1. FetchPlansForRangeAsync — Adds GridEmptyMessage.IsVisible = false alongside GridLoadingOverlay.IsVisible = true at the start of every fetch, so any lingering empty message is dismissed before the next request.

2. FetchGroupedPlansAsync — When IntermediateRows.Count == 0 and the mode is Module: sets the message text to "No module found in the selected period", shows the overlay, and returns — without writing to StatusText. For QueryHash mode (or any other non-Module grouped mode) that still hits the empty case, the original status bar message is preserved.

Author: rferraton

src/PlanViewer.App/Controls/QueryStoreGridControl.axaml

@@ -363,6 +363,16 @@
                            Foreground="{DynamicResource ForegroundBrush}"/>
             </StackPanel>
         </Border>
+        <!-- Empty-state overlay (Module groupby with no module data) -->
+        <Border x:Name="GridEmptyMessage" IsVisible="False"
+                HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
+                IsHitTestVisible="False">
+            <TextBlock x:Name="GridEmptyMessageText"
+                       HorizontalAlignment="Center" VerticalAlignment="Center"
+                       FontSize="20" FontWeight="SemiBold"
+                       Foreground="{DynamicResource ForegroundMutedBrush}"
+                       TextAlignment="Center"/>
+        </Border>
         </Grid>
     </Grid>
 </UserControl>

src/PlanViewer.App/Controls/QueryStoreGridControl.axaml.cs

@@ -187,6 +187,7 @@ private async System.Threading.Tasks.Task FetchPlansForRangeAsync()
         StatusText.Text = "Fetching plans...";
         GridLoadingOverlay.IsVisible = true;
         GridLoadingText.Text = "Fetching plans...";
+        GridEmptyMessage.IsVisible = false;
         _rows.Clear();
         _filteredRows.Clear();
         _groupedRootRows.Clear();
@@ -266,10 +267,19 @@ private async System.Threading.Tasks.Task FetchGroupedPlansAsync(
         }
 
         GridLoadingOverlay.IsVisible = false;
+        GridEmptyMessage.IsVisible = false;
 
         if (grouped.IntermediateRows.Count == 0)
         {
-            StatusText.Text = "No Query Store data found for the selected range.";
+            if (_groupByMode == QueryStoreGroupBy.Module)
+            {
+                GridEmptyMessageText.Text = "No module found in the selected period";
+                GridEmptyMessage.IsVisible = true;
+            }
+            else
+            {
+                StatusText.Text = "No Query Store data found for the selected range.";
+            }
             return;
         }