New page covering the geometry/renderer/system trio that registry-driven
kinds opt into. Documents:
- The three optional fields on NodeDefinition and when each applies
- Generic <GeometrySystem> + <ParametricNodeRenderer> runtime
- GeometryContext shape (resolve / children / siblings / parent)
- Combination matrix for shelf / spawn / zone / door / window / GLB items
- Migration recipe from custom renderer+system files to def.geometry
- Rules around purity, dispose-on-rebuild, register-once
renderers.md and systems.md gain "prefer registry-driven" banners and
link out to the new page. Architecture README adds the page to the
index so review-architecture skill picks it up.
The pattern was validated by the shelf spike: inline-JSX geometry was
visibly laggy on parametric edits; moving to a per-kind system reading
dirtyNodes (mirroring door/wall/item) restored smoothness. The three-
checkbox model generalises that win so most future kinds need only a
pure geometry function.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
