HomeMCPBridge

The MCP client launches the app's own executable as its server and talks JSON-RPC to it over standard input and output. The server answers the handshake, lists its tools and dispatches each call, so MCP needs no network port at all.

It is built as a Mac Catalyst app, which gives it Apple's HomeKit framework on the Mac. It runs from the menu bar, with a status window, a device browser, a setup guide and a log of every tool call.

Calls into HomeKit and the plugins are asynchronous; the server waits for each result before answering, so the line-by-line request loop stays simple.

Five tools list homes, rooms and devices, read a device's state and control it: on and off, brightness, hue and saturation, lock and unlock, open and close.

Two list cameras and capture snapshots as base64 images. Four cover motion, occupancy, doorbells and contact sensors, including buffering events for an assistant to poll. Three reach cameras on a Scrypted NVR.

The app holds no automation logic of its own. The assistant decides; HomeMCPBridge only exposes what HomeKit can read and do.

Devices outside HomeKit come in through plugins that share one protocol: list devices, read state, control a device, configure credentials. HomeKit, Govee and Scrypted are built in, and plugin credentials are kept in the Keychain.

Scrypted cameras are discovered over MQTT, through a small MQTT 3.1.1 client written on Apple's Network framework with no third-party dependency.

When the same light shows up in HomeKit and in a plugin, the two can be linked so the assistant sees one device, and commands go to the more capable source.

MCP is request and response, so events need another path. MCPPost sends motion, occupancy, doorbell and contact events to an HTTP endpoint the user chooses, as JSON with the sensor, its room and home and the new state. An assistant can then react, for example by taking a snapshot when motion starts.

Device control runs on the Mac and needs no internet connection. Apart from plugins that talk to their own service, nothing leaves the machine except the events the user chooses to send.