Bridge

SXL Studio Bridge is a small program that runs on your computer and links the running SXL Studio plugin with external tools: Cursor, Claude Desktop and other MCP clients, as well as scripts. Through it an AI agent can read and change tokens, variables, styles, compositions and data in the open Figma file. The same program serves Local Workspace and Local Storage.

#Requirements

Several tabs, Figma Desktop control and destructive commands that turn on by themselves need Bridge 1.11 and plugin 2.9.6.

Bridge listens only on the local address 127.0.0.1: it cannot be reached from another computer.

#Install and run

npm install -g @sxl-studio/bridge

sxl-bridge

Bridge takes one port, 37830 by default. The plugin connection, the MCP address http://127.0.0.1:37830/mcp and HTTP requests to http://127.0.0.1:37830/api/... all use it. If the port is busy, set another one with an environment variable:

BRIDGE_PORT=39999 sxl-bridge

The same port then has to be set in the plugin and in the MCP client settings.

To check that the program is running:

sxl-bridge health

#Connecting the plugin: Remote Connect

Remote Connect turns on by itself. Each time the plugin starts in Design mode, it connects to Bridge on the saved port and waits for commands in the background. The plugin interface stays usable and nothing needs to be pressed. If Bridge is not running, the plugin keeps trying: the first retry comes after a second, later ones less often but at least once every 30 seconds. It connects as soon as Bridge appears. The link comes back by itself after a Bridge restart and after a hot reload of a development build. A Pro Plus licence is required.

To see the connection:

1. In the plugin footer press the Remote Connect button. The plugin collapses into a compact bar with the connection state.
2. Expand the bar with the arrows button to open the connection window. It has the Port field, the Token field for the protected mode and the Allow destructive commands toggle.
3. The state Connected — Waiting for commands means the agent can send commands.

The compact Remote Connect bar in the plugin footer: the connection state, Disconnect and the expand button.

The Remote Connect window: port, token, session and client identifiers, the Allow destructive commands toggle.

While the connection window is open the plugin tabs are hidden. Disconnect turns Remote Connect off until the next plugin start and brings the usual interface back. The plugin remembers the port between sessions.

#Destructive commands

Destructive commands: deleting layers, variables and collections, resetting synchronization identifiers and hard pull. They turn on by themselves as soon as Bridge 1.11 or newer answers the connection, except in protected files. An older Bridge cannot tell files apart, so with it destructive commands stay off until someone turns them on explicitly. Even when they are allowed, the agent has to confirm every destructive command explicitly.

In a protected file a session starts with destructive commands off. You can turn them on in two ways:

• with the Allow destructive commands toggle;
• with the agent command set_session_policy and a file confirmation: confirmFile carries this file's key or name.

A file counts as protected when any of its keys is on the list. It also counts as protected when the plugin cannot read its key or the list itself. The protect_file command protects a file: the current file, a file key or a file link. The same command with protect: false and confirmFile (the file's key or name) removes the protection. Protection added from another tab turns destructive commands off in this file before its next destructive command. The list is kept on this computer and applies in every file. Protect files that hold a published library. A choice made with the command or the toggle lasts until the session ends.

Token export can be previewed with preview_export_variables before export_variables. Sort arranges styles and style folders without changing their IDs; existing collections, modes and variables cannot be reordered through Figma’s public API. The old allowDestructiveReorder option is ignored by these MCP tools. Deleting orphaned objects remains a separate destructive action. See Export variables and styles.

#Protected mode

If Bridge is started with the BRIDGE_AUTH_TOKEN variable, every connection must present the same token: enter it in the Token field of the Remote Connect window, in the Local Storage connection form and in the MCP client settings.

BRIDGE_AUTH_TOKEN=my-secret sxl-bridge

#Several files and Figma control

Bridge 1.11 keeps the plugin connected in several Figma tabs at once. A command goes to one file, chosen in this order:

1. An explicit target: targetFileKey on any MCP tool that works with the plugin, or fileKey in the POST /api/command body. The answer shows where the command went: bridgeTarget in MCP, target in HTTP.
2. The current selection: the later of two actions, choosing a file with select_plugin_session (by key, name or link) and the agent opening a file with figma_open_file, figma_run_plugin or restart_plugin. An explicit selection cancels files opened earlier that have not connected yet.
3. The first unprotected file that connected.
4. The only connected unprotected file.

If no file can be chosen, the command is rejected with ambiguous-target. A protected file is never chosen by itself: opening it or running the plugin in it does not choose it either. Commands reach it only through an explicit target or after select_plugin_session. When several files are connected, pass targetFileKey on every write. list_plugin_sessions shows the connected files and the current target. While the selected file reconnects, for example when the plugin restarts, a command waits for it up to 20 seconds.

The agent drives Figma Desktop on macOS by itself:

Running the plugin through the menu needs one macOS permission for the process that runs Bridge: System Settings → Privacy & Security → Accessibility. For Bridge running as a service this is its node program; figma_desktop_status shows the path. Before pressing the menu, Bridge brings Figma to the front: Figma ignores a menu command while it is in the background. Opening files and hot reload work without the permission.

While the Figma window is off screen — in another Space, minimized or hidden — Figma pauses document work. Apply, Generate and export wait, although the plugin still answers other commands. figma_desktop_status shows whether the window is visible. /api/status reports FIGMA_WINDOW_HIDDEN when a plugin command has been running for more than 20 seconds with the window off screen. Before long work, bring the file on screen: figma_open_file does that.

#Connecting an AI tool

Bridge speaks the MCP protocol. For Cursor add this to .cursor/mcp.json:

{
  "mcpServers": {
    "sxl-studio": {
      "url": "http://127.0.0.1:37830/mcp"
    }
  }
}

Other MCP clients connect to the same address. Start Bridge before opening the chat with the agent, otherwise the tools do not appear in the list. The first things worth asking the agent: call get_operator_runbook, which describes where to start, and get_plugin_status, which shows whether Bridge sees the plugin.

#What the agent can do

Bridge itself returns the full list: the list_tools tool or the address http://127.0.0.1:37830/api/tools.

Preview and audit tools change nothing. Write tools accept dryRun: true for a check without changes. Bridge shortens large responses to a summary; the full version can be requested separately.

#Bridge and Figma modes

#Local Workspace

Bridge reads and writes token and data files in a folder on disk for the Local Workspace mode and stores large Local Storage files for Git connections. Remote Connect is not needed for that: a running Bridge and an active profile in the synchronization settings are enough. The port and token are set on the Local Workspace tab of the Synchronization settings window. More: Local Workspace and Local Storage.

#If something does not work

#Related pages

• Local Workspace
• Local Storage
• Compositions
• Code generation