Add jump-to-message feature when clicking on reply

src/Decho/Converters/StringConverters.cs

@@ -21,3 +21,16 @@ public static class StringConverters
         }
     }
 }
+
+public sealed class BoolToOpacityConverter : IValueConverter
+{
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        return value is true ? 0.3 : 0.0;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        throw new NotSupportedException();
+    }
+}

src/Decho/ViewModels/ChatViewModel.cs

@@ -9,6 +9,8 @@ public sealed class ChatViewModel : ViewModelBase
 {
     public Action? LoadMoreRequested;
 
+    public Action<string>? ScrollToMessageRequested;
+
     public ObservableCollection<MessageViewModel> Messages
     {
         get;

src/Decho/ViewModels/MessageViewModel.cs

@@ -60,6 +60,12 @@ public sealed class MessageViewModel(MessageModel model) : ViewModelBase
 
     public bool ShowContent => !string.IsNullOrEmpty(Content);
 
+    public bool IsHighlighted
+    {
+        get;
+        set => this.RaiseAndSetIfChanged(ref field, value);
+    }
+
     public string TimeText
     {
         get

src/Decho/Views/MessageComposerView.axaml

@@ -80,7 +80,7 @@
                          Margin="0 0 5 0"
                          Text="{Binding Draft, Mode=TwoWay}"
                          IsEnabled="{Binding IsEditable}"
-                         AcceptsReturn="False"
+                         AcceptsReturn="True"
                          TextWrapping="Wrap"
                          KeyDown="OnTextBoxKeyDown" />
                 <Popup x:Name="MentionPopup"

src/Decho/Views/MessageComposerView.axaml.cs

@@ -7,6 +7,7 @@ using Avalonia.Platform.Storage;
 using Decho.Models;
 using Decho.ViewModels;
 
+using System.Diagnostics;
 using System.Globalization;
 using System.Reactive;
 
@@ -21,6 +22,9 @@ public partial class MessageComposerView : UserControl
         AddHandler(DragDrop.DropEvent, OnDrop);
         DragDrop.SetAllowDrop(this, true);
         DataContextChanged += OnDataContextChanged;
+
+        // Intercept Enter before the TextBox processes it (AcceptsReturn=True would insert a newline)
+        MessageTextBox.AddHandler(InputElement.KeyDownEvent, OnTextBoxTunnelingKeyDown, RoutingStrategies.Tunnel);
     }
 
     private void OnDataContextChanged(object? sender, EventArgs e)
@@ -81,23 +85,35 @@ public partial class MessageComposerView : UserControl
             return;
         }
 
-        if (e.Key == Key.Enter)
+        if (e.Key == Key.Escape)
         {
-            if (e.KeyModifiers.HasFlag(KeyModifiers.Shift))
+            bool hasReply = vm.HasReplyTarget;
+            bool hasFiles = vm.HasStagedFiles;
+            if (hasReply || hasFiles)
             {
-                int caret = MessageTextBox.CaretIndex;
-                string text = vm.Draft ?? "";
-                vm.Draft = text[..caret] + "\n" + text[caret..];
-                Avalonia.Threading.Dispatcher.UIThread.Post(() => MessageTextBox.CaretIndex = caret + 1);
+                if (hasReply) vm.ClearReplyTarget();
+                if (hasFiles) vm.ClearStagedFiles();
                 e.Handled = true;
                 return;
             }
+        }
+    }
+
+    private void OnTextBoxTunnelingKeyDown(object? sender, KeyEventArgs e)
+    {
+        if (e.Key != Key.Enter) return;
+        if (e.KeyModifiers.HasFlag(KeyModifiers.Shift)) return;
+
+        MessageComposerViewModel? vm = this.GetDataContext<MessageComposerViewModel>();
+        if (vm is null) return;
+
+        // Don't intercept Enter when autocomplete is open (bubbling handler handles it)
+        if (vm.Autocomplete.ShowPopup) return;
 
         vm.Draft = MessageTextBox.Text ?? "";
         vm.Send();
         e.Handled = true;
     }
-    }
 
     private void OnMentionPointerPressed(object? sender, PointerPressedEventArgs e)
     {

src/Decho/Views/MessageItemView.axaml

@@ -5,7 +5,18 @@
 			 xmlns:conv="using:Decho.Converters"
 			 x:Class="Decho.Views.MessageItemView"
 			 x:DataType="vm:MessageViewModel">
+	<UserControl.Resources>
+		<conv:BoolToOpacityConverter x:Key="BoolOpacityConverter" />
+	</UserControl.Resources>
 	<Grid Margin="5" ColumnDefinitions="Auto, *">
+		<Border Grid.ColumnSpan="2" Background="#2645a1" IsHitTestVisible="False" CornerRadius="4"
+				Opacity="{Binding IsHighlighted, Converter={StaticResource BoolOpacityConverter}}">
+			<Border.Transitions>
+				<Transitions>
+					<DoubleTransition Property="Opacity" Duration="0:0:0.3" />
+				</Transitions>
+			</Border.Transitions>
+		</Border>
 		<Ellipse VerticalAlignment="Top"
 				 Width="40"
 				 Height="40"

src/Decho/Views/MessageItemView.axaml.cs

@@ -7,6 +7,7 @@ using Avalonia.Media;
 using Avalonia.Media.Imaging;
 using Avalonia.Platform.Storage;
 
+using Decho.Models;
 using Decho.ViewModels;
 
 using EchoHub.Core.DTOs;
@@ -64,7 +65,7 @@ public partial class MessageItemView : UserControl
             TextBlock? replyQuote = ReplyQuote;
             if (replyQuote is not null && msg.ReplyTo is { } reply)
             {
-                replyQuote.Text = $"\u2514 {reply.SenderUsername}: {reply.Content}";
+                replyQuote.Text = $"\u2514 {reply.SenderUsername}: {reply.Content.Replace('\n', ' ')[..Math.Min(100, reply.Content.Length)]}";
             }
         }
     }
@@ -421,8 +422,66 @@ public partial class MessageItemView : UserControl
         if (channel is null)
             return;
 
-        // Switch to the channel containing the original message
-        if (!string.Equals(channel.Name, mainVm.Chat.CurrentChannelName, StringComparison.OrdinalIgnoreCase))
+        string targetId = msg.ReplyTo.MessageId.ToString("N");
+        bool needsSwitch = !string.Equals(channel.Name, mainVm.Chat.CurrentChannelName, StringComparison.OrdinalIgnoreCase);
+
+        if (needsSwitch)
+        {
             mainVm.Sidebar.SelectedChannel = channel;
         }
+
+        JumpToReply(targetId, needsSwitch);
+    }
+
+    private async void JumpToReply(string targetId, bool needsSwitch)
+    {
+        if (needsSwitch)
+        {
+            await Task.Delay(100);
+        }
+
+        MainWindowViewModel? mainVm = this.GetMainWindowViewModel();
+        if (mainVm is null) return;
+
+        bool found = mainVm.Chat.Messages.Any(m => m.Model.Id == targetId);
+
+        if (!found)
+        {
+            string serverUrl = ResolveServerUrl();
+            string channelName = mainVm.Chat.CurrentChannelName;
+            if (string.IsNullOrEmpty(serverUrl) || string.IsNullOrEmpty(channelName))
+                return;
+
+            try
+            {
+                List<MessageModel> allMessages = await mainVm.ChannelService.GetHistoryAsync(
+                    serverUrl, channelName, 200, 0);
+
+                if (allMessages.Any(m => m.Id == targetId))
+                {
+                    ChannelViewModel? channelVm = mainVm.Sidebar.GetServer(serverUrl)?.Channels
+                        .FirstOrDefault(c => string.Equals(c.Name, channelName, StringComparison.OrdinalIgnoreCase));
+
+                    if (channelVm is not null)
+                    {
+                        HashSet<string> existing = channelVm.Messages.Select(m => m.Model.Id).ToHashSet();
+                        foreach (MessageModel m in allMessages)
+                        {
+                            if (!existing.Contains(m.Id))
+                                channelVm.AddMessage(m);
+                        }
+                    }
+
+                    await Task.Delay(50);
+                }
+            }
+            catch (Exception ex)
+            {
+                Debug.WriteLine($"Failed to fetch reply target: {ex.Message}");
+                return;
+            }
+        }
+
+        mainVm.Chat.ScrollToMessageRequested?.Invoke(targetId);
+    }
 }

src/Decho/Views/MessageListView.axaml.cs

@@ -1,6 +1,7 @@
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Threading;
+using Avalonia.VisualTree;
 
 using Decho.ViewModels;
 
@@ -29,6 +30,7 @@ public partial class MessageListView : UserControl
             _chat.Messages.CollectionChanged -= OnMessagesChanged;
             _chat.PropertyChanged -= OnViewModelPropertyChanged;
             _chat.LoadMoreRequested -= OnLoadMoreRequested;
+            _chat.ScrollToMessageRequested -= ScrollToMessage;
         }
 
         ScrollViewer? scroll = this.FindControl<ScrollViewer>("MessageScrollViewer");
@@ -40,6 +42,7 @@ public partial class MessageListView : UserControl
             _chat.Messages.CollectionChanged += OnMessagesChanged;
             _chat.PropertyChanged += OnViewModelPropertyChanged;
             _chat.LoadMoreRequested += OnLoadMoreRequested;
+            _chat.ScrollToMessageRequested += ScrollToMessage;
             scroll?.ScrollChanged += OnScrollChanged;
         }
     }
@@ -138,4 +141,74 @@ public partial class MessageListView : UserControl
         _wasAtBottom = true;
         Dispatcher.UIThread.Post(scroll.ScrollToEnd, DispatcherPriority.Background);
     }
+
+    public void ScrollToMessage(string messageId)
+    {
+        if (_chat is null) return;
+
+        MessageViewModel? target = _chat.Messages.FirstOrDefault(m => m.Model.Id == messageId);
+        if (target is null) return;
+
+        ScrollViewer? scroll = this.FindControl<ScrollViewer>("MessageScrollViewer");
+        if (scroll is null) return;
+        
+        ClearHighlight();
+        target.IsHighlighted = true;
+        _highlightedMessage = target;
+        _highlightCts = new CancellationTokenSource();
+        CancellationToken ct = _highlightCts.Token;
+
+        Dispatcher.UIThread.Post(() =>
+        {
+            double? targetY = FindItemY(scroll, target);
+            if (targetY is not null)
+                scroll.Offset = new Vector(scroll.Offset.X, targetY.Value);
+        }, DispatcherPriority.Render);
+
+        _ = Task.Run(async () =>
+        {
+            try
+            {
+                await Task.Delay(2000, ct);
+                Dispatcher.UIThread.Post(() =>
+                {
+                    target.IsHighlighted = false;
+                    if (_highlightedMessage == target)
+                        _highlightedMessage = null;
+                });
+            }
+            catch (OperationCanceledException)
+            {
+            }
+        });
+    }
+
+    private static double? FindItemY(Visual parent, MessageViewModel target)
+    {
+        foreach (Visual child in parent.GetVisualChildren())
+        {
+            if (child.DataContext == target)
+                return child.Bounds.Y;
+
+            double? result = FindItemY(child, target);
+            if (result.HasValue)
+                return result;
+        }
+
+        return null;
+    }
+
+    private MessageViewModel? _highlightedMessage;
+    private CancellationTokenSource? _highlightCts;
+
+    private void ClearHighlight()
+    {
+        _highlightCts?.Cancel();
+        _highlightCts = null;
+        if (_highlightedMessage is not null)
+        {
+            _highlightedMessage.IsHighlighted = false;
+            _highlightedMessage = null;
+        }
+    }
 }