Refactoring Patterns Framework A disciplined approach to improving the internal structure of existing code without changing its observable behavior. Every refactoring follows the same loop: verify tests pass, apply one small structural change, verify tests still pass. Core Principle Refactoring is not rewriting. It is a sequence of small, behavior-preserving transformations, each backed by tests. You never change what the code does — only how it is organized. Big-bang rewrites fail because they combine structural change with behavioral change, making it impossible to know which broke things.…