描述
Use this skill whenever the user wants to write code using TDD, test-driven development, or test-first methodology. Triggers on: "/tdd", "let's do TDD", "write a failing test", "red green refactor", "test-first", "start a TDD cycle", or any request to implement a feature by writing tests before code. Adaptive five-step cycle (RED-DOMAIN-GREEN-DOMAIN-COMMIT) that detects harness capabilities and routes to guided (/tdd red|domain|green|commit) or automated (/tdd) mode. NOT for running existing tests, debugging test failures, or reviewing code -- only for the disciplined test-first cycle.