agents/tools/tdd-refactor.md

model

model
sonnet

Refactor code with confidence using comprehensive test safety net:

[Extended thinking: This tool uses the tdd-orchestrator agent (opus model) for sophisticated refactoring while maintaining all tests green. It applies design patterns, improves code quality, and optimizes performance with the safety of comprehensive test coverage.]

Refactoring Process

Use Task tool with subagent_type="tdd-orchestrator" to perform safe refactoring.

Prompt: "Refactor this code while keeping all tests green: $ARGUMENTS. Apply TDD refactor phase excellence:

1. Pre-Refactoring Assessment

   • Analyze current code structure and identify code smells
   • Review test coverage to ensure safety net is comprehensive
   • Identify refactoring opportunities and prioritize by impact
   • Run all tests to establish green baseline
   • Document current performance metrics for comparison
   • Create refactoring plan with incremental steps

2. Code Smell Detection

   • Duplicated Code: Extract methods, pull up to base classes
   • Long Methods: Decompose into smaller, focused functions
   • Large Classes: Split responsibilities, extract classes
   • Long Parameter Lists: Introduce parameter objects
   • Feature Envy: Move methods to appropriate classes
   • Data Clumps: Group related data into objects
   • Primitive Obsession: Replace with value objects
   • Switch Statements: Replace with polymorphism
   • Parallel Inheritance: Merge hierarchies
   • Dead Code: Remove unused code paths

3. Design Pattern Application

   • Creational Patterns: Factory, Builder, Singleton where appropriate
   • Structural Patterns: Adapter, Facade, Decorator for flexibility
   • Behavioral Patterns: Strategy, Observer, Command for decoupling
   • Domain Patterns: Repository, Service, Value Objects
   • Architecture Patterns: Hexagonal, Clean Architecture principles
   • Apply patterns only where they add clear value
   • Avoid pattern overuse and unnecessary complexity

4. SOLID Principles Enforcement

   • Single Responsibility: One reason to change per class
   • Open/Closed: Open for extension, closed for modification
   • Liskov Substitution: Subtypes must be substitutable
   • Interface Segregation: Small, focused interfaces
   • Dependency Inversion: Depend on abstractions
   • Balance principles with pragmatic simplicity

5. Refactoring Techniques Catalog

   • Extract Method: Isolate code blocks into named methods
   • Inline Method: Remove unnecessary indirection
   • Extract Variable: Name complex expressions
   • Rename: Improve names for clarity and intent
   • Move Method/Field: Relocate to appropriate classes
   • Extract Interface: Define contracts explicitly
   • Replace Magic Numbers: Use named constants
   • Encapsulate Field: Add getters/setters for control
   • Replace Conditional with Polymorphism: Object-oriented solutions
   • Introduce Null Object: Eliminate null checks

6. Performance Optimization

   • Profile code to identify actual bottlenecks
   • Optimize algorithms and data structures
   • Implement caching where beneficial
   • Reduce database queries and network calls
   • Lazy loading and pagination strategies
   • Memory usage optimization
   • Always measure before and after changes
   • Keep optimizations that provide measurable benefit

7. Code Quality Improvements

   • Naming: Clear, intentional, domain-specific names
   • Comments: Remove obvious, add why not what
   • Formatting: Consistent style throughout codebase
   • Error Handling: Explicit, recoverable, informative
   • Logging: Strategic placement, appropriate levels
   • Documentation: Update to reflect changes
   • Type Safety: Strengthen types where possible

8. Incremental Refactoring Steps

   • Make small, atomic changes
   • Run tests after each modification
   • Commit after each successful refactoring
   • Use IDE refactoring tools when available
   • Manual refactoring for complex transformations
   • Keep refactoring separate from behavior changes
   • Create temporary scaffolding when needed

9. Architecture Evolution

   • Layer separation and dependency management
   • Module boundaries and interface definition
   • Service extraction for microservices preparation
   • Event-driven patterns for decoupling
   • Async patterns for scalability
   • Database access patterns optimization
   • API design improvements

10. Quality Metrics Tracking

    • Cyclomatic Complexity: Reduce decision points
    • Code Coverage: Maintain or improve percentage
    • Coupling: Decrease interdependencies
    • Cohesion: Increase related functionality grouping
    • Technical Debt: Measure reduction achieved
    • Performance: Response time and resource usage
    • Maintainability Index: Track improvement
    • Code Duplication: Percentage reduction

11. Safety Verification

    • Run full test suite after each change
    • Use mutation testing to verify test effectiveness
    • Performance regression testing
    • Integration testing for architectural changes
    • Manual exploratory testing for UX changes
    • Code review checkpoint documentation
    • Rollback plan for each major change

12. Advanced Refactoring Patterns

    • Strangler Fig: Gradual legacy replacement
    • Branch by Abstraction: Large-scale changes
    • Parallel Change: Expand-contract pattern
    • Mikado Method: Dependency graph navigation
    • Preparatory Refactoring: Enable feature addition
    • Feature Toggles: Safe production deployment

Output should include:

• Refactored code with all improvements applied
• Test results confirming all tests remain green
• Before/after metrics comparison
• List of applied refactoring techniques
• Performance improvement measurements
• Code quality metrics improvement
• Documentation of architectural changes
• Remaining technical debt assessment
• Recommendations for future refactoring"

Refactoring Safety Checklist

Before committing refactored code:

1. ✓ All tests pass (100% green)
2. ✓ No functionality regression
3. ✓ Performance metrics acceptable
4. ✓ Code coverage maintained/improved
5. ✓ Documentation updated
6. ✓ Team code review completed

Recovery Process

If tests fail during refactoring:

• Immediately revert last change
• Identify which refactoring broke tests
• Apply smaller, incremental changes
• Consider if tests need updating (behavior change)
• Use version control for safe experimentation
• Leverage IDE's undo functionality

Integration Points

• Follows from tdd-green.md implementation
• Coordinates with test-automator for test updates
• Integrates with static analysis tools
• Triggers performance benchmarks
• Updates architecture documentation
• Links to CI/CD for deployment readiness

Best Practices

• Refactor in small, safe steps
• Keep tests green throughout process
• Commit after each successful refactoring
• Don't mix refactoring with feature changes
• Use tools but understand manual techniques
• Focus on high-impact improvements first
• Leave code better than you found it
• Document why, not just what changed

Code to refactor: $ARGUMENTS