Measured on an Android 15 emulator with the app backgrounded and the display
asleep: the siren played, the platform refused the takeover
("Background activity launch blocked! … BAL_BLOCK"), and the alarm was
destroyed mid-ring by its own receipt ack.
Takeover:
- the foreground service posts an alarm_firing notification whose
full-screen intent raises AlarmActivity — the only background launch
Android 14+ permits. Verified with the display asleep: wakefulness
Asleep → Awake, topResumedActivity=.AlarmActivity, the FSI on the record.
- the cancel lives on the four real silences (disarm, stop, JS ack, activity
destroy), not in AlarmPlayer.stop: play() calls stop() first, which
retracted the notification ~120 ms after posting it.
- "Back to alerts" now finishes the alarm window (AlarmModule
finishTakeover). A route pop is not an activity: the window stayed on top
for good with show-when-locked, keep-screen-on and no Recents entry — the
reported "no way back to the main menu".
The native-delivery contract test said "no notification ever announces an
alarm"; that was falsified on device, so it now pins one FSI notification and
a silent firing channel instead.
Verified end to end on the emulator (two runs, one with the screen off):
join without an account, armed service, background trigger → wake + takeover
+ siren, acknowledge → silence, notification retracted, alert delivered,
takeover closed by itself, Home reachable, reopening silent.
