Add support for NFC write in FrontendScreen

[TimoPtr]

Summary

Add support for NFC write action on the FrontendScreen.

Checklist

• New or updated tests have been added to cover the changes following the testing guidelines.
• The code follows the project's code style and best_practices.
• The changes have been thoroughly tested, and edge cases have been considered.
• Changes are backward compatible whenever feasible. Any breaking changes are documented in the changelog for users and/or in the code for developers depending on the relevance.

Any other notes

I'm not a super fan of adding more and more methods to the view model, we might need to think about how we can limit that a first "easy" thing might be using delegation, but let see how it goes.

[Copilot]

Pull request overview

Adds NFC tag write support to the Compose-based FrontendScreen flow by wiring the tag/write external-bus message through the handler + ViewModel into a host-launched NFC write activity contract, then responding back to the frontend with a result message.

Changes:

• Introduces tag/write as a typed incoming external-bus message and maps it to a new WriteNfcTag handler event
• Adds a new one-shot navigation event (LaunchNfcWrite) and launches WriteNfcTag via an ActivityResultContract from FrontendNavigation
• Sends a result response back to the frontend when the NFC write flow completes, plus adds/updates unit tests across parsing/handler/viewmodel/event-handler layers

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
app/src/main/kotlin/io/homeassistant/companion/android/frontend/externalbus/incoming/IncomingExternalBusMessage.kt	Adds TagWriteMessage / TagWritePayload for tag/write incoming messages
app/src/main/kotlin/io/homeassistant/companion/android/frontend/handler/FrontendMessageHandler.kt	Handles TagWriteMessage and emits FrontendHandlerEvent.WriteNfcTag
app/src/main/kotlin/io/homeassistant/companion/android/frontend/handler/FrontendHandlerEvent.kt	Adds WriteNfcTag handler event to carry messageId/tagId
app/src/main/kotlin/io/homeassistant/companion/android/frontend/navigation/FrontendEvent.kt	Adds FrontendEvent.LaunchNfcWrite one-shot event
app/src/main/kotlin/io/homeassistant/companion/android/frontend/navigation/FrontendNavigation.kt	Launches NFC write flow with rememberLauncherForActivityResult and consumes LaunchNfcWrite
app/src/main/kotlin/io/homeassistant/companion/android/frontend/externalbus/outgoing/OutgoingExternalBusMessage.kt	Adds ResultMessage.success(...) helper for sending empty success results
app/src/main/kotlin/io/homeassistant/companion/android/frontend/FrontendViewModel.kt	Emits LaunchNfcWrite on handler event and sends ResultMessage on NFC completion
app/src/test/kotlin/io/homeassistant/companion/android/frontend/externalbus/incoming/IncomingExternalBusMessageTest.kt	Adds JSON parsing tests for tag/write
app/src/test/kotlin/io/homeassistant/companion/android/frontend/handler/FrontendMessageHandlerTest.kt	Adds handler mapping tests for TagWriteMessage → WriteNfcTag
app/src/test/kotlin/io/homeassistant/companion/android/frontend/navigation/FrontendEventHandlerTest.kt	Adds event-handler tests for LaunchNfcWrite routing
app/src/test/kotlin/io/homeassistant/companion/android/frontend/FrontendViewModelTest.kt	Adds ViewModel tests for emitting LaunchNfcWrite and sending ResultMessage on completion

[jpelgrom]

For consistency with other events: why not navigate to / open NFC write?

[TimoPtr]

Addressed

[jpelgrom]

we might need to think about how we can limit that a first "easy" thing might be using delegation, but let see how it goes.

Did you already have something specific in mind for delegation/do you have an example?

[TimoPtr]

we might need to think about how we can limit that a first "easy" thing might be using delegation, but let see how it goes.

Did you already have something specific in mind for delegation/do you have an example?

Not yet TBH, I need to have another example to brainstorm about what I could do.

[jpelgrom]

OK. I also don't have another good approach at this point so let's continue with this for now.