Swing rig
Procedural 26-DOF biomechanical chain. Anchored at four key poses (address → top → impact → finish) and interpolated with smoothed lerp through the swing. Every joint is parameterized — no mocap, no physics simulation. The IMPACT clubhead lands on the ball at machine precision by construction (impact-frame contract). The trail-arm chain reaches its target at ADDRESS and FINISH only — across most of the backswing and downswing the trail wrist exceeds full arm reach (the rig has no per-frame trail-grip sliding model yet) and is rendered with reduced opacity to signal the gap. Real golfers' trail hand slides down the grip as the trail elbow folds; v1 keeps a fixed grip offset, so the visible gap is a deliberate v1 limitation, not a bug.
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Impact-frame inputs
Club path and attack angle are part of the impact-frame contract but
only modulate the trajectory (ball-launch direction), not the rig's
static impact geometry. They land here once /swing has a
trajectory readout to make their effect visible.
Causal diagnostics
Deterministic rules against published thresholds. 6 findings, 6 in band, 0 warn, 0 flag.
- IN BAND
X-factor at top
45degTorso–pelvis separation in tour-pro range — 45° vs target tour 30–50° (avg ~40°).
- IN BAND
Pelvic slide (top → impact)
7cmPelvic bump 7.0 cm toward target — within tour band.
- IN BAND
Secondary spine tilt at impact
10degTrail-side lean 10° — lead shoulder rises above trail as expected.
- IN BAND
Lead-knee post-up
11degLead leg straightens 11° from address — clean post-up.
- IN BAND
Trail heel lift at impact
15degTrail heel beginning to lift (15° plantar) — natural ground-up sequence.
- IN BAND
Spine angle maintenance
10degForward bend changes 10° from address to impact — posture held cleanly.