Muse Code in VS Code and Cursor: a side panel instead of a terminal

Muse Code is Meta's coding agent, and it lives in the terminal. That works until you have three threads going, an approval prompt has scrolled out of view, and you can't tell which thread touched which file.

I built Helicon to fix that for myself. It's an open-source (MIT) side panel for the Muse Code CLI that runs in VS Code, Cursor, Windsurf and Antigravity. It's unofficial: I'm not affiliated with Meta, and Muse Code itself does all the agent work.

What it is

Helicon drives the muse CLI you already have, with your own login and plan. There's no API key to paste, and the extension stores no credentials.

When you open the panel, the extension starts a small local server on your editor's own Node runtime, bound to 127.0.0.1 only. That server runs muse serve and talks to it over MSP, the protocol Muse Code speaks to its clients. So you get the same models, the same tools and the same approval rules as in the terminal. Nothing is sent anywhere except to Muse Code itself, and the extension has no telemetry.

Setup (about 5 minutes)

1. Install the muse CLI and run muse login once. You need a Muse Code plan or pay-as-you-go billing on Meta's Model API; the free Muse app doesn't include Muse Code.
2. Install Helicon:
   • VS Code: Visual Studio Marketplace
   • Cursor, Windsurf, Antigravity, VSCodium: Open VSX, or search "Helicon" in the Extensions view
3. Click the Helicon icon in the activity bar, or press Cmd+Alt+H on macOS or Ctrl+Alt+H on Windows and Linux. The panel opens on the folder you have open.
4. Type what you want changed. Each new thread opens as a tab.

If the panel says it can't find the CLI, the CLI-not-found guide covers the PATH fixes for each OS.

Working on another machine? In a Remote-SSH, WSL or dev container window, the extension runs on the remote side, next to your code and its muse install, and the editor forwards the port for you.

Want to look before you install? There's a browser demo on sample data.

Three things it does that the terminal doesn't

1. Approvals you can read

When Muse Code wants to run a command or edit a file, Helicon shows you the exact command, or the edit as a diff, before it runs. You allow or deny it, or let the thread run without asking until you close Helicon. No more approving things because the prompt was half off-screen.

2. The files each thread changed

Each thread lists the files it changed, one click from opening them, and the diffs sit inline at the point in the thread where the change happened. When you come back to a thread after lunch, you can see what it did without running git diff and guessing which thread did what.

3. Every thread for the folder, and your usage

Open threads sit as tabs across the top. History lists every earlier thread for the folder, grouped by day and searchable, including the ones you started in the terminal. Reopen any of them with its turns, tool calls and diffs. The panel also shows your 5-hour and weekly plan windows, and what each thread would have cost at API rates.

It also understands Muse Code monitors: a thread that's watching a build or a pull request's checks says so, with a Stop button, and the turn a monitor woke up is marked.

Recommend it to your team

If your team uses Muse Code, add Helicon to the repo's recommended extensions. VS Code and the editors built on it then suggest it to anyone who opens the folder.

Create or edit .vscode/extensions.json:

{ "recommendations": ["harjjotsinghh.helicon"] }

Each person still uses their own muse login and plan. Nothing about accounts is shared through the repo.

A few commands worth knowing

• Helicon: New Thread in This Folder, from the Explorer's right-click menu, starts a thread in any subfolder.
• Helicon: Open Full Helicon in Editor opens the full app, with every project, in an editor tab.
• Helicon: Show Log gives you the server output for bug reports.

The unofficial part

Helicon is a community project. It's not made, sponsored or endorsed by Meta. "Muse Code" is Meta's trademark, used here only to say what Helicon works with. The code is MIT-licensed and on GitHub, and there's also a desktop app for Windows, macOS and Linux if you'd rather keep it out of your editor.

If something breaks, open an issue with the output of Helicon: Show Log. This week I'm answering issues within a day.