xtralab

An opinionated JupyterLab meta-package.

xtralab bundles a curated set of JupyterLab extensions, ships its own JupyterLab extension with a path-first file browser and a VS Code-style git changes panel, and applies a quieter default workspace configuration. The defaults are shipped under etc/jupyter/labconfig and the bundled labextension is shipped under share/jupyter/labextensions/xtralab.

The goal is to keep the package easy to inspect: most behavior comes from the upstream Jupyter packages, while xtralab defines the default environment we want out of the box.

Approach

The package brings together:

• The ajlab meta-package (agent-ready JupyterLab — collaboration plumbing, MCP support, command tooling, and its own quieter defaults)
• JupyterLab 4.6+
• Git server integration (jupyterlab-git — backs the bundled changes panel)
• Quick file opening (jupyterlab-quickopen)
• Cursor styling helpers (jupyterlab-cursor-light, jupyterlab-cursor-theme)
• Day and night themes (jupyterlab-day, jupyterlab-night)

These are installed as normal Python dependencies, so deployments can still override versions and Jupyter configuration in the usual ways.

Bundled labextension

xtralab ships its own prebuilt labextension that contributes:

• A path-first file browser in the left sidebar, built on @pierre/trees.
• A VS Code-style "Source Control" panel in the left sidebar, powered by the jupyterlab-git server REST API and @pierre/diffs. The bundled @jupyterlab/git frontend is disabled automatically so the two panels do not coexist.
• An agent-focused launcher that replaces the stock JupyterLab launcher. The launcher tab shows an optional initial-prompt textarea, a row of agent buttons (Claude, Codex, Gemini, Copilot, Goose, OpenCode, Kiro, and Mistral Vibe), and a collapsible list of changed files (each clickable into the diff viewer) below them. Clicking an agent opens a fresh terminal and runs the agent's CLI; if the prompt textarea is non-empty, the prompt is shell-quoted and spliced into the launch line for agents that accept one. Agents are filtered by a which-based availability check at activation, so only the ones actually installed on the machine show up.

Customizing the launcher

The launcher reads xtralab:launcher settings from the JupyterLab settings registry. Open the Settings Editor (Settings → Settings Editor → xtralab launcher) and edit the agents array; xtralab merges your entries with the defaults by id.

{
  "agents": [
    // Hide an agent you never want to see, even if it's installed:
    { "id": "kiro", "enabled": false },

    // Override an agent's command — e.g. point Claude at a shell alias.
    // `requireAvailable: false` keeps the card visible even though
    // `which cl` returns nothing (interactive shells expand the alias).
    { "id": "claude", "command": "cl", "requireAvailable": false },

    // Add a brand-new agent. `iconSvg` is optional; without it the card
    // falls back to a generic terminal icon. `promptArgs: []` means the
    // launcher's prompt textarea is appended as a positional argument.
    {
      "id": "aider",
      "label": "Aider",
      "command": "aider",
      "promptArgs": []
    }
  ]
}

Field reference (every field except id is optional):

| Field | Effect | | ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | id | Built-in id to override, or a new id to define a new card. | | label | Card title. | | caption | Subtitle shown beneath the title. | | command | Literal text typed into the new terminal. | | iconSvg | Inline SVG for the card icon (only needed for new agents). | | rank | Sort order on the launcher; lower comes first. | | enabled | false hides the card from the launcher and palette. | | requireAvailable | false skips the which check (use for shell aliases that aren't on PATH but expand at runtime). | | promptArgs | How to splice the launcher's optional prompt into the command. [] appends it as a positional argument (<command> 'PROMPT'); ["-i"] or ["--prompt"] puts it after a flag. Set to null to opt out — the agent button is dimmed when the prompt textarea is non-empty so a typed prompt is never silently dropped. Defaults vary per agent. |

Default settings

xtralab ships the following JupyterLab defaults:

• The announcements plugin is disabled, so JupyterLab does not prompt to fetch news from the Jupyter news feed and does not check for application updates.
• The Table of Contents, Debugger, and Notebook Tools panels are disabled so they do not show up in the right sidebar by default.
• dockPanelPadding is off, so the main dock area is flush with the surrounding chrome.
• The terminal fontFamily defaults to MesloLGS NF, ui-monospace, monospace so Powerline / Nerd Font glyphs (used by Oh My Zsh themes such as powerlevel10k) render correctly when the font is installed; the ui-monospace, monospace fallback keeps things readable when it is not.

The JupyterLab frontend defaults are shipped as labconfig/*.d/00-xtralab.json fragments so downstream meta-packages can add their own Lab configuration fragments without replacing xtralab's files.

Install

pip install xtralab

Run as a desktop app

xtralab ships a tiny launcher that opens JupyterLab in a dedicated Chrome window (via Chrome's --app mode), with an isolated user-data directory so it does not share cookies, extensions, or history with your normal browser.

Requires Chrome or Chromium installed. macOS only for now; other platforms will be added later.

The simplest way, no install needed:

uvx xtralab

Or, after pip install xtralab into an environment:

xtralab

The launcher starts a local Jupyter server on a random port with a fresh token, waits for it to come up, opens the app window, and shuts the server down when you close the window. Ctrl-C in the launching terminal also shuts everything down cleanly.

Development

# Install dependencies and the package in editable mode
uv pip install -e ".[dev]"
jlpm
jlpm build

License

BSD-3-Clause