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](https://developers.home.google.com/apis/android/device/multipart.md.txt) for how to work with
multipart devices.

Then, for each part you want to use in your automation, create an
[`AutomationPartPath`](https://developers.home.google.com/reference/kotlin/com/google/home/automation/AutomationPartPath),
which lets you reference the part in automation starters, conditions, and
actions.

```kotlin
// 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):

```kotlin
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.

```kotlin
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))
    }
  }
}
```