UniSim

UniSim provides backend-neutral physics contracts and optional engine adapters. The PyPI distribution is unisim-core; the Python import namespace is unisim.

This repository is the extraction target for UniLab's unified physics backend. The 0.1.x line contains the public contract, seven production backend adapters, a deterministic fake backend, a lightweight conformance helper, and benchmark API/result-schema reservations. It does not run benchmark workloads or include engine SDKs in the base install.

Development

make sync       # locked environment plus the MuJoCo test extra
make check      # Ruff + pytest
make package    # source distribution and wheel for local inspection

The TestPyPI and automated production release procedure is documented in docs/release.md.

Engine adapters are optional extras and are loaded lazily. The MuJoCo adapter is available as unisim.MuJoCoBackend after installing the mujoco extra (or through unisim.create_backend("mujoco", scene=...)). Each adapter must document its supported Python/platform/runtime matrix and pass the conformance helper before it is published.

Motrix is available through unisim.MotrixBackend after installing the motrix extra. Drake, MJWarp and Genesis use the same lazy optional boundary; IsaacGym and IsaacSim are external-worker adapters because their vendor SDKs are not redistributable PyPI dependencies. All seven identities are exposed by the factory and fail closed with actionable diagnostics when their runtime is absent. Every adapter exposes the same state/control/reset contract; engine-native model and data objects remain private.

External worker roots can be configured with UNISIM_ISAACGYM_HOME, UNISIM_ISAACGYM_PYTHON, UNISIM_ISAACSIM_HOME, and UNISIM_ISAACSIM_PYTHON. The package also accepts the former UNILAB_* spellings as a migration fallback.

Relationship to UniLab

UniLab retains Hydra configuration, task/env/manager lifecycle, robot assets, RL training, checkpoint, and sim2sim ownership. UniSim must not import UniLab. The final state has one implementation owned by this repository; UniLab only assembles task-owned scene/configuration inputs.