Scene Setup & Hygiene

The execution model and verification steps are in blender-core.

Procedure

1. Run scripts/scene_audit.py (add --fix purge scale paths only on files you own). It reports units, unapplied/negative scale, default names, objects in the scene root, missing images, orphans and far-off origins.
2. Set units: Metric, Unit Scale 1.0, Length meters. Keep 1.0 even for Unreal/Roblox, because exporters handle the conversion (see blender-export-pipelines).
3. Build the collection layout (below). Every object must be in a named collection, never the scene root.
4. Name everything with the conventions below. Rename after every duplicate or join so no .001 suffixes remain.
5. Set origins: props at the bottom-center (they sit on the ground at Z=0), characters at world origin between the feet, doors/hinges at the pivot.
6. Apply rotation and scale on meshes (Ctrl+A). Keep location unless the asset should export at the origin.
7. Re-run the audit. It's done when issues is empty or every remaining issue is intentional and explained.