Add viser recording functionality

[ttktjmt]

Motivation

I'd like to propose adding interactive recording and replay functionality for mjlab. This would enable:

• Sharing RL experiment results - Researchers can easily share trained policy behaviors with others
• Debugging without re-running - Replay expensive simulations without recomputing
• Creating demonstrations - Generate interactive visualizations for papers, presentations, and documentation
• Collaboration - Share exact simulation runs with team members

Implementation

I've implemented this feature in the record branch on my fork:

• Branch: https://github.com/ttktjmt/mjlab/tree/record
• Comparison for PR: main...ttktjmt:mjlab:record

Changes

New record module:

• src/mjlab/scripts/record.py: Initializes the viser recording server and handles the MuJoCo simulation loop
• pyproject.toml: Registers the new uv run record CLI command entry point

GitHub Actions Workflow:

• .github/workflows/deploy-recordings.yml: Automatically deploys recorded .viser files from the recordings/ directory to GitHub Pages

Example Recordings:

• recordings/*.viser: Initial example recordings demonstrating functionality for registered environments

Usage Example

uv run record Mjlab-Velocity-Rough-Unitree-Go1 \
  --wandb-run-path your-entity/mjlab/run-id \
  --num-envs 12 \
  --num-steps 1000

Demo

Live example: https://ttktjmt.github.io/mjlab/rec/

Questions for Maintainers

Before I create a PR, I'd like to check if this feature is valuable for mjlab or not. If you are willing to include this, I'd love to create a PR!
I'm also happy to make any adjustments based on your feedback before submitting a PR.

Thanks for reviewing and considering this!

[kevinzakka]

@brentyi Can I get your thoughts on this?

[brentyi]

Looks cool! I'm hesitant to add a new script because of maintenance effort, but perhaps these rollouts could be embedded into the docs (#242)?

Another option is to integrate the recording capabilities into the Viser GUI, so it's always available and doesn't require a separate script. I could imagine some UI that lets you reset the environment and record N environment steps.

[ttktjmt]

@brentyi Thanks for sharing your thoughts!

Embedding the visualizations directly into the documentation is a great idea.

I also feel it would be better to implement this feature on the CLI side, enabling us to automate the recording processes via GitHub Actions.