fix: Improve message key handling and enhance contact tile key uniqueness

lib/screens/channel_chat_screen.dart

@@ -377,6 +377,7 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
                   final reversedMessages = messages.reversed.toList();
                   final itemCount =
                       reversedMessages.length + (_isLoadingOlder ? 1 : 0);
+                    final keyedMessageIds = <String>{};
 
                   // Auto-scroll to bottom if user is already at bottom
                   WidgetsBinding.instance.addPostFrameCallback((_) {
@@ -413,14 +414,20 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
                             }
                             final messageIndex = index;
                             final message = reversedMessages[messageIndex];
-                            if (!_messageKeys.containsKey(message.messageId)) {
+                            final shouldAttachMessageKey = keyedMessageIds.add(
+                              message.messageId,
+                            );
+                            if (shouldAttachMessageKey &&
+                                !_messageKeys.containsKey(message.messageId)) {
                               _messageKeys[message.messageId] = GlobalKey();
                             }
                             final isUnreadAnchor =
                                 _unreadDividerMessageId != null &&
                                 message.messageId == _unreadDividerMessageId;
                             return Container(
-                              key: _messageKeys[message.messageId]!,
+                              key: shouldAttachMessageKey
+                                  ? _messageKeys[message.messageId]
+                                  : null,
                               child: Builder(
                                 builder: (context) {
                                   final textScale = context

lib/screens/channels_screen.dart

@@ -394,7 +394,7 @@ class _ChannelsScreenState extends State<ChannelsScreen> {
     }
 
     return Card(
-      key: ValueKey('channel_${channel.index}'),
+      key: ValueKey('${channel.index}_${channel.pskHex}_${channel.name}'),
       margin: const EdgeInsets.only(bottom: 12),
       child: GestureDetector(
         onSecondaryTapUp: PlatformInfo.isDesktop

lib/screens/chat_screen.dart

@@ -451,6 +451,7 @@ class _ChatScreenState extends State<ChatScreen> {
   ) {
     // Reverse messages so newest appear at bottom with reverse: true
     final reversedMessages = messages.reversed.toList();
+    var unreadAnchorKeyAssigned = false;
     final itemCount = reversedMessages.length + (_isLoadingOlder ? 1 : 0);
 
     // Auto-scroll to bottom if user is already at bottom
@@ -525,7 +526,11 @@ class _ChatScreenState extends State<ChatScreen> {
                       children: [const UnreadDivider(), bubble],
                     )
                   : bubble;
-              if (identical(message, _pendingUnreadScrollTarget)) {
+              final shouldAttachUnreadScrollKey =
+                  !unreadAnchorKeyAssigned &&
+                  identical(message, _pendingUnreadScrollTarget);
+              if (shouldAttachUnreadScrollKey) {
+                unreadAnchorKeyAssigned = true;
                 return KeyedSubtree(key: _unreadScrollKey, child: child);
               }
               return child;

lib/screens/contacts_screen.dart

@@ -827,6 +827,7 @@ class _ContactsScreenState extends State<ContactsScreen> {
                         contact,
                       );
                       return _ContactTile(
+                        key: ValueKey(contact.publicKeyHex),
                         contact: contact,
                         lastSeen: _resolveLastSeen(contact),
                         unreadCount: unreadCount,
@@ -1495,6 +1496,7 @@ class _ContactTile extends StatelessWidget {
   final VoidCallback onLongPress;
 
   const _ContactTile({
+    super.key,
     required this.contact,
     required this.lastSeen,
     required this.unreadCount,