Senior Code Review

Purpose

Perform thorough code reviews with a senior engineer mindset, identifying issues across security, performance, maintainability, and correctness dimensions.

When to Use

Use this skill when the task involves:

• Reviewing pull requests or merge requests
• Analyzing code snippets for issues
• Auditing code for security vulnerabilities
• Identifying performance bottlenecks
• Evaluating architectural decisions

Constraints

• Never approve without reviewing — Always provide substantive feedback
• Prioritize issues by severity (critical → high → medium → low)
• Cite specific lines when pointing out issues
• Suggest concrete fixes, not just problem descriptions
• Flag security issues with OWASP references where applicable
• Consider backward compatibility for public APIs

Review Checklist

Security

• Input validation and sanitization
• SQL/NoSQL injection prevention
• XSS prevention (output encoding)
• CSRF protection
• Authentication/authorization checks
• Secrets not hardcoded
• Dependency vulnerabilities

Performance

• N+1 query patterns
• Unnecessary re-renders (React)
• Memory leaks (event listeners, subscriptions)
• Appropriate caching
• Database index usage

Maintainability

• Single Responsibility Principle
• Clear naming conventions
• Adequate error handling
• Proper logging
• Test coverage

Correctness

• Edge case handling
• Race condition prevention
• Type safety
• Business logic accuracy

Examples

Input

Review this endpoint for issues:

app.post('/users', (req, res) => {
  const query = `SELECT * FROM users WHERE email = '${req.body.email}'`;
  db.query(query).then((user) => res.json(user));
});

Output

🔴 CRITICAL: SQL Injection Vulnerability

• Line 2: Direct string interpolation in SQL query allows injection attacks
• OWASP Reference: A03:2021-Injection
• Fix: Use parameterized queries

app.post('/users', async (req, res) => {
  try {
    const user = await db.query('SELECT * FROM users WHERE email = $1', [
      req.body.email,
    ]);
    res.json(user);
  } catch (error) {
    res.status(500).json({ error: 'Internal server error' });
  }
});

🟡 MEDIUM: Missing Input Validation

• No validation on req.body.email format
• Fix: Add email format validation before query

🟡 MEDIUM: Missing Error Handling

• Unhandled promise rejection could crash server
• Fix: Wrap in try/catch with proper error response

Related Skills

• jest-testing-generator — Suggest missing test cases
• nest-backend-service-builder — Recommend architectural improvements

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