The spatial-grid manager, scene-store subscriptions, and the viewer
outliner's Object3D arrays are module-level singletons that previously
lived for the whole page lifetime. When an app unmounted the Editor
(e.g. navigating away from the 3D editor and back in an SPA host) they
retained references to the disposed Three.js scene graph, which caused
the app to freeze on re-entry as the stale data was replayed against a
fresh scene.
- initSpatialGridSync now returns the unsubscribe handle from its
scene-store subscription so callers can detach it.
- initializeEditorRuntime becomes reversible: it wires up the spatial
grid, space detection and SFX bus on mount and returns a teardown
closure that detaches both store subscriptions, clears the spatial
grid manager, and truncates the viewer outliner's selected/hovered
arrays in place.
- The Editor component's runtime-init effect now returns that teardown,
so the singletons are reset cleanly every time the Editor unmounts.
- initSFXBus is now idempotent via an internal guard so repeated
Editor mounts do not stack duplicate mitt listeners.
Co-authored-by: Claude <noreply@anthropic.com>
