Добавил класс для представления сообщения

AMessanger/AMessanger.csproj

@@ -7,7 +7,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <Folder Include="Models\" />
     <AvaloniaResource Include="Assets\**" />
     <None Update="ConnectionUrl">
         <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>

AMessanger/Models/Message.cs

@@ -0,0 +1,8 @@
+namespace AMessanger.Models
+{
+    public class Message(string userName, string content)
+    {
+        public string UserName { get; set; } = userName;
+        public string Content { get; set; } = content;
+    }
+}

AMessanger/Services/ChatService.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using AMessanger.Models;
 using Microsoft.AspNetCore.SignalR.Client;
 
 namespace AMessanger.Services;
@@ -9,7 +10,7 @@ public class ChatService
 {
     private readonly HubConnection _connection;
 
-    public event Action<string, string>? OnMessageRecieved;
+    public event Action<Message>? OnMessageRecieved;
     
     public bool IsConnected { get; private set; } = false;
 
@@ -20,8 +21,8 @@ public class ChatService
             .WithAutomaticReconnect()
             .Build();
 
-        _connection.On<string, string>("ReceiveMessage", (user, message) =>
-            OnMessageRecieved?.Invoke(user, message));
+        _connection.On<Message>("ReceiveMessage", m =>
+            OnMessageRecieved?.Invoke(m));
     }
 
     public Task ConnectAsync(CancellationToken cancellationToken = default)
@@ -42,8 +43,8 @@ public class ChatService
         return _connection.StopAsync(cancellationToken);
     }
 
-    public Task SendMessageAsync(string user, string message, CancellationToken cancellationToken = default)
+    public Task SendMessageAsync(Message message, CancellationToken cancellationToken = default)
     {
-        return _connection.InvokeAsync("SendMessage", user, message, cancellationToken);
+        return _connection.InvokeAsync("SendMessage", message, cancellationToken);
     }
 }

AMessanger/ViewModels/MainViewModel.cs

@@ -1,17 +1,17 @@
-using System.Collections.ObjectModel;
+using AMessanger.Models;
 using AMessanger.Services;
-using CommunityToolkit.Mvvm.ComponentModel;
 using Avalonia.Threading;
-using System.Windows.Input;
+using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
-using System.Diagnostics;
+using System.Collections.ObjectModel;
+using System.Windows.Input;
 
 namespace AMessanger.ViewModels;
 
 public partial class MainViewModel : ViewModelBase
 {
     [ObservableProperty]
-    public partial ObservableCollection<string> Messages { get; private set; } = new();
+    public partial ObservableCollection<Message> Messages { get; private set; } = new();
 
     [ObservableProperty]
     public partial string Message { get; set; } = string.Empty;
@@ -31,10 +31,9 @@ public partial class MainViewModel : ViewModelBase
         SendButtonCommand = new RelayCommand(SendMessage);
     }
 
-    private void OnMessageRecived(string user, string message)
+    private void OnMessageRecived(Message message)
     {
-        Dispatcher.UIThread.Post(() => Messages.Add($"{user}: {message}"));
-        Debug.WriteLine($"{user}: {message}");
+        Dispatcher.UIThread.Post(() => Messages.Add(message));
     }
 
     private void SendMessage()
@@ -42,7 +41,7 @@ public partial class MainViewModel : ViewModelBase
         if (string.IsNullOrWhiteSpace(Message))
             return;
 
-        _chat.SendMessageAsync(UserName, Message.Trim());
+        _chat.SendMessageAsync(new Message(UserName, Message.Trim()));
         Message = string.Empty;
     }
 }

AMessanger/Views/MainWindow.axaml

@@ -21,8 +21,16 @@
             <RowDefinition Height="Auto" />
         </Grid.RowDefinitions>
 
-        <ListBox Grid.Row="0"
-                 ItemsSource="{Binding Messages}" />
+        <ListBox Grid.Row="0" ItemsSource="{Binding Messages}">
+            <ListBox.ItemTemplate>
+                <DataTemplate>
+                    <StackPanel Orientation="Horizontal">
+                        <TextBlock Text="{Binding UserName}" Margin="5" />
+                        <TextBlock Text="{Binding Content}" Margin="5" />
+                    </StackPanel>
+                </DataTemplate>
+            </ListBox.ItemTemplate>
+        </ListBox>
 
         <Grid Grid.Row="1" Margin="5">
             <Grid.ColumnDefinitions>