Agent fixed the current set of issues, now the app at least runs (and is actually staying alive in the background successfully!) but the countdown is visually messed up on SDK24 (hours field is missing) and SDK36 (fields do not count down at all even though the app is making the noise), plus the Pause button no longer pauses and causes the right button to be disabled indefinitely after using it.

app/src/main/java/com/hyperling/apps/infinitetimer/MainActivity.java

@@ -704,8 +704,12 @@ public class MainActivity extends AppCompatActivity {
         syncVolume();
         
         // Register receiver to get live updates from ForegroundService while app is visible
-        // RECEIVER_NOT_EXPORTED (0x00010000) is required on Android 13+ for local broadcasts
-        registerReceiver(timerUpdateReceiver, new IntentFilter(TimerForegroundService.class.getName() + ".UPDATE"), 0x00010000);
+        IntentFilter filter = new IntentFilter(TimerForegroundService.class.getName() + ".UPDATE");
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE) {
+            registerReceiver(timerUpdateReceiver, filter, Context.RECEIVER_NOT_EXPORTED);
+        } else {
+            registerReceiver(timerUpdateReceiver, filter);
+        }
 
         if (DEBUG) Log.d(tag, "Finished");
     }