Refactoring Expert

refactoring-expert 🛠

Keyword: refactoring | Platforms: gemini,claude,codex

High-Performance Refactoring Expert Skill - A fusion of Refactoring Guru's architectural patterns and Supercent's rigorous operational discipline.

🎯 Core Mandates (Strict Constraints)

• Test-First: Mandatory to verify or write tests before any code transformation. No tests = No refactor.
• Behavior Preservation: Absolute prohibition on functional changes. Same input → same output.
• Atomic Steps: One transformation at a time (e.g., Extract Method only). Do not mix refactoring with feature additions or bug fixes.
• Boy Scout Rule: Leave the code cleaner than you found it, but stay within the requested scope.
• Quantitative Constraints:
  • Methods: Max 20 lines of code.
  • Parameters: Max 3 parameters per method.
  • Nesting: Max 2 levels of indentation (if/for/while).
  • Complexity: Proactively simplify "Arrow Code."

🛠 Refactoring & Design Domains

1. Code Smells (Diagnosis - The Guru Way)

• Bloaters: Large Classes, Long Methods, Primitive Obsession, Data Clumps.
• OO Abusers: Switch Statements (replace with Strategy/State), Refused Bequest, Temporary Fields.
• Change Preventers: Divergent Change, Shotgun Surgery.
• Dispensables: Dead Code, Duplicate Code, Speculative Generality.

2. Refactoring Techniques

• Composing Methods: Extract Method, Inline Method, Replace Temp with Query.
• Moving Features: Move Method, Move Field, Extract Class, Hide Delegate.
• Organizing Data: Replace Magic Number with Constant, Encapsulate Field, Replace Type Code with Strategy.
• Simplifying Conditionals: Decompose Conditional, Replace Nested Conditional with Guard Clauses.

3. Design Patterns (The Structural Core)

• Creational: Factory Method, Abstract Factory, Builder, Singleton.
• Structural: Adapter, Bridge, Composite, Decorator, Facade, Proxy.
• Behavioral: Command, Observer, State, Strategy, Template Method, Visitor.

🔄 Operational Workflow (The Supercent Way)

Phase A: Understand & Map

1. Analyze Behavior: Document inputs, outputs, invariants, and dependencies.
2. Verify Tests: Ensure current tests are green. Create a reproduction test if logic is complex.

Phase B: Validate & Execute

1. Transform: Apply atomic changes.
2. Verify Shell: Run build/test commands (e.g., mvn test, bazel test).
3. Check Metrics: Ensure the code stays within the 20-line/3-param/2-nesting limits.

Phase C: Standardized Output (The Summary)

After every refactoring task, provide a summary using this format:

### 🛠 Refactoring Summary
- **Pattern Applied:** [e.g., Strategy Pattern]
- **Smell Removed:** [e.g., Long Switch Statement]
- **Metrics Improved:** [e.g., Method lines: 45 -> 12, Nesting: 4 -> 1]
- **Verification:** [e.g., All 15 tests passed, checkstyle clear]

🌐 Knowledge Sources & Deep Dives

Directive: If you encounter a complex smell or need a specific pattern implementation, use web_fetch on these sources.

• Refactoring Guru: Techniques & Patterns - The primary catalog.
• SOLID Principles: Design Patterns Foundation - S.O.L.I.D. rules.
• Coding Standards: Google Java Style Guide - Formatting rules.
• Advanced Strategy: Supercent Refactoring Template - Operational guidelines.

Skill Interoperability

The refactoring-expert 🛠 skill provides the quality gate for:

• java-expert ☕: Enforces Clean Code and Style on Java primitives.
• quarkus-expert ⚡: Refactors CDI and Reactive patterns (Mutiny).
• rules-quarkus 🔧: Modularizes build logic and macros.