pi-od-mcp

A pi extension that bridges Open Design's od mcp stdio MCP server into pi tools.

Open Design (OD) ships as a local-first design workspace with an MCP server surface (od mcp) that exposes ~18 tools for reading project files, managing artifacts, and commissioning design generation runs. OD's od mcp install pi only prints a snippet because pi has no built-in MCP host — so this extension spawns od mcp as a stdio process and dynamically registers each tool it discovers as a first-class pi tool the LLM can call directly.

How it works

• On first use (or at session_start), spawns the Open Design CLI's mcp subcommand as a stdio MCP server.
• Calls listTools() once and registers every tool as a pi tool named od_<tool> (e.g. od_list_projects, od_get_artifact, od_start_run).
• pi's argument validator accepts raw JSON Schema, so each tool's MCP inputSchema is passed straight through as the pi tool's parameters — no hand-maintained typebox schemas to drift when OD adds tools.
• Each tool forwards to client.callTool({ name, arguments }).
• The stdio process is lazy (nothing spawns until the first call) and is closed on session_shutdown.

Install

pi install git:github.com/ersintarhan/pi-od-mcp
# or once published to npm:
pi install npm:pi-od-mcp

Requirements

• Open Design installed and running. This extension auto-discovers the packaged CLI inside Open Design.app and the daemon socket under /tmp/open-design/ipc/<namespace>/daemon.sock.
• Node >= 22.19.

Configuration

Environment variables (all optional):

Variable	Purpose
OD_BIN	Absolute path to an od CLI script (dev checkout or custom build).
OD_DAEMON_URL	Override daemon discovery (passed through to od mcp).
OD_SIDECAR_IPC_PATH	Override daemon socket discovery (passed through to od mcp).
OD_USE_PATH_OD	Set to 1 to trust a bare od on PATH (note: system od is ignored).

Commands

• /od-mcp-status — show MCP connection state, discovered CLI path, and the daemon URL/socket in use.

Status command example

> /od-mcp-status
Open Design MCP: connected
odBin: /Applications/Open Design.app/.../daemon-cli.mjs
daemonUrl: /tmp/open-design/ipc/release-stable/daemon.sock

Development

git clone https://github.com/ersintarhan/pi-od-mcp
cd pi-od-mcp
npm install
npm run typecheck

The extension is a single index.ts loaded via jiti, so no build step is needed to run it. Typecheck validates against the pi type packages.

License

Apache-2.0