Applies specific refactoring moves from Fowler's catalog to improve code structure without changing behavior — language agnostic. Use when asked to "refactor this", "apply extract method", "remove duplication", "simplify this class", "this method is too long", "clean this up structurally", or "what refactoring should I apply here". Do NOT use for bug fixing, adding features, or architecture layer redesign. Requires existing behavior to be preserved.
