A systemExempted foreground service holds the ring: audio focus, USAGE_ALARM,
the volume ramp, vibration, and the ringtone URI. It goes foreground
synchronously before it reads anything from the database, because the platform
kills a service that reaches startForeground late — including on the path where
there turns out to be no session to ring.
The chain that matters is the one that never ends in silence. A full-screen
intent when canUseFullScreenIntent() allows it; a high-priority heads-up
notification that still rings when it does not; the device's default alarm
ringtone when the configured URI will not open; and forced vibration when no
audio source will play at all.
Preparing a MediaPlayer is done off the main thread — a synchronous prepare at
the moment the alarm fires is an ANR — and a player is released rather than
orphaned on every failure path, so a dismissal cannot be outlived by the ring
it cancelled.
The ring screen here is plumbing and a placeholder: window flags to show over
the lockscreen and turn the screen on. Its UI is M4.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
makiolajandClaude Opus 5
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