Contract

• Input: problem or task defined by the skill body.
• Output: Markdown artifact or structured result with completion criteria met.
• Side effects: none (design/review/documentation only unless explicitly stated).
• Dependencies: none (self-contained unless linked to other skills).
• Stop condition: all process steps completed; artifact saved; criteria checked.
• Risk: low.
• Boundary: produces reasoning or documentation artifacts; does not modify external systems unless explicitly instructed.

Test-Driven Development

TDD is the red → green loop. This skill is the reference that makes that loop produce tests worth keeping: what a good test is, where tests go, the anti-patterns, and the rules of the loop. Every section applies on every cycle — consult them before and during the loop, not after.

When exploring the codebase, read CONTEXT.md (if it exists) so test names and interface vocabulary match the project's domain language, and respect ADRs in the area you're touching.

What a good test is