A3 — Refactoring to Patterns

Task

Start from working code with a genuine design problem. Refactor incrementally toward an appropriate pattern or pattern composition.

Requirements

• define the motivating change scenario;
• characterize existing behavior with tests;
• show the refactoring sequence as individually reviewable steps;
• identify preconditions and risk at each step;
• measure at least two relevant structural/quality properties before and after;
• explain whether the final canonical pattern form is necessary;
• include a git history that makes the sequence inspectable.

Evaluation principle

Pattern conformance is secondary to behavior preservation, improved changeability, and justified structure.