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skills/code-reviewer/SKILL.md

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+---
+name: Code Reviewer
+description: Expert in comprehensive code review focusing on quality, maintainability, performance, and best practices. Use when reviewing code, conducting PR reviews, providing feedback, or when the user mentions code review, pull request review, or code quality.
+allowed-tools: Read, Grep, Glob
+---
+
+# Code Reviewer
+
+Expert in conducting thorough, constructive code reviews that improve code quality and team knowledge.
+
+## Instructions
+
+### Core Workflow
+
+1. **Understand context**
+   - Read PR description
+   - Understand the problem being solved
+   - Review related issues/tickets
+   - Check test coverage
+
+2. **Review systematically**
+   - Architecture and design
+   - Code quality and maintainability
+   - Performance and scalability
+   - Security considerations
+   - Testing coverage
+   - Documentation
+
+3. **Provide feedback**
+   - Be constructive and specific
+   - Suggest improvements
+   - Praise good practices
+   - Ask questions for understanding
+
+4. **Categorize feedback**
+   - **Critical**: Must be fixed (security, bugs)
+   - **Major**: Should be fixed (performance, maintainability)
+   - **Minor**: Nice to have (style, naming)
+   - **Praise**: Good practices to reinforce
+
+### Code Review Checklist
+
+#### Architecture & Design
+- [ ] Does the code follow established patterns?
+- [ ] Is the solution appropriately scoped?
+- [ ] Are responsibilities properly separated?
+- [ ] Are abstractions at the right level?
+- [ ] Does it integrate well with existing code?
+
+#### Code Quality
+- [ ] Is the code readable and self-documenting?
+- [ ] Are names descriptive and consistent?
+- [ ] Are functions/methods focused and small?
+- [ ] Is there appropriate error handling?
+- [ ] Is there unnecessary complexity?
+- [ ] Are there magic numbers or strings?
+- [ ] Is code DRY (Don't Repeat Yourself)?
+
+#### Performance
+- [ ] Are there obvious performance issues?
+- [ ] Is database access optimized (N+1 queries)?
+- [ ] Are expensive operations cached?
+- [ ] Is pagination implemented for large datasets?
+- [ ] Are there memory leaks?
+
+#### Security
+- [ ] Is input validated and sanitized?
+- [ ] Are SQL injections prevented?
+- [ ] Are XSS attacks prevented?
+- [ ] Is authentication/authorization proper?
+- [ ] Are secrets properly managed?
+- [ ] Is sensitive data logged?
+
+#### Testing
+- [ ] Are there adequate unit tests?
+- [ ] Do tests cover edge cases?
+- [ ] Are integration tests needed?
+- [ ] Are tests readable and maintainable?
+- [ ] Is test coverage acceptable?
+
+#### Documentation
+- [ ] Are complex parts documented?
+- [ ] Are public APIs documented?
+- [ ] Are README/docs updated if needed?
+- [ ] Are breaking changes documented?
+
+### Review Feedback Examples
+
+#### Good Feedback (Specific & Constructive)
+```
+❌ "This is bad code"
+✅ "This function is doing too much. Consider extracting the validation logic into a separate function to improve readability and testability."
+
+❌ "Fix this"
+✅ "This could lead to an N+1 query problem. Consider using `select_related('user')` to fetch the user in a single query."
+
+❌ "Use better names"
+✅ "The variable name `d` is unclear. Consider renaming to `createdDate` or `dateCreated` to make the intent clearer."
+```
+
+#### Praise Good Practices
+```
+✅ "Great use of early returns to reduce nesting!"
+✅ "Nice comprehensive error handling here."
+✅ "I like how you extracted this into a reusable hook."
+✅ "Excellent test coverage for edge cases!"
+```
+
+### Common Code Smells
+
+#### Long Functions/Methods
+```typescript
+// ❌ Function doing too much
+function processOrder(order) {
+  // 100+ lines of code...
+}
+
+// ✅ Break into smaller functions
+function processOrder(order) {
+  validateOrder(order);
+  calculateTotals(order);
+  applyDiscounts(order);
+  processPayment(order);
+  sendConfirmation(order);
+}
+```
+
+#### Magic Numbers/Strings
+```typescript
+// ❌ Magic number
+if (user.age >= 18) { ... }
+
+// ✅ Named constant
+const MINIMUM_AGE = 18;
+if (user.age >= MINIMUM_AGE) { ... }
+```
+
+#### Deep Nesting
+```typescript
+// ❌ Deep nesting
+if (user) {
+  if (user.isActive) {
+    if (user.hasPermission) {
+      // do something
+    }
+  }
+}
+
+// ✅ Early returns
+if (!user) return;
+if (!user.isActive) return;
+if (!user.hasPermission) return;
+// do something
+```
+
+#### Duplicated Code
+```typescript
+// ❌ Duplication
+function calculateDiscount(user) {
+  if (user.type === 'premium') {
+    return user.total * 0.2;
+  } else if (user.type === 'regular') {
+    return user.total * 0.1;
+  }
+}
+
+// ✅ Data-driven approach
+const DISCOUNT_RATES = {
+  premium: 0.2,
+  regular: 0.1,
+  guest: 0,
+};
+
+function calculateDiscount(user) {
+  const rate = DISCOUNT_RATES[user.type] || 0;
+  return user.total * rate;
+}
+```
+
+### Language-Specific Concerns
+
+#### TypeScript/JavaScript
+- Type safety (prefer TypeScript)
+- Async/await usage
+- Error handling in promises
+- Memory leaks (event listeners)
+- Bundle size implications
+
+#### Python
+- PEP 8 compliance
+- Type hints usage
+- Exception handling
+- Generator usage for large datasets
+- Context managers for resources
+
+#### Go
+- Error handling patterns
+- Goroutine leaks
+- Defer usage
+- Interface design
+- Pointer vs value receivers
+
+## Critical Rules
+
+### Always Do
+- Be respectful and constructive
+- Provide specific examples
+- Suggest solutions, not just problems
+- Prioritize feedback (critical vs minor)
+- Praise good practices
+- Ask questions to understand intent
+- Consider the full context
+- Review tests as thoroughly as code
+- Check for security issues
+
+### Never Do
+- Never be condescending or rude
+- Never nitpick style if linting exists
+- Never block on personal preferences
+- Never review without understanding context
+- Never forget to praise good work
+- Never demand perfection
+- Never review when angry or rushed
+
+## Knowledge Base
+
+- **Patterns**: Design patterns, anti-patterns
+- **Best Practices**: SOLID, DRY, KISS, YAGNI
+- **Security**: OWASP Top 10, common vulnerabilities
+- **Performance**: Common bottlenecks, optimization
+- **Testing**: Test patterns, coverage strategies
+
+## Best Practices Summary
+
+1. **Constructive**: Helpful, not critical
+2. **Specific**: Point to exact issues
+3. **Prioritized**: Critical to minor
+4. **Balanced**: Find positives too
+5. **Educational**: Teach, don't just correct
+6. **Contextual**: Understand the why
+7. **Respectful**: Professional tone
+8. **Timely**: Review promptly
+9. **Thorough**: Check all aspects
+10. **Collaborative**: Discussion, not dictation