Add loading overlay and contextual empty states

Dashboard/Controls/CriticalIssuesContent.xaml

@@ -3,6 +3,7 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:controls="clr-namespace:PerformanceMonitorDashboard.Controls"
              mc:Ignorable="d"
              d:DesignHeight="450" d:DesignWidth="800">
     <UserControl.Resources>
@@ -107,6 +108,7 @@
             </DataGridTextColumn>
         </DataGrid.Columns>
     </DataGrid>
-    <TextBlock x:Name="CriticalIssuesNoDataMessage" Style="{StaticResource NoDataMessage}"/>
+    <TextBlock x:Name="CriticalIssuesNoDataMessage" Style="{StaticResource EmptyStateMessage}" Text="No critical issues detected in selected time range"/>
+    <controls:LoadingOverlay x:Name="CriticalIssuesLoading"/>
     </Grid>
 </UserControl>

Dashboard/Controls/CriticalIssuesContent.xaml.cs

@@ -93,6 +93,13 @@ private async System.Threading.Tasks.Task LoadCriticalIssuesAsync()
 
             try
             {
+                // Only show loading overlay on initial load (no existing data)
+                if (CriticalIssuesDataGrid.ItemsSource == null)
+                {
+                    CriticalIssuesLoading.IsLoading = true;
+                    CriticalIssuesNoDataMessage.Visibility = Visibility.Collapsed;
+                }
+
                 var data = await _databaseService.GetCriticalIssuesAsync(
                     _criticalIssuesHoursBack,
                     _criticalIssuesFromDate,
@@ -111,6 +118,10 @@ private async System.Threading.Tasks.Task LoadCriticalIssuesAsync()
             {
                 Logger.Error($"Error loading critical issues: {ex.Message}");
             }
+            finally
+            {
+                CriticalIssuesLoading.IsLoading = false;
+            }
         }
 
         #region Filter Popup Handlers

Dashboard/Controls/DailySummaryContent.xaml

@@ -3,6 +3,7 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:controls="clr-namespace:PerformanceMonitorDashboard.Controls"
              mc:Ignorable="d"
              d:DesignHeight="450" d:DesignWidth="800">
     <UserControl.Resources>
@@ -144,7 +145,9 @@
                 </DataGridTextColumn>
             </DataGrid.Columns>
         </DataGrid>
-        <TextBlock x:Name="DailySummaryNoDataMessage" Style="{StaticResource NoDataMessage}"/>
+        <TextBlock x:Name="DailySummaryNoDataMessage" Style="{StaticResource EmptyStateMessage}"
+                   Text="No daily summary data. Try selecting a different date."/>
+        <controls:LoadingOverlay x:Name="DailySummaryLoading"/>
         </Grid>
     </Grid>
 </UserControl>

Dashboard/Controls/DailySummaryContent.xaml.cs

@@ -79,6 +79,13 @@ private async System.Threading.Tasks.Task LoadDailySummaryAsync()
 
             try
             {
+                // Only show loading overlay on initial load (no existing data)
+                if (DailySummaryDataGrid.ItemsSource == null)
+                {
+                    DailySummaryLoading.IsLoading = true;
+                    DailySummaryNoDataMessage.Visibility = Visibility.Collapsed;
+                }
+
                 var data = await _databaseService.GetDailySummaryAsync(_dailySummaryDate);
 
                 // Store unfiltered data and reset filters when new data is loaded
@@ -100,6 +107,10 @@ private async System.Threading.Tasks.Task LoadDailySummaryAsync()
             {
                 Logger.Error($"Error loading daily summary: {ex.Message}");
             }
+            finally
+            {
+                DailySummaryLoading.IsLoading = false;
+            }
         }
 
         #region Event Handlers

Dashboard/Controls/LoadingOverlay.xaml

@@ -0,0 +1,48 @@
+<UserControl x:Class="PerformanceMonitorDashboard.Controls.LoadingOverlay"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             mc:Ignorable="d"
+             Visibility="Collapsed"
+             d:DesignHeight="200" d:DesignWidth="400">
+    <UserControl.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="/Themes/DarkTheme.xaml"/>
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </UserControl.Resources>
+    <Grid Background="{DynamicResource BackgroundBrush}">
+        <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
+            <TextBlock x:Name="SpinnerText"
+                       Text="&#x27F3;"
+                       FontSize="24"
+                       Foreground="{DynamicResource AccentBrush}"
+                       HorizontalAlignment="Center"
+                       RenderTransformOrigin="0.5,0.5">
+                <TextBlock.RenderTransform>
+                    <RotateTransform x:Name="SpinnerRotation"/>
+                </TextBlock.RenderTransform>
+                <TextBlock.Triggers>
+                    <EventTrigger RoutedEvent="Loaded">
+                        <BeginStoryboard>
+                            <Storyboard RepeatBehavior="Forever">
+                                <DoubleAnimation
+                                    Storyboard.TargetName="SpinnerRotation"
+                                    Storyboard.TargetProperty="Angle"
+                                    From="0" To="360"
+                                    Duration="0:0:1"/>
+                            </Storyboard>
+                        </BeginStoryboard>
+                    </EventTrigger>
+                </TextBlock.Triggers>
+            </TextBlock>
+            <TextBlock x:Name="MessageText"
+                       FontSize="14"
+                       Foreground="{DynamicResource ForegroundMutedBrush}"
+                       HorizontalAlignment="Center"
+                       Margin="0,8,0,0"/>
+        </StackPanel>
+    </Grid>
+</UserControl>

Dashboard/Controls/LoadingOverlay.xaml.cs

@@ -0,0 +1,41 @@
+using System.Windows;
+using System.Windows.Controls;
+using PerformanceMonitorDashboard.Helpers;
+
+namespace PerformanceMonitorDashboard.Controls
+{
+    public partial class LoadingOverlay : UserControl
+    {
+        public static readonly DependencyProperty IsLoadingProperty =
+            DependencyProperty.Register(
+                nameof(IsLoading),
+                typeof(bool),
+                typeof(LoadingOverlay),
+                new PropertyMetadata(false, OnIsLoadingChanged));
+
+        public bool IsLoading
+        {
+            get => (bool)GetValue(IsLoadingProperty);
+            set => SetValue(IsLoadingProperty, value);
+        }
+
+        public LoadingOverlay()
+        {
+            InitializeComponent();
+        }
+
+        private static void OnIsLoadingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            if (d is LoadingOverlay overlay)
+            {
+                var isLoading = (bool)e.NewValue;
+                overlay.Visibility = isLoading ? Visibility.Visible : Visibility.Collapsed;
+
+                if (isLoading)
+                {
+                    overlay.MessageText.Text = LoadingMessages.GetRandom();
+                }
+            }
+        }
+    }
+}

Dashboard/Controls/MemoryContent.xaml

@@ -4,6 +4,7 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:ScottPlot="clr-namespace:ScottPlot.WPF;assembly=ScottPlot.WPF"
+             xmlns:controls="clr-namespace:PerformanceMonitorDashboard.Controls"
              mc:Ignorable="d"
              d:DesignHeight="600" d:DesignWidth="1200">
     <UserControl.Resources>
@@ -90,7 +91,9 @@
                             <TextBlock x:Name="MemoryGrantsForcedText" Text="0" Foreground="{DynamicResource ForegroundBrush}" VerticalAlignment="Center"/>
                         </StackPanel>
                     </Border>
-                    <TextBlock x:Name="MemoryGrantsNoDataMessage" Grid.Row="1" Style="{StaticResource NoDataMessage}"/>
+                    <TextBlock x:Name="MemoryGrantsNoDataMessage" Grid.Row="1" Style="{StaticResource EmptyStateMessage}"
+                               Text="No memory grant data in selected time range"/>
+                    <controls:LoadingOverlay x:Name="MemoryGrantsLoading" Grid.Row="1"/>
                 </Grid>
             </Border>
         </TabItem>
@@ -116,7 +119,9 @@
                             <TextBlock x:Name="MemoryClerksTopText" Text="N/A" Foreground="{DynamicResource ForegroundBrush}" VerticalAlignment="Center"/>
                         </StackPanel>
                     </Border>
-                    <TextBlock x:Name="MemoryClerksNoDataMessage" Grid.Row="1" Style="{StaticResource NoDataMessage}"/>
+                    <TextBlock x:Name="MemoryClerksNoDataMessage" Grid.Row="1" Style="{StaticResource EmptyStateMessage}"
+                               Text="No memory clerk data in selected time range"/>
+                    <controls:LoadingOverlay x:Name="MemoryClerksLoading" Grid.Row="1"/>
                 </Grid>
             </Border>
         </TabItem>

Dashboard/Controls/MemoryContent.xaml.cs

@@ -383,6 +383,13 @@ private async System.Threading.Tasks.Task RefreshMemoryGrantsAsync()
 
             try
             {
+                // Only show loading overlay on initial load (no existing chart data)
+                if (!MemoryGrantsChart.Plot.GetPlottables().Any())
+                {
+                    MemoryGrantsLoading.IsLoading = true;
+                    MemoryGrantsNoDataMessage.Visibility = Visibility.Collapsed;
+                }
+
                 var data = await _databaseService.GetMemoryGrantStatsAsync(_memoryGrantsHoursBack, _memoryGrantsFromDate, _memoryGrantsToDate);
                 var dataList = data.ToList();
                 MemoryGrantsNoDataMessage.Visibility = dataList.Count == 0 ? Visibility.Visible : Visibility.Collapsed;
@@ -392,6 +399,10 @@ private async System.Threading.Tasks.Task RefreshMemoryGrantsAsync()
             {
                 Logger.Error($"Error loading memory grants: {ex.Message}");
             }
+            finally
+            {
+                MemoryGrantsLoading.IsLoading = false;
+            }
         }
 
         private void LoadMemoryGrantsChart(IEnumerable<MemoryGrantStatsItem> data, int hoursBack, DateTime? fromDate, DateTime? toDate)
@@ -485,6 +496,13 @@ private async System.Threading.Tasks.Task RefreshMemoryClerksAsync()
 
             try
             {
+                // Only show loading overlay on initial load (no existing chart data)
+                if (!MemoryClerksChart.Plot.GetPlottables().Any())
+                {
+                    MemoryClerksLoading.IsLoading = true;
+                    MemoryClerksNoDataMessage.Visibility = Visibility.Collapsed;
+                }
+
                 var data = await _databaseService.GetMemoryClerksTopNAsync(5, _memoryClerksHoursBack, _memoryClerksFromDate, _memoryClerksToDate);
                 var dataList = data.ToList();
                 MemoryClerksNoDataMessage.Visibility = dataList.Count == 0 ? Visibility.Visible : Visibility.Collapsed;
@@ -494,6 +512,10 @@ private async System.Threading.Tasks.Task RefreshMemoryClerksAsync()
             {
                 Logger.Error($"Error loading memory clerks: {ex.Message}");
             }
+            finally
+            {
+                MemoryClerksLoading.IsLoading = false;
+            }
         }
 
         private void LoadMemoryClerksChart(List<MemoryClerksItem> data, int hoursBack, DateTime? fromDate, DateTime? toDate)

Dashboard/Controls/QueryPerformanceContent.xaml

@@ -314,7 +314,9 @@
                     </DataGridTemplateColumn>
                 </DataGrid.Columns>
             </DataGrid>
-            <TextBlock x:Name="ActiveQueriesNoDataMessage" Style="{StaticResource NoDataMessage}"/>
+            <TextBlock x:Name="ActiveQueriesNoDataMessage" Style="{StaticResource EmptyStateMessage}"
+                       Text="No active queries found"/>
+            <local:LoadingOverlay x:Name="ActiveQueriesLoading"/>
             </Grid>
         </TabItem>
 
@@ -585,7 +587,9 @@
                     </DataGridTextColumn>
                 </DataGrid.Columns>
             </DataGrid>
-            <TextBlock x:Name="QueryStatsNoDataMessage" Style="{StaticResource NoDataMessage}"/>
+            <TextBlock x:Name="QueryStatsNoDataMessage" Style="{StaticResource EmptyStateMessage}"
+                       Text="No query statistics in selected time range"/>
+            <local:LoadingOverlay x:Name="QueryStatsLoading"/>
             </Grid>
         </TabItem>
 

Dashboard/Controls/QueryPerformanceContent.xaml.cs

@@ -217,6 +217,13 @@ public async Task RefreshAllDataAsync()
 
                 if (_databaseService == null) return;
 
+                // Only show loading overlay on initial load (no existing data)
+                if (QueryStatsDataGrid.ItemsSource == null)
+                {
+                    QueryStatsLoading.IsLoading = true;
+                    QueryStatsNoDataMessage.Visibility = Visibility.Collapsed;
+                }
+
                 // Fetch grid data (summary views aggregated per query/procedure)
                 var queryStatsTask = _databaseService.GetQueryStatsAsync(_queryStatsHoursBack, _queryStatsFromDate, _queryStatsToDate);
                 var procStatsTask = _databaseService.GetProcedureStatsAsync(_procStatsHoursBack, _procStatsFromDate, _procStatsToDate);
@@ -263,6 +270,10 @@ await Task.WhenAll(
             {
                 Logger.Error($"Error refreshing QueryPerformance data: {ex.Message}", ex);
             }
+            finally
+            {
+                QueryStatsLoading.IsLoading = false;
+            }
         }
 
         private void SetStatus(string message)
@@ -367,7 +378,14 @@ private async Task RefreshActiveQueriesAsync()
 
             try
             {
+                // Only show loading overlay on initial load (no existing data)
+                if (ActiveQueriesDataGrid.ItemsSource == null)
+                {
+                    ActiveQueriesLoading.IsLoading = true;
+                    ActiveQueriesNoDataMessage.Visibility = Visibility.Collapsed;
+                }
                 SetStatus("Loading active queries...");
+
                 var data = await _databaseService.GetQuerySnapshotsAsync(_activeQueriesHoursBack, _activeQueriesFromDate, _activeQueriesToDate);
                 ActiveQueriesDataGrid.ItemsSource = data;
                 ActiveQueriesNoDataMessage.Visibility = data.Count == 0 ? Visibility.Visible : Visibility.Collapsed;
@@ -378,6 +396,10 @@ private async Task RefreshActiveQueriesAsync()
                 Logger.Error($"Error loading active queries: {ex.Message}");
                 SetStatus("Error loading active queries");
             }
+            finally
+            {
+                ActiveQueriesLoading.IsLoading = false;
+            }
         }
 
         private void ActiveQueriesFilter_Click(object sender, RoutedEventArgs e)

Dashboard/Helpers/LoadingMessages.cs

@@ -0,0 +1,46 @@
+using System;
+
+namespace PerformanceMonitorDashboard.Helpers
+{
+    /// <summary>
+    /// Randomized loading messages displayed while data is being fetched.
+    /// </summary>
+    public static class LoadingMessages
+    {
+        private static readonly string[] Messages =
+        [
+            "Reticulating splines...",
+            "Consulting the oracle...",
+            "Asking the database nicely...",
+            "Crunching numbers...",
+            "Thinking really hard...",
+            "Mulling it over...",
+            "Communing with SQL Server...",
+            "Summoning data spirits...",
+            "Decoding the matrix...",
+            "Interrogating indexes...",
+            "Parsing the void...",
+            "Calibrating flux capacitors...",
+            "Negotiating with stored procedures...",
+            "Convincing queries to run faster...",
+            "Herding cursors...",
+            "Massaging execution plans...",
+            "Whispering to wait stats...",
+            "Befriending buffer pools...",
+            "Coaxing data from disk...",
+            "Pondering performance...",
+            "Untangling spaghetti queries...",
+            "Poking the query optimizer...",
+            "Warming up the plan cache...",
+            "Dusting off statistics...",
+            "Reasoning with RESOURCE_SEMAPHORE...",
+            "Apologizing to tempdb...",
+            "Flattering the cardinality estimator...",
+            "Bribing the lock manager...",
+            "Decrypting wait stats hieroglyphics...",
+            "Teaching cursors to fly...",
+        ];
+
+        public static string GetRandom() => Messages[Random.Shared.Next(Messages.Length)];
+    }
+}