Jolly CLI

Jolly is a local robot-arm physics simulator for terminal users and LLM agents. It uses PyBullet in deterministic direct mode and saves state between commands.

Jolly includes two offline robot profiles:

• jolly6: an original six-axis arm with a parallel gripper.
• so101: the official five-axis SO-101 URDF and CAD meshes with a gripper.

The package also accepts scenes, challenges, an engine benchmark, a native PyBullet viewer, and an optional local web viewer. No cloud service, MCP server, API key, or network connection is required at runtime.

See Jolly in action

Local web simulator

The viewport above is a real PyBullet render of the official SO-101 CAD meshes. It is not a diagram or a hand-drawn robot substitute.

Terminal-native control

Watch the MP4 recording

Install

Install the command from PyPI with Python 3.10 or later:

python -m pip install jolly-cli
jolly state --json

For Python development, create a virtual environment on Python 3.10 or later:

python -m venv .venv
. .venv/bin/activate
pip install -e '.[web,dev]'

PyBullet publishes limited binary wheels. On platforms without a matching wheel, use conda-forge or install a C++ build toolchain for the source build.

Install the local LLM skill with the Skills CLI:

npx skills add ./skills/jolly

Quick start

jolly models --json
jolly reset --model so101 --scene blocks --json
jolly state --json
jolly move --joints "0,-20,40,-20,0" --gripper 0.0 --json
jolly reach --x 0.30 --y 0.10 --z 0.18 --gripper 0.0 --json
jolly render
jolly challenge list --json
jolly benchmark --json

Start the optional local web viewer:

jolly serve --host 127.0.0.1 --port 8765

Open http://127.0.0.1:8765. The JSON API documentation is at http://127.0.0.1:8765/api/docs.

The clean web viewer displays the physical PyBullet world. PyBullet's local TinyRenderer draws the official SO-101 STL meshes, scene objects, shadows, and floor. Drag the viewport to orbit. Scroll to zoom. The viewer has no CDN, external 3D service, or proprietary rendering dependency.

Open the native PyBullet window on a machine with a display:

jolly viewer --model so101 --scene blocks

Command contract

All motion uses meters and degrees. Gripper 0.0 means open. Gripper 1.0 means closed. Mutating commands save state under the operating system state directory. Set JOLLY_STATE_DIR to isolate or relocate state.

Important commands:

Command	Purpose
jolly state --json	Read joints, FK pose, collisions, objects, and grasp state.
jolly move --joints CSV	Move to exact joint angles.
jolly reach --x X --y Y --z Z	Solve IK and move to a Cartesian point.
jolly fk [--joints CSV] --json	Compute forward kinematics without saving a new pose.
jolly render	Show a Rich status table and terminal stick figure.
jolly reset	Select a model and scene, then home the robot.
jolly scene list/load	Discover and load deterministic scenes.
jolly challenge list/start/status	Run seeded randomized manipulation challenges.
jolly benchmark [--seed N] [--cases N]	Run randomized engine checks with reproducible inputs.

Jolly rejects joint-limit violations and unsafe workspace targets. By default, Jolly rolls back a motion that creates a collision. Use --allow-collision only for controlled collision tests.

Architecture

jolly-cli/
├── pyproject.toml
├── README.md
├── SKILL.md
├── LICENSE-MIT
├── LICENSE-APACHE
├── THIRD_PARTY_LICENSES.md
├── jolly/
│   ├── cli.py
│   ├── benchmark.py
│   ├── challenges.py
│   ├── driver.py
│   ├── engine.py
│   ├── assets/
│   │   ├── jolly6.urdf
│   │   └── robots/so101/
│   │       ├── so101_new_calib.urdf
│   │       ├── assets/*.stl
│   │       ├── LICENSE-APACHE
│   │       ├── CITATION.cff
│   │       └── SOURCE.md
│   ├── core/
│   │   ├── physics.py
│   │   ├── models.py
│   │   ├── scenes.py
│   │   └── store.py
│   └── web/
│       ├── app.py
│       └── index.html
├── skills/jolly/SKILL.md
└── tests/

Physics scope

JollyEngine owns state, safety, motion rollback, grasping, rendering, and the public simulator contract. JollyDriver generates seeded challenge and benchmark cases. The project does not depend on Inspect, Inspect AI, or an external robotics benchmark driver.

PyBullet is the low-level open-source physics backend. It performs rigid-body simulation, FK, IK, contact generation, and scene settling. Jolly uses deterministic state restoration across short CLI processes. The grasp helper attaches a nearby graspable object while the gripper is closed. This helper makes terminal pick-and-place repeatable. It is not a soft-contact or motor-current model.

Randomized evaluation

Every challenge start generates a new target, object layout, or obstacle layout. The result includes the seed and full instance so results stay auditable. Omit --seed for a fresh unpredictable case. Supply a seed to reproduce a failure:

jolly challenge start sort-red --seed 42017 --json
jolly benchmark --seed 42017 --cases 5 --json

The benchmark generates new joint configurations for every robot case and new object layouts for every scene case. This prevents a policy from passing only by memorizing the original fixed coordinates.

The bundled SO-101 model is the official Apache-2.0 new-calibration URDF from The Robot Studio. Jolly includes the 13 referenced STL meshes from pinned commit 5f6d2b876a53a4872e405b991dd925556c9e38a4. Jolly keeps the upstream files unmodified and includes their license, citation, source record, and README.

License

Jolly source code and original assets are available under your choice of the MIT License or Apache License 2.0. See LICENSE-MIT and LICENSE-APACHE. Third-party details appear in THIRD_PARTY_LICENSES.md.