Library collections can be extended in a consuming file (inherited modes, per-mode overrides with reset, extra variables; library updates keep overrides). Variables export to the REST JSON shape or CSS custom properties and import back (merged by name, validated by the REST reader, one undo step). Gradient stops and variant properties bind to variables. Also fixes clicking a gradient stop adding a new stop.
Progress docs per craftrules standards/progress-docs.md: target-app parity, gaps, roadmap with alpha gate, readiness by audience (full / mainstream / essentials) with Opus 5.5 hours, and auto layout, components, prototyping, dev mode, collaboration, format, hardware, UI and localization parity docs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>