Started with the token layer first — primitives to semantic tokens to component tokens, light and dark mode built in from day one, never hardcoded values. Each of the 25 components went through the same pipeline: designed and Figma-verified in both themes, documented on a versioned static site with full variant/size/state matrices, then ported 1:1 into React for engineering. Every change, no matter how small, got a semantic-versioned changelog entry; the system is on v2.53.4 across 50+ tracked releases, not a single unversioned drop. The React port wasn't just a copy — building it in parallel with the docs surfaced real bugs the design-only version had hidden: Dropdown and Tag were silently missing from the package's exports, disabled on Link and DropdownItem changed the cursor but didn't actually stop clicks or navigation, DatePicker's minDate broke after midnight, UploadMedia's drag-and-drop was fully undocumented-but-broken. Fixing those in the React layer made the system correct, not just consistent-looking.