Define a product's design language and write DESIGN.md — essence, colour, typography, motion signature, voice, guardrails, and standing overrides. Use to create or revise DESIGN.md, when a run finds it missing, when code and DESIGN.md drift (it revises DESIGN.md and files fix-todos; changing product code is dx-design-execute), or to promote a repeated waiver into a standing override. Health-scan first: evidence-first on a token-healthy repo (mine the code, confirm or correct), interview-first on a token-less one; ingests Figma and brand docs with a per-session source-of-truth election. NOT for catalogue rule or waiver questions — that is dx-design.
