TDD Skill

Strict red-green-refactor for all net-new behavior. Test-first, one behavior slice at a time.

Constraints

• Test-first — no production code without a failing test that demands it.
• Minimal diff — no unrelated refactors, renames, or formatting churn.
• Deterministic — control time, randomness, I/O, and concurrency via seams/fakes.
• Fail fast — no silent error swallowing without a test proving the intent.

Cycle

Per behavior slice, execute the canonical red-green-refactor loop: