android: group push notifications by chat

android/CHANGELOG.md

@@ -815,3 +815,14 @@
   - `SettingsScreen`
   - `SettingsFolderView`
 - Updated `AppNavGraph` Settings destination call-site accordingly.
+
+### Step 118 - Android push notifications grouped by chat
+- Reworked `NotificationDispatcher` to aggregate incoming messages into one notification per chat:
+  - stable notification id per `chatId`,
+  - per-chat unread counter,
+  - multi-line inbox preview of recent messages.
+- Added app-level summary notification that groups all active chat notifications.
+- Added deduplication guard for repeated push deliveries of the same `messageId`.
+- Added notification cleanup on chat open:
+  - when push-open intent targets a chat in `MainActivity`,
+  - when `ChatViewModel` enters a chat directly from app UI.

android/app/src/main/java/ru/daemonlord/messenger/MainActivity.kt

@@ -15,6 +15,7 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.app.AppCompatDelegate
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.runBlocking
+import ru.daemonlord.messenger.core.notifications.NotificationDispatcher
 import ru.daemonlord.messenger.core.notifications.NotificationIntentExtras
 import ru.daemonlord.messenger.domain.settings.model.AppThemeMode
 import ru.daemonlord.messenger.domain.settings.repository.ThemeRepository
@@ -26,6 +27,10 @@ import javax.inject.Inject
 class MainActivity : AppCompatActivity() {
     @Inject
     lateinit var themeRepository: ThemeRepository
+
+    @Inject
+    lateinit var notificationDispatcher: NotificationDispatcher
+
     private var pendingInviteToken by mutableStateOf<String?>(null)
     private var pendingVerifyEmailToken by mutableStateOf<String?>(null)
     private var pendingResetPasswordToken by mutableStateOf<String?>(null)
@@ -52,6 +57,7 @@ class MainActivity : AppCompatActivity() {
         val notificationPayload = intent.extractNotificationOpenPayload()
         pendingNotificationChatId = notificationPayload?.first
         pendingNotificationMessageId = notificationPayload?.second
+        notificationPayload?.first?.let(notificationDispatcher::clearChatNotifications)
         enableEdgeToEdge()
         setContent {
             MessengerTheme {
@@ -85,6 +91,7 @@ class MainActivity : AppCompatActivity() {
         if (notificationPayload != null) {
             pendingNotificationChatId = notificationPayload.first
             pendingNotificationMessageId = notificationPayload.second
+            notificationDispatcher.clearChatNotifications(notificationPayload.first)
         }
     }
 }

android/app/src/main/java/ru/daemonlord/messenger/core/notifications/NotificationDispatcher.kt

@@ -15,6 +15,8 @@ import kotlin.math.abs
 class NotificationDispatcher @Inject constructor(
     @ApplicationContext private val context: Context,
 ) {
+    private val chatStates = linkedMapOf<Long, ChatNotificationState>()
+
     fun showChatMessage(payload: ChatNotificationPayload) {
         NotificationChannels.ensureCreated(context)
         val channelId = if (payload.isMention) {
@@ -22,34 +24,126 @@ class NotificationDispatcher @Inject constructor(
         } else {
             NotificationChannels.CHANNEL_MESSAGES
         }
+
+        val state = synchronized(chatStates) {
+            val existing = chatStates[payload.chatId]
+            if (existing != null && payload.messageId != null && existing.lastMessageId == payload.messageId) {
+                return
+            }
+            val updated = (existing ?: ChatNotificationState(title = payload.title))
+                .copy(title = payload.title)
+                .appendMessage(payload.body, payload.messageId)
+            chatStates[payload.chatId] = updated
+            updated
+        }
+
         val openIntent = Intent(context, MainActivity::class.java)
             .putExtra(NotificationIntentExtras.EXTRA_CHAT_ID, payload.chatId)
             .putExtra(NotificationIntentExtras.EXTRA_MESSAGE_ID, payload.messageId ?: -1L)
             .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP or Intent.FLAG_ACTIVITY_CLEAR_TOP)
         val pendingIntent = PendingIntent.getActivity(
             context,
-            notificationId(payload.chatId, payload.messageId),
+            chatNotificationId(payload.chatId),
             openIntent,
             PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE,
         )
+
+        val contentText = when {
+            state.unreadCount <= 1 -> state.lines.firstOrNull() ?: payload.body
+            else -> "${state.unreadCount} new messages"
+        }
+        val inboxStyle = NotificationCompat.InboxStyle()
+            .setBigContentTitle(state.title)
+            .setSummaryText("${state.unreadCount} messages")
+        state.lines.reversed().forEach { inboxStyle.addLine(it) }
+
         val notification = NotificationCompat.Builder(context, channelId)
             .setSmallIcon(android.R.drawable.ic_dialog_info)
-            .setContentTitle(payload.title)
-            .setContentText(payload.body)
-            .setStyle(NotificationCompat.BigTextStyle().bigText(payload.body))
+            .setContentTitle(state.title)
+            .setContentText(contentText)
+            .setStyle(inboxStyle)
             .setAutoCancel(true)
             .setContentIntent(pendingIntent)
-            .setGroup("chat_${payload.chatId}")
+            .setGroup(GROUP_KEY_CHATS)
+            .setOnlyAlertOnce(false)
+            .setNumber(state.unreadCount)
             .setPriority(
                 if (payload.isMention) NotificationCompat.PRIORITY_HIGH else NotificationCompat.PRIORITY_DEFAULT
             )
             .build()
 
-        NotificationManagerCompat.from(context).notify(notificationId(payload.chatId, payload.messageId), notification)
+        val manager = NotificationManagerCompat.from(context)
+        manager.notify(chatNotificationId(payload.chatId), notification)
+        showSummaryNotification(manager)
     }
 
-    private fun notificationId(chatId: Long, messageId: Long?): Int {
-        val raw = (chatId * 1_000_003L) + (messageId ?: 0L)
-        return abs(raw.toInt())
+    fun clearChatNotifications(chatId: Long) {
+        val manager = NotificationManagerCompat.from(context)
+        synchronized(chatStates) {
+            chatStates.remove(chatId)
+        }
+        manager.cancel(chatNotificationId(chatId))
+        showSummaryNotification(manager)
+    }
+
+    private fun showSummaryNotification(manager: NotificationManagerCompat) {
+        val snapshot = synchronized(chatStates) { chatStates.values.toList() }
+        if (snapshot.isEmpty()) {
+            manager.cancel(SUMMARY_NOTIFICATION_ID)
+            return
+        }
+        val totalUnread = snapshot.sumOf { it.unreadCount }
+        val inboxStyle = NotificationCompat.InboxStyle()
+            .setBigContentTitle("Benya Messenger")
+            .setSummaryText("$totalUnread messages")
+        snapshot.take(6).forEach { state ->
+            val preview = state.lines.firstOrNull().orEmpty()
+            val line = if (preview.isBlank()) {
+                "${state.title} (${state.unreadCount})"
+            } else {
+                "${state.title}: $preview (${state.unreadCount})"
+            }
+            inboxStyle.addLine(line)
+        }
+        val summary = NotificationCompat.Builder(context, NotificationChannels.CHANNEL_MESSAGES)
+            .setSmallIcon(android.R.drawable.ic_dialog_info)
+            .setContentTitle("Benya Messenger")
+            .setContentText("$totalUnread new messages in ${snapshot.size} chats")
+            .setStyle(inboxStyle)
+            .setGroup(GROUP_KEY_CHATS)
+            .setGroupSummary(true)
+            .setAutoCancel(true)
+            .build()
+        manager.notify(SUMMARY_NOTIFICATION_ID, summary)
+    }
+
+    private fun chatNotificationId(chatId: Long): Int {
+        return abs((chatId * 1_000_003L).toInt())
+    }
+
+    private data class ChatNotificationState(
+        val title: String,
+        val unreadCount: Int = 0,
+        val lines: List<String> = emptyList(),
+        val lastMessageId: Long? = null,
+    ) {
+        fun appendMessage(body: String, messageId: Long?): ChatNotificationState {
+            val normalized = body.trim().ifBlank { "New message" }
+            val updatedLines = buildList {
+                add(normalized)
+                lines.forEach { add(it) }
+            }.distinct().take(MAX_LINES)
+            return copy(
+                unreadCount = unreadCount + 1,
+                lines = updatedLines,
+                lastMessageId = messageId ?: lastMessageId,
+            )
+        }
+    }
+
+    private companion object {
+        private const val GROUP_KEY_CHATS = "messenger_chats_group"
+        private const val SUMMARY_NOTIFICATION_ID = 0x4D53_4752 // "MSGR"
+        private const val MAX_LINES = 5
     }
 }

android/app/src/main/java/ru/daemonlord/messenger/ui/chat/ChatViewModel.kt

@@ -14,6 +14,7 @@ import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import ru.daemonlord.messenger.core.notifications.ActiveChatTracker
+import ru.daemonlord.messenger.core.notifications.NotificationDispatcher
 import ru.daemonlord.messenger.domain.chat.usecase.ObserveChatUseCase
 import ru.daemonlord.messenger.domain.chat.usecase.ObserveChatsUseCase
 import ru.daemonlord.messenger.domain.common.AppError
@@ -58,6 +59,7 @@ class ChatViewModel @Inject constructor(
     private val observeChatsUseCase: ObserveChatsUseCase,
     private val handleRealtimeEventsUseCase: HandleRealtimeEventsUseCase,
     private val activeChatTracker: ActiveChatTracker,
+    private val notificationDispatcher: NotificationDispatcher,
 ) : ViewModel() {
 
     private val chatId: Long = checkNotNull(savedStateHandle["chatId"])
@@ -69,6 +71,7 @@ class ChatViewModel @Inject constructor(
 
     init {
         activeChatTracker.setActiveChat(chatId)
+        notificationDispatcher.clearChatNotifications(chatId)
         handleRealtimeEventsUseCase.start()
         observeChatPermissions()
         observeMessages()