Multipart device automations on Android

An automation may reference multipart devices similarly to an automation that doesn't use multipart devices.

First, obtain the component part(s) as you would normally. See Multipart devices for how to work with multipart devices.

Then, for each part you want to use in your automation, create an AutomationPartPath, which lets you reference the part in automation starters, conditions, and actions.

// Obtain a reference to the device:
val multipartDevices = structure.devices(enableMultipartDevices = true).first().toList()

val lights = multipartDevices.filter { it.has(OnOffLightDevice) && it.has(OnOff) }

val light = lights.first()

// get the AutomationPartPath for the device
val lightPartPath = light.automationPart(light.part(OnOffLightDevice).first())

Another thing to note is that automation actions usually take a device and a device type as parameters. However, an automation action that references a component part device - again, using an AutomationPartPath - only needs the AutomationPartPath, because the AutomationPartPath already contains a reference to the device type in addition to the component device reference.

For example, in the Automation API, a Refrigerator device type may be treated as a multipart device. It consists of a root RefrigeratorDevice which can contain multiple subpart cabinets, such as freezers or standard cabinets of type TemperatureControlledCabinetDevice.

To build refrigerator automations, you primarily interact with two standard Matter traits:

  • RefrigeratorAlarm: Exposes door status alarms through the doorOpen attribute of the state field.
  • RefrigeratorAndTemperatureControlledCabinetMode: Allows reading and commanding modes. For example, running commands like changeToMode to switch to modes like LowEnergy, RapidCool, or LowNoise.

This example automation triggers when the refrigerator door is opened. If the door is left open for more than two minutes, the automation broadcasts a voice notification on smart speakers, flashes the kitchen lights, and sends a push notification. Note that this automation impacts only the refrigerator compartment of the device, ignoring the freezer compartment (if it exists):

import com.google.home.automation.action
import com.google.home.automation.automation
import com.google.home.automation.condition
import com.google.home.automation.equals
import com.google.home.automation.starter
import com.google.home.google.AssistantBroadcast
import com.google.home.google.Notification
import com.google.home.matter.standard.OnOff
import com.google.home.matter.standard.OnOffLightDevice
import com.google.home.matter.standard.RefrigeratorAlarm
import com.google.home.matter.standard.RefrigeratorAlarm.Companion.state
import com.google.home.matter.standard.RefrigeratorDevice
import com.google.home.matter.standard.SpeakerDevice
import java.time.Duration

val structure: Structure = home.structures().first()

// Fetch devices using the multipart device model.
var multipartDevices = homeManager.devices(enableMultipartDevices = true)

// Obtain a reference to the refrigerator device.
val refrigeratorDevice = multipartDevices.first {
  it.has(TemperatureControlledCabinetDevice) &&
  it.has(RefrigeratorAndTemperatureControlledCabinetMode) &&
  it.has(RefrigeratorAlarm)
}

// Get all temperature-controlled cabinet parts of the refrigerator
val cabinets = refrigeratorDevice.parts(TemperatureControlledCabinetDevice)

// Find the cabinet part with the 'refrigerator' semantic tag
val refrigeratorCabinet = cabinets.firstOrNull {
  it.metadata.tags.contains(SemanticTag.Refrigerator.refrigerator)
}

val cabinetPartPath = refrigeratorCabinet.automationPath(TemperatureControlledCabinetDevice)

val speaker = home.devices().list().first { device -> device.has(SpeakerDevice) }

val refrigeratorDoorAlert = automation {
  name = "Refrigerator Door Open Alert"
  description = "Warn when the refrigerator door has been open for over 2 min"
  isActive = true

  sequential {
    // 1. Starter: Monitor the refrigerator door alarm trait
    val alarmStarter = starter<_>(cabinetPartPath, RefrigeratorAlarm)

    // 2. Condition: Ensure the 'doorOpen' alarm remains active for 2 continuous min
    condition {
      expression = alarmStarter.state.doorOpen equals true
      forDuration(Duration.ofMinutes(2))
    }

    // 3. Actions: Execute parallel reactions
    parallel {
      // Broadcast warning to household speakers
      action(speaker, SpeakerDevice) {
        command(AssistantBroadcast.broadcast("The refrigerator door has been left open!"))
      }

      // Push a notification alerts to home members' mobile devices
      action(structure) {
        command(Notification.sendNotifications(
          "Fridge Alert",
          { body = "The refrigerator door has been open for over 2 min" }
        ))
      }
    }
  }
}

The following example switches the refrigerator to Low Energy mode when it detects that no one is home.

import com.google.home.automation.action
import com.google.home.automation.automation
import com.google.home.automation.condition
import com.google.home.automation.equals
import com.google.home.automation.starter
import com.google.home.google.AreaPresenceState
import com.google.home.google.AreaPresenceState.Companion.presenceState
import com.google.home.google.AreaPresenceStateTrait.PresenceState
import com.google.home.matter.standard.RefrigeratorAndTemperatureControlledCabinetMode
import com.google.home.matter.standard.RefrigeratorAndTemperatureControlledCabinetMode.Companion.changeToMode
import com.google.home.matter.standard.RefrigeratorDevice
import com.google.home.matter.standard.TemperatureControlledCabinetDevice

val structure: Structure = home.structures().first()

// Fetch devices using the multipart device model.
var multipartDevices = homeManager.devices(enableMultipartDevices = true)

// Obtain a reference to the refrigerator device.
val refrigeratorDevice = multipartDevices.first {
  it.has(TemperatureControlledCabinetDevice) &&
  it.has(RefrigeratorAndTemperatureControlledCabinetMode) &&
  it.has(RefrigeratorAlarm)
}

val refrigeratorPartPath = refrigeratorDevice.automationPart(refrigeratorDevice.part(RefrigeratorDevice).first())

// Get all temperature-controlled cabinet parts of the refrigerator
val cabinets = refrigeratorDevice.parts(TemperatureControlledCabinetDevice )

// Find the cabinet part with the 'refrigerator' semantic tag
val refrigeratorCabinet = cabinets.firstOrNull {
  it.metadata.tags.contains(SemanticTag.Refrigerator.refrigerator)
}

val refrigeratorEcoMode = automation {
  name = "Refrigerator Eco Mode"
  description = "Automatically changes refrigerator to low energy mode when house is vacant."
  isActive = true

  sequential {
    // 1. Starter: Monitor household presence changes
    val presenceStarter = starter<_>(structure, AreaPresenceState)

    // 2. Condition: Verify presence state transitions to vacant
    condition {
      expression = presenceStarter.presenceState equals PresenceState.PresenceStateVacant
    }

    // 3. Action: Set refrigerator cabinet Mode to 'Low Energy' (e.g. Mode 1u)
    action(refrigeratorPartPath {
      command(RefrigeratorAndTemperatureControlledCabinetMode.changeToMode(1u))
    }
  }
}