RFD 1104: Uploaded VRM, rotate the scene root, never the hips
Problem
This project once mutated an uploaded .vrm after load, instead of rendering it as-is: rotating the armature or hips alone, running AIGC rig-repair on it, and always yawing on export. On a VRM0 UniGLTF multi-skin file (each of body, head, eyes, cornea, hair carrying its own skin index, bones as scene siblings), rotating only the armature moves bone world matrices relative to the mesh nodes it does not touch, drifting the bind worst at the eyes and finger extremities.
Decision
Rotate vrm.scene, the root, never the hips or the armature alone. Skip AIGC rig repair entirely when userData.vrmNormalized is set. Build the skeleton overlay from the primary skinned mesh, not from humanoid Normalized_* nodes. Yaw on export only when the model’s world-forward direction actually needs it (getWorldDirection().z > 0.5), never an unconditional rotateY(π). processModel early-returns for any VRM or vrmBindPassthrough model: no autoscale, no AIGC yaw repair.
See DETAILS.md for the passthrough policy, the display-path rules, the export-path steps, the implementation map, and the retest checklist.