| name | purpose-first-tdd |
| description | Use when making or evaluating any behavior, plan, prompt, skill, code, test, or operational change that needs purpose, proof, consumer, or falsifier clarity. |
Purpose First TDD
If dispatched as a subagent for a specific task, skip this skill.
Purpose comes first. Tests are executable purpose. Code and instructions exist
to satisfy a real consumer.
Redteam forwarder: For falsifier validation, run /redteam:verify to cross-check that the falsifier actually catches the intended failure mode. A falsifier that never fires is not a real falsifier. For high-stakes contracts (security, billing, policy gates), use /redteam:review to validate the contract holds before declaring it done.
Purpose: make every change defensible before implementation.
Consumer: agents planning, implementing, reviewing, debugging, or editing
instructions.
Failure consequence: changes optimize activity instead of value; tests prove
implementation details instead of purpose; reviewers cannot tell what failure
means.
Falsifier: the change is purely cosmetic or self-contained with no behavior,
policy, proof, consumer, or public-contract impact.
Contract
Before behavior changes, fill the canonical 9-field PDD contract:
purpose: why this exists.consumer: who or what uses it.contract: what the change must achieve.failureBoundary: what breaks or is contained when it fails.evidence: test, command, observation, trace, or invariant proving it.falsifier: executable or observable condition that would prove it wrong.nonGoals: what this intentionally excludes.invariants: truths that must remain true while changing it.assumptions: facts not yet proven.
TDD Rule
For behavior, plan, prompt, skill, code, test, or operational changes:
- Write or identify failing proof from the
evidence/falsifier fields.
- Run it and see the expected failure.
- Implement the smallest change.
- Run proof again and relevant regression checks.
If the task is operational/config-only, define the equivalent proof command or
live-state check before changing it.
Judgment Rule
Any judgment call needs confidence and falsifier:
confidence=<level>; falsifier=<specific evidence that would change this>.
No falsifier means the decision is not ready.
