dat-conventions

DAT SDK Conventions (Android)

Quick Reference

Task	Command
Build app	./gradlew assembleDebug
Run tests	./gradlew test
Install app	./gradlew installDebug
Lint app	./gradlew lint

Architecture

The SDK is organized into four public modules:

• mwdat-core: Registration, permissions, devices, and session creation
• mwdat-camera: Stream capability, video frames, and photo capture
• mwdat-display: Display capability, display UI components, icons, images, buttons, and video
• mwdat-mockdevice: MockDeviceKit for testing without hardware

Initialization and session setup

Wearables.initialize(context)

val session = Wearables.createSession(AutoDeviceSelector()).getOrElse { error ->
    throw IllegalStateException(error.description)
}
session.start()

val stream = session.addStream(StreamConfiguration()).getOrElse { error ->
    throw IllegalStateException(error.description)
}
stream.start().getOrElse { error ->
    throw IllegalStateException(error.description)
}

Kotlin patterns

• Use DatResult<T, E> for typed success and failure handling
• Observe state with StateFlow and Flow
• Create a Session first, then attach capabilities such as Stream or Display
• Keep frame handling off the main thread when doing heavier processing

Error handling

Wearables.checkPermissionStatus(Permission.CAMERA)
    .onSuccess { status -> /* handle status */ }
    .onFailure { error, _ -> /* handle error */ }

Avoid getOrThrow() in user-facing samples. Surface typed errors from DatResult instead.

Naming conventions

Type	Purpose	Example
Session	Device connection lifecycle	Wearables.createSession(...)
Stream	Camera capability on a session	session.addStream(...)
Display	Display capability on a session	session.addDisplay(...)
*Selector	Device targeting	AutoDeviceSelector
*Error	Typed failure surface	SessionError, StreamError

Key types

• Wearables — SDK entry point
• Session — lifecycle for an interaction with a linked device
• Stream — camera capability attached to a session
• Display — display capability attached to a session
• StreamConfiguration — video quality and frame rate configuration
• MockDeviceKit — simulated device environment for testing

Live docs search

If your editor supports remote MCP servers, connect https://mcp.facebook.com/wearables_dat and use search_dat_docs for current DAT setup, session lifecycle, camera streaming, MockDeviceKit, permissions, and exact API symbols.

Use llms.txt when your tool only supports static reference context.

Testing with MockDeviceKit

val mockDeviceKit = MockDeviceKit.getInstance(context)
mockDeviceKit.enable()
val device = mockDeviceKit.pairRaybanMeta()

Use MockDeviceKit to drive registration, device availability, streaming media, and permission scenarios without physical hardware.

Common pitfalls

• Do not call SDK APIs before Wearables.initialize(context)
• Do not assume a session implies streaming or display access; capabilities are attached separately
• Do not ignore DatResult failures from createSession, start, addStream, addDisplay, or capturePhoto
• Do not reuse terminally stopped sessions

Links

• Android API reference
• Developer documentation
• GitHub repository