Prefetch nearby scene assets in the background

docs/grid-agent-llm.md

@@ -78,6 +78,14 @@ objects are selected by that distance; avatar attachments are rigged through
 their linkset hierarchy and included only when the camera is focused on the
 avatar, after world-object capacity is reserved.
 
+Raw mesh, texture, and material assets are treated as immutable by UUID and persist in the
+platform MetaCrate cache. `vision.asset_cache_max_bytes` bounds that cache with a 2 GiB default;
+successful reads refresh its LRU order and pruning removes the least recently used assets first.
+While logged in, the live scene source continuously runs its normal distance-bounded collection,
+asset fetch, texture decode, material parse, and mesh reconstruction path in the background. A
+snapshot therefore reuses the warm persistent, decoded, geometry, material, and GPU caches instead
+of beginning asset discovery when the model asks to look.
+
 `behavior_camera_set` gives an authorized model a bounded position, target, and
 vertical field of view; `behavior_camera_reset` restores the avatar-facing
 view. Full avatar body/attachment mesh fidelity and baking remain separately