Contributing

Development install¶

Note: You will need Node.js to build the extension package. You may install it from nodejs.org. We recommend using the latest LTS version of Node.js.

The jlpm command is JupyterLab’s pinned version of yarn that is installed with JupyterLab.

# Clone the repo to your local environment
# Change directory to the jupyter-webmcp directory

# Set up a virtual environment and install the package in development mode,
# with JupyterLab, jupyter-builder and jupyterlab-ai-commands
uv venv
source .venv/bin/activate
uv pip install --editable ".[dev]"

# Link your development version of the extension with JupyterLab
jupyter-builder develop . --overwrite

# Rebuild extension Typescript source after making changes
# IMPORTANT: Unlike the steps above which are performed only once, do this step
# every time you make a change.
jlpm build

You can watch the source directory and run JupyterLab at the same time in different terminals to watch for changes in the extension’s source and automatically rebuild the extension.

# Watch the source directory in one terminal, automatically rebuilding when needed
jlpm watch
# Run JupyterLab in another terminal
jupyter lab

With the watch command running, every saved change will immediately be built locally and available in your running JupyterLab. Refresh JupyterLab to load the change in your browser (you may need to wait several seconds for the extension to be rebuilt).

Open JupyterLab in a Chrome with WebMCP enabled (see the requirements), and call the tools with one of the clients, for example the example client.

By default, the jlpm build command generates the source maps for this extension to make it easier to debug using the browser dev tools. To also generate source maps for the JupyterLab core extensions, you can run the following command:

jupyter lab build --minimize=False

Jupyter Notebook and JupyterLite¶

The development install also works in Jupyter Notebook:

uv pip install notebook
jupyter notebook

jupyterlite-pyodide-kernel installs a labextension that fails to load in JupyterLab and logs errors, so keep the JupyterLite packages out of the development environment. The demo folder builds a JupyterLite site with the extension in an environment of its own, with uv:

cd demo
uv sync
uv run jupyter lite build
uv run jupyter lite serve

Then open http://127.0.0.1:8000/lab/index.html. Run uv run jupyter lite build again after jlpm build.

Development uninstall¶

uv pip uninstall jupyter_webmcp

In development mode, you will also need to remove the symlink created by jupyter-builder develop command. To find its location, you can run jupyter labextension list to figure out where the labextensions folder is located. Then you can remove the symlink named jupyter-webmcp within that folder.

Testing the extension¶

Frontend tests¶

This extension is using Jest for JavaScript code testing.

To execute them, execute:

jlpm
jlpm test

Integration tests¶

This extension uses Playwright for the integration tests (aka user level tests). More precisely, the JupyterLab helper Galata is used to handle testing the extension in JupyterLab.

More information is provided within the ui-tests README.

Linting¶

jlpm lint:check  # or jlpm lint to fix the problems

Documentation¶

The documentation is built with MyST from the pages listed in myst.yml, and published on Read the Docs. It needs only Node.js:

npm run docs        # preview the documentation
npm run docs:build  # build the HTML in _build/html

Packaging the extension¶

See RELEASE