Companion MCP

An MCP server for Bitfocus Companion. Exposes 53 tools covering verified button control, styling, page discovery, runtime summaries, inventory diffing, checkpointed rollback/restore workflows, preset management, variable management, and batch show programming — so AI assistants can operate Stream Deck surfaces and other Companion-connected devices through Companion's current APIs.

Built for live production. Pairs with grandMA2 MCP, Resolume MCP, MADRIX MCP, and Beyond MCP for full AI-driven show control.

The repo also includes a lightweight local browser UI for humans who want the same verified flows without manually issuing MCP tool calls.

Why this exists

Companion is the physical button layer that ties a live production stack together. An operator presses a Stream Deck button and it fires a grandMA2 cue, triggers a Resolume clip, or starts a laser sequence. But programming those buttons is manual — you click through the Companion UI, one button at a time, configuring actions, labels, and colors.

This MCP server lets an AI do that work. It can read your current button layout, preview changes before applying them, and batch-program entire pages in seconds. Combined with MA2 Agent and Resolume MCP, an AI assistant can program the entire show control surface from a single conversation.

Quick start

git clone https://github.com/drohi-r/companion-mcp && cd companion-mcp
uv sync
uv run python -m companion_mcp

Browser UI

Run the local operator UI:

uv run companion-mcp-ui

Then open:

http://127.0.0.1:8088

The UI is intentionally local-first. It sits on top of the same backend logic as the MCP tools, so verified writes, snapshots, presets, and rollback behave the same in the browser as they do through MCP.

Make sure Companion is running on the target host and port. Current Companion builds use:

• HTTP endpoints for button actions and style writes
• websocket tRPC at /trpc for richer reads, discovery, preview, and variable inspection

Configuration

Variable	Default	Description
COMPANION_HOST	127.0.0.1	Companion instance IP
COMPANION_PORT	8000	Companion HTTP and websocket port
COMPANION_TIMEOUT_S	10.0	HTTP request timeout in seconds
COMPANION_ALLOWED_HOSTS	127.0.0.1,localhost,::1	Comma-separated allowlist for target hosts. Set * to allow any.
COMPANION_WRITE_ENABLED	1	Set to 0 for read-only mode
COMPANION_TRANSPORT	stdio	MCP transport (stdio, sse, streamable-http)
COMPANION_UI_HOST	127.0.0.1	Browser UI bind address
COMPANION_UI_PORT	8088	Browser UI port

Architecture

graph TD
    A["Companion MCP Server<br/><code>companion_mcp</code><br/>53 tools · safety gate"] --> B
    B["HTTP Client<br/>Button actions · style writes"] --> D
    A --> C
    C["WebSocket tRPC Client<br/>Discovery · preview · variables"] --> D
    D["Bitfocus Companion<br/>HTTP + WebSocket at /trpc"]

    E["Browser UI<br/><code>companion-mcp-ui</code><br/>Local operator console"] -.-> A
    F["Snapshot Engine<br/>Inventory · presets · rollback"] -.-> A
    G["Verification Layer<br/>Render polling · diff · transactions"] -.-> A

    style A fill:#1a1a2e,stroke:#14B8A6,color:#fff
    style B fill:#1a1a2e,stroke:#14B8A6,color:#fff
    style C fill:#1a1a2e,stroke:#14B8A6,color:#fff
    style D fill:#1a1a2e,stroke:#0f3460,color:#fff
    style E fill:#0f3460,stroke:#0f3460,color:#fff
    style F fill:#0f3460,stroke:#0f3460,color:#fff
    style G fill:#0f3460,stroke:#0f3460,color:#fff

Loading

Tools

Discovery and reads

Safe, read-only tools for understanding the current state of Companion.

Tool	What it does
get_server_config	Return current MCP server configuration and safety settings
health_check	Probe Companion API reachability and return status
list_surfaces	List connected control surfaces (Stream Deck, etc.)
get_button_info	Read the current control and preview state for a specific button
get_button_runtime_summary	Return a compact operator-oriented runtime summary for a button
get_page_grid	Read a rectangular grid of buttons from a page
snapshot_page_inventory	Export a page region with concise button summaries, style, feedback, and preview hashes
save_page_inventory_snapshot	Save a named page inventory checkpoint to disk
load_page_inventory_snapshot	Load a saved page inventory checkpoint from disk
list_page_inventory_snapshots	List saved page inventory checkpoint files
delete_page_inventory_snapshot	Delete a saved page inventory checkpoint file
diff_page_inventory	Compare two page inventory snapshots and summarize changed buttons
preview_restore_page_style_from_inventory	Turn a saved inventory snapshot into a restore plan without writing to Companion
preview_restore_page_style_from_snapshot	Preview a restore plan from a named saved snapshot
save_page_style_preset	Save current page style entries as a reusable preset
load_page_style_preset	Load a saved page style preset
list_page_style_presets	List saved page style presets
delete_page_style_preset	Delete a saved page style preset
preview_apply_page_style_preset	Preview applying a saved page style preset with optional offsets
find_buttons	Search a page region by visible text, control id, control type, connection id, or definition id
export_page_layout	Export a page region as a reusable layout payload
get_custom_variable	Read a Companion custom variable
get_module_variable	Read a variable from a Companion module connection
snapshot_custom_variables	Read a named list of custom variables in one call
verify_button_render_change	Compare a current button preview hash to a previous one

Preview (plan before you write)

Validate and preview operations without touching Companion. Use these to inspect what a batch operation will do before committing.

Tool	What it does
preview_page_style	Validate and preview a page-style batch
preview_label_button_grid	Resolve a label grid into coordinates
preview_button_template	Place a reusable template at an origin and preview the result

Button actions

Require COMPANION_WRITE_ENABLED=1 (default).

Tool	What it does
press_button	Press and release a button
press_button_verified	Press a button and poll for visible/runtime state change
hold_button	Press and hold (down actions only)
release_button	Release a held button (up actions)
rotate_left	Rotate encoder left
rotate_right	Rotate encoder right
set_step	Set the current action step

Button styling

Tool	What it does
set_button_text	Change button display text
set_button_color	Change text and/or background color (6-digit hex)
set_button_style	Set multiple style properties at once
set_button_style_verified	Apply style changes and poll until the render catches up or the timeout expires

Batch operations

Tool	What it does
press_button_sequence	Press multiple buttons in order with configurable delay
set_page_style	Batch-set style on multiple buttons on a page
set_page_style_verified	Batch-set styles on a page and return per-button verification plus an inventory diff
restore_page_style_from_inventory	Restore button styles from a previously captured page inventory
restore_selected_page_style_from_inventory	Restore only selected coordinates from an inventory snapshot
restore_page_style_from_snapshot	Restore styles from a named saved snapshot
apply_page_style_transaction	Save a rollback checkpoint, apply verified styles, and return rollback metadata
rollback_page_style_transaction	Roll back a named transaction snapshot
apply_page_style_preset	Apply a saved page style preset with optional offsets
label_button_grid	Label a grid of buttons from a flat list of names
apply_button_template	Apply a reusable button template at a page origin

Variables and system

Tool	What it does
set_custom_variable	Write a Companion custom variable
rescan_surfaces	Rescan connected USB surfaces
press_bank_button	Legacy bank API (deprecated, still works)

Claude Desktop

{
  "mcpServers": {
    "companion": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/companion-mcp", "python", "-m", "companion_mcp"],
      "env": {
        "COMPANION_HOST": "127.0.0.1",
        "COMPANION_PORT": "8000"
      }
    }
  }
}

VS Code / Cursor

{
  "servers": {
    "companion": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/companion-mcp", "python", "-m", "companion_mcp"],
      "env": {
        "COMPANION_HOST": "127.0.0.1",
        "COMPANION_PORT": "8000"
      }
    }
  }
}

Codex

Create a codex.json MCP config file:

{
  "mcpServers": {
    "companion": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/companion-mcp", "python", "-m", "companion_mcp"],
      "env": {
        "COMPANION_HOST": "127.0.0.1",
        "COMPANION_PORT": "8000"
      }
    }
  }
}

Then run Codex with:

codex --mcp-config codex.json

Production safety

This server is designed for live show environments where accidental writes can disrupt a running production.

• Host allowlisting — only 127.0.0.1, localhost, and ::1 are permitted by default. Add LAN hosts explicitly via COMPANION_ALLOWED_HOSTS.
• Write gating — set COMPANION_WRITE_ENABLED=0 to block all write operations. Read and preview tools remain available.
• Preview before apply — every batch operation has a corresponding preview tool that validates inputs and shows exactly what will change, without touching Companion.
• Verified writes — prefer press_button_verified and set_button_style_verified when you care about actual visible or runtime state changes, not just HTTP acceptance.
• Snapshot and diff workflow — use snapshot_page_inventory before and after batch changes, or let set_page_style_verified produce an inventory diff automatically.
• Rollback path — capture a page with snapshot_page_inventory or save_page_inventory_snapshot, inspect the restore plan with preview_restore_page_style_from_inventory or preview_restore_page_style_from_snapshot, then use the matching restore tool to roll styles back cleanly.
• Transaction flow — apply_page_style_transaction creates a named rollback checkpoint before it writes. rollback_page_style_transaction restores from that named snapshot.
• Preset workflow — save reusable page styles with save_page_style_preset, inspect with preview_apply_page_style_preset, and deploy with apply_page_style_preset.
• Input validation — page, row, column, color hex, delay bounds, and template structure are all validated before any API call is made. Invalid inputs return structured JSON errors, never raw exceptions.
• Error isolation — all tools are wrapped in _handle_errors. Network failures, JSON parse errors, and validation failures return {"ok": false, "error": "...", "blocked": true} instead of crashing the MCP session.

Live behavior notes

• A successful HTTP write does not always mean the button visibly changed immediately.
• Current Companion builds can update stored style state first, then repaint the preview a short time later.
• set_button_style_verified and press_button_verified include bounded polling so the MCP can distinguish:
  • write accepted but nothing observable changed
  • write accepted and the preview changed after a short delay
  • write accepted and style state changed, but visible render still did not change

Why the UI helps

The MCP backend is already the real product. The UI does not replace it; it makes it faster and safer for humans:

• click buttons in a page grid instead of remembering page,row,column
• inspect preview, style, runtime summary, and the last verified response in one place
• save and browse snapshots and presets without opening JSON files
• run verified style changes and transaction rollback from a browser during show prep
• hand the system to an operator who is not going to type MCP calls by hand

Development

uv sync
uv run python -m pytest -v

License

Apache 2.0