Orbit

A livecoding pair-programming harness for Smalltalk in VSCode.

Orbit augments the GitHub Copilot Chat agent so it can pair-program with you in a live Smalltalk image. The agent sees what you see, manipulates the same tools you use, and can evaluate code, browse classes, and handle exceptions in the running system.

What you get

• A VSCode extension that runs a local web server and opens a SqueakJS-hosted webapp in the Integrated Browser. The webapp presents windows from a remote Smalltalk environment (class browsers, workspaces, debuggers, inspectors, etc.).
• A Copilot chat participant (@orbit) preloaded with steering instructions for working in this environment.
• An MCP server registration pointing at the remote Smalltalk backend, giving the agent a evaluate tool for running Smalltalk expressions, plus tools for class/method introspection and refactoring.
• A WebDAV virtual filesystem that exposes the remote Smalltalk system as files and directories — class comments, method source, senders, implementors, and a shared sessions/ area usable as agentic memory.

Repository layout

Path	Purpose
website/	The VSCode extension and its webapp (Express + SqueakJS).
website/src/extension.js	Extension entry point: commands, chat participant, MCP provider.
website/agents/orbit.agent.md	Steering instructions for the @orbit chat participant.
website/public/	Webapp assets: orbit.html, components, SqueakJS, icons.
website/public/js/components/	Web Components (morphic-window, transient-window, icon-manager).
designs/	Design notes.
summaries/	Per-conversation summaries written by the agent.

Getting started

1. Install the Orbit extension from the VSCode extensions marketplace.

2. Run Orbit: Start from the VSCode command palette.

3. In Copilot Chat, address the agent as @orbit. Share the browser page with the chat (the agent will offer to do this for you if you forget).

Commands

• Orbit: Start — launch the web server and open the webapp.
• Orbit: Stop — shut down the web server.
• Orbit: Open Steering — open agents/orbit.agent.md for editing.

Working with the agent

The @orbit participant reads website/agents/orbit.agent.md on every invocation. That file is the single source of truth for agent behavior: page-sharing, Playwright instrumentation, MCP usage, WebDAV conventions, and livecoding sync rules. Edit it to change how the agent works; no rebuild of the extension is required.

The @orbit participant is a quick-start, not a workhorse

The @orbit participant exists so you can try Orbit's steering with zero configuration — install the extension, type @orbit, and the steering is already loaded without touching your workspace. That makes it ideal for a first look or a demo in an otherwise-empty directory.

It is not suitable for serious work. A VS Code chat participant must run its own tool-calling loop, and the stable extension API gives it no way to borrow the host's native agent loop. As a consequence, @orbit does not get the agent-mode features you may rely on:

• No checkpoints and no edit-review (Keep/Undo) UI for the files it changes.
• Session "Bypass Approvals" is ignored. That toggle is part of the built-in agent's private machinery, so tools that normally prompt will still prompt under @orbit.
• No host tool grouping / overflow management. The participant forwards the full tool registry, so in a tool-heavy workspace it can hit the model's per-request tool cap.

For real work, install the steering into your workspace and use the default Copilot agent (not a participant), which gives you the full agent loop, checkpoints, edit review, and approval handling. The simplest way is to copy Orbit's steering into your workspace's .github/copilot-instructions.md (it is auto-loaded by the default agent). Note that this overrides/merges with your existing workspace steering — a deliberate disruption that the participant deliberately avoids.

More

See the architecture notes for a deeper description of the design.