fix(chat): fix jump-to-oldest-unread scroll not reaching target message

- Pass initialUnreadCount to chat screens before markRead clears it
- Use two-phase scroll: jumpTo estimated offset to build lazy items,
  then ensureVisible for precise positioning
- Await ensureVisible before clearing scroll guard to prevent
  scrollToBottomIfAtBottom from overriding the animation

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

lib/helpers/chat_scroll_controller.dart

@@ -49,6 +49,25 @@ class ChatScrollController extends ScrollController {
     }
   }
 
+  /// Jumps toward an off-screen message so that lazy ListView.builder builds
+  /// items near it. Only visible + cacheExtent items have real heights, so we
+  /// use proportion of maxScrollExtent (itself an estimate from built items'
+  /// avg height). Call [onJumped] on the next frame to ensureVisible/scroll
+  /// to the exact target.
+  void jumpToEstimatedOffset({
+    required int unreadCount,
+    required int totalMessages,
+    required VoidCallback onJumped,
+  }) {
+    if (!hasClients || totalMessages == 0) return;
+    final maxExtent = position.maxScrollExtent;
+    final jumpOffset = maxExtent * (unreadCount / totalMessages);
+    if (jumpOffset > 100) {
+      jumpTo(jumpOffset);
+    }
+    WidgetsBinding.instance.addPostFrameCallback((_) => onJumped());
+  }
+
   void scrollToBottomIfAtBottom() {
     // Only scroll if jump button is NOT showing (i.e., already at bottom)
     if (!showJumpToBottom.value && hasClients && position.maxScrollExtent > 0) {

lib/screens/channel_chat_screen.dart

@@ -37,8 +37,13 @@ import 'map_screen.dart';
 
 class ChannelChatScreen extends StatefulWidget {
   final Channel channel;
+  final int initialUnreadCount;
 
-  const ChannelChatScreen({super.key, required this.channel});
+  const ChannelChatScreen({
+    super.key,
+    required this.channel,
+    this.initialUnreadCount = 0,
+  });
 
   @override
   State<ChannelChatScreen> createState() => _ChannelChatScreenState();
@@ -66,13 +71,11 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
       final connector = context.read<MeshCoreConnector>();
       final settings = context.read<AppSettingsService>().settings;
       final idx = widget.channel.index;
-      final unread = connector.getUnreadCountForChannelIndex(idx);
+      final unread = widget.initialUnreadCount;
+      final messages = connector.getChannelMessages(widget.channel);
       ChannelMessage? anchor;
       if (settings.jumpToOldestUnread && unread > 0) {
-        anchor = _findOldestUnreadChannelAnchor(
-          connector.getChannelMessages(widget.channel),
-          unread,
-        );
+        anchor = _findOldestUnreadChannelAnchor(messages, unread);
       }
       connector.setActiveChannel(idx);
       _connector = connector;
@@ -80,7 +83,14 @@ class _ChannelChatScreenState extends State<ChannelChatScreen> {
         _channelSkipNextBottomSnap = true;
         WidgetsBinding.instance.addPostFrameCallback((_) {
           if (!mounted) return;
-          _scrollToMessage(anchor!.messageId);
+          _scrollController.jumpToEstimatedOffset(
+            unreadCount: unread,
+            totalMessages: messages.length,
+            onJumped: () {
+              if (!mounted) return;
+              _scrollToMessage(anchor!.messageId);
+            },
+          );
         });
       }
     });

lib/screens/channels_screen.dart

@@ -492,13 +492,18 @@ class _ChannelsScreenState extends State<ChannelsScreen>
             ],
           ),
           onTap: () async {
+            final unread =
+                connector.getUnreadCountForChannelIndex(channel.index);
             connector.markChannelRead(channel.index);
             await Future.delayed(const Duration(milliseconds: 50));
             if (context.mounted) {
               Navigator.push(
                 context,
                 MaterialPageRoute(
-                  builder: (context) => ChannelChatScreen(channel: channel),
+                  builder: (context) => ChannelChatScreen(
+                    channel: channel,
+                    initialUnreadCount: unread,
+                  ),
                 ),
               );
             }

lib/screens/chat_screen.dart

@@ -48,8 +48,13 @@ import 'telemetry_screen.dart';
 
 class ChatScreen extends StatefulWidget {
   final Contact contact;
+  final int initialUnreadCount;
 
-  const ChatScreen({super.key, required this.contact});
+  const ChatScreen({
+    super.key,
+    required this.contact,
+    this.initialUnreadCount = 0,
+  });
 
   @override
   State<ChatScreen> createState() => _ChatScreenState();
@@ -75,13 +80,11 @@ class _ChatScreenState extends State<ChatScreen> {
       final connector = context.read<MeshCoreConnector>();
       final settings = context.read<AppSettingsService>().settings;
       final keyHex = widget.contact.publicKeyHex;
-      final unread = connector.getUnreadCountForContactKey(keyHex);
+      final unread = widget.initialUnreadCount;
+      final messages = connector.getMessages(widget.contact);
       Message? anchor;
       if (settings.jumpToOldestUnread && unread > 0) {
-        anchor = _findOldestUnreadAnchor(
-          connector.getMessages(widget.contact),
-          unread,
-        );
+        anchor = _findOldestUnreadAnchor(messages, unread);
       }
       connector.setActiveContact(keyHex);
       _connector = connector;
@@ -89,15 +92,24 @@ class _ChatScreenState extends State<ChatScreen> {
         setState(() => _pendingUnreadScrollTarget = anchor);
         WidgetsBinding.instance.addPostFrameCallback((_) {
           if (!mounted) return;
-          final ctx = _unreadScrollKey.currentContext;
-          if (ctx != null) {
-            Scrollable.ensureVisible(
-              ctx,
-              duration: const Duration(milliseconds: 350),
-              alignment: 0.15,
-            );
-          }
-          setState(() => _pendingUnreadScrollTarget = null);
+          _scrollController.jumpToEstimatedOffset(
+            unreadCount: unread,
+            totalMessages: messages.length,
+            onJumped: () async {
+              if (!mounted) return;
+              final ctx = _unreadScrollKey.currentContext;
+              if (ctx != null) {
+                await Scrollable.ensureVisible(
+                  ctx,
+                  duration: const Duration(milliseconds: 350),
+                  alignment: 0.15,
+                );
+              }
+              if (mounted) {
+                setState(() => _pendingUnreadScrollTarget = null);
+              }
+            },
+          );
         });
       }
     });
@@ -1305,11 +1317,18 @@ class _ChatScreenState extends State<ChatScreen> {
   }
 
   void _openChat(BuildContext context, Contact contact) {
-    // Check if this is a repeater
-    context.read<MeshCoreConnector>().markContactRead(contact.publicKeyHex);
+    final connector = context.read<MeshCoreConnector>();
+    final unread =
+        connector.getUnreadCountForContactKey(contact.publicKeyHex);
+    connector.markContactRead(contact.publicKeyHex);
     Navigator.push(
       context,
-      MaterialPageRoute(builder: (context) => ChatScreen(contact: contact)),
+      MaterialPageRoute(
+        builder: (context) => ChatScreen(
+          contact: contact,
+          initialUnreadCount: unread,
+        ),
+      ),
     );
   }
 

lib/screens/contacts_screen.dart

@@ -930,10 +930,18 @@ class _ContactsScreenState extends State<ContactsScreen>
     } else if (contact.type == advTypeRoom) {
       _showRoomLogin(context, contact, RoomLoginDestination.chat);
     } else {
-      context.read<MeshCoreConnector>().markContactRead(contact.publicKeyHex);
+      final connector = context.read<MeshCoreConnector>();
+      final unread =
+          connector.getUnreadCountForContactKey(contact.publicKeyHex);
+      connector.markContactRead(contact.publicKeyHex);
       Navigator.push(
         context,
-        MaterialPageRoute(builder: (context) => ChatScreen(contact: contact)),
+        MaterialPageRoute(
+          builder: (context) => ChatScreen(
+            contact: contact,
+            initialUnreadCount: unread,
+          ),
+        ),
       );
     }
   }
@@ -988,7 +996,10 @@ class _ContactsScreenState extends State<ContactsScreen>
       builder: (context) => RoomLoginDialog(
         room: room,
         onLogin: (password, isAdmin) {
-          context.read<MeshCoreConnector>().markContactRead(room.publicKeyHex);
+          final connector = context.read<MeshCoreConnector>();
+          final unread =
+              connector.getUnreadCountForContactKey(room.publicKeyHex);
+          connector.markContactRead(room.publicKeyHex);
           Navigator.push(
             context,
             MaterialPageRoute(
@@ -999,7 +1010,10 @@ class _ContactsScreenState extends State<ContactsScreen>
                       password: password,
                       isAdmin: isAdmin,
                     )
-                  : ChatScreen(contact: room),
+                  : ChatScreen(
+                      contact: room,
+                      initialUnreadCount: unread,
+                    ),
             ),
           );
         },

lib/screens/map_screen.dart

@@ -1391,11 +1391,18 @@ class _MapScreenState extends State<MapScreen> {
         room: room,
         // onLogin(password, isAdmin) isAdmin not used for room caht screen
         onLogin: (password, _) {
-          // Navigate to chat screen after successful login
-          context.read<MeshCoreConnector>().markContactRead(room.publicKeyHex);
+          final connector = context.read<MeshCoreConnector>();
+          final unread =
+              connector.getUnreadCountForContactKey(room.publicKeyHex);
+          connector.markContactRead(room.publicKeyHex);
           Navigator.push(
             context,
-            MaterialPageRoute(builder: (context) => ChatScreen(contact: room)),
+            MaterialPageRoute(
+              builder: (context) => ChatScreen(
+                contact: room,
+                initialUnreadCount: unread,
+              ),
+            ),
           );
         },
       ),