feat(android): add preferConnectedAudioDevice flag to route audio to …

[lw-manoj]

…earphones or Bluetooth

STREAM_ALARM / USAGE_ALARM (introduced in 5.4.0) forces audio to the built-in speaker by Android design, bypassing connected earphones and Bluetooth devices. This is correct for wake-up alarms but is a regression for developers who need external device routing.

Adds preferConnectedAudioDevice (default false) to AlarmSettings. When true, both AudioService and VolumeService switch to STREAM_MUSIC + USAGE_MEDIA, routing to a connected earphone or Bluetooth device if present and falling back to the speaker if not. The trade-off is that the media volume slider controls the volume instead of the alarm slider.

Also fixes androidStopAlarmOnTermination being absent from AlarmSettings copyWith() and props — two callers relying on equality or copyWith for this field would have seen silent incorrect behaviur.

Threads the flag through the full stack: AlarmSettingsWire pigeon definition → Dart AlarmSettings model → regenerated platform bindings → Android AlarmSettings.kt (with = false default for safe deserialization of persisted alarms) → AlarmService.kt → AudioService.kt and VolumeService.kt.

Fixes #400.

Tested on: Pixel 9a, Android 16

[gdelataillade]

Thanks @lw-manoj, the fix looks great — clean threading through every layer, backward compat is solid, and nice catch on the stale alarm_settings.g.dart (it was silently dropping androidStopAlarmOnTermination from persisted alarms).

Two small things before I merge:

1. Audio focus stream consistency

VolumeService.requestAudioFocus() still hardcodes USAGE_ALARM / STREAM_ALARM even when preferConnectedAudioDevice is true. The MediaPlayer playback uses USAGE_MEDIA but the focus request stays alarm-typed, which is inconsistent and may affect how other apps duck/yield. Could you thread the flag into requestAudioFocus() as well (and through the AlarmService call site)?

2. README docs

Could you add a row for preferConnectedAudioDevice to the AlarmSettings table in README.md (around line 89, next to androidStopAlarmOnTermination)? Something like:

| preferConnectedAudioDevice | `bool` | If true, routes alarm audio to a connected earphone or Bluetooth device when present, falling back to the speaker. Uses the media volume slider instead of the alarm slider. Android-only. Disabled by default. |

Once those are in I'll merge. Thanks again for the fast turnaround!

[lw-manoj]

Thanks @gdelataillade for reviewing and catching the missing update. I will fix it later tonight and update the PR.

[lw-manoj]

Thanks for the thorough review @gdelataillade. Both points addressed:

1. Audio focus consistency: requestAudioFocus() now branches on preferConnectedAudioDevice the same way AudioService does: USAGE_MEDIA (API 26+) and STREAM_MUSIC (pre-26) when true, USAGE_ALARM / STREAM_ALARM when false. Audio focus and playback are now consistent.

2. README: Added preferConnectedAudioDevice row to the AlarmSettings table, with wording adjusted to "Has no effect on iOS" rather than "Android-only" to be more precise and consistent with the existing doc style.

[gdelataillade]

Thank you! Added to version 5.4.1 !