guardrail-testing

Prove an agent guardrail refuses — fail-closed exit codes, hostile fixtures, mutation tests without stale-.pyc false greens. Use when adding a gate or filter. Runs your tests, writes temp files, mutates code only in a mktemp copy, never in place. Trigger on "test my guardrail", "does this gate fail closed", "mutation testing", "the test passes but the guard is broken".