Cmdpal: user research on extension invokes (#43905)

## Summary of the Pull Request

Added two events that Niels asked for:

- `CmdPal_ExtensionInvoked`
- Track which extensions are being used (e.g., file search, app
launching, calculator, etc.).
    - Properties logged
        - ExtensionId - Unique identifier of the extension provider
        - CommandType - Display name of the command being invoked
        - Success - Whether the command executed successfully
        - ExecutionTimeMs - Execution time in milliseconds
- `CmdPal_SessionDuration`
    - Tracks how long Command Palette stays open (launch → close). 
    - Properties logged
        - DurationMs - Session duration in milliseconds
        - CommandsExecuted - Number of commands executed
        - PagesVisited - Number of pages visited
- DismissalReason - Why the session ended (Escape, LostFocus, Command,
etc.)
        - SearchQueriesCount - Number of search queries executed
        - MaxNavigationDepth - Maximum navigation depth reached
        - ErrorCount - Number of errors encountered



<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [ ] Closes: #xxx
<!-- - [ ] Closes: #yyy (add separate lines for additional resolved
issues) -->
- [x] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

DATA_AND_PRIVACY.md

@@ -262,6 +262,7 @@ _If you want to find diagnostic data events in the source code, these two links
 </table>
 
 ### Command Palette
+
 <table style="width:100%">
   <tr>
     <th>Event Name</th>
@@ -315,6 +316,14 @@ _If you want to find diagnostic data events in the source code, these two links
     <td>Microsoft.PowerToys.CmdPalProcessStarted</td>
     <td>Triggered when the Command Palette process is started.</td>
   </tr>
+  <tr>
+    <td>Microsoft.PowerToys.CmdPal_ExtensionInvoked</td>
+    <td>Tracks extension usage including extension ID, command details, success status, and execution time.</td>
+  </tr>
+  <tr>
+    <td>Microsoft.PowerToys.CmdPal_SessionDuration</td>
+    <td>Logs session metrics from launch to dismissal including duration, commands executed, pages visited, search queries, navigation depth, and errors.</td>
+  </tr>
 </table>
 
 ### Crop And Lock

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/ErrorOccurredMessage.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Message sent when an error occurs during command execution.
+/// Used to track session error count for telemetry.
+/// </summary>
+public record ErrorOccurredMessage();

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/ExtensionInvokedMessage.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Message sent when an extension command or page is invoked.
+/// Captures extension usage metrics for telemetry tracking.
+/// </summary>
+public record ExtensionInvokedMessage(string ExtensionId, string CommandId, string CommandName, bool Success, ulong ExecutionTimeMs);

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/NavigationDepthMessage.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Message containing the current navigation depth (BackStack count) when navigating to a page.
+/// Used to track maximum navigation depth reached during a session for telemetry.
+/// </summary>
+public record NavigationDepthMessage(int Depth);

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/SearchQueryMessage.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Message sent when a search query is executed in the Command Palette.
+/// Used to track session search activity for telemetry.
+/// </summary>
+public record SearchQueryMessage();

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/SessionDurationMessage.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Message containing session telemetry data from Command Palette launch to dismissal.
+/// Used to aggregate metrics like duration, commands executed, pages visited, and search activity.
+/// </summary>
+public record SessionDurationMessage(ulong DurationMs, int CommandsExecuted, int PagesVisited, string DismissalReason, int SearchQueriesCount, int MaxNavigationDepth, int ErrorCount);

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/TelemetryBeginInvokeMessage.cs

@@ -0,0 +1,10 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Telemetry message sent when command invocation begins.
+/// </summary>
+public record TelemetryBeginInvokeMessage;

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/TelemetryExtensionInvokedMessage.cs

@@ -0,0 +1,11 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Telemetry message sent when an extension command or page is invoked.
+/// Captures extension usage metrics for telemetry tracking.
+/// </summary>
+public record TelemetryExtensionInvokedMessage(string ExtensionId, string CommandId, string CommandName, bool Success, ulong ExecutionTimeMs);

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/Messages/TelemetryInvokeResultMessage.cs

@@ -0,0 +1,10 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CmdPal.Core.ViewModels.Messages;
+
+/// <summary>
+/// Telemetry message sent when command invocation completes with a result.
+/// </summary>
+public record TelemetryInvokeResultMessage(Microsoft.CommandPalette.Extensions.CommandResultKind Kind);

src/modules/cmdpal/Core/Microsoft.CmdPal.Core.ViewModels/ShellViewModel.cs

@@ -270,8 +270,18 @@ public partial class ShellViewModel : ObservableObject,
                 var isMainPage = command == _rootPage;
                 _isNested = !isMainPage;
 
+                // Telemetry: Track extension page navigation for session metrics
+                if (host is not null)
+                {
+                    string extensionId = host.GetExtensionDisplayName() ?? "builtin";
+                    string commandId = command?.Id ?? "unknown";
+                    string commandName = command?.Name ?? "unknown";
+                    WeakReferenceMessenger.Default.Send<TelemetryExtensionInvokedMessage>(
+                        new(extensionId, commandId, commandName, true, 0));
+                }
+
                 // Construct our ViewModel of the appropriate type and pass it the UI Thread context.
-                var pageViewModel = _pageViewModelFactory.TryCreatePageViewModel(page, _isNested, host);
+                var pageViewModel = _pageViewModelFactory.TryCreatePageViewModel(page, _isNested, host!);
                 if (pageViewModel is null)
                 {
                     CoreLogger.LogError($"Failed to create ViewModel for page {page.GetType().Name}");
@@ -306,7 +316,7 @@ public partial class ShellViewModel : ObservableObject,
             {
                 CoreLogger.LogDebug($"Invoking command");
 
-                WeakReferenceMessenger.Default.Send<BeginInvokeMessage>();
+                WeakReferenceMessenger.Default.Send<TelemetryBeginInvokeMessage>();
                 StartInvoke(message, invokable, host);
             }
         }
@@ -339,6 +349,14 @@ public partial class ShellViewModel : ObservableObject,
 
     private void SafeHandleInvokeCommandSynchronous(PerformCommandMessage message, IInvokableCommand invokable, AppExtensionHost? host)
     {
+        // Telemetry: Track command execution time and success
+        var stopwatch = System.Diagnostics.Stopwatch.StartNew();
+        var command = message.Command.Unsafe;
+        string extensionId = host?.GetExtensionDisplayName() ?? "builtin";
+        string commandId = command?.Id ?? "unknown";
+        string commandName = command?.Name ?? "unknown";
+        bool success = false;
+
         try
         {
             // Call out to extension process.
@@ -349,16 +367,28 @@ public partial class ShellViewModel : ObservableObject,
             // But if it did succeed, we need to handle the result.
             UnsafeHandleCommandResult(result);
 
+            success = true;
             _handleInvokeTask = null;
         }
         catch (Exception ex)
         {
+            success = false;
             _handleInvokeTask = null;
 
+            // Telemetry: Track errors for session metrics
+            WeakReferenceMessenger.Default.Send<ErrorOccurredMessage>(new());
+
             // TODO: It would be better to do this as a page exception, rather
             // than a silent log message.
             host?.Log(ex.Message);
         }
+        finally
+        {
+            // Telemetry: Send extension invocation metrics (always sent, even on failure)
+            stopwatch.Stop();
+            WeakReferenceMessenger.Default.Send<TelemetryExtensionInvokedMessage>(
+                new(extensionId, commandId, commandName, success, (ulong)stopwatch.ElapsedMilliseconds));
+        }
     }
 
     private void UnsafeHandleCommandResult(ICommandResult? result)
@@ -372,7 +402,7 @@ public partial class ShellViewModel : ObservableObject,
         var kind = result.Kind;
         CoreLogger.LogDebug($"handling {kind.ToString()}");
 
-        WeakReferenceMessenger.Default.Send<CmdPalInvokeResultMessage>(new(kind));
+        WeakReferenceMessenger.Default.Send<TelemetryInvokeResultMessage>(new(kind));
         switch (kind)
         {
             case CommandResultKind.Dismiss:

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandPaletteHost.cs

@@ -34,6 +34,6 @@ public sealed partial class CommandPaletteHost : AppExtensionHost, IExtensionHos
 
     public override string? GetExtensionDisplayName()
     {
-        return Extension?.ExtensionDisplayName;
+        return Extension?.ExtensionDisplayName ?? _builtInProvider?.DisplayName ?? _builtInProvider?.Id;
     }
 }

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/SearchBar.xaml.cs

@@ -379,6 +379,12 @@ public sealed partial class SearchBar : UserControl,
         if (CurrentPageViewModel is not null)
         {
             CurrentPageViewModel.SearchTextBox = FilterBox.Text;
+
+            // Telemetry: Track search query count for session metrics (only non-empty queries)
+            if (!string.IsNullOrWhiteSpace(FilterBox.Text))
+            {
+                WeakReferenceMessenger.Default.Send<SearchQueryMessage>(new());
+            }
         }
     }
 

src/modules/cmdpal/Microsoft.CmdPal.UI/Events/CmdPalExtensionInvoked.cs

@@ -0,0 +1,56 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.Tracing;
+using Microsoft.PowerToys.Telemetry;
+using Microsoft.PowerToys.Telemetry.Events;
+
+namespace Microsoft.CmdPal.UI.Events;
+
+/// <summary>
+/// Tracks extension usage with extension name and invocation details.
+/// Purpose: Identify popular vs. unused plugins and track extension performance.
+/// </summary>
+[EventData]
+[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)]
+public class CmdPalExtensionInvoked : EventBase, IEvent
+{
+    /// <summary>
+    /// Gets or sets the unique identifier of the extension provider.
+    /// </summary>
+    public string ExtensionId { get; set; }
+
+    /// <summary>
+    /// Gets or sets the non-localized identifier of the command being invoked.
+    /// </summary>
+    public string CommandId { get; set; }
+
+    /// <summary>
+    /// Gets or sets the localized display name of the command being invoked.
+    /// </summary>
+    public string CommandName { get; set; }
+
+    /// <summary>
+    /// Gets or sets whether the command executed successfully.
+    /// </summary>
+    public bool Success { get; set; }
+
+    /// <summary>
+    /// Gets or sets the execution time in milliseconds.
+    /// </summary>
+    public ulong ExecutionTimeMs { get; set; }
+
+    public CmdPalExtensionInvoked(string extensionId, string commandId, string commandName, bool success, ulong executionTimeMs)
+    {
+        EventName = "CmdPal_ExtensionInvoked";
+        ExtensionId = extensionId;
+        CommandId = commandId;
+        CommandName = commandName;
+        Success = success;
+        ExecutionTimeMs = executionTimeMs;
+    }
+
+    public PartA_PrivTags PartA_PrivTags => PartA_PrivTags.ProductAndServiceUsage;
+}

src/modules/cmdpal/Microsoft.CmdPal.UI/Events/CmdPalInvokeResult.cs

@@ -18,6 +18,7 @@ public class CmdPalInvokeResult : EventBase, IEvent
 
     public CmdPalInvokeResult(CommandResultKind resultKind)
     {
+        EventName = "CmdPal_InvokeResult";
         ResultKind = resultKind.ToString();
     }
 

src/modules/cmdpal/Microsoft.CmdPal.UI/Events/CmdPalSessionDuration.cs

@@ -0,0 +1,68 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.Tracing;
+using Microsoft.PowerToys.Telemetry;
+using Microsoft.PowerToys.Telemetry.Events;
+
+namespace Microsoft.CmdPal.UI.Events;
+
+/// <summary>
+/// Tracks Command Palette session duration from launch to close.
+/// Purpose: Understand user engagement patterns - quick actions vs. browsing behavior.
+/// </summary>
+[EventData]
+[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)]
+public class CmdPalSessionDuration : EventBase, IEvent
+{
+    /// <summary>
+    /// Gets or sets the session duration in milliseconds.
+    /// </summary>
+    public ulong DurationMs { get; set; }
+
+    /// <summary>
+    /// Gets or sets the number of commands executed during the session.
+    /// </summary>
+    public int CommandsExecuted { get; set; }
+
+    /// <summary>
+    /// Gets or sets the number of pages visited during the session.
+    /// </summary>
+    public int PagesVisited { get; set; }
+
+    /// <summary>
+    /// Gets or sets the reason for dismissal (Escape, LostFocus, Command, etc.).
+    /// </summary>
+    public string DismissalReason { get; set; }
+
+    /// <summary>
+    /// Gets or sets the number of search queries executed during the session.
+    /// </summary>
+    public int SearchQueriesCount { get; set; }
+
+    /// <summary>
+    /// Gets or sets the maximum navigation depth reached during the session.
+    /// </summary>
+    public int MaxNavigationDepth { get; set; }
+
+    /// <summary>
+    /// Gets or sets the number of errors encountered during the session.
+    /// </summary>
+    public int ErrorCount { get; set; }
+
+    public CmdPalSessionDuration(ulong durationMs, int commandsExecuted, int pagesVisited, string dismissalReason, int searchQueriesCount, int maxNavigationDepth, int errorCount)
+    {
+        EventName = "CmdPal_SessionDuration";
+        DurationMs = durationMs;
+        CommandsExecuted = commandsExecuted;
+        PagesVisited = pagesVisited;
+        DismissalReason = dismissalReason;
+        SearchQueriesCount = searchQueriesCount;
+        MaxNavigationDepth = maxNavigationDepth;
+        ErrorCount = errorCount;
+    }
+
+    public PartA_PrivTags PartA_PrivTags => PartA_PrivTags.ProductAndServiceUsage;
+}

src/modules/cmdpal/Microsoft.CmdPal.UI/Helpers/TelemetryForwarder.cs

@@ -6,40 +6,78 @@ using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.CmdPal.Core.Common.Services;
 using Microsoft.CmdPal.Core.ViewModels.Messages;
 using Microsoft.CmdPal.UI.Events;
+using Microsoft.CommandPalette.Extensions;
 using Microsoft.PowerToys.Telemetry;
 
 namespace Microsoft.CmdPal.UI;
 
 /// <summary>
 /// TelemetryForwarder is responsible for forwarding telemetry events from the
-/// command palette core to PowerToys Telemetry.
+/// command palette to PowerToys Telemetry.
-/// This allows us to emit telemetry events as messages from the core,
+/// Listens to telemetry-specific messages from the core layer and logs them to PowerToys telemetry.
-/// and then handle them by logging to our PT telemetry provider.
+/// Also implements ITelemetryService for dependency injection in extensions.
-///
-/// We may in the future want to replace this with a more generic "ITelemetryService"
-/// or something similar, but this works for now.
 /// </summary>
 internal sealed class TelemetryForwarder :
     ITelemetryService,
-    IRecipient<BeginInvokeMessage>,
+    IRecipient<TelemetryBeginInvokeMessage>,
-    IRecipient<CmdPalInvokeResultMessage>
+    IRecipient<TelemetryInvokeResultMessage>,
+    IRecipient<TelemetryExtensionInvokedMessage>
 {
     public TelemetryForwarder()
     {
-        WeakReferenceMessenger.Default.Register<BeginInvokeMessage>(this);
+        WeakReferenceMessenger.Default.Register<TelemetryBeginInvokeMessage>(this);
-        WeakReferenceMessenger.Default.Register<CmdPalInvokeResultMessage>(this);
+        WeakReferenceMessenger.Default.Register<TelemetryInvokeResultMessage>(this);
+        WeakReferenceMessenger.Default.Register<TelemetryExtensionInvokedMessage>(this);
     }
 
-    public void Receive(CmdPalInvokeResultMessage message)
+    // Message handlers for telemetry events from core layer
-    {
+    public void Receive(TelemetryBeginInvokeMessage message)
-        PowerToysTelemetry.Log.WriteEvent(new CmdPalInvokeResult(message.Kind));
-    }
-
-    public void Receive(BeginInvokeMessage message)
     {
         PowerToysTelemetry.Log.WriteEvent(new BeginInvoke());
     }
 
+    public void Receive(TelemetryInvokeResultMessage message)
+    {
+        PowerToysTelemetry.Log.WriteEvent(new CmdPalInvokeResult(message.Kind));
+    }
+
+    public void Receive(TelemetryExtensionInvokedMessage message)
+    {
+        PowerToysTelemetry.Log.WriteEvent(new CmdPalExtensionInvoked(
+            message.ExtensionId,
+            message.CommandId,
+            message.CommandName,
+            message.Success,
+            message.ExecutionTimeMs));
+
+        // Increment session counter for commands executed
+        if (App.Current.AppWindow is MainWindow mainWindow)
+        {
+            mainWindow.IncrementCommandsExecuted();
+        }
+    }
+
+    // Static method for logging session duration from UI layer
+    public static void LogSessionDuration(
+        ulong durationMs,
+        int commandsExecuted,
+        int pagesVisited,
+        string dismissalReason,
+        int searchQueriesCount,
+        int maxNavigationDepth,
+        int errorCount)
+    {
+        PowerToysTelemetry.Log.WriteEvent(new CmdPalSessionDuration(
+            durationMs,
+            commandsExecuted,
+            pagesVisited,
+            dismissalReason,
+            searchQueriesCount,
+            maxNavigationDepth,
+            errorCount));
+    }
+
+    // ITelemetryService implementation for dependency injection in extensions
     public void LogRunQuery(string query, int resultCount, ulong durationMs)
     {
         PowerToysTelemetry.Log.WriteEvent(new CmdPalRunQuery(query, resultCount, durationMs));

src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs

@@ -52,6 +52,10 @@ public sealed partial class MainWindow : WindowEx,
     IRecipient<ShowWindowMessage>,
     IRecipient<HideWindowMessage>,
     IRecipient<QuitMessage>,
+    IRecipient<NavigateToPageMessage>,
+    IRecipient<NavigationDepthMessage>,
+    IRecipient<SearchQueryMessage>,
+    IRecipient<ErrorOccurredMessage>,
     IRecipient<DragStartedMessage>,
     IRecipient<DragCompletedMessage>,
     IDisposable
@@ -75,6 +79,14 @@ public sealed partial class MainWindow : WindowEx,
     private bool _ignoreHotKeyWhenFullScreen = true;
     private bool _themeServiceInitialized;
 
+    // Session tracking for telemetry
+    private Stopwatch? _sessionStopwatch;
+    private int _sessionCommandsExecuted;
+    private int _sessionPagesVisited;
+    private int _sessionSearchQueriesCount;
+    private int _sessionMaxNavigationDepth;
+    private int _sessionErrorCount;
+
     private DesktopAcrylicController? _acrylicController;
     private SystemBackdropConfiguration? _configurationSource;
     private TimeSpan _autoGoHomeInterval = Timeout.InfiniteTimeSpan;
@@ -123,6 +135,10 @@ public sealed partial class MainWindow : WindowEx,
         WeakReferenceMessenger.Default.Register<QuitMessage>(this);
         WeakReferenceMessenger.Default.Register<ShowWindowMessage>(this);
         WeakReferenceMessenger.Default.Register<HideWindowMessage>(this);
+        WeakReferenceMessenger.Default.Register<NavigateToPageMessage>(this);
+        WeakReferenceMessenger.Default.Register<NavigationDepthMessage>(this);
+        WeakReferenceMessenger.Default.Register<SearchQueryMessage>(this);
+        WeakReferenceMessenger.Default.Register<ErrorOccurredMessage>(this);
         WeakReferenceMessenger.Default.Register<DragStartedMessage>(this);
         WeakReferenceMessenger.Default.Register<DragCompletedMessage>(this);
 
@@ -524,6 +540,11 @@ public sealed partial class MainWindow : WindowEx,
     {
         var settings = App.Current.Services.GetService<SettingsModel>()!;
 
+        // Start session tracking
+        _sessionStopwatch = Stopwatch.StartNew();
+        _sessionCommandsExecuted = 0;
+        _sessionPagesVisited = 0;
+
         ShowHwnd(message.Hwnd, settings.SummonOn);
     }
 
@@ -532,6 +553,7 @@ public sealed partial class MainWindow : WindowEx,
         // This might come in off the UI thread. Make sure to hop back.
         DispatcherQueue.TryEnqueue(() =>
         {
+            EndSession("Hide");
             HideWindow();
         });
     }
@@ -551,10 +573,67 @@ public sealed partial class MainWindow : WindowEx,
         // This might come in off the UI thread. Make sure to hop back.
         DispatcherQueue.TryEnqueue(() =>
         {
+            EndSession("Dismiss");
             HideWindow();
         });
     }
 
+    // Session telemetry: Track metrics during the Command Palette session
+    // These receivers increment counters that are sent when EndSession is called
+    public void Receive(NavigateToPageMessage message)
+    {
+        _sessionPagesVisited++;
+    }
+
+    public void Receive(NavigationDepthMessage message)
+    {
+        if (message.Depth > _sessionMaxNavigationDepth)
+        {
+            _sessionMaxNavigationDepth = message.Depth;
+        }
+    }
+
+    public void Receive(SearchQueryMessage message)
+    {
+        _sessionSearchQueriesCount++;
+    }
+
+    public void Receive(ErrorOccurredMessage message)
+    {
+        _sessionErrorCount++;
+    }
+
+    /// <summary>
+    /// Ends the current telemetry session and emits the CmdPal_SessionDuration event.
+    /// Aggregates all session metrics collected since ShowWindow and sends them to telemetry.
+    /// </summary>
+    /// <param name="dismissalReason">The reason the session ended (e.g., Dismiss, Hide, LostFocus).</param>
+    private void EndSession(string dismissalReason)
+    {
+        if (_sessionStopwatch is not null)
+        {
+            _sessionStopwatch.Stop();
+            TelemetryForwarder.LogSessionDuration(
+                (ulong)_sessionStopwatch.ElapsedMilliseconds,
+                _sessionCommandsExecuted,
+                _sessionPagesVisited,
+                dismissalReason,
+                _sessionSearchQueriesCount,
+                _sessionMaxNavigationDepth,
+                _sessionErrorCount);
+            _sessionStopwatch = null;
+        }
+    }
+
+    /// <summary>
+    /// Increments the session commands executed counter for telemetry.
+    /// Called by TelemetryForwarder when an extension command is invoked.
+    /// </summary>
+    internal void IncrementCommandsExecuted()
+    {
+        _sessionCommandsExecuted++;
+    }
+
     private void HideWindow()
     {
         // Cloak our HWND to avoid all animations.
@@ -764,6 +843,7 @@ public sealed partial class MainWindow : WindowEx,
             }
 
             // This will DWM cloak our window:
+            EndSession("LostFocus");
             HideWindow();
 
             PowerToysTelemetry.Log.WriteEvent(new CmdPalDismissedOnLostFocus());

src/modules/cmdpal/Microsoft.CmdPal.UI/Pages/ShellPage.xaml.cs

@@ -161,6 +161,9 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
 
             PowerToysTelemetry.Log.WriteEvent(new OpenPage(RootFrame.BackStackDepth, message.Page.Id));
 
+            // Telemetry: Send navigation depth for session max depth tracking
+            WeakReferenceMessenger.Default.Send(new NavigationDepthMessage(RootFrame.BackStackDepth));
+
             if (!ViewModel.IsNested)
             {
                 // todo BODGY