2026: OpenSCAD robot and remote, physical joint limits, model in Unity

hardware/openscad/ rebuilds the broken Fusion models as OpenSCAD:
body (top/bottom plate, standoffs, battery bay, switch), legs (coxa
bracket, femur link, tibia, horn adapters, TPU socks, servo cables),
the whole robot, and the remote (shell, lid, Nextion 3.5", JH-D400X-R4
sticks, 18650 UPS board, IMU, Teensy 4.0, USB-C breakout). Every part
was checked by slicing against the original STEP solids; the original's
bugs are fixed and listed in PLANNING.md.

The robot now uses a hexagon leg layout (corner legs 60 deg round from
the mid legs; the corner coxa brackets need turning on their splines).
Physical limits from a collision sweep of the model are in Config.h:
per-leg coxa limits and LEG_CLEARANCE_MM 56 (a leg is 55.2 mm wide at
the joints); the sim API exports them (version 7). sim_smoke passes.

Unity loads the model (export_unity.py -> Resources/OpenScadModel,
OpenScadModel.cs builds a new rig in place of the old scene's robot).
The PCB model's mounting holes now use the exact EasyEDA grid. README
shows renders of both.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-current/CLAUDE.md

@@ -168,6 +168,11 @@ Remote stick-frame convention: logical X + = right, Y + = forward, twist +
   - `HexapodSimBootstrap` auto-adds `HexapodSimulation` in any scene and
     disables the old scripts (`Walk`, `RotationControl`, `Leg`,
     `HandleHoystick`). Those are kept for reference only.
+  - `OpenScadModel` replaces the old scene's robot with the OpenSCAD model
+    (meshes from `hardware/openscad/export_unity.py` in
+    `Resources/OpenScadModel/`): it builds a new rig with the same names at
+    the Config.h geometry, whose rest pose (coxa 0, femur 0, tibia -90) is
+    the zero rotation. `HexapodSimulation.useOpenScadModel` turns it off.
   - `HexapodSimNative` loads a temp copy of the DLL via
     LoadLibrary/GetProcAddress, so there's no file lock and each Play is a
     fresh power-on.
@@ -212,14 +217,25 @@ Robot (`robot/README.md` has detail):
 - `Config.h` geometry now comes from the Unity model (owner's request),
   1 unit = 10 mm:
   - legs at X ±100 / 0, Y ±50 / ±65 mm,
-  - mount angles ±90° (coxa straight sideways at servo center),
+  - mount angles ±30° / ±90° / ±150° (hexagon layout, owner's request: mid
+    legs sideways, corner legs 60° further round; coxa direction at servo
+    centre — the corner brackets sit 60° round on their splines),
   - coxa/femur/tibia 55/100/150 mm,
   - stance radius 75 (so 130 mm out from the coxa pivot), height 150 mm.
 
   The old scene's `Leg.translateX` = ±5 was only the old code's rotation
   pivot; the rig hips are at x ±10. Still to confirm on the real chassis:
-  joint limits, servo pins, µs/deg calibration, `MAX_JOINT_DEG_S` (in
+  servo pins, µs/deg calibration, `MAX_JOINT_DEG_S` (in
   robot.ino), the Limits envelope, InputMapper maxima.
+- **Geometry and limits confirmed against the CAD (owner's request):** the
+  OpenSCAD rebuild of the real chassis (`hardware/openscad/`, see its
+  `PLANNING.md`) has exactly these mounts and 55/100/150 mm links (tibia to
+  the centre of a 10 mm foot ball; femur/knee axes in the coxa pivot plane,
+  13.5 mm above the bottom plate). Its collision sweep gave the joint
+  limits now in `Config.h`: coxa limits are **per leg**
+  (`COXA_MIN_DEG[i]`/`COXA_MAX_DEG[i]`; all ±60 in the hexagon layout, but in
+  the old sideways layout a corner leg only swung ~36° towards its mid leg),
+  and `LEG_CLEARANCE_MM` is 56 (a leg is 55.2 mm wide at the joints). The sim API exports the per-leg coxa limits (version 7).
 - **Fixed (owner-approved):** the `Kinematics.cpp` femur elevation sign
   (`atan2(local_z, horiz)`; it used to solve for a foot above the hip, so
   every solution was invalid). Stance pose is now femur −1.2°, tibia