# START HERE V401 · Lunges / ATG split squats

Base: V400 canonical-authority process reset.

Read `HANDOVER_V401_ATG_SPLIT_SQUAT_LUNGES.md`, then `diagnostics/v401/V401_DYNAMIC_WARMUP_CANONICAL_AUTHORITY_GATE.json` and `diagnostics/v401/V401_ATG_SPLIT_SQUAT_LUNGES_INTEGRATION_CHECK.json`.

V401 keeps the locked canonical lunge lower body and contact rules unchanged. The user film supplies 7.0 s two-lunge timing and an explicit upper-body source-conformity patch only: torso lateral direction, contralateral overhead arm, free hand across abdomen. No new IK profile, no new solver, no post-solve quaternion reset. Human visual acceptance remains pending.