Test-First Discipline

Internal shared skill. Single source of truth for failing-test-first implementation order. Hosts declare it in dependencies and abort if missing — no silent fallback.

Name note: intentionally not named tdd or test-driven-development (external skills repos). Use this name only.

Iron Law

NO PRODUCTION BEHAVIOR CODE WITHOUT A FAILING TEST OBSERVED FIRST.

1. Write the failing test (or equivalent automated failing check).
2. Run it and observe the failure in the current session.
3. Write the minimal production code to pass.
4. Re-run; then refactor if needed while staying green.

If production behavior code was written before step 2: delete it and restart from the failing test. Do not keep it as "reference" or "adapt while writing tests".

When it applies