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/Hexapod_Simulation_Unity/Assets/HexapodSim/HexapodSimNative.cs

@@ -36,7 +36,9 @@ namespace HexapodSim
         [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)] public float[] mountAngleDeg;
         public float coxaMm, femurMm, tibiaMm;
         public float stanceRadiusMm, stanceHeightMm;
-        public float coxaMinDeg, coxaMaxDeg, femurMinDeg, femurMaxDeg, tibiaMinDeg, tibiaMaxDeg;
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)] public float[] coxaMinDeg;
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6)] public float[] coxaMaxDeg;
+        public float femurMinDeg, femurMaxDeg, tibiaMinDeg, tibiaMaxDeg;
         public float controlHz;
         public float legClearanceMm;
         public float stanceHeightRangeMm;
@@ -71,7 +73,7 @@ namespace HexapodSim
     // "Reload firmware" and the new code runs. Each load is a fresh power-on.
     public sealed class HexapodSimNative : IDisposable
     {
-        public const int ExpectedApiVersion = 6;   // HXSIM_API_VERSION
+        public const int ExpectedApiVersion = 7;   // HXSIM_API_VERSION
 
         [UnmanagedFunctionPointer(CallingConvention.Cdecl)] delegate int IntFn();
         [UnmanagedFunctionPointer(CallingConvention.Cdecl)] delegate void VoidFn();