The control port

The control port lets an agent running outside Studio work on the open project: read the model, edit it, take screenshots, export files, and use the window as a person does. It is off unless you start Studio with it.

Start Studio with the control port

Run Studio's executable with --control and a port:

Platform	Command
macOS	"/Applications/Urbium Studio.app/Contents/MacOS/studio" --control 7777
Windows	"%LOCALAPPDATA%\Programs\Urbium Studio\studio.exe" --control 7777
Linux	./Urbium_Studio-x86_64.AppImage --control 7777

(Adjust the path to where Studio is installed.) Studio writes the port's token to control.json in its data folder; see Platforms, releases and updates for where that is.

Connect an agent

The same executable is an MCP server that forwards to the running app:

studio mcp --control 7777

Add it to your agent as an MCP server. For Claude Code, for example:

claude mcp add urbium -- "/Applications/Urbium Studio.app/Contents/MacOS/studio" mcp --control 7777

Cursor and Codex take the same command in their MCP server settings.

What the agent can do

• The model: list and run every command the app has (move, draw walls, set parameters, annotate sheets...), in order or in a batch; inspect elements, rules, parameters and solids; measure; read quantities, schedules and sheet checks; take a screenshot or a render; export files; undo and redo.
• The window: see the app's state (the open project, every project, the conversations and which are busy, running jobs); open a project; create one on a lot from an address; send a message to the app's own agent; answer its permission requests; accept or discard; read the rule checks; switch the inspector tab.

Long actions, such as opening a project or an agent's turn, run as jobs the agent follows through the app's state.

Where its edits go

Edits from the control port land on Manual edits, with the app's own undo, Accept, Discard and Before and After. You review them as you review any change. See Review the agent's changes.

Unlike the agent in the chat, an agent on the control port can change the base model (place the building on the lot, set a rule value, issue sheets) and write files.

Security

• The port listens on this computer only (loopback), never on the network.
• Every request carries a token Studio writes to control.json in its data folder, so a web page cannot use it. On macOS and Linux the file is readable by your user alone, so another account on the machine cannot use it either.
• At most eight clients at once; a client idle for a minute, or sending a request over 1 MiB, is dropped.

The protocol

For your own client: one JSON object per line each way. A request is {"token": "…", "tool": "execute", "args": {…}}; the answer is {"ok": true, "result": {…}} or {"ok": false, "error": {"code": "…", "message": "…"}}. Lengths in arguments are metres, or any length Studio's fields read (12'6").