Add ReadOnlyIntent connection option to Lite

Lite/Models/ServerConnection.cs

@@ -70,6 +70,13 @@ public bool UseWindowsAuth
     /// </summary>
     public string? DatabaseName { get; set; }
 
+    /// <summary>
+    /// When true, sets ApplicationIntent=ReadOnly on the connection string.
+    /// Required for connecting to AG listener read-only replicas and
+    /// Azure SQL Business Critical / Managed Instance built-in read replicas.
+    /// </summary>
+    public bool ReadOnlyIntent { get; set; } = false;
+
     /// <summary>
     /// Display-only property for showing authentication type in UI.
     /// </summary>
@@ -153,7 +160,8 @@ private string BuildConnectionString(string? username, string? password)
             ConnectTimeout = 15,
             CommandTimeout = 60,
             TrustServerCertificate = TrustServerCertificate,
-            MultipleActiveResultSets = true
+            MultipleActiveResultSets = true,
+            ApplicationIntent = ReadOnlyIntent ? ApplicationIntent.ReadOnly : ApplicationIntent.ReadWrite
         };
 
         // Set encryption mode

Lite/Windows/AddServerDialog.xaml

@@ -88,6 +88,9 @@
                 <TextBox x:Name="DatabaseNameBox" Width="250"
                          ToolTip="Required for Azure SQL Database. Leave empty for on-premises SQL Server."/>
             </StackPanel>
+            <CheckBox x:Name="ReadOnlyIntentCheckBox" Content="Read-only intent (for AG listeners and readable replicas)"
+                      Foreground="{DynamicResource ForegroundBrush}" Margin="0,6,0,0"
+                      ToolTip="Sets ApplicationIntent=ReadOnly. Required when connecting via an AG listener or Azure failover group endpoint to route to a readable secondary."/>
         </StackPanel>
 
         <!-- Status -->

Lite/Windows/AddServerDialog.xaml.cs

@@ -59,6 +59,7 @@ public AddServerDialog(ServerManager serverManager, ServerConnection existing) :
         FavoriteCheckBox.IsChecked = existing.IsFavorite;
         DescriptionTextBox.Text = existing.Description ?? "";
         DatabaseNameBox.Text = existing.DatabaseName ?? "";
+        ReadOnlyIntentCheckBox.IsChecked = existing.ReadOnlyIntent;
 
         // Set authentication mode
         if (existing.AuthenticationType == AuthenticationTypes.EntraMFA)
@@ -140,7 +141,10 @@ private SqlConnectionStringBuilder BuildConnectionBuilder()
             ApplicationName = "PerformanceMonitorLite",
             ConnectTimeout = 10,
             TrustServerCertificate = TrustCertCheckBox.IsChecked == true,
-            Encrypt = ParseEncryptOption(GetSelectedEncryptMode())
+            Encrypt = ParseEncryptOption(GetSelectedEncryptMode()),
+            ApplicationIntent = ReadOnlyIntentCheckBox.IsChecked == true
+                ? ApplicationIntent.ReadOnly
+                : ApplicationIntent.ReadWrite
         };
 
         if (WindowsAuthRadio.IsChecked == true)
@@ -342,6 +346,7 @@ private async void SaveButton_Click(object sender, RoutedEventArgs e)
                 AddedServer.IsFavorite = FavoriteCheckBox.IsChecked == true;
                 AddedServer.Description = DescriptionTextBox.Text.Trim();
                 AddedServer.DatabaseName = string.IsNullOrWhiteSpace(DatabaseNameBox.Text) ? null : DatabaseNameBox.Text.Trim();
+                AddedServer.ReadOnlyIntent = ReadOnlyIntentCheckBox.IsChecked == true;
 
                 _serverManager.UpdateServer(AddedServer, username, password);
             }
@@ -358,7 +363,8 @@ private async void SaveButton_Click(object sender, RoutedEventArgs e)
                     EncryptMode = GetSelectedEncryptMode(),
                     IsFavorite = FavoriteCheckBox.IsChecked == true,
                     Description = DescriptionTextBox.Text.Trim(),
-                    DatabaseName = string.IsNullOrWhiteSpace(DatabaseNameBox.Text) ? null : DatabaseNameBox.Text.Trim()
+                    DatabaseName = string.IsNullOrWhiteSpace(DatabaseNameBox.Text) ? null : DatabaseNameBox.Text.Trim(),
+                    ReadOnlyIntent = ReadOnlyIntentCheckBox.IsChecked == true
                 };
 
                 _serverManager.AddServer(AddedServer, username, password);