Structural type for a loader that supports predictive prefetch.
The concrete spatial-index loaders implement prefetchChunkBoundary;
loaders without chunk metadata can expose prefetchChunks for the
historical one-step behavior. The base loader interfaces don't declare
either method, so this structural type avoids coupling scene-loader.ts
to concrete loader classes.
Structural type for a loader that supports predictive prefetch. The concrete spatial-index loaders implement
prefetchChunkBoundary; loaders without chunk metadata can exposeprefetchChunksfor the historical one-step behavior. The base loader interfaces don't declare either method, so this structural type avoids coupling scene-loader.ts to concrete loader classes.