Add boilerplate code option for handling cross device dismissal

app/src/main/AndroidManifest.xml

@@ -182,7 +182,8 @@
 
         </provider>
 
-        <receiver android:name="com.google.android.samples.socialite.ReplyReceiver" />
+        <receiver android:name=".ReplyReceiver" />
+        <receiver android:name=".fcm.MessagingBroadcastReceiver" />
 
         <!-- Trigger Google Play services to install the backported photo picker module.
          Refer https://developer.android.com/training/data-storage/shared/photopicker#device-availability -->

app/src/main/java/com/google/android/samples/socialite/MainActivity.kt

@@ -70,10 +70,12 @@ class MainActivity : ComponentActivity() {
                 if (!task.isSuccessful) {
                     Log.w("FCM", "Fetching FCM registration token failed", task.exception)
                     return@OnCompleteListener
-                } // Get new FCM registration token
+                } // Get new FCM registration token.
+                //  A unique key for this specific app instance and used for sending messages to
+                //  this specific app instance.
                 val token = task.result
                 // Log token, for testing purposes only.
-                // Log.d("FCM", "FCM message token $token")
+                // Log.d(MainActivity::class::simpleName.toString(), "FCM message token $token")
             },
         )
     }

app/src/main/java/com/google/android/samples/socialite/fcm/MessagingBroadcastReceiver.kt

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2026 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.samples.socialite.fcm
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.util.Log
+import com.google.android.samples.socialite.repository.NOTIFICATION_DISMISSED
+import com.google.android.samples.socialite.repository.NOTIFICATION_ID
+
+/**
+ * Receiver for handling notification dismissals set via
+ * Notification$Builder#setDeleteIntent(Intent).
+ *
+ * In a multi-device world (mobile, large screen), notification
+ * dismissal on one client should propagate to all other clients
+ * to dismiss the notification.
+ */
+class MessagingBroadcastReceiver : BroadcastReceiver() {
+
+    override fun onReceive(context: Context?, intent: Intent?) {
+        if (intent?.action == NOTIFICATION_DISMISSED) {
+            intent.extras?.getInt(NOTIFICATION_ID)?.let {
+                Log.d(
+                    MessagingBroadcastReceiver::class::simpleName.toString(),
+                    "Dismissing notification w/ ID $it",
+                )
+                // Here is where your app server is notified of a notification dismissal.
+                // The app server can then talk to FCM backend to route a message to
+                // all clients to dismiss/cancel the notification.
+                // See sending messages to devices in
+                // https://firebase.google.com/docs/cloud-messaging/server-environment
+            }
+        }
+    }
+}

app/src/main/java/com/google/android/samples/socialite/fcm/MessagingService.kt

@@ -16,9 +16,17 @@
 
 package com.google.android.samples.socialite.fcm
 
+import android.app.NotificationManager
+import android.util.Log
+import androidx.core.content.getSystemService
+import com.google.android.samples.socialite.repository.NOTIFICATION_ACTION
+import com.google.android.samples.socialite.repository.NOTIFICATION_ID
 import com.google.firebase.messaging.FirebaseMessagingService
 import com.google.firebase.messaging.RemoteMessage
 
+/**
+ * Service for handling Firebase Cloud Messaging.
+ */
 class MessagingService : FirebaseMessagingService() {
 
     override fun onNewToken(token: String) {
@@ -30,15 +38,43 @@ class MessagingService : FirebaseMessagingService() {
     override fun onMessageReceived(remoteMessage: RemoteMessage) {
         super.onMessageReceived(remoteMessage)
 
+        val notificationManager: NotificationManager =
+            this.getSystemService() ?: throw IllegalStateException()
+
         // Handle data payload
         if (remoteMessage.data.isNotEmpty()) {
-            // Log.d("FCM", "Message data payload: ${remoteMessage.data}")
-        }
+            // If payload is relevant to dismissal, cancel the notification.
+            // For the device that triggered this dismissal, it is noop but
+            // for other devices that belongs to the user, the notification will be
+            // removed.
+            // Note that the below is just an example of a payload that can be
+            // relevant to dismissal.
+            if (remoteMessage.data[NOTIFICATION_ACTION] == "DISMISSAL" &&
+                remoteMessage.data[NOTIFICATION_ID] != null
+            ) {
+                Log.d(
+                    MessagingService::class::simpleName.toString(),
+                    "Message data payload: ${remoteMessage.data}",
+                )
+                remoteMessage.data[NOTIFICATION_ID]?.toIntOrNull()
+                    ?.let { notificationManager.cancel(it) }
+            }
 
-        // Handle notification payload
-        remoteMessage.notification?.let {
-            // Log.d("FCM", "Message Notification Body: ${it.body}")
-            // Trigger local notification here
+            // Handle notification payload
+            remoteMessage.notification?.let {
+                // Log.d("FCM", "Message Notification Body: ${it.body}")
+                // Trigger local notification here
+                // This notif should have unique ID as well.
+            }
         }
     }
+
+    /**
+     * It is good practice to handle deleted messages in FCM
+     * See https://firebase.google.com/docs/cloud-messaging/android/receive-messages#override-on-deleted-messages
+     */
+    override fun onDeletedMessages() {
+        super.onDeletedMessages()
+        // Up to the developer on how to handle this and surface this behavior to the end user.
+    }
 }

app/src/main/java/com/google/android/samples/socialite/repository/NotificationHelper.kt

@@ -41,6 +41,7 @@ import com.google.android.samples.socialite.BubbleActivity
 import com.google.android.samples.socialite.MainActivity
 import com.google.android.samples.socialite.R
 import com.google.android.samples.socialite.ReplyReceiver
+import com.google.android.samples.socialite.fcm.MessagingBroadcastReceiver
 import com.google.android.samples.socialite.model.Contact
 import com.google.android.samples.socialite.model.Message
 import dagger.hilt.android.qualifiers.ApplicationContext
@@ -55,6 +56,10 @@ enum class PushReason {
     OutgoingMessage,
 }
 
+const val NOTIFICATION_ACTION = "NOTIFICATION_ACTION"
+const val NOTIFICATION_DISMISSED = "NOTIFICATION_DISMISSED"
+const val NOTIFICATION_ID = "NOTIFICATION_ID"
+
 /**
  * Handles all operations related to [Notification].
  */
@@ -197,6 +202,9 @@ class NotificationHelper @Inject constructor(@ApplicationContext context: Contex
             }
         }
 
+        val lastMessage = messages.last()
+        val notificationId = contact.id.toInt() + lastMessage.id.toInt()
+
         val builder = NotificationCompat.Builder(appContext, CHANNEL_NEW_MESSAGES)
             // A notification can be shown as a bubble by calling setBubbleMetadata()
             .setBubbleMetadata(
@@ -268,12 +276,25 @@ class NotificationHelper @Inject constructor(@ApplicationContext context: Contex
             // Let's add some more content to the notification in case it falls back to a normal
             // notification.
             .setStyle(messagingStyle)
-            .setWhen(messages.last().timestamp)
+            .setWhen(lastMessage.timestamp)
+            .setDeleteIntent(createNotificationDismissIntent(notificationId))
         // Don't sound/vibrate if an update to an existing notification.
         if (update) {
             builder.setOnlyAlertOnce(true)
         }
-        notificationManager.notify(contact.id.toInt(), builder.build())
+        notificationManager.notify(notificationId, builder.build())
+    }
+
+    private fun createNotificationDismissIntent(notificationId: Int): PendingIntent {
+        val deleteIntent = Intent(appContext, MessagingBroadcastReceiver::class.java)
+        deleteIntent.action = NOTIFICATION_DISMISSED
+        deleteIntent.putExtra(NOTIFICATION_ID, notificationId)
+        return PendingIntent.getBroadcast(
+            appContext,
+            notificationId,
+            deleteIntent,
+            flagUpdateCurrent(mutable = false),
+        )
     }
 
     fun dismissNotification(chatId: Long) {