fix: play through the alarm stream so the ring cuts through DND

DND silences the media stream by default, so playback on STREAM_MUSIC was
invisible during DND even though the notification showed. Switch to
STREAM_ALARM + USAGE_ALARM, which DND exempts by default, and restore/force
the alarm stream volume instead of media.

README.md

@@ -49,11 +49,14 @@ refuse to play any sound.** This is enforced at two points:
 Only after the user flips that toggle will a trigger actually ring.
 
 When access **is** granted, `RingService`:
-- saves the current music volume,
+- saves the current **alarm-stream** volume,
-- forces `AudioManager.STREAM_MUSIC` to max,
+- forces `AudioManager.STREAM_ALARM` to max,
-- requests `AUDIOFOCUS_GAIN_TRANSIENT` using `USAGE_NOTIFICATION_RINGTONE` and
+- requests `AUDIOFOCUS_GAIN_TRANSIENT` using `AudioAttributes.USAGE_ALARM`,
-  sets `AudioManager.mode = MODE_RINGTONE` so the sound cuts through DND,
+- plays on the **alarm stream** — the one stream Do Not Disturb does **not**
-- plays for 30 s, then restores the volume and abandons focus.
+  silence by default (media/music *is* silenced), which is what lets the ring
+  cut through DND,
+- plays for the configured number of seconds, then restores the volume and
+  abandons focus.
 
 ---
 

app/src/main/java/com/example/lostmyphone/RingService.kt

@@ -147,19 +147,20 @@ class RingService : Service() {
      */
     private suspend fun beginPlayback(uri: Uri): Boolean {
         return try {
-            // Step 1: save current volume.
+            // Step 1: save current alarm-stream volume so we can restore it later.
-            originalVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC)
+            originalVolume = audioManager.getStreamVolume(AudioManager.STREAM_ALARM)
 
-            // Step 2: force max volume.
+            // Step 2: force the alarm stream to max volume.
-            val maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
+            val maxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_ALARM)
             audioManager.setStreamVolume(
-                AudioManager.STREAM_MUSIC,
+                AudioManager.STREAM_ALARM,
                 maxVolume,
                 0 // flags = 0 so we do NOT show the system volume UI.
             )
 
-            // Step 3: request focus. Use USAGE_NOTIFICATION_RINGTONE so the
+            // Step 3: request focus. Playing on the ALARM stream with
-            // system lets it play even during DND, and set MODE_RINGTONE.
+            // USAGE_ALARM is what cuts through Do Not Disturb — DND does not
+            // silence alarms by default (unlike media/music).
             previousFocusMode = audioManager.mode
             requestAudioFocus()
 
@@ -168,7 +169,7 @@ class RingService : Service() {
             mediaPlayer = MediaPlayer()
             mediaPlayer.setAudioAttributes(
                 AudioAttributes.Builder()
-                    .setUsage(AudioAttributes.USAGE_NOTIFICATION_RINGTONE)
+                    .setUsage(AudioAttributes.USAGE_ALARM)
                     .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
                     .build()
             )
@@ -215,7 +216,7 @@ class RingService : Service() {
         }
 
         val attributes = AudioAttributes.Builder()
-            .setUsage(AudioAttributes.USAGE_NOTIFICATION_RINGTONE)
+            .setUsage(AudioAttributes.USAGE_ALARM)
             .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
             .build()
 
@@ -230,7 +231,7 @@ class RingService : Service() {
             @Suppress("DEPRECATION")
             audioManager.requestAudioFocus(
                 listener,
-                AudioManager.STREAM_MUSIC,
+                AudioManager.STREAM_ALARM,
                 AudioManager.AUDIOFOCUS_GAIN_TRANSIENT
             )
         }
@@ -276,7 +277,7 @@ class RingService : Service() {
             // Restore the previous volume.
             if (originalVolume >= 0) {
                 audioManager.setStreamVolume(
-                    AudioManager.STREAM_MUSIC,
+                    AudioManager.STREAM_ALARM,
                     originalVolume,
                     0
                 )