Add tianji marvin | Fix solver tcp inversion

[matafela]

Description

• Add Tianji Marvin: embodichain/lab/sim/robots/tianji_marvin.py
• Fix PytorchSolver get_ik tcp pose inversion error.
• Unify the TCP pose inversion operation across solvers.

Type of change

• Bug fix (non-breaking change which fixes an existing functionality)
• Enhancement (non-breaking change which improves an existing functionality)

Checklist

• I have run the black . command to format the code base.
• I reviewed affected documentation and agent context, updated it where needed, or explained why no update was needed.
• Public API changes are reflected in the API docs (python docs/scripts/check_api_docs.py), if applicable
• I have added tests that prove my fix is effective or that my feature works
• Dependencies have been updated, if applicable.

[greptile-apps]

Confidence Score: 2/5

[High risk] Replaces matrix inversion with validated rigid-transform function across solvers.

The PR does not appear safe to merge while Tianji Marvin can select or download the wrong asset and a failed USDZ rebuild can leave a stale deliverable.

Findings

1.  Local overrides trigger downloads ▶
2.  Variant can load wrong URDF ▶

Fix with agent prompt

### Issue 1
embodichain/lab/sim/robots/tianji_marvin.py:undefined-109
If a caller supplies a local `fpath` on a machine without the Tianji Marvin asset cached, this line resolves the default asset before the override is applied. That starts a download, so configuration creation fails offline even though the caller provided a usable local URDF. Resolve the default asset only when no path override was supplied.

### Issue 2
embodichain/lab/sim/robots/tianji_marvin.py:undefined-109
If someone changes `with_gripper` in a saved configuration but keeps its serialized `fpath`, the merge restores the old variant’s URDF after this method selects control parts and solver frames for the new variant. Simulation then loads a model that does not match those controls and FK/IK frames. Reconcile the asset path with the selected variant when rebuilding the configuration.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

The PR adds the Tianji Marvin robot and a shared rigid-TCP inversion path. It also expands Gym action and recording contracts, physical objectives, scene USD delivery, task-program articulation bindings, and asset handling.

• A failed scene USDZ rebuild can leave an obsolete package beside the new scene export.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  E[Updated scene export] --> U[Build scene.usda]
  U --> Z{Build scene.usdz}
  Z -- succeeds --> N[Replace old USDZ]
  Z -- fails --> O[Old USDZ remains]
  O --> P[Preview or distribution may use stale scene]

Loading

_{Reviews (6) · Last reviewed commit: "Merge branch 'main' into cj/add-tianji-m..."}

[greptile-apps]

Local overrides trigger downloads

If a caller supplies a local fpath on a machine without the Tianji Marvin asset cached, this line resolves the default asset before the override is applied. That starts a download, so configuration creation fails offline even though the caller provided a usable local URDF. Resolve the default asset only when no path override was supplied.

Knowledge Base Used: Asset and dataset management

Prompt To Fix With AI

This is a comment left during a code review.
Path: embodichain/lab/sim/robots/tianji_marvin.py
Line: 99

Comment:
**Local overrides trigger downloads**

If a caller supplies a local `fpath` on a machine without the Tianji Marvin asset cached, this line resolves the default asset before the override is applied. That starts a download, so configuration creation fails offline even though the caller provided a usable local URDF. Resolve the default asset only when no path override was supplied.

**Knowledge Base Used:** [Asset and dataset management](https://app.greptile.com/dexforce/-/custom-context/knowledge-base/dexforce/embodichain/-/docs/asset-data-management.md)

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

[greptile-apps]

Variant can load wrong URDF

If someone changes with_gripper in a saved configuration but keeps its serialized fpath, the merge restores the old variant’s URDF after this method selects control parts and solver frames for the new variant. Simulation then loads a model that does not match those controls and FK/IK frames. Reconcile the asset path with the selected variant when rebuilding the configuration.

Knowledge Base Used:

• Simulation lab
• Motion planning and kinematics

Prompt To Fix With AI

This is a comment left during a code review.
Path: embodichain/lab/sim/robots/tianji_marvin.py
Line: 99

Comment:
**Variant can load wrong URDF**

If someone changes `with_gripper` in a saved configuration but keeps its serialized `fpath`, the merge restores the old variant’s URDF after this method selects control parts and solver frames for the new variant. Simulation then loads a model that does not match those controls and FK/IK frames. Reconcile the asset path with the selected variant when rebuilding the configuration.

**Knowledge Base Used:**
- [Simulation lab](https://app.greptile.com/dexforce/-/custom-context/knowledge-base/dexforce/embodichain/-/docs/simulation-lab.md)
- [Motion planning and kinematics](https://app.greptile.com/dexforce/-/custom-context/knowledge-base/dexforce/embodichain/-/docs/motion-planning-and-kinematics.md)

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.