Gate alarm session option on app state and add notification fallback

Limit the .duckOthers option to the only state where legacy options: []
fails: background without Silent Tune holding a mixable session alive.
In foreground or with Silent Tune, restore options: [] so the alarm
continues to dominate other audio with no behavioral change for those
users.

In that same fail-prone state, plumb the alarm's soundFile through
AlarmManager.sendNotification so the system-delivered notification
carries the user's configured alarm sound as an audible fallback. In
other states the notification keeps .default to avoid an echo with the
in-app AVAudioPlayer loop.

Author: bjorkert

LoopFollow/Alarm/Alarm.swift

@@ -3,6 +3,7 @@
 
 import Foundation
 import HealthKit
+import UIKit
 import UserNotifications
 
 protocol DayNightDisplayable {
@@ -259,7 +260,19 @@ struct Alarm: Identifiable, Codable, Equatable {
             }
         }()
 
-        AlarmManager.shared.sendNotification(title: type.rawValue, actionTitle: snoozeDuration == 0 ? "Acknowledge" : "Snooze")
+        // When backgrounded without Silent Tune holding a session alive, the in-app
+        // AVAudioSession activation can fail (cannotInterruptOthers, 560557684). Pass
+        // the alarm's soundFile to the notification so the system delivers the user's
+        // configured sound as a fallback. In foreground or with Silent Tune, the in-app
+        // player is reliable and we keep .default to avoid an echo with the looping player.
+        let inBackgroundWithoutSilentTune = UIApplication.shared.applicationState != .active
+            && Storage.shared.backgroundRefreshType.value != .silentTune
+        let notificationSound: SoundFile? = (playSound && inBackgroundWithoutSilentTune) ? soundFile : nil
+        AlarmManager.shared.sendNotification(
+            title: type.rawValue,
+            actionTitle: snoozeDuration == 0 ? "Acknowledge" : "Snooze",
+            soundFile: notificationSound
+        )
 
         if playSound {
             AlarmSound.setSoundFile(str: soundFile.rawValue)

LoopFollow/Alarm/AlarmManager.swift

@@ -176,7 +176,7 @@ class AlarmManager {
         UNUserNotificationCenter.current().removeAllPendingNotificationRequests()
     }
 
-    func sendNotification(title: String, actionTitle: String? = nil) {
+    func sendNotification(title: String, actionTitle: String? = nil, soundFile: SoundFile? = nil) {
         UNUserNotificationCenter.current().removeAllPendingNotificationRequests()
 
         let content = UNMutableNotificationContent()
@@ -185,7 +185,11 @@ class AlarmManager {
         content.subtitle += Observable.shared.directionText.value + " "
         content.subtitle += Observable.shared.deltaText.value
         content.categoryIdentifier = "category"
-        content.sound = .default
+        if let soundFile {
+            content.sound = UNNotificationSound(named: UNNotificationSoundName("\(soundFile.rawValue).caf"))
+        } else {
+            content.sound = .default
+        }
 
         let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 1, repeats: false)
         let request = UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: trigger)

LoopFollow/Controllers/AlarmSound.swift

@@ -88,7 +88,7 @@ class AlarmSound {
             audioPlayer = try AVAudioPlayer(contentsOf: soundURL)
             audioPlayer!.delegate = audioPlayerDelegate
 
-            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .duckOthers)
+            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: sessionCategoryOptions())
             try AVAudioSession.sharedInstance().setActive(true)
 
             audioPlayer?.numberOfLoops = 0
@@ -126,7 +126,7 @@ class AlarmSound {
             audioPlayer = try AVAudioPlayer(contentsOf: soundURL)
             audioPlayer!.delegate = audioPlayerDelegate
 
-            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .duckOthers)
+            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: sessionCategoryOptions())
             try AVAudioSession.sharedInstance().setActive(true)
 
             // Only use numberOfLoops if we're not using delay-based repeating
@@ -184,7 +184,7 @@ class AlarmSound {
                 audioPlayer = try AVAudioPlayer(contentsOf: soundURL)
                 audioPlayer!.delegate = audioPlayerDelegate
 
-                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .duckOthers)
+                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: sessionCategoryOptions())
                 try AVAudioSession.sharedInstance().setActive(true)
 
                 audioPlayer!.numberOfLoops = 0
@@ -213,7 +213,7 @@ class AlarmSound {
             audioPlayer = try AVAudioPlayer(contentsOf: soundURL)
             audioPlayer!.delegate = audioPlayerDelegate
 
-            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .duckOthers)
+            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: sessionCategoryOptions())
             try AVAudioSession.sharedInstance().setActive(true)
 
             // Play endless loops
@@ -262,13 +262,25 @@ class AlarmSound {
 
     fileprivate static func enableAudio() {
         do {
-            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .duckOthers)
+            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: sessionCategoryOptions())
             try AVAudioSession.sharedInstance().setActive(true)
             LogManager.shared.log(category: .alarm, message: "Audio session configured for alarm playback")
         } catch {
             LogManager.shared.log(category: .alarm, message: "Enable audio error: \(error)")
         }
     }
+
+    // Background activation of a non-mixable .playback session is denied by iOS
+    // (cannotInterruptOthers, 560557684) unless the app is already actively playing
+    // audio. In foreground, or with Silent Tune holding a mixable session alive,
+    // the legacy options: [] succeeds and lets the alarm dominate other audio.
+    // For Bluetooth-heartbeat users with no Silent Tune, fall back to .duckOthers
+    // (mixable + ducks others) so activation is permitted from background.
+    fileprivate static func sessionCategoryOptions() -> AVAudioSession.CategoryOptions {
+        let inBackgroundWithoutSilentTune = UIApplication.shared.applicationState != .active
+            && Storage.shared.backgroundRefreshType.value != .silentTune
+        return inBackgroundWithoutSilentTune ? .duckOthers : []
+    }
 }
 
 class AudioPlayerDelegate: NSObject, AVAudioPlayerDelegate {