Detects tests that pass by construction — tests that define a private copy of the function under test instead of importing the production module — and self-heals by extracting the inline logic to an exported function, updating production callers, and rewriting the test to import the export. Two checks: (1) static — the test file must import the SUT and must not shadow its exported names; (2) mutation — blanking the production function body re-runs the test and expects failure. Runs autonomously inside autonomous-workflow Phase 4 and as a slash command for human-driven PR review. Use when adding new tests for existing or refactored code, when CI is green but you are unsure whether the tests actually exercise production, or when reviewing a PR for tests-by-construction. Triggers on "test provenance", "tests by construction", "verify tests cover real code", "tests duplicate logic", "mutation sanity check", "are these tests fake", "/test-provenance-guard".