refactor

Surgical code refactoring to improve maintainability without changing behavior. Improve code structure and readability without changing external behavior. Refactoring is gradual evolution, not revolution. Use this for improving existing code, not rewriting from scratch. Use this skill when: - Covers 10 common code smells: long methods, duplication, large classes, long parameter lists, feature envy, primitive obsession, magic numbers, nested conditionals, dead code, and inappropriate intimacy - Includes extract method, extract class, and introduce type safety patterns with before/after examples - Provides design pattern refactoring strategies: Strategy, Chain of Responsibility, and others for replacing conditional logic - Emphasizes safe refactoring process: prepare with tests, make small changes, verify with tests, commit incrementally - Code is hard to understand or maintain - Functions/classes are too large - Code smells need addressing - Adding features is difficult due to code structure - User asks "clean up this code", "refactor this", "improve this" - Behavior is preserved - Refactoring doesn't change what the code does, only how - Small steps - Make tiny changes, test after each - Version control is your friend - Commit before and after each safe state - Tests are essential - Without tests, you're not refactoring, you're editing - One thing at a time - Don't mix...