Name the preselected data sources that cannot be used right now

app/MindWork AI Studio/Components/DataSourceSelection.razor

@@ -67,6 +67,13 @@
                                 <MudTextSwitch Label="@T("AI-based data validation")" Value="@this.aiBasedValidation" LabelOn="@T("Yes, let the AI validate & filter the retrieved data.")" LabelOff="@T("No, use all data retrieved from the data sources.")" ValueChanged="@this.ValidationModeChanged"/>
                             }
 
+                            @if (!this.aiBasedSourceSelection && this.GetUnavailablePreselectedDataSourceNames().Length > 0)
+                            {
+                                <MudText Typo="Typo.body2" Color="Color.Warning" Class="mb-3">
+                                    @T("These data sources are preselected, but cannot be used right now, either due to data privacy or confidence-level requirements, or because they are unavailable:") @this.GetUnavailablePreselectedDataSourceNames()
+                                </MudText>
+                            }
+
                             @switch (this.aiBasedSourceSelection)
                             {
                                 case true when this.availableDataSources.Count == 0:

app/MindWork AI Studio/Components/DataSourceSelection.razor.cs

@@ -181,6 +181,22 @@ public partial class DataSourceSelection : MSGComponentBase
         var preselectedDataSourceIds = this.DataSourceOptions.PreselectedDataSourceIds.ToHashSet(StringComparer.Ordinal);
         return this.GetConfiguredDataSourcesSnapshot().Where(ds => preselectedDataSourceIds.Contains(ds.Id)).ToList();
     }
+
+    /// <summary>
+    /// Names the preselected data sources which the filters removed.
+    /// </summary>
+    /// <remarks>
+    /// This list shows what survived the filters, while the preselection keeps what the user asked
+    /// for. Without this, a preselected source which cannot be used right now is simply missing
+    /// from the list, and nothing says so. Preselected ids without a configured source are left
+    /// out: that source is gone, not unavailable.
+    /// </remarks>
+    /// <returns>The names of the unusable preselected data sources, or an empty string when there are none.</returns>
+    private string GetUnavailablePreselectedDataSourceNames()
+    {
+        var availableDataSourceIds = this.availableDataSources.Select(ds => ds.Id).ToHashSet(StringComparer.Ordinal);
+        return string.Join(", ", this.GetDataSourcesFromConfiguredIds().Where(ds => !availableDataSourceIds.Contains(ds.Id)).Select(ds => ds.Name));
+    }
     
     private async Task LoadAndApplyFilters()
     {