The Quest offers XR_FB_hand_tracking_mesh without the app declaring hand
tracking, so a Quest 3 draws the runtime's own hand mesh rather than the
procedural gloves, and its fingers bent backwards on grip: the mesh's
joints point -Z towards the fingertip and +Y out of the back of the hand,
so flexion is negative about the joint's own X, on both hands. Fix and
test by the repository owner; OPENXR.md said the Quest always drew the
gloves, which was wrong.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>