refactoring-patterns

# 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. **The foundation:** Bad code is a natural consequence of delivering under time pressure, not a character flaw. Code smells are objective signals of degraded structure; the smell catalog tells you *where* to look, and the refactoring catalog tells you *what to do*. ## Scoring **Goal: 10/10.** Score structural quality by how many of the eight [Quick Diagnostic](#quick-diagnostic) rows pass — `score = round(passed / 8 × 10)`, adjusting down when a single smell is severe. Bands: - **9-10**: no obvious smells remain, each function does one thing, names reveal intent, duplication is eliminated, conditionals use polymorphism where apt, and tests cover the refactored paths. - **5-6**: a few smells remain (a Long Method, some duplication) but structure is mostly sound. - **≤3**: pervasive smells — tangled conditionals, God classes, duplication everywhere — or no tests to refactor sa...