Build and document the canonical quaternius_base.glb (welded, skinned, 62-joint, 1.81m)

docs/npc-model-sourcing.md

@@ -122,6 +122,20 @@ region first, then material — the same material name can mean `cloth` on the b
 | `Orange`, `LightBlue`, `LightBrown`, `Brown`, `Brown2` | Legs | `pants` |
 | `Worker_Vest` | Worker body | `cloth` |
 
+### Canonical base (built 2026-11-05)
+
+`tmp/npc-research/quaternius_base.glb` is the welded, triangulated, grounded, animation-free
+canonical base built from `Casual_Hoodie.glb` (the most detailed body) by
+`tmp/npc-research/build_quaternius_base.py`:
+
+- one `npc_base` mesh — 3,199 welded verts / 6,206 tris (Body + Feet + Head + Legs joined);
+- 62 joints, skinned (no unskinned faces);
+- height 1.81 m, feet at y 0, front on Godot +Z / Blender −Y (T-pose rest);
+- no animation clips; `inspect` clean (no issues).
+
+This is the §2 contract-bake input: the 62-joint rig is authoring-only and is mapped to the
+13-core contract next, not shipped as-is.
+
 ## Contract mismatch
 
 The expensive part is the rig and proportions, not the mesh. The source has a