Three solver defects made limbs teleport, twist, or windmill: write-back
angles wrapped at ±180 and lerped the long way around; branch flips landed
on configurations the anatomical write-back cannot represent, silently
pulling pinned extremities off their pins; and the degenerate straight-limb
bend plane fell back to the camera axis instead of the anatomical anterior.
solve_limb now verifies each branch reproduces the solved end before
accepting it, resolve unwraps written-back angles toward the pose they
replace, and the degenerate plane comes from the parent's anterior axis.
render.py --check replays every exercise's full tween loop and fails hard
on six invariants (pin fidelity, continuity, wraps, authored-vs-resolved
drift, ground penetration, resolved ROM); --export refuses to ship a
failing exercise. All 66 motions re-authored or retouched to pass: honest
authored angles where pins used to override them silently, grounded feet
on the seated machines, a vertical bench-press bar path, straight-armed
child's pose, a butterfly stretch seated on the mat, and FK arms where
pins forced impossible reaches. MotionSolver.swift mirrors the solver
changes line for line, held by regenerated fixtures.
Claude-Session: https://claude.ai/code/session_01PKptrgbx74peTwHGRxBojv
Shoulder and pelvis widths grow to human-like proportions per profile
(shoulders wider than hips for neutral/male, reversed for female) and
are now drawn — bars across the attach points that read near-full-width
face-on and as a shoulder/hip nub in profile, so limbs visibly hang
from a torso instead of a point. Orbiting no longer re-solves IK pins
in the rotated view (pins are canvas targets in the authored camera):
the pose resolves first and the posed body rotates, which fixes hands
sticking to stale screen points mid-orbit (Cat-Cow, Bird Dog, Plank).
Leg Extension and Leg Curl swap their ankle bars for a machine roller
disc — a new `roller` prop riding the shin's press side. Fixtures
regenerated; both renderers updated in lockstep.
Claude-Session: https://claude.ai/code/session_01LEoff8bXGBS83tK1c55Mf7
The library's planar world-angle rig becomes a genuine 3D anatomical
model: skeleton.json holds bone-length profiles (real shoulder/pelvis
widths, feet, neutral/female/male) and per-joint ROM; motions pose
joints with anatomical angles (flexion/abduction/rotation from neutral
standing) under a per-exercise orthographic camera, resolved by
kinematics.py (3D FK, analytic two-bone IK with anatomical write-back)
and validated against physiological ranges. All 20 sagittal motions
were migrated by planar decomposition with 0.00 px golden parity against
the old renderer — relabeled to true anatomy, since shading is now
near-dark/far-light by camera depth rather than by limb suffix — and
the face-on machines are re-authored honestly: Abductor/Adductor with
real hip abduction (the foreshortened "frontal" profile is retired) and
Rotary with genuine spine axial rotation. Figures gain articulated
feet; profiles swap without touching a single motion script; --orbit
sweeps the camera 360° while a motion loops.
The in-app SwiftUI renderer (iOS + watch) is ported to the same model
and consumes the exported motions verbatim; figure-fixtures.json pins
its geometry to the Python pipeline within 0.5 px across every
exercise, key frame, tween, and orbit sample. Also makes the watch
bridge logger nonisolated for the newer SDK's stricter isolation
checking.
Claude-Session: https://claude.ai/code/session_01LEoff8bXGBS83tK1c55Mf7
rzen