test-driven-development

TDD discipline for STANDARD-profile Implement phase. Daily protocol without opening SKILL.md: - RED first: write the test from an AC, RUN it, confirm it fails. No implementation yet. - GREEN second: write the minimum code to pass. Resist adding "while I'm here" code. - REFACTOR third: clean up only after green. Tests stay green throughout. - One test = one AC. If a test asserts multiple behaviors, split it. - Never modify a test to make a failing implementation pass — fix the implementation. - Skipping RED (writing test+impl together) violates the discipline; you do not know the test actually tests anything. Open SKILL.md when deciding: how to test code without obvious seams, when to stub vs mock vs use a real dependency, refactor patterns that preserve green.