fix: improve chat auto-scroll logic, reduce socket timeout, and prevent duplicate message sends

lib/features/messaging/data/socket_service.dart

@@ -277,7 +277,7 @@ class SocketService {
     });
 
     return completer.future.timeout(
-      const Duration(seconds: 10),
+      const Duration(seconds: 5),
       onTimeout: () => null,
     );
   }

lib/features/messaging/presentation/providers/messaging_provider.dart

@@ -366,6 +366,7 @@ class MessagingNotifier extends StateNotifier<MessagingState> {
   Future<void> sendMessage(String conversationId, String content) async {
     final currentUserId = _currentUserId;
     if (currentUserId == null) return;
+    if (state.isSending) return; // Prevent double-send
 
     final tempId = 'temp_${DateTime.now().millisecondsSinceEpoch}';
     final now = DateTime.now().toIso8601String();
@@ -401,11 +402,9 @@ class MessagingNotifier extends StateNotifier<MessagingState> {
     );
 
     try {
-      // Send via socket so the backend broadcasts new_message to the other user.
-      // The REST endpoint does NOT emit socket events, so using REST here
-      // would prevent real-time delivery to the other participant.
       ChatMessage? realMessage;
 
+      // Try socket first (enables real-time delivery to other user)
       if (_socket.isConnected) {
         realMessage = await _socket.sendMessage(conversationId, {
           'content': content,
@@ -413,19 +412,35 @@ class MessagingNotifier extends StateNotifier<MessagingState> {
         });
       }
 
-      // Fallback to REST if socket send failed or not connected
-      realMessage ??= await _repository.sendMessage(
-        conversationId,
-        content: content,
-      );
+      // Fallback to REST if socket failed or not connected
+      if (realMessage == null) {
+        try {
+          realMessage = await _repository.sendMessage(
+            conversationId,
+            content: content,
+          );
+        } catch (restError) {
+          _log.e('REST send also failed', error: restError);
+          rethrow;
+        }
+      }
+
+      if (!mounted) return;
 
       final messagesAfterSend =
           List<ChatMessage>.from(state.messages[conversationId] ?? []);
       final tempIndex = messagesAfterSend.indexWhere((m) => m.id == tempId);
       if (tempIndex != -1) {
         messagesAfterSend[tempIndex] = realMessage;
+      } else {
+        // Temp message was removed (e.g., by a reload) — add the real one
+        messagesAfterSend.insert(0, realMessage);
       }
 
+      // Deduplicate — socket broadcast might have already added this message
+      final seen = <String>{};
+      messagesAfterSend.removeWhere((m) => !seen.add(m.id));
+
       final finalMessages =
           Map<String, List<ChatMessage>>.from(state.messages)
             ..[conversationId] = messagesAfterSend;
@@ -457,6 +472,8 @@ class MessagingNotifier extends StateNotifier<MessagingState> {
         isSending: false,
       );
     } catch (e) {
+      if (!mounted) return;
+
       final messagesAfterError =
           List<ChatMessage>.from(state.messages[conversationId] ?? []);
       messagesAfterError.removeWhere((m) => m.id == tempId);
@@ -465,7 +482,6 @@ class MessagingNotifier extends StateNotifier<MessagingState> {
           Map<String, List<ChatMessage>>.from(state.messages)
             ..[conversationId] = messagesAfterError;
 
-      // Show specific error for connection-required failures
       final errorMsg = e.toString().contains('connection')
           ? 'You must be connected to send messages'
           : 'Failed to send message';

lib/features/messaging/presentation/screens/chat_screen.dart

@@ -360,10 +360,15 @@ class _ChatScreenState extends ConsumerState<ChatScreen>
           orElse: () => null,
         );
 
+    // Auto-scroll only when a NEW message is added (not on any rebuild)
     if (messages.length > _previousMessageCount && _previousMessageCount > 0) {
-      WidgetsBinding.instance.addPostFrameCallback((_) {
-        _scrollToBottom(animated: true);
-      });
+      // Only scroll if user is near the bottom (not scrolled up reading history)
+      if (_scrollController.hasClients &&
+          _scrollController.position.pixels < 150) {
+        WidgetsBinding.instance.addPostFrameCallback((_) {
+          if (mounted) _scrollToBottom(animated: true);
+        });
+      }
     }
     _previousMessageCount = messages.length;