From 8960da7eba072edd13b58b3b636c6cd4032e4d08 Mon Sep 17 00:00:00 2001
From: "-T.K.-" <tk233.xyz@gmail.com>
Date: Fri, 7 Aug 2026 22:45:11 -0700
Subject: [PATCH 1/2] feat(lite_biped_debug): add the deployment scene wrapper

lite_biped_debug shipped the generated robot-only MJCF but never the scene
wrapper its sibling lite_biped has, so there was no floor and no spawn keyframe
to bring it up against.

humanoid_control's biped_mujoco.launch now resolves `scene` from the selected
robot_variant (defaulting to <variant>_scene) and errors if the file is absent,
so `robot_variant:=lite_biped_debug` cannot work without this. Hand-authored,
mirroring lite_biped_scene.xml -- the generator emits only the robot-only
VARIANT.xml, which mjlab training reuses as-is with its own terrain.

Floor friction and the visual block are byte-identical to lite_biped_scene so a
lite_biped vs lite_biped_debug run isolates the FOOT and nothing else. The home
keyframe differs only in base z: the box foot sits the pelvis 25 mm lower at the
same joint angles, so 0.80 -> 0.775 preserves the spawn clearance. Verified in
MuJoCo 3.8.1 -- both scenes load with nq=21 / nu=14 / 14 hinges and spawn at
30.6 mm clearance with zero contacts. The 14 leg joint values match the training
default pose (= standby_controller_a).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 .../mjcf/lite_biped_debug_scene.xml           | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml

diff --git a/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml b/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml
new file mode 100644
index 0000000..7165bf3
--- /dev/null
+++ b/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml
@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Deployment sim SCENE for the floating-base lite_biped_debug: the generated
+     robot (lite_biped_debug.xml: freejoint + IMU site/sensors + actuators) on a
+     ground plane, with a `home` keyframe for the standing spawn pose.
+
+     Hand-authored (NOT generated), mirroring lite_biped/mjcf/lite_biped_scene.xml
+     -- the generator emits the robot-only lite_biped_debug.xml (reused as-is by
+     mjlab training, which adds its own terrain); this wrapper adds the deployment
+     floor + spawn pose. It lives in this mjcf/ dir so the included robot's
+     meshdir ("../meshes/visual/") resolves. Consumed by humanoid_bringup_lite
+     biped_mujoco.launch (robot_variant:=lite_biped_debug).
+
+     Floor friction and the visual block are byte-identical to lite_biped_scene so
+     that a lite_biped vs lite_biped_debug A/B isolates the FOOT, nothing else.
+
+     home keyframe qpos differs from lite_biped only in the base z: the debug box
+     foot puts the pelvis 25 mm lower at the same joint angles (0.7443 m
+     above the sole vs 0.7693 m), so 0.80 -> 0.775 keeps the same ~31 mm of
+     spawn clearance. The 14 leg joints are unchanged (L hip p/r/y, knee,
+     ankle y/p/r; then R), matching the training default pose. -->
+<mujoco model="lite_biped_debug_scene">
+  <include file="lite_biped_debug.xml"/>
+
+  <statistic center="0 0 0.5" extent="1.6"/>
+
+  <visual>
+    <headlight diffuse="0.6 0.6 0.6" ambient="0.35 0.35 0.35" specular="0 0 0"/>
+    <rgba haze="0.15 0.25 0.35 1"/>
+    <global azimuth="120" elevation="-20"/>
+  </visual>
+
+  <asset>
+    <texture type="2d" name="groundplane" builtin="checker" mark="edge"
+             rgb1="0.2 0.3 0.4" rgb2="0.1 0.15 0.2" markrgb="0.8 0.8 0.8"
+             width="300" height="300"/>
+    <material name="groundplane" texture="groundplane" texuniform="true"
+              texrepeat="5 5" reflectance="0.1"/>
+  </asset>
+
+  <worldbody>
+    <light pos="0 0 3.0" dir="0 0 -1" directional="true"/>
+    <geom name="floor" type="plane" size="0 0 0.05" material="groundplane"
+          condim="3" friction="1.0 0.005 0.0001"/>
+  </worldbody>
+
+  <keyframe>
+    <key name="home"
+         qpos="0 0 0.775 1 0 0 0
+               -0.1745 0 0 0.3491 0 -0.1745 0
+               -0.1745 0 0 0.3491 0 -0.1745 0"/>
+  </keyframe>
+</mujoco>

From d3f6c38d780683218001fa6180e1f8e43d57d074 Mon Sep 17 00:00:00 2001
From: "-T.K.-" <tk233.xyz@gmail.com>
Date: Fri, 7 Aug 2026 22:49:36 -0700
Subject: [PATCH 2/2] fix: no literal '--' inside the scene's XML comment

A double hyphen is illegal inside an XML comment. MuJoCo's tinyxml2 accepts it,
which is why the model loaded fine and the `ros` lane passed, but Python's expat
does not -- so tests/test_mesh.py failed to even parse the file at collection.

Reworded to a colon, matching how lite_biped_scene.xml phrases the same
sentence. Verified with both parsers now: xml.etree parses it, MuJoCo 3.8.1
still loads it (nq=21, nu=14, 30.6 mm spawn gap, 0 contacts), and the full suite
passes (1569 passed, 6 skipped).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml b/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml
index 7165bf3..8da4c61 100644
--- a/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml
+++ b/robots/lite_biped_debug/mjcf/lite_biped_debug_scene.xml
@@ -3,8 +3,8 @@
      robot (lite_biped_debug.xml: freejoint + IMU site/sensors + actuators) on a
      ground plane, with a `home` keyframe for the standing spawn pose.
 
-     Hand-authored (NOT generated), mirroring lite_biped/mjcf/lite_biped_scene.xml
-     -- the generator emits the robot-only lite_biped_debug.xml (reused as-is by
+     Hand-authored (NOT generated), mirroring lite_biped/mjcf/lite_biped_scene.xml:
+     the generator emits the robot-only lite_biped_debug.xml (reused as-is by
      mjlab training, which adds its own terrain); this wrapper adds the deployment
      floor + spawn pose. It lives in this mjcf/ dir so the included robot's
      meshdir ("../meshes/visual/") resolves. Consumed by humanoid_bringup_lite