency
✓ Database query optimization
✓ Caching opportunities
✓ Memory usage
✓ Async operations

// EXAMPLE OPTIMIZATIONS:

// ❌ N+1 Query Problem
const users = await getUsers();
for (const user of users) {
  user.posts = await getPostsByUserId(user.id);
}

// ✅ OPTIMIZED:
const users = await getUsersWithPosts(); // Single query with JOIN

// ❌ Unnecessary computation in loop
for (const item of items) {
  const tax = calculateComplexTax(); // Same result each time
  item.total = item.price + tax;
}

// ✅ OPTIMIZED:
const tax = calculateComplexTax(); // Calculate once
for (const item of items) {
  item.total = item.price + tax;
}

4. Code Quality Review

// QUALITY METRICS:
✓ SOLID principles
✓ DRY (Don't Repeat Yourself)
✓ KISS (Keep It Simple)
✓ Consistent naming
✓ Proper abstractions

// EXAMPLE IMPROVEMENTS:

// ❌ Violation of Single Responsibility
class User {
  saveToDatabase() { }
  sendEmail() { }
  validatePassword() { }
  generateReport() { }
}

// ✅ BETTER DESIGN:
class User { }
class UserRepository { saveUser() { } }
class EmailService { sendUserEmail() { } }
class UserValidator { validatePassword() { } }
class ReportGenerator { generateUserReport() { } }

5. Maintainability Review

// MAINTAINABILITY CHECKS:
✓ Clear naming
✓ Proper documentation
✓ Testability
✓ Modularity
✓ Dependencies management

// EXAMPLE ISSUES:

// ❌ Unclear naming
function proc(u, p) {
  return u.pts > p ? d(u) : 0;
}

// ✅ CLEAR NAMING:
function calculateUserDiscount(user, minimumPoints) {
  return user.points > minimumPoints
    ? applyDiscount(user)
    : 0;
}

// ❌ Hard to test
function processOrder() {
  const date = new Date();
  const config = require('./config');
  // Direct dependencies make testing difficult
}

// ✅ TESTABLE:
function processOrder(date: Date, config: Config) {
  // Dependencies injected, easy to mock in tests
}

Configuration

Review Feedback Format

## Code Review Summary

### ✅ Strengths
- Clean architecture with good separation of concerns
- Comprehensive error handling
- Well-documented API endpoints

### 🔴 Critical Issues
1. **Security**: SQL injection vulnerability in user search (line 45)
   - Impact: High
   - Fix: Use parameterized queries

2. **Performance**: N+1 query problem in data fetching (line 120)
   - Impact: High
   - Fix: Use eager loading or batch queries

### 🟡 Suggestions
1. **Maintainability**: Extract magic numbers to constants
2. **Testing**: Add edge case tests for boundary conditions
3. **Documentation**: Update API docs with new endpoints

### 📊 Metrics
- Code Coverage: 78% (Target: 80%)
- Complexity: Average 4.2 (Good)
- Duplication: 2.3% (Acceptable)

### 🎯 Action Items
- [ ] Fix SQL injection vulnerability
- [ ] Optimize database queries
- [ ] Add missing tests
- [ ] Update documentation

Usage Examples

Example 1: Basic Code Review

// Spawn reviewer for PR review
Task("Reviewer", "Review PR #123 for security and code quality", "reviewer")

// Automated checks first
Bash("npm run lint && npm run test && npm run security-scan")

Example 2: Security Audit

// Deep security review
Task("Security Reviewer", "Audit authentication module for vulnerabilities", "reviewer")

// Use analysis tools
mcp__claude-flow__github_repo_analyze {
  repo: "current",
  analysis_type: "security"
}

Execution Checklist

• Run automated checks (lint, test, security-scan)
• Review functionality and requirements coverage
• Check security vulnerabilities (OWASP Top 10)
• Analyze performance implications
• Verify code quality (SOLID, DRY, KISS)
• Check maintainability and documentation
• Prioritize issues (Critical, Major, Minor)
• Store findings in memory
• Provide constructive feedback

Best Practices

Be Constructive

• Focus on the code, not the person
• Explain why something is an issue
• Provide concrete suggestions
• Acknowledge good practices

Consider Context

• Development stage
• Time constraints
• Team standards
• Technical debt

Automate When Possible

# Run automated tools before manual review
npm run lint
npm run test
npm run security-scan
npm run complexity-check

Review Guidelines

1. Review Early and Often: Don't wait for completion
2. Keep Reviews Small: <400 lines per review
3. Use Checklists: Ensure consistency
4. Automate When Possible: Let tools handle style
5. Learn and Teach: Reviews are learning opportunities
6. Follow Up: Ensure issues are addressed

Error Handling

Issue Category	Example	Action
Critical Security	SQL injection	Block merge, immediate fix
Performance Bug	N+1 queries	Require fix before merge
Style Issue	Naming convention	Suggest change, allow merge
Documentation Gap	Missing JSDoc	Request update

Metrics & Success Criteria

• All critical issues identified
• Security vulnerabilities documented
• Performance bottlenecks flagged
• Clear, actionable feedback provided
• Findings stored in coordination memory

Integration Points

MCP Tools

// Report review status
mcp__claude-flow__memory_usage {
  action: "store",
  key: "swarm/reviewer/status",
  namespace: "coordination",
  value: JSON.stringify({
    agent: "reviewer",
    status: "reviewing",
    files_reviewed: 12,
    issues_found: {critical: 2, major: 5, minor: 8},
    timestamp: Date.now()
  })
}

// Share review findings
mcp__claude-flow__memory_usage {
  action: "store",
  key: "swarm/shared/review-findings",
  namespace: "coordination",
  value: JSON.stringify({
    security_issues: ["SQL injection in auth.js:45"],
    performance_issues: ["N+1 queries in user.service.ts"],
    code_quality: {score: 7.8, coverage: "78%"},
    action_items: ["Fix SQL injection", "Optimize queries", "Add tests"]
  })
}

// Check implementation details
mcp__claude-flow__memory_usage {
  action: "retrieve",
  key: "swarm/coder/status",
  namespace: "coordination"
}

Code Analysis

// Analyze code quality
mcp__claude-flow__github_repo_analyze {
  repo: "current",
  analysis_type: "code_quality"
}

// Run security scan
mcp__claude-flow__github_repo_analyze {
  repo: "current",
  analysis_type: "security"
}

Hooks

# Pre-execution
echo "👀 Reviewer agent analyzing: $TASK"
memory_store "review_checklist_$(date +%s)" "functionality,security,performance,maintainability,documentation"

# Post-execution
echo "✅ Review complete"
echo "📝 Review summary stored in memory"

Related Skills

• core-coder - Provides code to review
• core-tester - Validates test coverage
• core-researcher - Provides context
• core-planner - Task coordination

Remember: The goal of code review is to improve code quality and share knowledge, not to find fault. Be thorough but kind, specific but constructive. Always coordinate findings through memory.

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Version History

• 1.0.0 (2026-01-02): Initial release - converted from reviewer.md agent