An MCP plugin for controlling Google Home devices: lights, plugs, switches, locks, thermostats, speakers, and routines. It talks to Google's undocumented Home "foyer" API (the one home.google.com uses), authenticating with a gpsoauth master token — so it needs no Google Cloud project, Device Access, or partner API.

It runs as a JavaScript plugin on the CoreApp / Pebble Index MCP runtime (coredevices/CoreApp#174): a single esbuilt index.js, sandboxed on-device (WebView on Android, JavaScriptCore on iOS), reaching Google only through the host's allow-listed fetch.

Every tool below is verified live against real devices.

Read (all homes/devices, unrestricted):

• list_homes, list_devices (name, room, type, capabilities, online/on state), get_device_state

Control (any device; selectors are name and/or room and/or type):

• turn_on / turn_off — single device, a room, or a group ("all lights" = type=light)
• set_brightness, set_color_temperature
• set_volume, set_muted
• lock, unlock (PIN-gated: unlock takes a pin; set_passcode saves it)
• set_thermostat (temperature in C or F, and/or mode)
• media_control (play / pause / stop)
• list_automations, run_automation (start a household routine by name)

There is no add/create or remove/delete surface — control only.

cd js
npm install
npm run build     # -> js/dist/{index.js, manifest.json, settings.html}
npm test          # vitest

The dist/ output is packaged into a .pbw (appinfo.json + mcp/) by the CoreApp tooling and installed from the Pebble app's MCP settings → Add → Plugin.

Auth happens on the plugin's settings page (js/settings.html): "Sign in to Google" opens the real Google page — a host-pinned cookie capture, so the plugin never sees your password — captures the oauth_token, and the plugin mints a gpsoauth master token from it. All secrets stay on the phone in the plugin's namespaced store.

• docs/PROTOCOL.md — the foyer API protocol (JSON + protobuf).
• docs/TRAITS.md — device traits and the control mapping.
• js/src/ — the plugin source (TypeScript): foyer client/codec, gpsoauth, the 16 tools.