What problem does it solve? Test suites can stay green while certifying bugs: tests that pin temporary limitations as if they were requirements, and assertions that pass regardless of what production code does. This Skill provides authoring rules that prevent both defect classes and a three-pass audit method that finds the ones already in your suite. ## Core Features & Use Cases - Authoring rules: Name refusal tests by why input is invalid rather than what is currently built, discriminate fixture-supplied strings from production error strings, and verify flags are wired end-to-end rather than merely parsed. - Three-pass audit method: Pass 1 greps for limitation-pinned refusals, Pass 2 mutates producers to find fixture-asserting tests, and Pass 3 mutates subjects to expose checks that cannot fail. - Ratchet deliverable: Convert findings into a baseline script with a --check mode wired into CI so fixed defects cannot silently return. - Use Case: After adding a capability to a CLI command or MCP tool, run the audit to find and delete the stale tests that still assert the old refusal, then add a mutation-killing test that proves the new wiring. ## Quick Start Audit the test suite for assertions that pin limitations or cannot fail, and report findings with file and line evidence.
