- MaterialPaintPanel owns its scroll: the eraser/reset row stays pinned and the category tabs stick to the top, so only the material list scrolls. - Selected catalog swatch + active scene-material card use the same `ring-1 ring-primary ring-inset` outline as item/preset tiles. - Choosing a material category auto-selects its first material. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>