Add notification support and background sync service for Android

src-tauri/gen/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+    <uses-permission android:name="android.permission.VIBRATE" />
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
+    <uses-permission android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
 
     <!-- AndroidTV support -->
     <uses-feature android:name="android.software.leanback" android:required="false" />
@@ -24,6 +31,23 @@
             </intent-filter>
         </activity>
 
+        <!-- Background sync service -->
+        <service
+            android:name=".SyncService"
+            android:enabled="true"
+            android:exported="false"
+            android:foregroundServiceType="dataSync" />
+
+        <!-- Boot receiver to restart service -->
+        <receiver
+            android:name=".BootReceiver"
+            android:enabled="true"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="android.intent.action.BOOT_COMPLETED" />
+            </intent-filter>
+        </receiver>
+
         <provider
           android:name="androidx.core.content.FileProvider"
           android:authorities="${applicationId}.fileprovider"

src-tauri/gen/android/app/src/main/java/in/cinny/app/BootReceiver.kt

@@ -0,0 +1,18 @@
+package `in`.cinny.app
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+
+/**
+ * Receives boot completed broadcast to restart the sync service
+ * after device reboot.
+ */
+class BootReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent) {
+        if (intent.action == Intent.ACTION_BOOT_COMPLETED) {
+            // Start the sync service after boot
+            SyncService.start(context)
+        }
+    }
+}

src-tauri/gen/android/app/src/main/java/in/cinny/app/MainActivity.kt

@@ -1,11 +1,48 @@
 package `in`.cinny.app
 
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
 import android.os.Bundle
-import androidx.activity.enableEdgeToEdge
+import androidx.core.app.ActivityCompat
+import androidx.core.content.ContextCompat
 
+/**
+ * Main activity for Cinny. Handles permission requests and
+ * starts the background sync service for notifications.
+ */
 class MainActivity : TauriActivity() {
-  override fun onCreate(savedInstanceState: Bundle?) {
-    enableEdgeToEdge()
-    super.onCreate(savedInstanceState)
-  }
+
+    companion object {
+        private const val NOTIFICATION_PERMISSION_CODE = 1001
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        requestNotificationPermission()
+        startSyncService()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        // Ensure sync service is running when app is in foreground
+        startSyncService()
+    }
+
+    private fun requestNotificationPermission() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            if (ContextCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS) 
+                != PackageManager.PERMISSION_GRANTED) {
+                ActivityCompat.requestPermissions(
+                    this,
+                    arrayOf(Manifest.permission.POST_NOTIFICATIONS),
+                    NOTIFICATION_PERMISSION_CODE
+                )
+            }
+        }
+    }
+
+    private fun startSyncService() {
+        SyncService.start(this)
+    }
 }

src-tauri/gen/android/app/src/main/java/in/cinny/app/SyncService.kt

@@ -0,0 +1,114 @@
+package `in`.cinny.app
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+import android.os.IBinder
+import android.os.PowerManager
+import androidx.core.app.NotificationCompat
+
+/**
+ * Foreground service to keep Matrix sync connection alive in background.
+ * This service maintains a wake lock and shows a persistent notification
+ * to prevent Android from killing the app while syncing.
+ */
+class SyncService : Service() {
+
+    companion object {
+        private const val CHANNEL_ID = "cinny_sync_channel"
+        private const val NOTIFICATION_ID = 1001
+        private const val WAKE_LOCK_TAG = "Cinny:SyncWakeLock"
+
+        fun start(context: Context) {
+            val intent = Intent(context, SyncService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            val intent = Intent(context, SyncService::class.java)
+            context.stopService(intent)
+        }
+    }
+
+    private var wakeLock: PowerManager.WakeLock? = null
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        createNotificationChannel()
+        acquireWakeLock()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        val notification = createNotification()
+        startForeground(NOTIFICATION_ID, notification)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        releaseWakeLock()
+        super.onDestroy()
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                "Matrix Sync",
+                NotificationManager.IMPORTANCE_LOW
+            ).apply {
+                description = "Keeps Cinny connected for message notifications"
+                setShowBadge(false)
+            }
+            val manager = getSystemService(NotificationManager::class.java)
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    private fun createNotification(): Notification {
+        val intent = Intent(this, MainActivity::class.java)
+        val pendingIntent = PendingIntent.getActivity(
+            this, 0, intent,
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        return NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle("Cinny")
+            .setContentText("Connected to Matrix")
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setOngoing(true)
+            .setContentIntent(pendingIntent)
+            .setPriority(NotificationCompat.PRIORITY_LOW)
+            .setCategory(NotificationCompat.CATEGORY_SERVICE)
+            .build()
+    }
+
+    private fun acquireWakeLock() {
+        val powerManager = getSystemService(Context.POWER_SERVICE) as PowerManager
+        wakeLock = powerManager.newWakeLock(
+            PowerManager.PARTIAL_WAKE_LOCK,
+            WAKE_LOCK_TAG
+        ).apply {
+            acquire(10 * 60 * 1000L) // 10 minutes, will be renewed
+        }
+    }
+
+    private fun releaseWakeLock() {
+        wakeLock?.let {
+            if (it.isHeld) {
+                it.release()
+            }
+        }
+        wakeLock = null
+    }
+}