Add foreground service for reliable broadcast reception

Android 8.0+ blocks implicit broadcasts to manifest-registered
receivers. Added ListenerService that dynamically registers the
NtfyReceiver, ensuring LOCATE commands from the ntfy app are
always received. Also handles POST_NOTIFICATIONS permission.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/main/AndroidManifest.xml

@@ -6,6 +6,9 @@
     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
     <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_LOCATION" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
 
     <application
         android:allowBackup="true"
@@ -28,6 +31,11 @@
             </intent-filter>
         </activity>
 
+        <service
+            android:name=".ListenerService"
+            android:foregroundServiceType="location"
+            android:exported="false" />
+
         <receiver
             android:name=".NtfyReceiver"
             android:exported="true">

app/src/main/java/com/example/helios_location_finder/ListenerService.kt

@@ -0,0 +1,80 @@
+package com.example.helios_location_finder
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Intent
+import android.content.IntentFilter
+import android.os.IBinder
+import android.util.Log
+import androidx.core.content.ContextCompat
+
+class ListenerService : Service() {
+
+    companion object {
+        private const val TAG = "ListenerService"
+        private const val CHANNEL_ID = "helios_listener"
+        private const val NOTIFICATION_ID = 1
+
+        fun start(context: android.content.Context) {
+            val intent = Intent(context, ListenerService::class.java)
+            ContextCompat.startForegroundService(context, intent)
+        }
+    }
+
+    private val receiver = NtfyReceiver()
+
+    override fun onCreate() {
+        super.onCreate()
+        createNotificationChannel()
+        startForeground(NOTIFICATION_ID, buildNotification())
+
+        val filter = IntentFilter("io.heckel.ntfy.MESSAGE_RECEIVED")
+        ContextCompat.registerReceiver(
+            this, receiver, filter, ContextCompat.RECEIVER_EXPORTED
+        )
+        Log.d(TAG, "Listener service started, receiver registered")
+    }
+
+    override fun onDestroy() {
+        unregisterReceiver(receiver)
+        Log.d(TAG, "Listener service stopped, receiver unregistered")
+        super.onDestroy()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        return START_STICKY
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun createNotificationChannel() {
+        val channel = NotificationChannel(
+            CHANNEL_ID,
+            "Helios Tracker",
+            NotificationManager.IMPORTANCE_LOW
+        ).apply {
+            description = "Keeps Helios Tracker listening for LOCATE commands"
+            setShowBadge(false)
+        }
+        getSystemService(NotificationManager::class.java).createNotificationChannel(channel)
+    }
+
+    private fun buildNotification(): Notification {
+        val pendingIntent = PendingIntent.getActivity(
+            this, 0,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_IMMUTABLE
+        )
+
+        return Notification.Builder(this, CHANNEL_ID)
+            .setContentTitle("Helios Tracker")
+            .setContentText("Lauscht auf LOCATE-Anfragen")
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+    }
+}

app/src/main/java/com/example/helios_location_finder/MainActivity.kt

@@ -50,6 +50,7 @@ class MainActivity : ComponentActivity() {
 
     private val foregroundGranted = mutableStateOf(false)
     private val backgroundGranted = mutableStateOf(false)
+    private val serviceRunning = mutableStateOf(false)
 
     private val foregroundPermissionLauncher = registerForActivityResult(
         ActivityResultContracts.RequestMultiplePermissions()
@@ -62,11 +63,19 @@ class MainActivity : ComponentActivity() {
         ActivityResultContracts.RequestPermission()
     ) { granted ->
         backgroundGranted.value = granted
+        if (granted) startListenerService()
+    }
+
+    private val notificationPermissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestPermission()
+    ) { granted ->
+        if (granted) startListenerService()
     }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         checkPermissions()
+        startListenerService()
 
         val listenTopic = mutableStateOf(Prefs.getListenTopic(this))
         val replyTopic = mutableStateOf(Prefs.getReplyTopic(this))
@@ -133,6 +142,20 @@ class MainActivity : ComponentActivity() {
             backgroundPermissionLauncher.launch(Manifest.permission.ACCESS_BACKGROUND_LOCATION)
         }
     }
+
+    private fun startListenerService() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            if (ContextCompat.checkSelfPermission(
+                    this, Manifest.permission.POST_NOTIFICATIONS
+                ) != PackageManager.PERMISSION_GRANTED
+            ) {
+                notificationPermissionLauncher.launch(Manifest.permission.POST_NOTIFICATIONS)
+                return
+            }
+        }
+        ListenerService.start(this)
+        serviceRunning.value = true
+    }
 }
 
 @Composable