A skeleton→content crossfade whose loading/loaded state is a pure function of the timeline. The Skeleton renderer is pure (reads no frame); only the composed SkeletonBlock shimmer reads it. SkeletonStyle opacities sum to 1 so the box never dims; real children sit in normal flow and the placeholder (a lines/card layout or a custom node) is an absolute overlay.
pnpm dlx shadcn@latest add "https://www.remocn.dev/r/skeleton.json"