Fix converted assets spawning without physics, and install the standalone importers by default

.github/actions/validate-kitless-image/action.yml

@@ -54,20 +54,20 @@ runs:
       print("ovrtx renderer initialized")
       '
 
-      # The Newton training probe is the shared one architecture CI also runs, so
-      # the command and its assertions live in one place. pytest goes only into
-      # this disposable layer; reinstalling the workspace would fail against the
-      # read-only source mount.
+      # Files are discovered by grep, not by pointing pytest at a directory: this image has no
+      # Isaac Sim, and collecting a directory imports every module in it to read its markers,
+      # which most of the suite cannot survive. Adding coverage is a `kitless` marker, nothing
+      # here. pytest goes only into this disposable layer; reinstalling the workspace would fail
+      # against the read-only source mount.
       docker run --rm --gpus all --network host \
         "${mount_args[@]}" \
         "$IMAGE_TAG" \
         bash -lc '
       set -euo pipefail
       uv pip install --python "$VIRTUAL_ENV/bin/python" pytest
-      python -m pytest \
-        source/isaaclab/test/install_ci/misc/cartpole_training_smoke.py::test_train_cartpole_state_completes \
-        source/isaaclab_newton/test/test_mock_interfaces \
-        -q -p no:cacheprovider
+      mapfile -t suite < <(grep -rl --include="*.py" "pytest\.mark\.kitless" source/)
+      [ "${#suite[@]}" -gt 0 ] || { echo "::error::no tests carry the kitless marker"; exit 1; }
+      python -m pytest -m kitless "${suite[@]}" -q -p no:cacheprovider
       '
 
       runtime_identity="$(docker run --rm --entrypoint bash "$IMAGE_TAG" \

docker/Dockerfile.kitless

@@ -45,13 +45,14 @@ COPY pyproject.toml uv.lock VERSION LICENSE LICENSE-mimic README.md ./
 COPY source/ source/
 COPY isaaclab.sh ./
 
-# Same entry point as Dockerfile.base. The selector is explicit because OVRTX
-# lives in the `ov` feature a bare --install excludes; OVPhysX stays out until
-# its OmniClient pin is compatible. The venv pins python3.12 to match the
-# runtime stage's libpython3.12, and isaaclab.sh resolves VIRTUAL_ENV first.
+# Same entry point as Dockerfile.base. Selectors are explicit: OVRTX lives in the `ov`
+# feature a bare --install excludes, and `importers` carries the standalone URDF/MJCF
+# importers that replace the Isaac Sim ones. OVPhysX stays out until its OmniClient pin
+# is compatible. The venv pins python3.12 to match the runtime stage's libpython3.12,
+# and isaaclab.sh resolves VIRTUAL_ENV first.
 RUN uv venv --python /usr/bin/python3.12 --seed --no-managed-python "${VIRTUAL_ENV}" \
  && chmod +x "${ISAACLAB_PATH}/isaaclab.sh" \
- && "${ISAACLAB_PATH}/isaaclab.sh" --install newton,rl[all],ov[ovrtx] \
+ && "${ISAACLAB_PATH}/isaaclab.sh" --install newton,rl[all],ov[ovrtx],importers \
  && python -c "import importlib.metadata as m; \
       names = {d.metadata['Name'].lower() for d in m.distributions()}; \
       assert 'isaacsim' not in names; \

docs/source/api/lab/isaaclab.sim.converters.rst

@@ -38,7 +38,7 @@ Mesh Converter
     :members:
     :inherited-members:
     :show-inheritance:
-    :exclude-members: __init__
+    :exclude-members: __init__, PhysicsVariant
 
 
 URDF Converter
@@ -53,7 +53,7 @@ URDF Converter
     :members:
     :inherited-members:
     :show-inheritance:
-    :exclude-members: __init__
+    :exclude-members: __init__, PhysicsVariant
 
 MJCF Converter
 --------------
@@ -67,4 +67,4 @@ MJCF Converter
     :members:
     :inherited-members:
     :show-inheritance:
-    :exclude-members: __init__
+    :exclude-members: __init__, PhysicsVariant

docs/source/how-to/import_new_asset.rst

@@ -25,8 +25,8 @@ use the Omniverse Kit to edit the asset and export it to other file formats. Isa
 these importers by default. They can also be enabled manually in Omniverse Kit.
 
 Isaac Lab's URDF and MJCF converter utilities first use the importer APIs from
-Isaac Sim when the full runtime is installed. In kit-less environments, install
-the standalone importer wheel as described in
+Isaac Sim when the full runtime is installed. In kit-less environments they use the
+standalone importers that ship with Isaac Lab, as described in
 :ref:`installation-standalone-importers` below.
 The Kit visualizer and GUI import dialogs still require an Omniverse Kit runtime.
 
@@ -43,18 +43,23 @@ For more details on instanceable assets, please check the Isaac Sim `documentati
 Standalone URDF/MJCF importers
 ------------------------------
 
-The URDF and MJCF converter scripts can run without Isaac Sim when the standalone
-``isaacsim-asset-isolated`` wheel is installed in the active environment. The wheel is not
-published on PyPI, so replace ``PACKAGE_INDEX_URL`` with the package index that hosts it:
+The URDF and MJCF converter scripts run without Isaac Sim, using the standalone
+``isaacsim-asset-isolated`` importers. They ship in the ``importers`` extra, which is not
+installed by default because it cannot share an environment with Isaac Sim -- both provide the
+same ``isaacsim.asset`` importers. Install it from a source checkout:
 
 .. code-block:: bash
 
-   uv pip install "isaacsim-asset-isolated>=6.0,<6.1" \
-     --extra-index-url "PACKAGE_INDEX_URL"
+   ./isaaclab.sh --install 'newton,rl[rsl-rl],importers'
 
-After installing the wheel, run conversion in the kit-less environment. Optionally pass
-``--viz newton`` (or ``rerun`` / ``viser``) to preview the converted asset in a kit-less
-Isaac Lab visualizer:
+or into an environment built from the published wheel:
+
+.. code-block:: bash
+
+   uv pip install 'isaaclab[importers]'
+
+Run conversion in the kit-less environment. Optionally pass ``--viz newton`` (or ``rerun`` /
+``viser``) to preview the converted asset in a kit-less Isaac Lab visualizer:
 
 .. code-block:: bash
 

pyproject.toml

@@ -67,11 +67,11 @@ dependencies = [
     "pin ; platform_system == 'Linux' and (platform_machine == 'x86_64' or platform_machine == 'aarch64')",
     "pin-pink==3.3.0 ; platform_system == 'Linux' and (platform_machine == 'x86_64' or platform_machine == 'aarch64')",
     "daqp==0.8.5 ; platform_system == 'Linux' and (platform_machine == 'x86_64' or platform_machine == 'aarch64')",
-    # OpenUSD (kit-less mode). Both packages vendor a complete ``pxr`` runtime, so
-    # they must never co-install: usd-core supplies pxr where it has wheels (x86_64),
-    # usd-exchange supplies it on aarch64 (where usd-core has no wheel).
-    "usd-core>=25.11,<26.0 ; platform_machine == 'x86_64' or platform_machine == 'AMD64'",
-    "usd-exchange>=2.2 ; platform_machine == 'aarch64'",
+    # OpenUSD (kit-less mode). Use the same provider required by the URDF and MJCF importer
+    # packages so another complete ``pxr`` runtime cannot co-install with it. Two providers in
+    # one environment overwrite each other's files, and removing either then breaks ``pxr``.
+    # usd-exchange 2.3.0 vendors USD 25.5, matching the Isaac Sim 6.0 wheel stack.
+    "usd-exchange==2.3.0",
     # avoid broken hf-xet pre-release cached on NVIDIA Artifactory
     "hf-xet>=1.4.1,<2.0.0 ; platform_machine == 'x86_64' or platform_machine == 'AMD64' or platform_machine == 'aarch64'",
     # ----- tasks -----
@@ -88,9 +88,19 @@ dependencies = [
     # ----- newton (default physics engine) -----
     # Loose bound so the wheel co-resolves with isaacsim's newton[sim]==1.2.0 pin; the
     # exact git commit is forced via [tool.uv].override-dependencies (uv sync only).
-    # The importers extra carries the mesh-processing deps (coacd, fast-simplification,
-    # ...) that honoring USD-authored ``physics:approximation`` requires.
-    "newton[sim,importers]>=1.2.0",
+    "newton[sim]>=1.2.0",
+    # Import and mesh-processing packages used by Newton, including the ones that honoring
+    # USD-authored ``physics:approximation`` requires. Keep these explicit instead of selecting
+    # newton[importers], whose standalone USD dependency would overlap with usd-exchange.
+    "requests>=2.25.0",
+    "scipy>=1.11.0",
+    "coacd>=1.0.7",
+    "fast-simplification>=0.1.11",
+    "alphashape>=1.3.1",
+    "meshio>=5.3.5",
+    "pycollada>=0.9",
+    "resolve-robotics-uri-py>=0.4.0",
+    "open3d>=0.19.0 ; python_version < '3.13' and (sys_platform != 'linux' or platform_machine != 'aarch64')",
     # Loose bound co-resolves with isaacsim's ==0.2.0; the override below forces >=0.4.1.
     "newton-usd-schemas>=0.2.0",
     "PyOpenGL-accelerate>=3.1.0",
@@ -150,6 +160,19 @@ rerun = [
 
 isaacsim = ["isaacsim[all,extscache]==6.0.1.0"]
 
+# Packages that cannot share an environment with Isaac Sim, because they provide the same
+# import paths it does. This is not "everything a kit-less setup installs" -- Newton, the RL
+# frameworks and the visualizers work with and without Isaac Sim and stay in the base set.
+# Membership rule: it belongs here only when co-installing it with Isaac Sim breaks imports.
+#
+#   * isaacsim-asset-isolated -- standalone URDF/MJCF importers. Contributes to the
+#     ``isaacsim`` namespace, so alongside a real Isaac Sim it displaces the Kit extension
+#     serving the same import and conversion fails with ``No module named 'isaacsim.asset'``.
+#
+# Runtime-only incompatibilities (ovrtx, ovphysx) do NOT belong here: they install fine
+# beside Isaac Sim and are rejected at launch by ``sim_launcher._validate_runtime``.
+importers = ["isaacsim-asset-isolated>=6.0,<6.1"]
+
 ov = ["ovphysx==0.5.9", "ovrtx>=0.4.0,<0.5.0", "ovstage==0.1.0.346039"]
 ovphysx = ["ovphysx==0.5.9", "ovstage==0.1.0.346039"]
 ovrtx = ["ovrtx>=0.4.0,<0.5.0", "ovstage==0.1.0.346039"]
@@ -200,6 +223,7 @@ leapp = [
 # ``test_version_single_source`` fails CI if they drift.
 [tool.isaaclab.versions]
 isaacsim = "6.0.1.0"
+usd_exchange = "2.3.0"
 torch = "2.11.0"
 torchvision = "0.26.0"
 torchaudio = "2.11.0"
@@ -343,6 +367,7 @@ markers = [
     "benchmark: test covers the Isaac Lab benchmark framework and infrastructure",
     "rendering: test exercises the rendering / camera / visualizer pipeline",
     "smoke: tests for core installation, task, and RL functionality",
+    "importers: test must pass inside the Kit-less container, which has no Isaac Sim runtime",
 ]
 
 # Add pypi.nvidia.com so that `uv pip install isaaclab[isaacsim]` works without --extra-index-url.
@@ -388,7 +413,7 @@ override-dependencies = [
     "numpy>=2",
     "mujoco~=3.11.0",
     "mujoco-warp~=3.11.0",
-    "newton[sim,importers] @ git+https://github.com/newton-physics/newton.git@release-1.5",
+    "newton[sim] @ git+https://github.com/newton-physics/newton.git@release-1.5",
     # Force the Newton-matched schemas over isaacsim's ==0.2.0 pin.
     "newton-usd-schemas>=0.4.1",
     "torch==2.11.0",
@@ -408,6 +433,8 @@ conflicts = [
     [{ extra = "teleop" }, { extra = "ovphysx" }],
     [{ extra = "isaacsim" }, { extra = "ov" }],
     [{ extra = "isaacsim" }, { extra = "ovphysx" }],
+    # both supply the ``isaacsim.asset`` importers; together the wheel shadows the Kit extension
+    [{ extra = "isaacsim" }, { extra = "importers" }],
 ]
 python-preference = "only-managed"
 package = false

source/isaaclab/changelog.d/jichuanh-standalone-importers-extra.minor.rst

@@ -0,0 +1,31 @@
+Added
+^^^^^
+
+* Added an ``importers`` extra carrying the standalone URDF and MJCF importers, so conversion
+  works without Isaac Sim. It cannot be combined with the ``isaacsim`` extra, which ships its own
+  copies of the same importers.
+
+* Added :attr:`~isaaclab.sim.converters.AssetConverterBaseCfg.physics_variant` to choose which
+  ``"Physics"`` variant the URDF and MJCF converters select on the generated USD file.
+
+Fixed
+^^^^^
+
+* Fixed URDF and MJCF conversion producing assets with no joints, articulation roots, or mass
+  properties.
+
+* Fixed MJCF conversion failing with ``Cannot find a valid schema for 'MjcSceneAPI'`` when another
+  package queried a USD schema first.
+
+* Fixed :meth:`~isaaclab.utils.dict.class_to_dict` expanding enum values into their internal
+  members, which wrote unusable entries into serialized configurations.
+
+Changed
+^^^^^^^
+
+* Changed :func:`~isaaclab.sim.utils.select_usd_variants` to raise for a variant set listed in
+  :obj:`~isaaclab.sim.utils.REQUIRED_VARIANT_SETS` that is absent or does not offer the requested
+  variant. Other variant sets still log a warning and continue.
+
+* Changed ``./isaaclab.sh --install`` to reject extras that the root ``pyproject.toml`` declares
+  conflicting, instead of installing a combination ``uv sync`` refuses.

source/isaaclab/changelog.d/kellyguo11-use-usd-exchange.rst

@@ -0,0 +1,6 @@
+Fixed
+^^^^^
+
+* Fixed installation failures caused by overlapping standalone USD providers by using
+  ``usd-exchange`` on all supported platforms and installing required Newton mesh-processing
+  packages directly.

source/isaaclab/isaaclab/__init__.py

@@ -6,6 +6,7 @@
 """Package containing the core framework."""
 
 import importlib.metadata
+import importlib.util
 import os
 import sys
 
@@ -79,7 +80,33 @@ def _should_demote(path: str) -> bool:
         os.environ["PYTHONPATH"] = os.pathsep.join(env_clean + env_demoted)
 
 
+def _expose_mujoco_usd_schemas():
+    """Put the MuJoCo USD schemas on OpenUSD's plugin search path.
+
+    ``mujoco-usd-converter`` ships them as a codeless schema plugin that it registers when the
+    package is imported. OpenUSD builds its schema registry once, on the first schema query, and
+    ignores plugins registered after that -- so MJCF conversion fails with "Cannot find a valid
+    schema for ``MjcSceneAPI``" whenever anything touched a schema first. Adding the plugin to the
+    search path lets OpenUSD find it while building the registry, so importing the converter late
+    no longer matters.
+
+    OpenUSD reads the search path while building the registry, so this only helps while the
+    registry is still unbuilt. A host that queries a schema before importing Isaac Lab has to put
+    the plugin directory on ``PXR_PLUGINPATH_NAME`` itself.
+    """
+    spec = importlib.util.find_spec("mujoco_usd_converter")
+    if spec is None or spec.origin is None:
+        return
+    plugins = os.path.join(os.path.dirname(spec.origin), "plugins")
+    if not os.path.isdir(plugins):
+        return
+    search_path = os.environ.get("PXR_PLUGINPATH_NAME", "")
+    if plugins not in search_path.split(os.pathsep):
+        os.environ["PXR_PLUGINPATH_NAME"] = os.pathsep.join(filter(None, (search_path, plugins)))
+
+
 _deprioritize_prebundle_paths()
+_expose_mujoco_usd_schemas()
 
 
 try:

source/isaaclab/isaaclab/cli/commands/install.py

@@ -674,15 +674,17 @@ def _install_isaacsim() -> None:
 # core set.
 VALID_EXTRA_FEATURES: set[str] = {
     "contrib",
+    "importers",
     "newton",
     "ov",
     "rl",
     "tetrahedralization",
     "visualizer",
 }
 
-# Extra features excluded from the automatic ``-i all`` / ``-i`` install.
-MANUAL_EXTRA_FEATURES: set[str] = {"contrib", "ov", "tetrahedralization"}
+# Extra features excluded from the automatic ``-i all`` / ``-i`` install. ``importers`` is
+# here because it cannot coexist with Isaac Sim, so it must be asked for deliberately.
+MANUAL_EXTRA_FEATURES: set[str] = {"contrib", "importers", "ov", "tetrahedralization"}
 
 
 def split_install_items(install_type: str) -> list[str]:
@@ -817,6 +819,11 @@ def _install_extra_feature(feature_name: str, selector: str = "") -> None:
     """
     if feature_name == "contrib":
         _install_contrib_extra_dependencies(selector)
+    elif feature_name == "importers":
+        if selector:
+            print_warning(f"'importers' does not support selectors (got '{selector}').")
+        print_info("Installing the kit-less stand-ins for Isaac Sim (URDF/MJCF importers)...")
+        _install_root_extra("importers")
     elif feature_name == "newton":
         if selector:
             print_warning(f"'newton' does not support selectors (got '{selector}').")
@@ -1097,6 +1104,48 @@ def _repoint_prebundle_packages() -> None:
             )
 
 
+def _requested_root_extras(
+    install_isaacsim: bool, optional_submodules: list[str], extra_features: list[tuple[str, str]]
+) -> set[str]:
+    """Return the root extras this install would apply.
+
+    Tokens are not extras: ``ov[ovrtx]`` installs ``ovrtx``, not ``ov``.
+    """
+    extras = set(optional_submodules)
+    if install_isaacsim:
+        extras.add("isaacsim")
+    for feature, selector in extra_features:
+        if feature == "ov":
+            chosen = {item.strip().lower() for item in selector.split(",") if item.strip()}
+            extras |= {"ovphysx", "ovrtx"} if "all" in chosen else chosen
+        else:
+            extras.add(feature)
+    return extras
+
+
+def _reject_conflicting_extras(requested: set[str]) -> None:
+    """Reject extras that ``[tool.uv].conflicts`` declares incompatible.
+
+    That table only binds a resolver, and each feature here installs in its own pip pass, so
+    nothing else would catch the combination.
+
+    Args:
+        requested: Names of the extras this install would apply.
+
+    Raises:
+        SystemExit: When the request covers every extra of a declared conflict.
+    """
+    conflicts = _load_root_pyproject().get("tool", {}).get("uv", {}).get("conflicts", [])
+    for conflict in conflicts:
+        extras = {entry["extra"] for entry in conflict if "extra" in entry}
+        if len(extras) > 1 and extras <= requested:
+            names = ", ".join(f"'{extra}'" for extra in sorted(extras))
+            raise SystemExit(
+                f"error: {names} cannot be installed together; the root pyproject.toml declares"
+                " them conflicting. Drop one of the tokens."
+            )
+
+
 def command_install(install_type: str = "all") -> None:
     """Install Isaac Lab extensions and optional extras.
 
@@ -1195,6 +1244,8 @@ def append_submodules_once(package_dirs: tuple[str, ...]) -> None:
                 valid = sorted(OPTIONAL_ISAACLAB_SUBMODULES) + sorted(VALID_EXTRA_FEATURES) + ["isaacsim"]
                 print_warning(f"Unknown install token '{name}'. Valid values: {', '.join(valid)}. Skipping.")
 
+    _reject_conflicting_extras(_requested_root_extras(install_isaacsim, requested_optional_submodules, extra_features))
+
     # Configure extra package indexes for NVIDIA and MuJoCo wheels.
     os.environ.setdefault("UV_EXTRA_INDEX_URL", "https://pypi.nvidia.com")
     os.environ.setdefault("PIP_EXTRA_INDEX_URL", "https://pypi.nvidia.com")