[WIP] Unify Isaac Lab assets with Isaac Sim

[matthewtrepte]

Description

Rebasing and testing out Steven Feng's unify assets change - #3608

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (existing functionality will not work without user modification)
• Documentation update

Screenshots

Please attach before and after screenshots of the change if applicable.

Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[greptile-apps]

Greptile Summary

Migrated Isaac Lab asset paths from ISAACLAB_NUCLEUS_DIR to ISAAC_NUCLEUS_DIR to unify with Isaac Sim's asset structure. This changes all robot USD paths to reference the shared Isaac Sim asset repository on the Nucleus server.

Key Changes:

• All robot configurations now use ISAAC_NUCLEUS_DIR (Isaac/Robots/) instead of ISAACLAB_NUCLEUS_DIR (Isaac/IsaacLab/Robots/)
• Updated directory structures for ANYmal variants (ANYmal-B → anymal_b, ANYmal-C → anymal_c, ANYmal-D → anymal_d)
• Franka Panda path updated to Robots/FrankaRobotics/FrankaEmika/
• Unitree G1 paths updated to specify DOF variants (G1 → G1_23dof, G1_29dof)
• Humanoid28 moved to Robots/IsaacSim/Humanoid28/
• All test files, demos, and task environments updated consistently
• Removed unused ISAACLAB_NUCLEUS_DIR imports where no longer needed

Asset Path Pattern:

• Before: {ISAACLAB_NUCLEUS_DIR}/Robots/[Manufacturer]/[Model]/[file].usd
• After: {ISAAC_NUCLEUS_DIR}/Robots/[Manufacturer]/[model]/[file].usd

The migration is systematic and comprehensive, touching all robot assets, examples, and tests.

Confidence Score: 4/5

• This PR is safe to merge after verifying that the new asset paths exist on the Nucleus server
• The changes are purely path migrations with no logic modifications. All updates are consistent and systematic. Score is 4 (not 5) because this depends on the corresponding assets being available at the new paths on the Nucleus server, which cannot be verified from the code alone
• Verify that all new asset paths exist on the Nucleus server before merging, particularly the reorganized paths for ANYmal variants, G1 DOF-specific paths, and the FrankaRobotics directory structure

Important Files Changed

Filename	Overview
source/isaaclab/isaaclab/sim/spawners/init.py	Updated documentation examples to use new ISAAC_NUCLEUS_DIR paths instead of ISAACLAB_NUCLEUS_DIR
source/isaaclab_assets/isaaclab_assets/robots/franka.py	Migrated Franka Panda asset path from ISAACLAB_NUCLEUS_DIR to ISAAC_NUCLEUS_DIR/Robots/FrankaRobotics/FrankaEmika
source/isaaclab_assets/isaaclab_assets/robots/anymal.py	Migrated all ANYmal variants (B, C, D) to ISAAC_NUCLEUS_DIR with updated directory structure (lowercase names)
source/isaaclab_assets/isaaclab_assets/robots/unitree.py	Migrated all Unitree robots (A1, Go1, Go2, H1, G1, G1_29DOF) to ISAAC_NUCLEUS_DIR with updated paths for G1 variants
source/isaaclab/test/sim/test_spawn_from_files.py	Updated test cases to use new ISAAC_NUCLEUS_DIR path for Franka Panda robot
source/isaaclab/test/deps/isaacsim/check_legged_robot_clone.py	Unified isaaclab and oige asset paths to both use ISAAC_NUCLEUS_DIR for ANYmal-C

Sequence Diagram

sequenceDiagram
    participant User as User Code
    participant Config as Robot Config
    participant Assets as isaaclab.utils.assets
    participant Spawner as sim_utils.UsdFileCfg
    participant NucleusServer as Nucleus Server
    participant Stage as USD Stage

    User->>Config: Import robot configuration
    Config->>Assets: Use ISAAC_NUCLEUS_DIR constant
    Note over Assets: ISAAC_NUCLEUS_DIR = carb.settings<br/>/persistent/isaac/asset_root/cloud/Isaac
    Config->>Config: Build asset path<br/>(e.g., {ISAAC_NUCLEUS_DIR}/Robots/FrankaRobotics/FrankaEmika/panda.usd)
    User->>Spawner: Create UsdFileCfg with usd_path
    Spawner->>Assets: check_file_path(usd_path)
    Assets->>NucleusServer: omni.client.stat(usd_path)
    NucleusServer-->>Assets: Return file status
    Assets-->>Spawner: File exists on Nucleus
    Spawner->>NucleusServer: Load USD from remote path
    NucleusServer-->>Spawner: USD file data
    Spawner->>Stage: Spawn prim at prim_path
    Stage-->>User: Robot instantiated

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[greptile-apps]

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[pascal-roth]

what is the status with the combination of the assets?