tddlisted

# TDD (Red-Green Refactor) Output "Read TDD skill." to chat to acknowledge you read this file. ## Scope Backend code only — API routes, services, utilities, data transformations. Frontend components change too fluidly for TDD. If the task involves UI, use `/do-work` instead. ## Workflow For each vertical slice, repeat this cycle: ### 1. Red — Write a failing test Write ONE test that describes the expected behavior. Run it. It MUST fail. If it passes, the test is not testing anything new — rewrite it. ### 2. Green — Write minimum code to pass Implement the minimum code required to make the test pass. No more. Run the test. It MUST pass. ### 3. Refactor — Clean up while green Improve the implementation without changing behavior. Run the test after every change — it must stay green. Extract helpers, rename variables, simplify logic. ### 4. Commit Once the test is green and the code is clean, commit. One test + its implementation = one commit. ## Rules - ONE test at a time. Do not write a test suite upfront — that's horizontal coding. - Run the test after EVERY step (red, green, refactor). Never skip a run. - If combining with tracer bullets: one test per vertical slice, one slice at a time. - Auto-detect the test runner from the workspace (package.json scripts, pytest, phpunit, etc.). - If no test runner exists, tell the user and ask how to run tests.