keel-tdd-or-test-firstlisted

# keel-tdd-or-test-first ## Purpose Use this skill when Keel execution should start with evidence: software tests first, or hardware testbench, assertion, lint, or equivalent static evidence first. This skill owns the Verify strategy taxonomy, the evidence contract, and their binding to the task capsule; generic test-writing mechanics (how to loop red-green, what to mock) belong to the host runtime and are not restated here. ## Context to read Read the selected task's compiled capsule: resolved Acceptance, Verify strategy and M<n> checks, Mode, Read, and Touch. `keel gate task-start` returns that capsule and its fingerprint; the fingerprint belongs in the task's Evidence `Contract` line before implementation. Inspect the public interface under test and keep new tests inside the authorized Touch scope. ## Strategy selection `Verify` names one supported strategy chosen at authoring time as the least-cost proof of the resolved Acceptance: - `vertical-tdd`: new independently testable deterministic behavior; one check red then green at a time. - `regression-first`: an observable defect; reproduce it through the public interface first, then prove the fix with the same check. - `characterization` / `snapshot-characterization`: deterministic or generated outputs kept stable by byte or snapshot comparison; not downgraded to build success. - `rendered-behavior`: interactive surfaces exercised through the real rendered interface; strict red-green optional by cost. - `evidence-firs