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"mattpocock-skills": patch
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Reshape **`tdd`** into a reference-only skill and add a missing anti-pattern.

**Reference-only.** The red → green → refactor loop is anchored by leading words the model already holds, so the step-by-step Workflow was largely restating the loop. Dropped the Workflow and per-cycle checklist; folded their one durable idea — vertical slices / tracer bullets — into the Anti-patterns section and a short Rules-of-the-loop list. Introduced **seam** as the leading word for where tests go: test only at pre-agreed seams, confirmed with the user before any test is written. Also dropped the refactor stage — TDD is now red → green; refactoring belongs to the review stage, so the refactor rule and `refactoring.md` moved out (its home is `code-review`).

**Tautological tests.** Added the tautological-test anti-pattern: a test whose assertion is recomputed the way the code computes it passes by construction and gives zero confidence — distinct from the implementation-coupling anti-pattern already covered. Added as a peer at the same sites: a Philosophy principle (expected values must come from an independent source of truth), a checklist gate, and a BAD/GOOD example pair in `tests.md`.