Prepare the modular part intake: inventory, extract, verify, join and the part contract

docs/asset-tooling.md

@@ -302,6 +302,24 @@ python3 tools/blender_assets.py texels --json     # machine-readable
 python3 tools/blender_assets.py texels --only npc_coat
 ```
 
+
+### Quaternius modular parts (outfit variety)
+
+`tools/quaternius_parts.py` is the intake for the upstream modular pack, which ships as a Google
+Drive folder and is therefore downloaded once by hand into `tmp/quaternius-intake/` (gitignored):
+
+| Step | Command | Runs in |
+| --- | --- | --- |
+| list what the download contains | `python3 tools/quaternius_parts.py inventory --dir tmp/quaternius-intake` | plain Python (parses the GLB container) |
+| cut one mesh out as a part | `... extract --file <glb> --mesh <name> --part <name>` | Blender (rewrites the skin) |
+| hash and validate the kept parts | `... verify --dir assets/models/blender_src/quaternius/parts` | plain Python |
+
+A part is one skinned mesh on the 62-joint rig; the contract and the join behaviour are in
+`assets/models/blender_src/quaternius/parts/README.md`. `build` joins a role's
+`CHARACTERS[...]["parts"]` onto its base body before the slot map, keeping the part's weights and
+dropping its redundant armature. The pack is never committed — only the parts that are used, with
+their SHA-256 in `CREDITS.md`.
+
 ## Local map development (planned)
 
 The local map workstreams (H–M) in [`TODO.md`](../TODO.md#3d-model-re-evaluation) are