The scene root (LuxarScene), for probe resolution and physical-mesh hiding.
Push the cube camera's params to the material manager (fov 90°, square buffer).
Restore the main camera's params (the ordinary camera-materials push).
Whether the loader has settled (no update sweep, load pass or LOD load in flight).
Base URL of the store, for a store-relative hdri url.
What a live capture needs from the running app — attached by the init pipeline once those pieces exist. Without it,
scenefalls back to the room.