tdd

Write a failing test for new behavior before implementing it, then implement only enough to pass, then refactor — red, green, refactor for code that has never worked yet. Use when building a new feature, function, endpoint, or component from scratch and no prior bug is being reproduced. Not for fixing a bug, defect, regression, or wrong output in existing code — that is failing-test-first, which owns the bugfix case specifically; defer to it whenever a prior working state exists to reproduce a break against.