Muse Spark 1.2 for VS Code

Muse Spark is a VS Code extension for coding with Meta's Muse Spark 1.2 models. It supports two complementary agent experiences:

• Muse Code CLI sidebar — runs the official Muse Code agent harness behind the extension's sidebar for repository inspection, file editing, terminal commands, verification, long-running tasks, and persistent sessions.
• VS Code Agent Mode provider — contributes Muse Spark models to VS Code Chat so they can use the tools supplied by VS Code/Copilot Agent Mode.

The extension also provides selection actions, inline completions, code generation, model/pricing controls, and live token and cost tracking.

Requirements

• Windows with WSL and an Ubuntu distribution for the Muse Code CLI backend
• VS Code 1.134.0 or newer
• Node.js and npm when developing or packaging the extension
• Meta Model API access and a valid API key
• GitHub Copilot/VS Code Chat when using the Language Model provider in Agent Mode

Feature overview

Official Muse Code agent backend

The sidebar uses muse exec --json by default. The extension:

• Starts Muse Code inside the Ubuntu WSL distribution.
• Uses Muse's legacy shell tool for WSL1 compatibility, avoiding managed process-owner host failures.
• Limits workspace tools to the currently opened VS Code workspace.
• Streams Muse JSON events and assistant output into the sidebar.
• Lets Muse inspect and edit files, execute commands, and verify its changes.
• Keeps one Muse session ID for follow-up messages.
• Uses the same ID for the saved VS Code transcript and underlying Muse CLI session so resumed chats can continue executing tasks.
• Starts a new Muse session when chat is cleared.
• Supports configurable reasoning effort and maximum model steps.
• Can run with unrestricted --yolo access or with the Muse sandbox enabled.

Only the first open VS Code workspace folder is currently used. The workspace must be on a local Windows drive available to WSL under /mnt/<drive>/....

VS Code Agent Mode provider

The extension registers Muse Spark 1.2, Muse Spark 1.2 Contributor, and Muse Spark 1.2 Code in the VS Code Chat model picker.

The provider supports streamed text, VS Code tool definitions, tool calls, tool results, automatic tool selection, and required-tool mode. VS Code invokes Agent Mode tools and displays its own approval UI.

This route calls the Meta