jupyterlite-webmcp

A JupyterLab 4 frontend extension that exposes your live, in-browser notebook — the open cells, the running kernel, your mouse selection, the review comments — to a browser-based AI agent through WebMCP, the emerging W3C proposal for a web page to register callable tools with an agent sharing the same browser tab (document.modelContext.registerTool).

Concretely: once installed, a WebMCP-aware agent in your browser can read your notebook's live cells (not stale .ipynb bytes off disk — the actual unsaved state in memory), run code on the kernel you're already using, insert or edit cells with conflict detection, and read/reply to review comments — all subject to per-cell access control (write / read / none) that you set. If your browser doesn't expose document.modelContext yet, the extension registers nothing and your notebook behaves exactly as it always has; nothing about the normal editing experience is gated behind it.

It is frontend-only: no server extension, no backend, no API keys, no Python runtime dependencies (dependencies = []). Works unmodified in JupyterLab 4.6, Notebook 7, and JupyterLite.

Live demo: https://jupyterlite-web-mcp.vercel.app/lab/index.html Documentation, quickstart and the 22-tool reference: https://alliecatowo.github.io/jupyterlite-web-mcp/ Source and issues: https://github.com/alliecatowo/jupyterlite-web-mcp

Install

pip install jupyterlite-webmcp

Installs a prebuilt extension: no Node.js and no jupyter lab build. For JupyterLite, add it to your site's requirements and run jupyter lite build; see docs/install.md.

Once installed, confirm it registered:

jupyter labextension list
# jupyterlite-webmcp vX.Y.Z enabled OK (python, jupyterlite_webmcp)

Then start jupyter lab or jupyter notebook as usual — no configuration is required.

pip uninstall jupyterlite_webmcp

What it contributes

Seven frontend plugins, all autoStart: true; the two you'll notice first:

• jupyterlite-webmcp:tools — registers the WebMCP tool surface (22 tools) when document.modelContext is present; otherwise a no-op beyond an optional status-bar indicator.
• jupyterlite-webmcp:review — the review-comment store, commands and cell markers: threaded comments on a cell, a text range, or an output, stored in the notebook's own metadata. Works whether or not the browser supports WebMCP. The comments are shown in the Agent panel (:panel, Comments tab).

The rest provide the access controls and cell menu, the activity/presence layer, Propose mode, the Agent panel and output selection.

See the tool reference for the full list of tools and their schemas, and docs/install.md for the JupyterLite requirements.txt variant and how to check whether WebMCP is active in your browser.

Building from source (contributors)

Installing the published wheel never requires Node.js; it ships prebuilt JS/CSS. Building from a clone does: the labextension build uses jupyter-builder from the jupyterlab Python package, so install that first (Node.js 22+ must be on your PATH):

git clone https://github.com/alliecatowo/jupyterlite-web-mcp.git
cd jupyterlite-web-mcp/packages/jupyterlite-webmcp
python -m venv .venv && source .venv/bin/activate
pip install "jupyterlab~=4.6.0"
npm ci
npm run build:prod
pip install -e .

Other useful scripts (see package.json): npm run build (development build), npm test (Jest unit tests), npm run typecheck, npm run lint:check. See CONTRIBUTING.md for the development loop and browser tests.

License

MIT — see LICENSE.