feat(chat): add "Mark as Unread" action and unread messages divider

- Add "Mark as Unread" option to message context menu in both
  contact and channel chats
- Show "New messages" divider line between read and unread messages
- Add setContactUnreadCount/setChannelUnreadCount methods to connector

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/connector/meshcore_connector.dart

@@ -658,6 +658,27 @@ class MeshCoreConnector extends ChangeNotifier {
     }
   }
 
+  void setContactUnreadCount(String contactKeyHex, int count) {
+    _contactUnreadCount[contactKeyHex] = count;
+    _unreadStore.saveContactUnreadCount(
+      Map<String, int>.from(_contactUnreadCount),
+    );
+    notifyListeners();
+  }
+
+  void setChannelUnreadCount(int channelIndex, int count) {
+    final channel = _findChannelByIndex(channelIndex);
+    if (channel != null) {
+      channel.unreadCount = count;
+      unawaited(
+        _channelStore.saveChannels(
+          _channels.isNotEmpty ? _channels : _cachedChannels,
+        ),
+      );
+      notifyListeners();
+    }
+  }
+
   void markChannelRead(int channelIndex) {
     final channel = _findChannelByIndex(channelIndex);
     if (channel != null && channel.unreadCount > 0) {

lib/l10n/app_en.arb

@@ -824,6 +824,8 @@
       }
     }
   },
+  "chat_markAsUnread": "Mark as Unread",
+  "chat_newMessages": "New messages",
   "chat_openLink": "Open Link?",
   "chat_openLinkConfirmation": "Do you want to open this link in your browser?",
   "chat_open": "Open",

lib/l10n/app_localizations_en.dart

@@ -1527,6 +1527,12 @@ class AppLocalizationsEn extends AppLocalizations {
     return 'Unread: $count';
   }
 
+  @override
+  String get chat_markAsUnread => 'Mark as Unread';
+
+  @override
+  String get chat_newMessages => 'New messages';
+
   @override
   String get chat_openLink => 'Open Link?';
 

lib/screens/channel_chat_screen.dart

@@ -32,6 +32,7 @@ import '../widgets/message_translation_button.dart';
 import '../widgets/message_status_icon.dart';
 import '../widgets/radio_stats_entry.dart';
 import '../widgets/translated_message_content.dart';
+import '../widgets/unread_divider.dart';
 import 'channel_message_path_screen.dart';
 import 'map_screen.dart';
 
@@ -60,12 +61,14 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
   MeshCoreConnector? _connector;
   DateTime? _lastChannelSendAt;
   bool _channelSkipNextBottomSnap = false;
+  String? _unreadDividerMessageId;
 
   @override
   void initState() {
     super.initState();
     _textFieldFocusNode.addListener(_onTextFieldFocusChange);
     _scrollController.onScrollNearTop = _loadOlderMessages;
+    _scrollController.showJumpToBottom.addListener(_clearDividerAtBottom);
     SchedulerBinding.instance.addPostFrameCallback((_) {
       if (!mounted) return;
       final connector = context.read<MeshCoreConnector>();
@@ -74,12 +77,15 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
       final unread = widget.initialUnreadCount;
       final messages = connector.getChannelMessages(widget.channel);
       ChannelMessage? anchor;
-      if (settings.jumpToOldestUnread && unread > 0) {
+      if (unread > 0) {
         anchor = _findOldestUnreadChannelAnchor(messages, unread);
       }
+      setState(() {
+        if (anchor != null) _unreadDividerMessageId = anchor.messageId;
+      });
       connector.setActiveChannel(idx);
       _connector = connector;
-      if (anchor != null) {
+      if (anchor != null && settings.jumpToOldestUnread) {
         _channelSkipNextBottomSnap = true;
         WidgetsBinding.instance.addPostFrameCallback((_) {
           if (!mounted) return;
@@ -112,6 +118,13 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
     return oldest;
   }
 
+  void _clearDividerAtBottom() {
+    if (!_scrollController.showJumpToBottom.value &&
+        _unreadDividerMessageId != null) {
+      setState(() => _unreadDividerMessageId = null);
+    }
+  }
+
   void _onTextFieldFocusChange() {
     if (_textFieldFocusNode.hasFocus && mounted) {
       _scrollController.handleKeyboardOpen();
@@ -133,6 +146,7 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
   @override
   void dispose() {
     _connector?.setActiveChannel(null);
+    _scrollController.showJumpToBottom.removeListener(_clearDividerAtBottom);
     _textFieldFocusNode.removeListener(_onTextFieldFocusChange);
     _textFieldFocusNode.dispose();
     _textController.dispose();
@@ -331,6 +345,10 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
                             if (!_messageKeys.containsKey(message.messageId)) {
                               _messageKeys[message.messageId] = GlobalKey();
                             }
+                            final isUnreadAnchor =
+                                _unreadDividerMessageId != null &&
+                                    message.messageId ==
+                                        _unreadDividerMessageId;
                             return Container(
                               key: _messageKeys[message.messageId]!,
                               child: Builder(
@@ -339,10 +357,20 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
                                       .select<ChatTextScaleService, double>(
                                         (service) => service.scale,
                                       );
-                                  return _buildMessageBubble(
+                                  final bubble = _buildMessageBubble(
                                     message,
                                     textScale,
                                   );
+                                  if (isUnreadAnchor) {
+                                    return Column(
+                                      mainAxisSize: MainAxisSize.min,
+                                      children: [
+                                        const UnreadDivider(),
+                                        bubble,
+                                      ],
+                                    );
+                                  }
+                                  return bubble;
                                 },
                               ),
                             );
@@ -362,6 +390,19 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
     );
   }
 
+  void _markAsUnread(ChannelMessage message) {
+    final connector = context.read<MeshCoreConnector>();
+    final messages = connector.getChannelMessages(widget.channel);
+    var count = 0;
+    var found = false;
+    for (final m in messages) {
+      if (m.messageId == message.messageId) found = true;
+      if (found && !m.isOutgoing) count++;
+    }
+    connector.setChannelUnreadCount(widget.channel.index, count);
+    Navigator.pop(context);
+  }
+
   Widget _buildMessageBubble(ChannelMessage message, double textScale) {
     final settingsService = context.watch<AppSettingsService>();
     final enableTracing = settingsService.settings.enableMessageTracing;
@@ -1288,6 +1329,15 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
                 _copyMessageText(message.text);
               },
             ),
+            if (!message.isOutgoing)
+              ListTile(
+                leading: const Icon(Icons.mark_chat_unread_outlined),
+                title: Text(context.l10n.chat_markAsUnread),
+                onTap: () {
+                  Navigator.pop(sheetContext);
+                  _markAsUnread(message);
+                },
+              ),
             ListTile(
               leading: const Icon(Icons.delete_outline),
               title: Text(context.l10n.common_delete),

lib/screens/chat_screen.dart

@@ -44,6 +44,7 @@ import '../widgets/translated_message_content.dart';
 import '../utils/app_logger.dart';
 import '../l10n/l10n.dart';
 import '../helpers/snack_bar_builder.dart';
+import '../widgets/unread_divider.dart';
 import 'telemetry_screen.dart';
 
 class ChatScreen extends StatefulWidget {
@@ -68,6 +69,7 @@ class _ChatScreenState extends State<ChatScreen> {
   bool _isLoadingOlder = false;
   MeshCoreConnector? _connector;
   Message? _pendingUnreadScrollTarget;
+  String? _unreadDividerMessageId;
   DateTime? _lastTextSendAt;
 
   @override
@@ -75,6 +77,7 @@ class _ChatScreenState extends State<ChatScreen> {
     super.initState();
     _textFieldFocusNode.addListener(_onTextFieldFocusChange);
     _scrollController.onScrollNearTop = _loadOlderMessages;
+    _scrollController.showJumpToBottom.addListener(_clearDividerAtBottom);
     SchedulerBinding.instance.addPostFrameCallback((_) {
       if (!mounted) return;
       final connector = context.read<MeshCoreConnector>();
@@ -83,13 +86,18 @@ class _ChatScreenState extends State<ChatScreen> {
       final unread = widget.initialUnreadCount;
       final messages = connector.getMessages(widget.contact);
       Message? anchor;
-      if (settings.jumpToOldestUnread && unread > 0) {
+      if (unread > 0) {
         anchor = _findOldestUnreadAnchor(messages, unread);
       }
+      setState(() {
+        if (anchor != null) _unreadDividerMessageId = anchor.messageId;
+        if (anchor != null && settings.jumpToOldestUnread) {
+          _pendingUnreadScrollTarget = anchor;
+        }
+      });
       connector.setActiveContact(keyHex);
       _connector = connector;
-      if (anchor != null) {
-        setState(() => _pendingUnreadScrollTarget = anchor);
+      if (anchor != null && settings.jumpToOldestUnread) {
         WidgetsBinding.instance.addPostFrameCallback((_) {
           if (!mounted) return;
           _scrollController.jumpToEstimatedOffset(
@@ -128,6 +136,13 @@ class _ChatScreenState extends State<ChatScreen> {
     return oldest;
   }
 
+  void _clearDividerAtBottom() {
+    if (!_scrollController.showJumpToBottom.value &&
+        _unreadDividerMessageId != null) {
+      setState(() => _unreadDividerMessageId = null);
+    }
+  }
+
   void _onTextFieldFocusChange() {
     if (_textFieldFocusNode.hasFocus && mounted) {
       _scrollController.handleKeyboardOpen();
@@ -149,6 +164,7 @@ class _ChatScreenState extends State<ChatScreen> {
   @override
   void dispose() {
     _connector?.setActiveContact(null);
+    _scrollController.showJumpToBottom.removeListener(_clearDividerAtBottom);
     _textFieldFocusNode.removeListener(_onTextFieldFocusChange);
     _textFieldFocusNode.dispose();
     _textController.dispose();
@@ -498,10 +514,18 @@ class _ChatScreenState extends State<ChatScreen> {
                 onRetryReaction: (msg, emoji) =>
                     _sendReaction(msg, contact, emoji),
               );
+              final isUnreadAnchor = _unreadDividerMessageId != null &&
+                  message.messageId == _unreadDividerMessageId;
+              final child = isUnreadAnchor
+                  ? Column(
+                      mainAxisSize: MainAxisSize.min,
+                      children: [const UnreadDivider(), bubble],
+                    )
+                  : bubble;
               if (identical(message, _pendingUnreadScrollTarget)) {
-                return KeyedSubtree(key: _unreadScrollKey, child: bubble);
+                return KeyedSubtree(key: _unreadScrollKey, child: child);
               }
-              return bubble;
+              return child;
             },
           );
         },
@@ -509,6 +533,19 @@ class _ChatScreenState extends State<ChatScreen> {
     );
   }
 
+  void _markAsUnread(Message message) {
+    final connector = context.read<MeshCoreConnector>();
+    final messages = connector.getMessages(widget.contact);
+    var count = 0;
+    var found = false;
+    for (final m in messages) {
+      if (m.messageId == message.messageId) found = true;
+      if (found && !m.isOutgoing && !m.isCli) count++;
+    }
+    connector.setContactUnreadCount(widget.contact.publicKeyHex, count);
+    Navigator.pop(context);
+  }
+
   Widget _buildInputBar(MeshCoreConnector connector) {
     final maxBytes = maxContactMessageBytes();
     final colorScheme = Theme.of(context).colorScheme;
@@ -1465,6 +1502,15 @@ class _ChatScreenState extends State<ChatScreen> {
                 _copyMessageText(message.text);
               },
             ),
+            if (!message.isOutgoing)
+              ListTile(
+                leading: const Icon(Icons.mark_chat_unread_outlined),
+                title: Text(context.l10n.chat_markAsUnread),
+                onTap: () {
+                  Navigator.pop(sheetContext);
+                  _markAsUnread(message);
+                },
+              ),
             ListTile(
               leading: const Icon(Icons.delete_outline),
               title: Text(context.l10n.common_delete),

lib/widgets/unread_divider.dart

@@ -0,0 +1,32 @@
+import 'package:flutter/material.dart';
+
+import '../l10n/l10n.dart';
+
+class UnreadDivider extends StatelessWidget {
+  const UnreadDivider({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final color = Theme.of(context).colorScheme.primary;
+    return Padding(
+      padding: const EdgeInsets.symmetric(vertical: 8),
+      child: Row(
+        children: [
+          Expanded(child: Divider(color: color)),
+          Padding(
+            padding: const EdgeInsets.symmetric(horizontal: 8),
+            child: Text(
+              context.l10n.chat_newMessages,
+              style: TextStyle(
+                color: color,
+                fontSize: 12,
+                fontWeight: FontWeight.w500,
+              ),
+            ),
+          ),
+          Expanded(child: Divider(color: color)),
+        ],
+      ),
+    );
+  }
+}