android: mark messages read when visible and sync unread across devices

android/CHANGELOG.md

@@ -706,3 +706,11 @@
   - read status is now acknowledged by the latest visible message id in chat (not only latest incoming),
   - delivery status still uses latest incoming message.
 - This removes cases where unread badge reappears after chat list refresh because the previous read ack used an outdated incoming id.
+
+### Step 107 - Read-on-visible + cross-device unread sync
+- Implemented read acknowledgement from actual visible messages in `ChatScreen`:
+  - tracks visible `LazyColumn` rows and sends read up to max visible incoming message id.
+  - unread now drops as messages appear on screen while scrolling.
+- Improved cross-device sync (web <-> android):
+  - `message_read` realtime event now parses `user_id` and `last_read_message_id`.
+  - on `message_read`, Android refreshes chat snapshot from backend to keep unread counters aligned across devices.

android/app/src/main/java/ru/daemonlord/messenger/data/realtime/RealtimeEventParser.kt

@@ -102,7 +102,12 @@ class RealtimeEventParser @Inject constructor(
             "message_read" -> {
                 val chatId = payload["chat_id"].longOrNull() ?: return RealtimeEvent.Ignored
                 val messageId = payload["message_id"].longOrNull() ?: return RealtimeEvent.Ignored
-                RealtimeEvent.MessageRead(chatId = chatId, messageId = messageId)
+                RealtimeEvent.MessageRead(
+                    chatId = chatId,
+                    messageId = messageId,
+                    userId = payload["user_id"].longOrNull(),
+                    lastReadMessageId = payload["last_read_message_id"].longOrNull(),
+                )
             }
 
             "typing_start" -> {

android/app/src/main/java/ru/daemonlord/messenger/domain/realtime/model/RealtimeEvent.kt

@@ -52,6 +52,8 @@ sealed interface RealtimeEvent {
     data class MessageRead(
         val chatId: Long,
         val messageId: Long,
+        val userId: Long?,
+        val lastReadMessageId: Long?,
     ) : RealtimeEvent
 
     data class TypingStart(

android/app/src/main/java/ru/daemonlord/messenger/domain/realtime/usecase/HandleRealtimeEventsUseCase.kt

@@ -168,6 +168,7 @@ class HandleRealtimeEventsUseCase @Inject constructor(
                             messageId = event.messageId,
                             status = "read",
                         )
+                        chatRepository.refreshChat(chatId = event.chatId)
                     }
 
                     is RealtimeEvent.TypingStart -> Unit

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

@@ -56,6 +56,7 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalConfiguration
@@ -91,6 +92,7 @@ import androidx.compose.material.icons.filled.RadioButtonChecked
 import androidx.compose.material.icons.filled.RadioButtonUnchecked
 import coil.compose.AsyncImage
 import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.distinctUntilChanged
 import ru.daemonlord.messenger.core.audio.AppAudioFocusCoordinator
 import ru.daemonlord.messenger.domain.message.model.MessageItem
 import ru.daemonlord.messenger.ui.chat.voice.VoiceRecorder
@@ -205,6 +207,7 @@ fun ChatRoute(
         },
         onInlineSearchChanged = viewModel::onInlineSearchChanged,
         onJumpInlineSearch = viewModel::jumpInlineSearch,
+        onVisibleIncomingMessageId = viewModel::onVisibleIncomingMessageId,
     )
 }
 
@@ -236,6 +239,7 @@ fun ChatScreen(
     onVoiceRecordSend: () -> Unit,
     onInlineSearchChanged: (String) -> Unit,
     onJumpInlineSearch: (Boolean) -> Unit,
+    onVisibleIncomingMessageId: (Long?) -> Unit,
 ) {
     val listState = rememberLazyListState()
     val allImageUrls = remember(state.messages) {
@@ -270,6 +274,18 @@ fun ChatScreen(
             listState.animateScrollToItem(index = index)
         }
     }
+    LaunchedEffect(listState, state.messages) {
+        snapshotFlow {
+            listState.layoutInfo.visibleItemsInfo
+                .mapNotNull { info -> state.messages.getOrNull(info.index) }
+                .filter { !it.isOutgoing }
+                .maxOfOrNull { it.id }
+        }
+            .distinctUntilChanged()
+            .collectLatest { visibleIncomingMaxId ->
+                onVisibleIncomingMessageId(visibleIncomingMaxId)
+            }
+    }
     Column(
         modifier = Modifier
             .fillMaxSize()

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

@@ -189,6 +189,17 @@ class ChatViewModel @Inject constructor(
         )
     }
 
+    fun onVisibleIncomingMessageId(messageId: Long?) {
+        val visibleIncomingId = messageId ?: return
+        if ((lastReadMessageId ?: 0L) >= visibleIncomingId) {
+            return
+        }
+        lastReadMessageId = visibleIncomingId
+        viewModelScope.launch {
+            markMessageReadUseCase(chatId = chatId, messageId = visibleIncomingId)
+        }
+    }
+
     fun onSelectMessage(message: MessageItem?) {
         if (message == null) {
             onClearSelection()
@@ -654,11 +665,8 @@ class ChatViewModel @Inject constructor(
                 markMessageDeliveredUseCase(chatId = chatId, messageId = latestIncoming.id)
             }
         }
-        if (lastReadMessageId != latestVisible.id) {
+        if ((lastReadMessageId ?: 0L) < latestVisible.id) {
             lastReadMessageId = latestVisible.id
-            viewModelScope.launch {
-                markMessageReadUseCase(chatId = chatId, messageId = latestVisible.id)
-            }
         }
     }