fix ruler

Comment out the ScreenResolutionUtility task for non-arm64 platforms.

.github/actions/spell-check/expect.txt

@@ -25,6 +25,8 @@ ADMINS
 adml
 admx
 advancedpaste
+advancedpasteui
+advancedpasteuishortcut
 advfirewall
 AFeature
 affordances
@@ -40,6 +42,7 @@ ALLINPUT
 Allman
 Allmodule
 ALLOWUNDO
+allpc
 ALLVIEW
 ALPHATYPE
 AModifier
@@ -115,6 +118,7 @@ bigbar
 bigobj
 binlog
 binres
+binskim
 BITMAPFILEHEADER
 bitmapimage
 BITMAPINFO
@@ -255,6 +259,7 @@ Corpor
 cotaskmem
 COULDNOT
 countof
+covrun
 cpcontrols
 cph
 cplusplus
@@ -627,6 +632,7 @@ HKCU
 hkey
 HKLM
 HKM
+hkmng
 HKPD
 HKU
 HMD
@@ -635,6 +641,7 @@ hmodule
 hmonitor
 homies
 homljgmgpmcbpjbnjpfijnhipfkiclkd
+HOOKPROC
 HORZRES
 HORZSIZE
 Hostbackdropbrush
@@ -643,7 +650,11 @@ Hostx
 hotfixes
 hotkeycontrol
 HOTKEYF
+hotkeylockmachine
+hotkeyreconnect
 hotkeys
+hotkeyswitch
+hotkeytoggleeasymouse
 hotlight
 hotspot
 HPAINTBUFFER
@@ -701,9 +712,12 @@ IMAGERESIZERCONTEXTMENU
 IMAGERESIZEREXT
 imageresizerinput
 imageresizersettings
+imagetotext
+imagetotextshortcut
 imagingdevices
 ime
 imgflip
+inapp
 inbox
 INCONTACT
 Indo
@@ -757,6 +771,7 @@ istep
 ith
 ITHUMBNAIL
 IUI
+IUWP
 IWIC
 jfif
 jgeosdfsdsgmkedfgdfgdfgbkmhcgcflmi
@@ -786,6 +801,7 @@ keyvault
 KILLFOCUS
 killrunner
 kmph
+kvp
 Kybd
 lastcodeanalysissucceeded
 LASTEXITCODE
@@ -824,6 +840,7 @@ localappdata
 localpackage
 LOCALSYSTEM
 LOCATIONCHANGE
+LOCKMACHINE
 LOCKTYPE
 LOGFONT
 LOGFONTW
@@ -909,6 +926,7 @@ MDL
 mdtext
 mdtxt
 mdwn
+measuretool
 meme
 memicmp
 MENUITEMINFO
@@ -958,6 +976,7 @@ MOUSEHWHEEL
 MOUSEINPUT
 mousejump
 mousepointer
+mousepointercrosshairs
 mouseutils
 MOVESIZEEND
 MOVESIZESTART
@@ -969,6 +988,7 @@ msc
 mscorlib
 msctls
 msdata
+msdia
 MSDL
 MSGFLT
 MSHCTX
@@ -1157,6 +1177,18 @@ PARENTRELATIVEFORADDRESSBAR
 PARENTRELATIVEPARSING
 parray
 PARTIALCONFIRMATIONDIALOGTITLE
+pasteashtmlfile
+pasteashtmlfileshortcut
+pasteasjson
+pasteasjsonshortcut
+pasteasmarkdown
+pasteasmarkdownshortcut
+pasteasplaintext
+pasteasplaintextshortcut
+pasteaspngfile
+pasteaspngfileshortcut
+pasteastxtfile
+pasteastxtfileshortcut
 PATCOPY
 PATHMUSTEXIST
 PATINVERT
@@ -1224,6 +1256,7 @@ Pomodoro
 Popups
 POPUPWINDOW
 POSITIONITEM
+powerocr
 POWERRENAMECONTEXTMENU
 powerrenameinput
 POWERRENAMETEST
@@ -1364,6 +1397,7 @@ Removelnk
 renamable
 RENAMEONCOLLISION
 reparented
+reparenthotkey
 reparenting
 reportfileaccesses
 requery
@@ -1613,6 +1647,7 @@ STYLECHANGED
 STYLECHANGING
 subkeys
 sublang
+Subdomain
 SUBMODULEUPDATE
 subresource
 Superbar
@@ -1683,6 +1718,7 @@ THH
 THICKFRAME
 THISCOMPONENT
 throughs
+thumbnailhotkey
 TILEDWINDOW
 TILLSON
 timedate
@@ -1697,6 +1733,7 @@ tlb
 tlbimp
 tlc
 TNP
+TOGGLEEASYMOUSE
 Toolhelp
 toolkitconverters
 toolwindow
@@ -1710,6 +1747,7 @@ tracelogging
 tracerpt
 trackbar
 trafficmanager
+transcodetomp
 transicc
 TRAYMOUSEMESSAGE
 triaging

.pipelines/v2/release.yml

@@ -64,6 +64,10 @@ extends:
       tsa:
         enabled: true
         configFile: '$(Build.SourcesDirectory)\.pipelines\tsa.json'
+      binskim:
+        enabled: true
+        # Exclude every dll/exe in tests/*, as well as all msdia*, covrun* and vcruntime*
+        analyzeTargetGlob: +:file|$(Build.ArtifactStagingDirectory)/**/*.dll;+:file|$(Build.ArtifactStagingDirectory)/**/*.exe;-:file:regex|tests.*\.(dll|exe)$;-:file:regex|(covrun.*)\.dll$;-:file:regex|(msdia.*)\.dll$;-:file:regex|(vcruntime.*)\.dll$
 
     stages:
       - stage: Build

.pipelines/v2/templates/job-test-project.yml

@@ -147,10 +147,10 @@ jobs:
           & "$(build.sourcesdirectory)\.pipelines\installPowerToys.ps1" -InstallMode "Machine"
         displayName: Install PowerToys (Machine-Level)
 
-  - ${{ if ne(parameters.platform, 'arm64') }}:
-    - task: ScreenResolutionUtility@1
-      inputs:
-        displaySettings: 'optimal'
+  # - ${{ if ne(parameters.platform, 'arm64') }}:
+  #   - task: ScreenResolutionUtility@1
+  #     inputs:
+  #       displaySettings: 'optimal'
 
   - ${{ if eq(length(parameters.uiTestModules), 0) }}:
     - task: VSTest@3

PowerToys.sln

@@ -788,6 +788,14 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.CmdPal.Ext.Window
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.CmdPal.Ext.UnitTestBase", "src\modules\cmdpal\Tests\Microsoft.CmdPal.Ext.UnitTestsBase\Microsoft.CmdPal.Ext.UnitTestBase.csproj", "{00D8659C-2068-40B6-8B86-759CD6284BBB}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{E11826E1-76DF-42AC-985C-164CC2EE57A1}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ScreenRuler.UITests", "src\modules\MeasureTool\Tests\ScreenRuler.UITests\ScreenRuler.UITests.csproj", "{66C069F8-C548-4CA6-8CDE-239104D68E88}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.CmdPal.Ext.Apps.UnitTests", "src\modules\cmdpal\Tests\Microsoft.CmdPal.Ext.Apps.UnitTests\Microsoft.CmdPal.Ext.Apps.UnitTests.csproj", "{E816D7B1-4688-4ECB-97CC-3D8E798F3830}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Microsoft.CmdPal.Ext.Bookmarks.UnitTests", "src\modules\cmdpal\Tests\Microsoft.CmdPal.Ext.Bookmarks.UnitTests\Microsoft.CmdPal.Ext.Bookmarks.UnitTests.csproj", "{E816D7B3-4688-4ECB-97CC-3D8E798F3832}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|ARM64 = Debug|ARM64
@@ -2850,6 +2858,22 @@ Global
 		{00D8659C-2068-40B6-8B86-759CD6284BBB}.Release|ARM64.Build.0 = Release|ARM64
 		{00D8659C-2068-40B6-8B86-759CD6284BBB}.Release|x64.ActiveCfg = Release|x64
 		{00D8659C-2068-40B6-8B86-759CD6284BBB}.Release|x64.Build.0 = Release|x64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Debug|ARM64.ActiveCfg = Debug|ARM64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Debug|ARM64.Build.0 = Debug|ARM64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Debug|x64.ActiveCfg = Debug|x64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Debug|x64.Build.0 = Debug|x64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Release|ARM64.ActiveCfg = Release|ARM64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Release|ARM64.Build.0 = Release|ARM64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Release|x64.ActiveCfg = Release|x64
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830}.Release|x64.Build.0 = Release|x64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Debug|ARM64.ActiveCfg = Debug|ARM64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Debug|ARM64.Build.0 = Debug|ARM64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Debug|x64.ActiveCfg = Debug|x64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Debug|x64.Build.0 = Debug|x64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Release|ARM64.ActiveCfg = Release|ARM64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Release|ARM64.Build.0 = Release|ARM64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Release|x64.ActiveCfg = Release|x64
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832}.Release|x64.Build.0 = Release|x64
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -3161,6 +3185,8 @@ Global
 		{E816D7AF-4688-4ECB-97CC-3D8E798F3828} = {8EF25507-2575-4ADE-BF7E-D23376903AB8}
 		{E816D7B0-4688-4ECB-97CC-3D8E798F3829} = {8EF25507-2575-4ADE-BF7E-D23376903AB8}
 		{00D8659C-2068-40B6-8B86-759CD6284BBB} = {8EF25507-2575-4ADE-BF7E-D23376903AB8}
+		{E816D7B1-4688-4ECB-97CC-3D8E798F3830} = {8EF25507-2575-4ADE-BF7E-D23376903AB8}
+		{E816D7B3-4688-4ECB-97CC-3D8E798F3832} = {8EF25507-2575-4ADE-BF7E-D23376903AB8}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {C3A2F9D1-7930-4EF4-A6FC-7EE0A99821D0}

doc/devdocs/core/settings/settings-implementation.md

@@ -71,6 +71,41 @@ When the user changes settings in the UI:
 3. The runner calls the `set_config` function on the appropriate module
 4. The module parses the JSON and applies the new settings
 
+# Shortcut Conflict Detection
+
+Steps to enable conflict detection for a hotkey:
+
+### 1. Implement module interface for hotkeys
+Ensure the module interface provides either `size_t get_hotkeys(Hotkey* hotkeys, size_t buffer_size)` or `std::optional<HotkeyEx> GetHotkeyEx()`.
+
+- If not yet implemented, you need to add it so that it returns all hotkeys used by the module.
+- **Important**: The order of the returned hotkeys matters. This order is used as an index to uniquely identify each hotkey for conflict detection and lookup.
+- For reference, see: `src/modules/AdvancedPaste/AdvancedPasteModuleInterface/dllmain.cpp`
+
+### 2. Implement IHotkeyConfig in the module settings (UI side)
+Make sure the module’s settings file inherits from `IHotkeyConfig` and implements `HotkeyAccessor[] GetAllHotkeyAccessors()`.
+
+- This method should return all hotkeys used in the module.
+- **Important**: The order of the returned hotkeys must be consistent with step 1 (`get_hotkeys()` or `GetHotkeyEx()`).
+- For reference, see: `src/settings-ui/Settings.UI.Library/AdvancedPasteSettings.cs`
+- **_Note:_** `HotkeyAccessor` is a wrapper around HotkeySettings. 
+It provides both `getter` and `setter` methods to read and update the corresponding hotkey.
+Additionally, each `HotkeyAccessor` requires a resource string that describes the purpose of the hotkey.
+This string is typically defined in: `src/settings-ui/Settings.UI/Strings/en-us/Resources.resw`
+
+### 3. Update the module’s ViewModel
+The corresponding ViewModel should inherit from `PageViewModelBase` and implement `Dictionary<string, HotkeySettings[]> GetAllHotkeySettings()`.
+
+- This method should return all hotkeys, maintaining the same order as in steps 1 and 2.
+- For reference, see: `src/settings-ui/Settings.UI/ViewModels/AdvancedPasteViewModel.cs`
+
+### 4. Ensure the module’s Views call `OnPageLoaded()`
+Once the module’s view is loaded, make sure to invoke the ViewModel’s `OnPageLoaded()` method:
+```cs
+Loaded += (s, e) => ViewModel.OnPageLoaded();
+```
+- For reference, see: `src/settings-ui/Settings.UI/SettingsXAML/Views/AdvancedPaste.xaml.cs`
+
 ## Debugging Settings
 
 To debug settings issues:

doc/devdocs/development/debugging.md

@@ -18,8 +18,8 @@ You can build the entire solution from the command line, which is sometimes fast
 1. Open Developer Command Prompt for VS 2022
 2. Navigate to the repository root directory
 3. Run the following command(don't forget to set the correct platform):
-   ```
-   msbuild -restore -p:RestorePackagesConfig=true -p:Platform=ARM64 -m PowerToys.sln
+   ```pwsh
+   msbuild -restore -p:RestorePackagesConfig=true -p:Platform=ARM64 -m PowerToys.sln /tl /p:NuGetInteractive="true"
    ```
 4. This process should complete in approximately 13-14 minutes for a full build
 

doc/devdocs/readme.md

@@ -52,7 +52,7 @@ Once you've discussed your proposed feature/fix/etc. with a team member, and an
 ## Rules
 
 - **Follow the pattern of what you already see in the code.**
-- [Coding style](development/style.md).
+- [Coding style](style.md).
 - Try to package new functionality/components into libraries that have nicely defined interfaces.
 - Package new functionality into classes or refactor existing functionality into a class as you extend the code.
 - When adding new classes/methods/changing existing code, add new unit tests or update the existing tests.

installer/PowerToysSetup/Resources.wxs

@@ -11,7 +11,7 @@
   <Fragment>
     <!-- Resource directories should be added only if the installer is built on the build farm -->
     <?ifdef env.IsPipeline?>
-      <?foreach ParentDirectory in INSTALLFOLDER;HistoryPluginFolder;CalculatorPluginFolder;FolderPluginFolder;ProgramPluginFolder;ShellPluginFolder;IndexerPluginFolder;UnitConverterPluginFolder;ValueGeneratorPluginFolder;UriPluginFolder;WindowWalkerPluginFolder;OneNotePluginFolder;RegistryPluginFolder;VSCodeWorkspacesPluginFolder;ServicePluginFolder;SystemPluginFolder;TimeDatePluginFolder;WindowsSettingsPluginFolder;WindowsTerminalPluginFolder;WebSearchPluginFolder;PowerToysPluginFolder?>
+      <?foreach ParentDirectory in INSTALLFOLDER;WinUI3AppsInstallFolder;HistoryPluginFolder;CalculatorPluginFolder;FolderPluginFolder;ProgramPluginFolder;ShellPluginFolder;IndexerPluginFolder;UnitConverterPluginFolder;ValueGeneratorPluginFolder;UriPluginFolder;WindowWalkerPluginFolder;OneNotePluginFolder;RegistryPluginFolder;VSCodeWorkspacesPluginFolder;ServicePluginFolder;SystemPluginFolder;TimeDatePluginFolder;WindowsSettingsPluginFolder;WindowsTerminalPluginFolder;WebSearchPluginFolder;PowerToysPluginFolder?>
         <DirectoryRef Id="$(var.ParentDirectory)">
           <!-- Resource file directories -->
           <?foreach Language in $(var.LocLanguageList)?>
@@ -181,7 +181,7 @@
       </Component>
       <Component
           Id="ImageResizer_$(var.IdSafeLanguage)_Component"
-          Directory="Resource$(var.IdSafeLanguage)INSTALLFOLDER"
+          Directory="Resource$(var.IdSafeLanguage)WinUI3AppsInstallFolder"
           Guid="$(var.CompGUIDPrefix)02">
         <RegistryKey Root="$(var.RegistryScope)" Key="Software\Classes\powertoys\components">
           <RegistryValue Type="string" Name="ImageResizer_$(var.IdSafeLanguage)_Component" Value="" KeyPath="yes"/>
@@ -553,6 +553,7 @@
           <RemoveFolder Id="RemoveFolderResourcesResource$(var.IdSafeLanguage)HistoryPluginFolder" Directory="Resource$(var.IdSafeLanguage)HistoryPluginFolder" On="uninstall"/>
           <RemoveFolder Id="RemoveFolderResourcesResource$(var.IdSafeLanguage)PowerToysPluginFolder" Directory="Resource$(var.IdSafeLanguage)PowerToysPluginFolder" On="uninstall"/>
           <RemoveFolder Id="RemoveFolderResourcesResource$(var.IdSafeLanguage)ValueGeneratorPluginFolder" Directory="Resource$(var.IdSafeLanguage)ValueGeneratorPluginFolder" On="uninstall"/>
+          <RemoveFolder Id="RemoveFolderResourcesResource$(var.IdSafeLanguage)WinUI3AppsInstallFolder" Directory="Resource$(var.IdSafeLanguage)WinUI3AppsInstallFolder" On="uninstall"/>
       <?undef IdSafeLanguage?>
         <?endforeach?>
       </Component>

src/common/UITestAutomation/ModuleConfigData.cs

@@ -33,6 +33,7 @@ namespace Microsoft.PowerToys.UITest
         Workspaces,
         PowerRename,
         CommandPalette,
+        ScreenRuler,
     }
 
     /// <summary>
@@ -104,6 +105,7 @@ namespace Microsoft.PowerToys.UITest
                 [PowerToysModule.Workspaces] = new ModuleInfo("PowerToys.WorkspacesEditor.exe", "Workspaces Editor"),
                 [PowerToysModule.PowerRename] = new ModuleInfo("PowerToys.PowerRename.exe", "PowerRename", "WinUI3Apps"),
                 [PowerToysModule.CommandPalette] = new ModuleInfo("Microsoft.CmdPal.UI.exe", "PowerToys Command Palette", "WinUI3Apps\\CmdPal"),
+                [PowerToysModule.ScreenRuler] = new ModuleInfo("PowerToys.MeasureToolUI.exe", "PowerToys.ScreenRuler", "WinUI3Apps"),
             };
         }
 

src/modules/AdvancedPaste/AdvancedPasteModuleInterface/dllmain.cpp

@@ -112,7 +112,7 @@ private:
         return {};
     }
 
-    static Hotkey parse_single_hotkey(const winrt::Windows::Data::Json::JsonObject& jsonHotkeyObject)
+    static Hotkey parse_single_hotkey(const winrt::Windows::Data::Json::JsonObject& jsonHotkeyObject, bool isShown = true)
     {
         try
         {
@@ -122,6 +122,7 @@ private:
             hotkey.shift = jsonHotkeyObject.GetNamedBoolean(JSON_KEY_SHIFT);
             hotkey.ctrl = jsonHotkeyObject.GetNamedBoolean(JSON_KEY_CTRL);
             hotkey.key = static_cast<unsigned char>(jsonHotkeyObject.GetNamedNumber(JSON_KEY_CODE));
+            hotkey.isShown = isShown;
             return hotkey;
         }
         catch (...)
@@ -231,8 +232,10 @@ private:
         return false;
     }
 
-    void process_additional_action(const winrt::hstring& actionName, const winrt::Windows::Data::Json::IJsonValue& actionValue)
+    void process_additional_action(const winrt::hstring& actionName, const winrt::Windows::Data::Json::IJsonValue& actionValue, bool actionsGroupIsShown = true)
     {
+        bool actionIsShown = true;
+
         if (actionValue.ValueType() != winrt::Windows::Data::Json::JsonValueType::Object)
         {
             return;
@@ -240,9 +243,9 @@ private:
 
         const auto action = actionValue.GetObjectW();
 
-        if (!action.GetNamedBoolean(JSON_KEY_IS_SHOWN, false))
+        if (!action.GetNamedBoolean(JSON_KEY_IS_SHOWN, false) || !actionsGroupIsShown)
         {
-            return;
+            actionIsShown = false;
         }
 
         if (action.HasKey(JSON_KEY_SHORTCUT))
@@ -250,7 +253,7 @@ private:
             const AdditionalAction additionalAction
             {
                 actionName.c_str(),
-                parse_single_hotkey(action.GetNamedObject(JSON_KEY_SHORTCUT))
+                parse_single_hotkey(action.GetNamedObject(JSON_KEY_SHORTCUT), actionIsShown)
             };
 
             m_additional_actions.push_back(additionalAction);
@@ -259,12 +262,12 @@ private:
         {
             for (const auto& [subActionName, subAction] : action)
             {
-                process_additional_action(subActionName, subAction);
+                process_additional_action(subActionName, subAction, actionIsShown);
             }
         }
     }
 
-    void read_settings(PowerToysSettings::PowerToyValues& settings)
+        void read_settings(PowerToysSettings::PowerToyValues& settings)
     {
         const auto settingsObject = settings.get_raw_json();
 
@@ -317,9 +320,21 @@ private:
                     {
                         const auto additionalActions = propertiesObject.GetNamedObject(JSON_KEY_ADDITIONAL_ACTIONS);
 
-                        for (const auto& [actionName, additionalAction] : additionalActions)
+                        // Define the expected order to ensure consistent hotkey ID assignment
+                        const std::vector<winrt::hstring> expectedOrder = {
+                            L"image-to-text",
+                            L"paste-as-file",
+                            L"transcode"
+                        };
+
+                        // Process actions in the predefined order
+                        for (auto& actionKey : expectedOrder)
                         {
-                            process_additional_action(actionName, additionalAction);
+                            if (additionalActions.HasKey(actionKey))
+                            {
+                                const auto actionValue = additionalActions.GetNamedValue(actionKey);
+                                process_additional_action(actionKey, actionValue);
+                            }
                         }
                     }
 
@@ -331,17 +346,14 @@ private:
                             for (const auto& customAction : customActions)
                             {
                                 const auto object = customAction.GetObjectW();
+                                bool actionIsShown = object.GetNamedBoolean(JSON_KEY_IS_SHOWN, false);
 
-                                if (object.GetNamedBoolean(JSON_KEY_IS_SHOWN, false))
-                                {
-                                    const CustomAction customActionData
-                                    {
-                                        static_cast<int>(object.GetNamedNumber(JSON_KEY_ID)),
-                                        parse_single_hotkey(object.GetNamedObject(JSON_KEY_SHORTCUT))
-                                    };
+                                const CustomAction customActionData{
+                                    static_cast<int>(object.GetNamedNumber(JSON_KEY_ID)),
+                                    parse_single_hotkey(object.GetNamedObject(JSON_KEY_SHORTCUT), actionIsShown)
+                                };
 
-                                    m_custom_actions.push_back(customActionData);
-                                }
+                                m_custom_actions.push_back(customActionData);
                             }
                         }
                     }

src/modules/Hosts/Hosts.Tests/HostsServiceTest.cs

@@ -298,5 +298,34 @@ namespace Hosts.Tests
             var hidden = fileSystem.FileInfo.New(service.HostsFilePath).Attributes.HasFlag(FileAttributes.Hidden);
             Assert.IsTrue(hidden);
         }
+
+        [TestMethod]
+        public async Task NoLeadingSpaces_Disabled_RemovesIndent()
+        {
+            var content =
+        @"10.1.1.1 host host.local # comment
+10.1.1.2 host2 host2.local # another comment
+";
+
+            var expected =
+        @"10.1.1.1  host host.local     # comment
+10.1.1.2  host2 host2.local   # another comment
+# 10.1.1.30 host30 host30.local # new entry
+";
+
+            var fs = new CustomMockFileSystem();
+            var settings = new Mock<IUserSettings>();
+            settings.Setup(s => s.NoLeadingSpaces).Returns(true);
+            var svc = new HostsService(fs, settings.Object, _elevationHelper.Object);
+            fs.AddFile(svc.HostsFilePath, new MockFileData(content));
+
+            var data = await svc.ReadAsync();
+            var entries = data.Entries.ToList();
+            entries.Add(new Entry(0, "10.1.1.30", "host30 host30.local", "new entry", false));
+            await svc.WriteAsync(data.AdditionalLines, entries);
+
+            var result = fs.GetFile(svc.HostsFilePath);
+            Assert.AreEqual(expected, result.TextContents);
+        }
     }
 }

src/modules/Hosts/Hosts/Settings/UserSettings.cs

@@ -26,6 +26,8 @@ namespace Hosts.Settings
 
         private bool _loopbackDuplicates;
 
+        public bool NoLeadingSpaces { get; private set; }
+
         public bool LoopbackDuplicates
         {
             get => _loopbackDuplicates;
@@ -88,6 +90,7 @@ namespace Hosts.Settings
                             AdditionalLinesPosition = (HostsAdditionalLinesPosition)settings.Properties.AdditionalLinesPosition;
                             Encoding = (HostsEncoding)settings.Properties.Encoding;
                             LoopbackDuplicates = settings.Properties.LoopbackDuplicates;
+                            NoLeadingSpaces = settings.Properties.NoLeadingSpaces;
                         }
 
                         retry = false;

src/modules/Hosts/HostsUILib/Helpers/HostsService.cs

@@ -157,7 +157,7 @@ namespace HostsUILib.Helpers
                         {
                             lineBuilder.Append('#').Append(' ');
                         }
-                        else if (anyDisabled)
+                        else if (anyDisabled && !_userSettings.NoLeadingSpaces)
                         {
                             lineBuilder.Append(' ').Append(' ');
                         }

src/modules/Hosts/HostsUILib/Settings/IUserSettings.cs

@@ -19,5 +19,7 @@ namespace HostsUILib.Settings
         event EventHandler LoopbackDuplicatesChanged;
 
         public delegate void OpenSettingsFunction();
+
+        public bool NoLeadingSpaces { get; }
     }
 }

src/modules/MeasureTool/MeasureToolCore/ToolState.h

@@ -31,7 +31,11 @@ struct CommonState
 
     Measurement::Unit units = Measurement::Unit::Pixel;
 
-    POINT cursorPosSystemSpace = {}; // updated atomically
+    #pragma warning(push)
+    #pragma warning(disable : 4324)
+    alignas(8) POINT cursorPosSystemSpace = {}; // updated atomically
+    #pragma warning(pop)
+    
     std::atomic_bool closeOnOtherMonitors = false;
 
     float GetPhysicalPx2MmRatio(HWND window) const

src/modules/MeasureTool/MeasureToolUI/MeasureToolXAML/MainWindow.xaml

@@ -5,6 +5,7 @@
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:winuiex="using:WinUIEx"
+    Title="PowerToys.ScreenRuler"
     IsAlwaysOnTop="True"
     IsMaximizable="False"
     IsMinimizable="False"
@@ -250,6 +251,7 @@
             <ToggleButton
                 Name="btnBounds"
                 x:Uid="BtnBounds"
+                AutomationProperties.AutomationId="Button_Bounds"
                 Click="BoundsTool_Click"
                 Content="&#xEF20;"
                 KeyboardAcceleratorPlacementMode="Auto"
@@ -267,6 +269,7 @@
             <ToggleButton
                 Name="btnSpacing"
                 x:Uid="BtnSpacing"
+                AutomationProperties.AutomationId="Button_Spacing"
                 Click="MeasureTool_Click"
                 Style="{StaticResource ToggleButtonRadioButtonStyle}">
                 <ToolTipService.ToolTip>
@@ -284,6 +287,7 @@
             <ToggleButton
                 Name="btnHorizontalSpacing"
                 x:Uid="BtnHorizontalSpacing"
+                AutomationProperties.AutomationId="Button_SpacingHorizontal"
                 Click="HorizontalMeasureTool_Click"
                 Style="{StaticResource ToggleButtonRadioButtonStyle}">
                 <ToolTipService.ToolTip>
@@ -304,6 +308,7 @@
             <ToggleButton
                 Name="btnVerticalSpacing"
                 x:Uid="BtnVerticalSpacing"
+                AutomationProperties.AutomationId="Button_SpacingVertical"
                 Click="VerticalMeasureTool_Click"
                 Style="{StaticResource ToggleButtonRadioButtonStyle}">
                 <ToolTipService.ToolTip>
@@ -324,6 +329,7 @@
             <AppBarSeparator />
             <Button
                 x:Uid="BtnClosePanel"
+                AutomationProperties.AutomationId="Button_Close"
                 Click="ClosePanelTool_Click"
                 Content="&#xE8BB;"
                 Foreground="{StaticResource CloseButtonBackgroundPointerOver}">

src/modules/MeasureTool/Tests/ScreenRuler.UITests/Package.appxmanifest

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<Package
+  xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
+  xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
+  xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
+  xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
+  IgnorableNamespaces="uap rescap">
+
+  <Identity
+    Name="d4d0f157-5c12-4390-9689-152b0c86a582"
+    Publisher="CN=gkhmyznikov"
+    Version="1.0.0.0" />
+
+  <mp:PhoneIdentity PhoneProductId="d4d0f157-5c12-4390-9689-152b0c86a582" PhonePublisherId="00000000-0000-0000-0000-000000000000"/>
+
+  <Properties>
+    <DisplayName>ScreenRuler.UITests</DisplayName>
+    <PublisherDisplayName>gkhmyznikov</PublisherDisplayName>
+    <Logo>Assets\StoreLogo.png</Logo>
+  </Properties>
+
+  <Dependencies>
+    <TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.17763.0" MaxVersionTested="10.0.19041.0" />
+    <TargetDeviceFamily Name="Windows.Desktop" MinVersion="10.0.17763.0" MaxVersionTested="10.0.19041.0" />
+  </Dependencies>
+
+  <Resources>
+    <Resource Language="x-generate"/>
+  </Resources>
+
+  <Applications>
+    <Application Id="App"
+      Executable="$targetnametoken$.exe"
+      EntryPoint="$targetentrypoint$">
+      <uap:VisualElements
+        DisplayName="ScreenRuler.UITests"
+        Description="ScreenRuler.UITests"
+        BackgroundColor="transparent"
+        Square150x150Logo="Assets\Square150x150Logo.png"
+        Square44x44Logo="Assets\Square44x44Logo.png">
+        <uap:DefaultTile Wide310x150Logo="Assets\Wide310x150Logo.png" />
+        <uap:SplashScreen Image="Assets\SplashScreen.png" />
+      </uap:VisualElements>
+    </Application>
+  </Applications>
+
+  <Capabilities>
+    <rescap:Capability Name="runFullTrust" />
+  </Capabilities>
+</Package>

src/modules/MeasureTool/Tests/ScreenRuler.UITests/ScreenRuler.UITests.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <Import Project="..\..\..\..\Common.Dotnet.CsWinRT.props" />
+  <PropertyGroup>
+	  <RootNamespace>PowerToys.ScreenRuler.UITests</RootNamespace>
+	  <AssemblyName>ScreenRuler.UITests</AssemblyName>
+	  <IsPackable>false</IsPackable>
+	  <IsTestProject>true</IsTestProject>
+	  <Nullable>enable</Nullable>
+	  <OutputType>Library</OutputType>
+
+	  <!-- This is a UI test, so don't run as part of MSBuild -->
+	  <RunVSTest>false</RunVSTest>
+  </PropertyGroup>
+  <PropertyGroup>
+	  <OutputPath>$(SolutionDir)$(Platform)\$(Configuration)\tests\ScreenRuler.UITests\</OutputPath>
+  </PropertyGroup>
+
+  <ItemGroup>
+	  <PackageReference Include="MSTest" />
+	  <ProjectReference Include="..\..\..\..\common\UITestAutomation\UITestAutomation.csproj" />
+  </ItemGroup>
+</Project>
+ 

src/modules/MeasureTool/Tests/ScreenRuler.UITests/TestBounds.cs

@@ -0,0 +1,27 @@
+// 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 Microsoft.PowerToys.UITest;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ScreenRuler.UITests
+{
+    [TestClass]
+    public class TestBounds : UITestBase
+    {
+        public TestBounds()
+            : base(PowerToysModule.PowerToysSettings, WindowSize.Large)
+        {
+        }
+
+        [TestMethod("ScreenRuler.BoundsTool")]
+        [TestCategory("Spacing")]
+        public void TestScreenRulerBoundsTool()
+        {
+            TestHelper.InitializeTest(this, "bounds test");
+            TestHelper.PerformBoundsToolTest(this);
+            TestHelper.CleanupTest(this);
+        }
+    }
+}

src/modules/MeasureTool/Tests/ScreenRuler.UITests/TestHelper.cs

@@ -0,0 +1,466 @@
+// 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;
+using System.Collections.Generic;
+using System.Text.RegularExpressions;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.PowerToys.UITest;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ScreenRuler.UITests
+{
+    public static class TestHelper
+    {
+        private static readonly string[] ShortcutSeparators = { " + ", "+", " " };
+
+        // Button automation names from Resources.resw
+        public const string BoundsButtonId = "Button_Bounds";
+        public const string SpacingButtonName = "Button_Spacing";
+        public const string HorizontalSpacingButtonName = "Button_SpacingHorizontal";
+        public const string VerticalSpacingButtonName = "Button_SpacingVertical";
+        public const string CloseButtonId = "Button_Close";
+
+        /// <summary>
+        /// Performs common test initialization: navigate to settings, enable toggle, verify shortcut
+        /// </summary>
+        /// <param name="testBase">The test base instance</param>
+        /// <param name="testName">Name of the test for assertions</param>
+        /// <returns>The activation keys for the test</returns>
+        public static Key[] InitializeTest(UITestBase testBase, string testName)
+        {
+            LaunchFromSetting(testBase);
+
+            var toggleSwitch = SetScreenRulerToggle(testBase, enable: true);
+            Assert.IsTrue(
+                toggleSwitch.IsOn,
+                $"Screen Ruler toggle switch should be ON for {testName}");
+
+            var activationKeys = ReadActivationShortcut(testBase);
+            Assert.IsNotNull(activationKeys, "Should be able to read activation shortcut");
+            Assert.IsTrue(activationKeys.Length > 0, "Activation shortcut should contain at least one key");
+
+            return activationKeys;
+        }
+
+        /// <summary>
+        /// Performs common test cleanup: close ScreenRuler UI
+        /// </summary>
+        /// <param name="testBase">The test base instance</param>
+        public static void CleanupTest(UITestBase testBase)
+        {
+            CloseScreenRulerUI(testBase);
+
+            // Ensure we're attached to settings after cleanup
+            try
+            {
+                testBase.Session.Attach(PowerToysModule.PowerToysSettings);
+            }
+            catch
+            {
+                // Ignore attachment errors - this is just cleanup
+            }
+        }
+
+        /// <summary>
+        /// Navigate to the Screen Ruler (Measure Tool) settings page
+        /// </summary>
+        public static void LaunchFromSetting(UITestBase testBase)
+        {
+            var screenRulers = testBase.Session.FindAll<NavigationViewItem>(By.AccessibilityId("Shell_Nav_ScreenRuler"));
+
+            if (screenRulers.Count == 0)
+            {
+                testBase.Session.Find<NavigationViewItem>(By.AccessibilityId("Shell_Nav_TopLevelSystemTools"), 5000).Click(msPostAction: 500);
+            }
+
+            testBase.Session.Find<NavigationViewItem>(By.AccessibilityId("Shell_Nav_ScreenRuler"), 5000).Click(msPostAction: 500);
+        }
+
+        /// <summary>
+        /// Set the Screen Ruler toggle switch to the specified state
+        /// </summary>
+        public static ToggleSwitch SetScreenRulerToggle(UITestBase testBase, bool enable)
+        {
+            var toggleSwitch = testBase.Session.Find<ToggleSwitch>(By.AccessibilityId("Toggle_ScreenRuler"), 5000);
+
+            if (toggleSwitch.IsOn != enable)
+            {
+                toggleSwitch.Click(msPreAction: 1000, msPostAction: 2000);
+            }
+
+            if (toggleSwitch.IsOn != enable)
+            {
+                testBase.Session.SendKey(Key.Space, msPreAction: 0, msPostAction: 2000);
+            }
+
+            return toggleSwitch;
+        }
+
+        /// <summary>
+        /// Set the Screen Ruler toggle and verify its state
+        /// </summary>
+        /// <param name="testBase">The test base instance</param>
+        /// <param name="enable">True to enable, false to disable</param>
+        /// <param name="testName">Name of the test for assertion messages</param>
+        public static void SetAndVerifyScreenRulerToggle(UITestBase testBase, bool enable, string testName)
+        {
+            var toggleSwitch = SetScreenRulerToggle(testBase, enable);
+            Assert.AreEqual(
+                enable,
+                toggleSwitch.IsOn,
+                $"Screen Ruler toggle switch should be {(enable ? "ON" : "OFF")} for {testName}");
+        }
+
+        /// <summary>
+        /// Read the current activation shortcut from the ShortcutControl
+        /// </summary>
+        public static Key[] ReadActivationShortcut(UITestBase testBase)
+        {
+            var shortcutCard = testBase.Session.Find<Element>(By.AccessibilityId("Shortcut_ScreenRuler"), 5000);
+            var shortcutButton = shortcutCard.Find<Element>(By.AccessibilityId("EditButton"), 5000);
+            return ParseShortcutText(shortcutButton.HelpText);
+        }
+
+        /// <summary>
+        /// Parse shortcut text like "Win + Ctrl + Shift + M" into Key array
+        /// </summary>
+        private static Key[] ParseShortcutText(string shortcutText)
+        {
+            if (string.IsNullOrEmpty(shortcutText))
+            {
+                return new Key[] { Key.Win, Key.Ctrl, Key.Shift, Key.M };
+            }
+
+            var keys = new List<Key>();
+            var parts = shortcutText.Split(ShortcutSeparators, StringSplitOptions.RemoveEmptyEntries);
+
+            foreach (var part in parts)
+            {
+                var cleanPart = part.Trim().ToLowerInvariant();
+                var key = cleanPart switch
+                {
+                    "win" or "windows" => Key.Win,
+                    "ctrl" or "control" => Key.Ctrl,
+                    "shift" => Key.Shift,
+                    "alt" => Key.Alt,
+                    _ when cleanPart.Length == 1 && char.IsLetter(cleanPart[0]) &&
+                         cleanPart[0] >= 'a' && cleanPart[0] <= 'z' =>
+                        (Key)Enum.Parse(typeof(Key), cleanPart.ToUpperInvariant()),
+                    _ => (Key?)null,
+                };
+
+                if (key.HasValue)
+                {
+                    keys.Add(key.Value);
+                }
+            }
+
+            return keys.Count > 0 ? keys.ToArray() : new Key[] { Key.Win, Key.Ctrl, Key.Shift, Key.M };
+        }
+
+        /// <summary>
+        /// Check if ScreenRulerUI window is open
+        /// </summary>
+        public static bool IsScreenRulerUIOpen(UITestBase testBase) => testBase.IsWindowOpen("PowerToys.ScreenRuler");
+
+        /// <summary>
+        /// Wait for ScreenRulerUI to reach the specified state within the timeout
+        /// </summary>
+        public static bool WaitForScreenRulerUIState(UITestBase testBase, bool shouldBeOpen, int timeoutMs = 5000, int pollingIntervalMs = 100)
+        {
+            var endTime = DateTime.Now.AddMilliseconds(timeoutMs);
+
+            while (DateTime.Now < endTime)
+            {
+                if (IsScreenRulerUIOpen(testBase) == shouldBeOpen)
+                {
+                    return true;
+                }
+
+                Task.Delay(pollingIntervalMs).Wait();
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Wait for ScreenRulerUI to appear within the specified timeout
+        /// </summary>
+        public static bool WaitForScreenRulerUI(UITestBase testBase, int timeoutMs = 5000) =>
+            WaitForScreenRulerUIState(testBase, shouldBeOpen: true, timeoutMs);
+
+        /// <summary>
+        /// Wait for ScreenRulerUI to disappear within the specified timeout
+        /// </summary>
+        public static bool WaitForScreenRulerUIToDisappear(UITestBase testBase, int timeoutMs = 5000) =>
+            WaitForScreenRulerUIState(testBase, shouldBeOpen: false, timeoutMs);
+
+        /// <summary>
+        /// Close ScreenRulerUI if it's open
+        /// </summary>
+        public static void CloseScreenRulerUI(UITestBase testBase)
+        {
+            if (IsScreenRulerUIOpen(testBase))
+            {
+                try
+                {
+                    // Attach to ScreenRuler window before trying to find and click close button
+                    testBase.Session.Attach(PowerToysModule.ScreenRuler);
+                    var closeButton = testBase.Session.Find<Element>(By.AccessibilityId(CloseButtonId), 15000, true);
+                    closeButton?.Click();
+                }
+                catch
+                {
+                    // If we can't find the close button, ignore - the window might have closed already
+                }
+                finally
+                {
+                    // Attach back to settings after closing
+                    try
+                    {
+                        testBase.Session.Attach(PowerToysModule.PowerToysSettings);
+                    }
+                    catch
+                    {
+                        // Ignore attachment errors
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Get a specific ScreenRulerUI button by its automation name
+        /// </summary>
+        public static Element? GetScreenRulerButton(UITestBase testBase, string buttonName, int timeoutMs = 1000)
+        {
+            return testBase.Session.Find<Element>(By.AccessibilityId(buttonName), timeoutMs, true);
+
+            /*
+            try
+            {
+                // Attach to ScreenRuler window before trying to find buttons
+                testBase.Session.Attach(PowerToysModule.ScreenRuler);
+                return testBase.Session.Find<Element>(By.AccessibilityId(buttonName), timeoutMs, true);
+            }
+            catch
+            {
+                return null;
+            }
+            finally
+            {
+                // Attach back to settings if needed for further operations
+                // This ensures we don't break the test flow
+                try
+                {
+                    testBase.Session.Attach(PowerToysModule.PowerToysSettings);
+                }
+                catch
+                {
+                    // Ignore attachment errors - the calling code will handle as needed
+                }
+            }
+            */
+        }
+
+        /// <summary>
+        /// Clear the clipboard content using STA thread
+        /// </summary>
+        public static void ClearClipboard()
+        {
+            ExecuteInSTAThread(() => System.Windows.Forms.Clipboard.Clear());
+        }
+
+        /// <summary>
+        /// Get text content from clipboard using STA thread
+        /// </summary>
+        public static string GetClipboardText()
+        {
+            string result = string.Empty;
+            ExecuteInSTAThread(() =>
+            {
+                if (System.Windows.Forms.Clipboard.ContainsText())
+                {
+                    result = System.Windows.Forms.Clipboard.GetText();
+                }
+            });
+            return result ?? string.Empty;
+        }
+
+        /// <summary>
+        /// Execute an action in an STA thread with error handling
+        /// </summary>
+        private static void ExecuteInSTAThread(Action action)
+        {
+            try
+            {
+                var staThread = new Thread(() =>
+                {
+                    try
+                    {
+                        action();
+                    }
+                    catch
+                    {
+                        // Ignore clipboard errors
+                    }
+                });
+
+                staThread.SetApartmentState(ApartmentState.STA);
+                staThread.Start();
+                staThread.Join(TimeSpan.FromSeconds(5));
+            }
+            catch
+            {
+                // Ignore clipboard errors
+            }
+        }
+
+        /// <summary>
+        /// Validate clipboard content contains valid spacing measurement for the specified type
+        /// </summary>
+        public static bool ValidateSpacingClipboardContent(string clipboardText, string spacingType)
+        {
+            if (string.IsNullOrEmpty(clipboardText))
+            {
+                return false;
+            }
+
+            return spacingType switch
+            {
+                "Spacing" => Regex.IsMatch(clipboardText, @"\d+\s*[<5B>x]\s*\d+"),
+                "Horizontal Spacing" or "Vertical Spacing" => Regex.IsMatch(clipboardText, @"^\d+$"),
+                _ => false,
+            };
+        }
+
+        /// <summary>
+        /// Perform a complete spacing tool test operation
+        /// </summary>
+        public static void PerformSpacingToolTest(UITestBase testBase, string buttonId, string testName)
+        {
+            ClearClipboard();
+
+            // Launch ScreenRuler UI
+            var activationKeys = ReadActivationShortcut(testBase);
+            testBase.SendKeys(activationKeys);
+
+            Assert.IsTrue(
+                WaitForScreenRulerUI(testBase, 2000),
+                $"ScreenRulerUI should appear after pressing activation shortcut for {testName}: {string.Join(" + ", activationKeys)}");
+
+            // Attach to ScreenRuler window and click spacing button
+            // testBase.Session.Attach(PowerToysModule.ScreenRuler);
+            var spacingButton = testBase.Session.Find<Element>(By.AccessibilityId(buttonId), 15000, true);
+            Assert.IsNotNull(spacingButton, $"{testName} button should be found");
+
+            spacingButton!.Click();
+            Task.Delay(500).Wait();
+
+            // Perform measurement action (stay attached to ScreenRuler for this)
+            PerformMeasurementAction(testBase);
+
+            // Validate results
+            ValidateClipboardResults(testName);
+
+            // Cleanup - this will handle session attachment properly
+            CloseScreenRulerUI(testBase);
+            Assert.IsTrue(
+                WaitForScreenRulerUIToDisappear(testBase, 2000),
+                $"{testName}: ScreenRulerUI should close after calling CloseScreenRulerUI");
+        }
+
+        /// <summary>
+        /// Perform a bounds tool test operation
+        /// </summary>
+        public static void PerformBoundsToolTest(UITestBase testBase)
+        {
+            ClearClipboard();
+
+            var activationKeys = ReadActivationShortcut(testBase);
+            testBase.SendKeys(activationKeys);
+
+            Assert.IsTrue(
+                WaitForScreenRulerUI(testBase, 2000),
+                $"ScreenRulerUI should appear after pressing activation shortcut: {string.Join(" + ", activationKeys)}");
+
+            // Attach to ScreenRuler window and click bounds button
+            // testBase.Session.Attach(PowerToysModule.ScreenRuler);
+            var boundsButton = testBase.Session.Find<Element>(By.AccessibilityId(BoundsButtonId), 15000, true);
+            Assert.IsNotNull(boundsButton, "Bounds button should be found");
+
+            boundsButton.Click();
+            Task.Delay(500).Wait();
+
+            // Perform drag operation to create 100x100 box (stay attached to ScreenRuler)
+            var currentPos = testBase.GetMousePosition();
+            int startX = currentPos.Item1;
+            int startY = currentPos.Item2 + 200;
+
+            testBase.MoveMouseTo(startX, startY);
+            Task.Delay(200).Wait();
+
+            // Drag operation
+            testBase.Session.PerformMouseAction(MouseActionType.LeftDown);
+            Task.Delay(100).Wait();
+
+            testBase.MoveMouseTo(startX + 99, startY + 99);
+            Task.Delay(200).Wait();
+
+            testBase.Session.PerformMouseAction(MouseActionType.LeftUp);
+            Task.Delay(500).Wait();
+
+            // Dismiss selection
+            testBase.Session.PerformMouseAction(MouseActionType.RightClick);
+            Task.Delay(500).Wait();
+
+            // Validate results
+            string clipboardText = GetClipboardText();
+            Assert.IsFalse(string.IsNullOrEmpty(clipboardText), "Clipboard should contain measurement data");
+            Assert.IsTrue(
+                clipboardText.Contains("100 <20> 100"),
+                $"Clipboard should contain '100 <20> 100', but contained: '{clipboardText}'");
+
+            // Cleanup - this will handle session attachment properly
+            CloseScreenRulerUI(testBase);
+            Assert.IsTrue(
+                WaitForScreenRulerUIToDisappear(testBase, 2000),
+                "ScreenRulerUI should close after calling CloseScreenRulerUI");
+        }
+
+        /// <summary>
+        /// Perform a measurement action (move mouse and click)
+        /// </summary>
+        private static void PerformMeasurementAction(UITestBase testBase)
+        {
+            var currentPos = testBase.GetMousePosition();
+            int startX = currentPos.Item1;
+            int startY = currentPos.Item2 + 200;
+
+            testBase.MoveMouseTo(startX, startY);
+            Task.Delay(200).Wait();
+
+            testBase.Session.PerformMouseAction(MouseActionType.LeftClick);
+            Task.Delay(500).Wait();
+
+            testBase.Session.PerformMouseAction(MouseActionType.RightClick);
+            Task.Delay(500).Wait();
+        }
+
+        /// <summary>
+        /// Validate clipboard results for spacing tests
+        /// </summary>
+        private static void ValidateClipboardResults(string testName)
+        {
+            string clipboardText = GetClipboardText();
+            Assert.IsFalse(string.IsNullOrEmpty(clipboardText), $"{testName}: Clipboard should contain measurement data");
+
+            bool containsValidPattern = ValidateSpacingClipboardContent(clipboardText, testName);
+            Assert.IsTrue(
+                containsValidPattern,
+                $"{testName}: Clipboard should contain valid spacing measurement, but contained: '{clipboardText}'");
+        }
+    }
+}

src/modules/MeasureTool/Tests/ScreenRuler.UITests/TestShortcutActivation.cs

@@ -0,0 +1,72 @@
+// 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.Threading.Tasks;
+using Microsoft.PowerToys.UITest;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ScreenRuler.UITests
+{
+    [TestClass]
+    public class TestShortcutActivation : UITestBase
+    {
+        public TestShortcutActivation()
+            : base(PowerToysModule.PowerToysSettings, WindowSize.Large)
+        {
+        }
+
+        [TestMethod("ScreenRuler.ShortcutActivation")]
+        [TestCategory("Activation")]
+        public void TestScreenRulerShortcutActivation()
+        {
+            var activationKeys = TestHelper.InitializeTest(this, "activation test");
+
+            // Test 1: Press the activation shortcut and verify the toolbar appears
+            SendKeys(activationKeys);
+            bool screenRulerAppeared = TestHelper.WaitForScreenRulerUI(this, 1000);
+            Assert.IsTrue(
+                screenRulerAppeared,
+                $"ScreenRulerUI should appear after pressing activation shortcut: {string.Join(" + ", activationKeys)}");
+
+            // Test 2: Press the activation shortcut again and verify the toolbar disappears
+            SendKeys(activationKeys);
+            bool screenRulerDisappeared = TestHelper.WaitForScreenRulerUIToDisappear(this, 1000);
+            Assert.IsTrue(
+                screenRulerDisappeared,
+                $"ScreenRulerUI should disappear after pressing activation shortcut again: {string.Join(" + ", activationKeys)}");
+
+            // Test 3: Disable Screen Ruler and verify that the activation shortcut no longer activates the utility
+            // Ensure we're attached to settings UI before toggling
+            Session.Attach(PowerToysModule.PowerToysSettings);
+            TestHelper.SetAndVerifyScreenRulerToggle(this, enable: false, "disabled state test");
+
+            // Try to activate with shortcut while disabled
+            SendKeys(activationKeys);
+            Task.Delay(1000).Wait();
+            Assert.IsFalse(
+                TestHelper.IsScreenRulerUIOpen(this),
+                "ScreenRulerUI should not appear when Screen Ruler is disabled");
+
+            // Test 4: Enable Screen Ruler and press the activation shortcut and verify the toolbar appears
+            // Ensure we're attached to settings UI before toggling
+            Session.Attach(PowerToysModule.PowerToysSettings);
+            TestHelper.SetAndVerifyScreenRulerToggle(this, enable: true, "re-enabled state test");
+
+            SendKeys(activationKeys);
+            screenRulerAppeared = TestHelper.WaitForScreenRulerUI(this, 1000);
+            Assert.IsTrue(
+                screenRulerAppeared,
+                $"ScreenRulerUI should appear after re-enabling and pressing activation shortcut: {string.Join(" + ", activationKeys)}");
+
+            // Test 5: Verify the utility can be closed via the cleanup method
+            TestHelper.CloseScreenRulerUI(this);
+            bool screenRulerClosed = TestHelper.WaitForScreenRulerUIToDisappear(this, 1000);
+            Assert.IsTrue(
+                screenRulerClosed,
+                "ScreenRulerUI should close after calling CloseScreenRulerUI");
+
+            TestHelper.CleanupTest(this);
+        }
+    }
+}

src/modules/MeasureTool/Tests/ScreenRuler.UITests/TestSpacing.cs

@@ -0,0 +1,27 @@
+// 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 Microsoft.PowerToys.UITest;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ScreenRuler.UITests
+{
+    [TestClass]
+    public class TestSpacing : UITestBase
+    {
+        public TestSpacing()
+            : base(PowerToysModule.PowerToysSettings, WindowSize.Large)
+        {
+        }
+
+        [TestMethod("ScreenRuler.SpacingTool")]
+        [TestCategory("Spacing")]
+        public void TestScreenRulerSpacingTool()
+        {
+            TestHelper.InitializeTest(this, "spacing test");
+            TestHelper.PerformSpacingToolTest(this, TestHelper.SpacingButtonName, "Spacing");
+            TestHelper.CleanupTest(this);
+        }
+    }
+}

src/modules/MeasureTool/Tests/ScreenRuler.UITests/TestSpacingHorizontal.cs

@@ -0,0 +1,27 @@
+// 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 Microsoft.PowerToys.UITest;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ScreenRuler.UITests
+{
+    [TestClass]
+    public class TestSpacingHorizontal : UITestBase
+    {
+        public TestSpacingHorizontal()
+            : base(PowerToysModule.PowerToysSettings, WindowSize.Large)
+        {
+        }
+
+        [TestMethod("ScreenRuler.HorizontalSpacingTool")]
+        [TestCategory("Spacing")]
+        public void TestScreenRulerHorizontalSpacingTool()
+        {
+            TestHelper.InitializeTest(this, "horizontal spacing test");
+            TestHelper.PerformSpacingToolTest(this, TestHelper.HorizontalSpacingButtonName, "Horizontal Spacing");
+            TestHelper.CleanupTest(this);
+        }
+    }
+}

src/modules/MeasureTool/Tests/ScreenRuler.UITests/TestSpacingVertical.cs

@@ -0,0 +1,27 @@
+// 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 Microsoft.PowerToys.UITest;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ScreenRuler.UITests
+{
+    [TestClass]
+    public class TestSpacingVertical : UITestBase
+    {
+        public TestSpacingVertical()
+            : base(PowerToysModule.PowerToysSettings, WindowSize.Large)
+        {
+        }
+
+        [TestMethod("ScreenRuler.VerticalSpacingTool")]
+        [TestCategory("Spacing")]
+        public void TestScreenRulerVerticalSpacingTool()
+        {
+            TestHelper.InitializeTest(this, "vertical spacing test");
+            TestHelper.PerformSpacingToolTest(this, TestHelper.VerticalSpacingButtonName, "Vertical Spacing");
+            TestHelper.CleanupTest(this);
+        }
+    }
+}

src/modules/MeasureTool/Tests/ScreenRuler.UITests/app.manifest

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <assemblyIdentity version="1.0.0.0" name="ScreenRuler.UITests.app"/>
+
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- The ID below informs the system that this application is compatible with OS features first introduced in Windows 10. 
+      It is necessary to support features in unpackaged applications, for example the custom titlebar implementation.
+      For more info see https://docs.microsoft.com/windows/apps/windows-app-sdk/use-windows-app-sdk-run-time#declare-os-compatibility-in-your-application-manifest -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
+    </application>
+  </compatibility>
+  
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
+    </windowsSettings>
+  </application>
+</assembly>

src/modules/MouseWithoutBorders/ModuleInterface/dllmain.cpp

@@ -556,6 +556,61 @@ public:
         return m_enabled;
     }
 
+    virtual size_t get_hotkeys(Hotkey* hotkeys, size_t buffer_size) override
+    {
+        constexpr size_t num_hotkeys = 4; // We have 4 hotkeys
+
+        if (hotkeys && buffer_size >= num_hotkeys)
+        {
+            PowerToysSettings::PowerToyValues values = PowerToysSettings::PowerToyValues::load_from_settings_file(MODULE_NAME);
+
+            // Cache the raw JSON object to avoid multiple parsing
+            json::JsonObject root_json = values.get_raw_json();
+            json::JsonObject properties_json = root_json.GetNamedObject(L"properties", json::JsonObject{});
+
+            size_t hotkey_index = 0;
+
+            // Helper lambda to extract hotkey from JSON properties
+            auto extract_hotkey = [&](const wchar_t* property_name) -> Hotkey {
+                if (properties_json.HasKey(property_name))
+                {
+                    try
+                    {
+                        json::JsonObject hotkey_json = properties_json.GetNamedObject(property_name);
+
+                        // Extract hotkey properties directly from JSON
+                        bool win = hotkey_json.GetNamedBoolean(L"win", false);
+                        bool ctrl = hotkey_json.GetNamedBoolean(L"ctrl", false);
+                        bool alt = hotkey_json.GetNamedBoolean(L"alt", false);
+                        bool shift = hotkey_json.GetNamedBoolean(L"shift", false);
+                        unsigned char key = static_cast<unsigned char>(
+                            hotkey_json.GetNamedNumber(L"code", 0));
+
+                        return { win, ctrl, shift, alt, key };
+                    }
+                    catch (...)
+                    {
+                        // If parsing individual hotkey fails, use defaults
+                        return { false, false, false, false, 0 };
+                    }
+                }
+                else
+                {
+                    // Property doesn't exist, use defaults
+                    return { false, false, false, false, 0 };
+                }
+            };
+
+            // Extract all hotkeys using the optimized helper
+            hotkeys[hotkey_index++] = extract_hotkey(L"ToggleEasyMouseShortcut"); // [0] Toggle Easy Mouse
+            hotkeys[hotkey_index++] = extract_hotkey(L"LockMachineShortcut");     // [1] Lock Machine
+            hotkeys[hotkey_index++] = extract_hotkey(L"Switch2AllPCShortcut");    // [2] Switch to All PCs
+            hotkeys[hotkey_index++] = extract_hotkey(L"ReconnectShortcut");       // [3] Reconnect
+        }
+
+        return num_hotkeys;
+    }
+
     void launch_add_firewall_process()
     {
         Logger::trace(L"Starting Process to add firewall rule");

src/modules/cmdpal/Microsoft.CmdPal.Common/Helpers/DiagnosticsHelper.cs

@@ -0,0 +1,66 @@
+// 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;
+using System.Runtime.InteropServices;
+
+namespace Microsoft.CmdPal.Common.Helpers;
+
+/// <summary>
+/// Provides utility methods for building diagnostic and error messages.
+/// </summary>
+public static class DiagnosticsHelper
+{
+    /// <summary>
+    /// Builds a comprehensive exception message with timestamp and detailed diagnostic information.
+    /// </summary>
+    /// <param name="exception">The exception that occurred.</param>
+    /// <param name="extensionHint">A hint about which extension caused the exception to help with debugging.</param>
+    /// <returns>A string containing the exception details, timestamp, and source information for diagnostic purposes.</returns>
+    public static string BuildExceptionMessage(Exception exception, string? extensionHint)
+    {
+        var locationHint = string.IsNullOrWhiteSpace(extensionHint) ? "application" : $"'{extensionHint}' extension";
+
+        // let's try to get a message from the exception or inferred it from the HRESULT
+        // to show at least something
+        var message = exception.Message;
+        if (string.IsNullOrWhiteSpace(message))
+        {
+            var temp = Marshal.GetExceptionForHR(exception.HResult)?.Message;
+            if (!string.IsNullOrWhiteSpace(temp))
+            {
+                message = temp + $" (inferred from HRESULT 0x{exception.HResult:X8})";
+            }
+        }
+
+        if (string.IsNullOrWhiteSpace(message))
+        {
+            message = "[No message available]";
+        }
+
+        // note: keep date time kind and format consistent with the log
+        return $"""
+                ============================================================
+                😢 An unexpected error occurred in the {locationHint}.
+
+                Summary:
+                  Message:    {message}
+                  Type:       {exception.GetType().FullName}
+                  Source:     {exception.Source ?? "N/A"}
+                  Time:       {DateTimeOffset.Now:yyyy-MM-dd HH:mm:ss.fffffff}
+                  HRESULT:    0x{exception.HResult:X8} ({exception.HResult})
+
+                Stack Trace:
+                {exception.StackTrace ?? "[No stack trace available]"}
+
+                ------------------ Full Exception Details ------------------
+                {exception}
+
+                ℹ️ If you need further assistance, please include this information in your support request.
+                ℹ️ Before sending, take a quick look to make sure it doesn't contain any personal or sensitive information.
+                ============================================================
+
+                """;
+    }
+}

src/modules/cmdpal/Microsoft.CmdPal.Common/Helpers/ExtensionHostInstance.cs

@@ -24,7 +24,7 @@ public partial class ExtensionHostInstance
     /// <param name="message">The log message to send</param>
     public void LogMessage(ILogMessage message)
     {
-        if (Host != null)
+        if (Host is not null)
         {
             _ = Task.Run(async () =>
             {
@@ -47,7 +47,7 @@ public partial class ExtensionHostInstance
 
     public void ShowStatus(IStatusMessage message, StatusContext context)
     {
-        if (Host != null)
+        if (Host is not null)
         {
             _ = Task.Run(async () =>
             {
@@ -64,7 +64,7 @@ public partial class ExtensionHostInstance
 
     public void HideStatus(IStatusMessage message)
     {
-        if (Host != null)
+        if (Host is not null)
         {
             _ = Task.Run(async () =>
             {

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

@@ -36,7 +36,7 @@ public abstract partial class AppExtensionHost : IExtensionHost
 
     public IAsyncAction HideStatus(IStatusMessage? message)
     {
-        if (message == null)
+        if (message is null)
         {
             return Task.CompletedTask.AsAsyncAction();
         }
@@ -55,7 +55,7 @@ public abstract partial class AppExtensionHost : IExtensionHost
 
     public IAsyncAction LogMessage(ILogMessage? message)
     {
-        if (message == null)
+        if (message is null)
         {
             return Task.CompletedTask.AsAsyncAction();
         }
@@ -80,7 +80,7 @@ public abstract partial class AppExtensionHost : IExtensionHost
                 try
                 {
                     var vm = StatusMessages.Where(messageVM => messageVM.Model.Unsafe == message).FirstOrDefault();
-                    if (vm != null)
+                    if (vm is not null)
                     {
                         StatusMessages.Remove(vm);
                     }
@@ -113,7 +113,7 @@ public abstract partial class AppExtensionHost : IExtensionHost
     {
         // If this message is already in the list of messages, just bring it to the top
         var oldVm = StatusMessages.Where(messageVM => messageVM.Model.Unsafe == message).FirstOrDefault();
-        if (oldVm != null)
+        if (oldVm is not null)
         {
             Task.Factory.StartNew(
                 () =>
@@ -142,7 +142,7 @@ public abstract partial class AppExtensionHost : IExtensionHost
 
     public IAsyncAction ShowStatus(IStatusMessage? message, StatusContext context)
     {
-        if (message == null)
+        if (message is null)
         {
             return Task.CompletedTask.AsAsyncAction();
         }

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

@@ -2,7 +2,6 @@
 // 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.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.CmdPal.Core.ViewModels.Messages;
@@ -35,13 +34,13 @@ public partial class CommandBarViewModel : ObservableObject,
     [NotifyPropertyChangedFor(nameof(HasPrimaryCommand))]
     public partial CommandItemViewModel? PrimaryCommand { get; set; }
 
-    public bool HasPrimaryCommand => PrimaryCommand != null && PrimaryCommand.ShouldBeVisible;
+    public bool HasPrimaryCommand => PrimaryCommand is not null && PrimaryCommand.ShouldBeVisible;
 
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(HasSecondaryCommand))]
     public partial CommandItemViewModel? SecondaryCommand { get; set; }
 
-    public bool HasSecondaryCommand => SecondaryCommand != null;
+    public bool HasSecondaryCommand => SecondaryCommand is not null;
 
     [ObservableProperty]
     public partial bool ShouldShowContextMenu { get; set; } = false;
@@ -58,14 +57,14 @@ public partial class CommandBarViewModel : ObservableObject,
 
     private void SetSelectedItem(ICommandBarContext? value)
     {
-        if (value != null)
+        if (value is not null)
         {
             PrimaryCommand = value.PrimaryCommand;
             value.PropertyChanged += SelectedItemPropertyChanged;
         }
         else
         {
-            if (SelectedItem != null)
+            if (SelectedItem is not null)
             {
                 SelectedItem.PropertyChanged -= SelectedItemPropertyChanged;
             }
@@ -88,7 +87,7 @@ public partial class CommandBarViewModel : ObservableObject,
 
     private void UpdateContextItems()
     {
-        if (SelectedItem == null)
+        if (SelectedItem is null)
         {
             SecondaryCommand = null;
             ShouldShowContextMenu = false;
@@ -127,13 +126,13 @@ public partial class CommandBarViewModel : ObservableObject,
     public ContextKeybindingResult CheckKeybinding(bool ctrl, bool alt, bool shift, bool win, VirtualKey key)
     {
         var keybindings = SelectedItem?.Keybindings();
-        if (keybindings != null)
+        if (keybindings is not null)
         {
             // Does the pressed key match any of the keybindings?
             var pressedKeyChord = KeyChordHelpers.FromModifiers(ctrl, alt, shift, win, key, 0);
             if (keybindings.TryGetValue(pressedKeyChord, out var matchedItem))
             {
-                return matchedItem != null ? PerformCommand(matchedItem) : ContextKeybindingResult.Unhandled;
+                return matchedItem is not null ? PerformCommand(matchedItem) : ContextKeybindingResult.Unhandled;
             }
         }
 
@@ -142,7 +141,7 @@ public partial class CommandBarViewModel : ObservableObject,
 
     private ContextKeybindingResult PerformCommand(CommandItemViewModel? command)
     {
-        if (command == null)
+        if (command is null)
         {
             return ContextKeybindingResult.Unhandled;
         }

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

@@ -20,7 +20,7 @@ public partial class CommandContextItemViewModel(ICommandContextItem contextItem
 
     public KeyChord? RequestedShortcut { get; private set; }
 
-    public bool HasRequestedShortcut => RequestedShortcut != null && (RequestedShortcut.Value != nullKeyChord);
+    public bool HasRequestedShortcut => RequestedShortcut is not null && (RequestedShortcut.Value != nullKeyChord);
 
     public override void InitializeProperties()
     {
@@ -32,7 +32,7 @@ public partial class CommandContextItemViewModel(ICommandContextItem contextItem
         base.InitializeProperties();
 
         var contextItem = Model.Unsafe;
-        if (contextItem == null)
+        if (contextItem is null)
         {
             return; // throw?
         }

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

@@ -68,7 +68,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
     {
         get
         {
-            List<IContextItemViewModel> l = _defaultCommandContextItem == null ?
+            List<IContextItemViewModel> l = _defaultCommandContextItem is null ?
                 new() :
                 [_defaultCommandContextItem];
 
@@ -100,7 +100,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         }
 
         var model = _commandItemModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
@@ -128,7 +128,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         }
 
         var model = _commandItemModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
@@ -136,7 +136,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         Command.InitializeProperties();
 
         var listIcon = model.Icon;
-        if (listIcon != null)
+        if (listIcon is not null)
         {
             _listItemIcon = new(listIcon);
             _listItemIcon.InitializeProperties();
@@ -172,13 +172,13 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         }
 
         var model = _commandItemModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
 
         var more = model.MoreCommands;
-        if (more != null)
+        if (more is not null)
         {
             MoreCommands = more
                 .Select(item =>
@@ -300,7 +300,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
     protected virtual void FetchProperty(string propertyName)
     {
         var model = this._commandItemModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -308,7 +308,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         switch (propertyName)
         {
             case nameof(Command):
-                if (Command != null)
+                if (Command is not null)
                 {
                     Command.PropertyChanged -= Command_PropertyChanged;
                 }
@@ -339,7 +339,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
 
             case nameof(model.MoreCommands):
                 var more = model.MoreCommands;
-                if (more != null)
+                if (more is not null)
                 {
                     var newContextMenu = more
                         .Select(item =>
@@ -394,7 +394,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
                 // Extensions based on Command Palette SDK < 0.3 CommandItem class won't notify when Title changes because Command
                 // or Command.Name change. This is a workaround to ensure that the Title is always up-to-date for extensions with old SDK.
                 var model = _commandItemModel.Unsafe;
-                if (model != null)
+                if (model is not null)
                 {
                     _itemTitle = model.Title;
                 }
@@ -430,7 +430,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         Command.SafeCleanup();
 
         var model = _commandItemModel.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.PropChanged -= Model_PropChanged;
         }

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

@@ -44,7 +44,7 @@ public partial class CommandViewModel : ExtensionObjectViewModel
         }
 
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
@@ -67,13 +67,13 @@ public partial class CommandViewModel : ExtensionObjectViewModel
         }
 
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
 
         var ico = model.Icon;
-        if (ico != null)
+        if (ico is not null)
         {
             Icon = new(ico);
             Icon.InitializeProperties();
@@ -98,7 +98,7 @@ public partial class CommandViewModel : ExtensionObjectViewModel
     protected void FetchProperty(string propertyName)
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -125,7 +125,7 @@ public partial class CommandViewModel : ExtensionObjectViewModel
         Icon = new(null); // necessary?
 
         var model = Model.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.PropChanged -= Model_PropChanged;
         }

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

@@ -25,7 +25,7 @@ public partial class ConfirmResultViewModel(IConfirmationArgs _args, WeakReferen
     public override void InitializeProperties()
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -28,7 +28,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
     public DetailsViewModel? Details { get; private set; }
 
     [MemberNotNullWhen(true, nameof(Details))]
-    public bool HasDetails => Details != null;
+    public bool HasDetails => Details is not null;
 
     /////// ICommandBarContext ///////
     public IEnumerable<IContextItemViewModel> MoreCommands => Commands.Skip(1);
@@ -67,7 +67,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
             foreach (var item in newItems)
             {
                 var viewModel = ViewModelFromContent(item, PageContext);
-                if (viewModel != null)
+                if (viewModel is not null)
                 {
                     viewModel.InitializeProperties();
                     newContent.Add(viewModel);
@@ -104,7 +104,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
         base.InitializeProperties();
 
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -133,7 +133,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
             });
 
         var extensionDetails = model.Details;
-        if (extensionDetails != null)
+        if (extensionDetails is not null)
         {
             Details = new(extensionDetails, PageContext);
             Details.InitializeProperties();
@@ -156,7 +156,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
         base.FetchProperty(propertyName);
 
         var model = this._model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -166,7 +166,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
             case nameof(Commands):
 
                 var more = model.Commands;
-                if (more != null)
+                if (more is not null)
                 {
                     var newContextMenu = more
                             .ToList()
@@ -216,7 +216,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
                 break;
             case nameof(Details):
                 var extensionDetails = model.Details;
-                Details = extensionDetails != null ? new(extensionDetails, PageContext) : null;
+                Details = extensionDetails is not null ? new(extensionDetails, PageContext) : null;
                 UpdateDetails();
                 break;
         }
@@ -248,7 +248,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
     [RelayCommand]
     private void InvokePrimaryCommand(ContentPageViewModel page)
     {
-        if (PrimaryCommand != null)
+        if (PrimaryCommand is not null)
         {
             WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(PrimaryCommand.Command.Model, PrimaryCommand.Model));
         }
@@ -258,7 +258,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
     [RelayCommand]
     private void InvokeSecondaryCommand(ContentPageViewModel page)
     {
-        if (SecondaryCommand != null)
+        if (SecondaryCommand is not null)
         {
             WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(SecondaryCommand.Command.Model, SecondaryCommand.Model));
         }
@@ -285,7 +285,7 @@ public abstract partial class ContentPageViewModel : PageViewModel, ICommandBarC
         Content.Clear();
 
         var model = _model.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.ItemsChanged -= Model_ItemsChanged;
         }

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

@@ -8,7 +8,6 @@ using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.CmdPal.Core.ViewModels.Messages;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.CommandPalette.Extensions.Toolkit;
-using Microsoft.Diagnostics.Utilities;
 using Windows.System;
 
 namespace Microsoft.CmdPal.Core.ViewModels;
@@ -51,7 +50,7 @@ public partial class ContextMenuViewModel : ObservableObject,
 
     public void UpdateContextItems()
     {
-        if (SelectedItem != null)
+        if (SelectedItem is not null)
         {
             if (SelectedItem.MoreCommands.Count() > 1)
             {
@@ -68,14 +67,14 @@ public partial class ContextMenuViewModel : ObservableObject,
             return;
         }
 
-        if (SelectedItem == null)
+        if (SelectedItem is null)
         {
             return;
         }
 
         _lastSearchText = searchText;
 
-        if (CurrentContextMenu == null)
+        if (CurrentContextMenu is null)
         {
             ListHelpers.InPlaceUpdateList(FilteredItems, []);
             return;
@@ -124,7 +123,7 @@ public partial class ContextMenuViewModel : ObservableObject,
     /// that have a shortcut key set.</returns>
     public Dictionary<KeyChord, CommandContextItemViewModel> Keybindings()
     {
-        if (CurrentContextMenu == null)
+        if (CurrentContextMenu is null)
         {
             return [];
         }
@@ -140,7 +139,7 @@ public partial class ContextMenuViewModel : ObservableObject,
     public ContextKeybindingResult? CheckKeybinding(bool ctrl, bool alt, bool shift, bool win, VirtualKey key)
     {
         var keybindings = Keybindings();
-        if (keybindings != null)
+        if (keybindings is not null)
         {
             // Does the pressed key match any of the keybindings?
             var pressedKeyChord = KeyChordHelpers.FromModifiers(ctrl, alt, shift, win, key, 0);
@@ -190,7 +189,7 @@ public partial class ContextMenuViewModel : ObservableObject,
         OnPropertyChanging(nameof(CurrentContextMenu));
         OnPropertyChanged(nameof(CurrentContextMenu));
 
-        if (CurrentContextMenu != null)
+        if (CurrentContextMenu is not null)
         {
             ListHelpers.InPlaceUpdateList(FilteredItems, [.. CurrentContextMenu!]);
         }
@@ -198,7 +197,7 @@ public partial class ContextMenuViewModel : ObservableObject,
 
     public ContextKeybindingResult InvokeCommand(CommandItemViewModel? command)
     {
-        if (command == null)
+        if (command is null)
         {
             return ContextKeybindingResult.Unhandled;
         }

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

@@ -22,7 +22,7 @@ public partial class DetailsCommandsViewModel(
     {
         base.InitializeProperties();
         var model = _dataModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -16,7 +16,7 @@ public abstract partial class DetailsElementViewModel(IDetailsElement _detailsEl
     public override void InitializeProperties()
     {
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -18,7 +18,7 @@ public partial class DetailsLinkViewModel(
 
     public Uri? Link { get; private set; }
 
-    public bool IsLink => Link != null;
+    public bool IsLink => Link is not null;
 
     public bool IsText => !IsLink;
 
@@ -26,14 +26,14 @@ public partial class DetailsLinkViewModel(
     {
         base.InitializeProperties();
         var model = _dataModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
 
         Text = model.Text ?? string.Empty;
         Link = model.Link;
-        if (string.IsNullOrEmpty(Text) && Link != null)
+        if (string.IsNullOrEmpty(Text) && Link is not null)
         {
             Text = Link.ToString();
         }

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

@@ -22,7 +22,7 @@ public partial class DetailsTagsViewModel(
     {
         base.InitializeProperties();
         var model = _dataModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -26,7 +26,7 @@ public partial class DetailsViewModel(IDetails _details, WeakReference<IPageCont
     public override void InitializeProperties()
     {
         var model = _detailsModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
@@ -41,7 +41,7 @@ public partial class DetailsViewModel(IDetails _details, WeakReference<IPageCont
         UpdateProperty(nameof(HeroImage));
 
         var meta = model.Metadata;
-        if (meta != null)
+        if (meta is not null)
         {
             foreach (var element in meta)
             {
@@ -53,7 +53,7 @@ public partial class DetailsViewModel(IDetails _details, WeakReference<IPageCont
                     IDetailsTags => new DetailsTagsViewModel(element, this.PageContext),
                     _ => null,
                 };
-                if (vm != null)
+                if (vm is not null)
                 {
                     vm.InitializeProperties();
                     Metadata.Add(vm);

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

@@ -16,7 +16,7 @@ public partial class IconDataViewModel : ObservableObject, IIconData
     // If the extension previously gave us a Data, then died, the data will
     // throw if we actually try to read it, but the pointer itself won't be
     // null, so this is relatively safe.
-    public bool HasIcon => !string.IsNullOrEmpty(Icon) || Data.Unsafe != null;
+    public bool HasIcon => !string.IsNullOrEmpty(Icon) || Data.Unsafe is not null;
 
     // Locally cached properties from IIconData.
     public string Icon { get; private set; } = string.Empty;
@@ -36,7 +36,7 @@ public partial class IconDataViewModel : ObservableObject, IIconData
     public void InitializeProperties()
     {
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -26,7 +26,7 @@ public partial class IconInfoViewModel : ObservableObject, IIconInfo
 
     public bool HasIcon(bool light) => IconForTheme(light).HasIcon;
 
-    public bool IsSet => _model.Unsafe != null;
+    public bool IsSet => _model.Unsafe is not null;
 
     IIconData? IIconInfo.Dark => Dark;
 
@@ -43,7 +43,7 @@ public partial class IconInfoViewModel : ObservableObject, IIconInfo
     public void InitializeProperties()
     {
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -27,7 +27,7 @@ public partial class ListItemViewModel(IListItem model, WeakReference<IPageConte
     public DetailsViewModel? Details { get; private set; }
 
     [MemberNotNullWhen(true, nameof(Details))]
-    public bool HasDetails => Details != null;
+    public bool HasDetails => Details is not null;
 
     public override void InitializeProperties()
     {
@@ -40,7 +40,7 @@ public partial class ListItemViewModel(IListItem model, WeakReference<IPageConte
         base.InitializeProperties();
 
         var li = Model.Unsafe;
-        if (li == null)
+        if (li is null)
         {
             return; // throw?
         }
@@ -50,7 +50,7 @@ public partial class ListItemViewModel(IListItem model, WeakReference<IPageConte
         TextToSuggest = li.TextToSuggest;
         Section = li.Section ?? string.Empty;
         var extensionDetails = li.Details;
-        if (extensionDetails != null)
+        if (extensionDetails is not null)
         {
             Details = new(extensionDetails, PageContext);
             Details.InitializeProperties();
@@ -67,7 +67,7 @@ public partial class ListItemViewModel(IListItem model, WeakReference<IPageConte
         base.FetchProperty(propertyName);
 
         var model = this.Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -85,7 +85,7 @@ public partial class ListItemViewModel(IListItem model, WeakReference<IPageConte
                 break;
             case nameof(Details):
                 var extensionDetails = model.Details;
-                Details = extensionDetails != null ? new(extensionDetails, PageContext) : null;
+                Details = extensionDetails is not null ? new(extensionDetails, PageContext) : null;
                 Details?.InitializeProperties();
                 UpdateProperty(nameof(Details));
                 UpdateProperty(nameof(HasDetails));
@@ -136,7 +136,7 @@ public partial class ListItemViewModel(IListItem model, WeakReference<IPageConte
         Details?.SafeCleanup();
 
         var model = Model.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             // We don't need to revoke the PropChanged event handler here,
             // because we are just overriding CommandItem's FetchProperty and

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

@@ -63,6 +63,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
 
     private Task? _initializeItemsTask;
     private CancellationTokenSource? _cancellationTokenSource;
+    private CancellationTokenSource? _fetchItemsCancellationTokenSource;
 
     private ListItemViewModel? _lastSelectedItem;
 
@@ -129,22 +130,38 @@ public partial class ListViewModel : PageViewModel, IDisposable
     //// Run on background thread, from InitializeAsync or Model_ItemsChanged
     private void FetchItems()
     {
+        // Cancel any previous FetchItems operation
+        _fetchItemsCancellationTokenSource?.Cancel();
+        _fetchItemsCancellationTokenSource?.Dispose();
+        _fetchItemsCancellationTokenSource = new CancellationTokenSource();
+
+        var cancellationToken = _fetchItemsCancellationTokenSource.Token;
+
         // TEMPORARY: just plop all the items into a single group
         // see 9806fe5d8 for the last commit that had this with sections
         _isFetching = true;
 
+        // Collect all the items into new viewmodels
+        Collection<ListItemViewModel> newViewModels = [];
+
         try
         {
+            // Check for cancellation before starting expensive operations
+            cancellationToken.ThrowIfCancellationRequested();
+
             var newItems = _model.Unsafe!.GetItems();
 
-            // Collect all the items into new viewmodels
-            Collection<ListItemViewModel> newViewModels = [];
+            // Check for cancellation after getting items from extension
+            cancellationToken.ThrowIfCancellationRequested();
 
             // TODO we can probably further optimize this by also keeping a
             // HashSet of every ExtensionObject we currently have, and only
             // building new viewmodels for the ones we haven't already built.
             foreach (var item in newItems)
             {
+                // Check for cancellation during item processing
+                cancellationToken.ThrowIfCancellationRequested();
+
                 ListItemViewModel viewModel = new(item, new(this));
 
                 // If an item fails to load, silently ignore it.
@@ -154,25 +171,57 @@ public partial class ListViewModel : PageViewModel, IDisposable
                 }
             }
 
+            // Check for cancellation before initializing first twenty items
+            cancellationToken.ThrowIfCancellationRequested();
+
             var firstTwenty = newViewModels.Take(20);
             foreach (var item in firstTwenty)
             {
+                cancellationToken.ThrowIfCancellationRequested();
                 item?.SafeInitializeProperties();
             }
 
             // Cancel any ongoing search
             _cancellationTokenSource?.Cancel();
 
+            // Check for cancellation before updating the list
+            cancellationToken.ThrowIfCancellationRequested();
+
+            List<ListItemViewModel> removedItems = [];
             lock (_listLock)
             {
                 // Now that we have new ViewModels for everything from the
                 // extension, smartly update our list of VMs
-                ListHelpers.InPlaceUpdateList(Items, newViewModels);
+                ListHelpers.InPlaceUpdateList(Items, newViewModels, out removedItems);
+
+                // DO NOT ThrowIfCancellationRequested AFTER THIS! If you do,
+                // you'll clean up list items that we've now transferred into
+                // .Items
+            }
+
+            // If we removed items, we need to clean them up, to remove our event handlers
+            foreach (var removedItem in removedItems)
+            {
+                removedItem.SafeCleanup();
             }
 
             // TODO: Iterate over everything in Items, and prune items from the
             // cache if we don't need them anymore
         }
+        catch (OperationCanceledException)
+        {
+            // Cancellation is expected, don't treat as error
+
+            // However, if we were cancelled, we didn't actually add these items to
+            // our Items list. Before we release them to the GC, make sure we clean
+            // them up
+            foreach (var vm in newViewModels)
+            {
+                vm.SafeCleanup();
+            }
+
+            return;
+        }
         catch (Exception ex)
         {
             // TODO: Move this within the for loop, so we can catch issues with individual items
@@ -298,11 +347,11 @@ public partial class ListViewModel : PageViewModel, IDisposable
     [RelayCommand]
     private void InvokeItem(ListItemViewModel? item)
     {
-        if (item != null)
+        if (item is not null)
         {
             WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(item.Command.Model, item.Model));
         }
-        else if (ShowEmptyContent && EmptyContent.PrimaryCommand?.Model.Unsafe != null)
+        else if (ShowEmptyContent && EmptyContent.PrimaryCommand?.Model.Unsafe is not null)
         {
             WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(
                 EmptyContent.PrimaryCommand.Command.Model,
@@ -314,14 +363,14 @@ public partial class ListViewModel : PageViewModel, IDisposable
     [RelayCommand]
     private void InvokeSecondaryCommand(ListItemViewModel? item)
     {
-        if (item != null)
+        if (item is not null)
         {
-            if (item.SecondaryCommand != null)
+            if (item.SecondaryCommand is not null)
             {
                 WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(item.SecondaryCommand.Command.Model, item.Model));
             }
         }
-        else if (ShowEmptyContent && EmptyContent.SecondaryCommand?.Model.Unsafe != null)
+        else if (ShowEmptyContent && EmptyContent.SecondaryCommand?.Model.Unsafe is not null)
         {
             WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(
                 EmptyContent.SecondaryCommand.Command.Model,
@@ -332,12 +381,12 @@ public partial class ListViewModel : PageViewModel, IDisposable
     [RelayCommand]
     private void UpdateSelectedItem(ListItemViewModel? item)
     {
-        if (_lastSelectedItem != null)
+        if (_lastSelectedItem is not null)
         {
             _lastSelectedItem.PropertyChanged -= SelectedItemPropertyChanged;
         }
 
-        if (item != null)
+        if (item is not null)
         {
             SetSelectedItem(item);
         }
@@ -383,7 +432,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
     private void SelectedItemPropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
     {
         var item = _lastSelectedItem;
-        if (item == null)
+        if (item is null)
         {
             return;
         }
@@ -438,7 +487,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
         base.InitializeProperties();
 
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -465,7 +514,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
     public void LoadMoreIfNeeded()
     {
         var model = this._model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
@@ -509,7 +558,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
         base.FetchProperty(propertyName);
 
         var model = this._model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -540,7 +589,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
     private void UpdateEmptyContent()
     {
         UpdateProperty(nameof(ShowEmptyContent));
-        if (!ShowEmptyContent || EmptyContent.Model.Unsafe == null)
+        if (!ShowEmptyContent || EmptyContent.Model.Unsafe is null)
         {
             return;
         }
@@ -560,6 +609,10 @@ public partial class ListViewModel : PageViewModel, IDisposable
         _cancellationTokenSource?.Cancel();
         _cancellationTokenSource?.Dispose();
         _cancellationTokenSource = null;
+
+        _fetchItemsCancellationTokenSource?.Cancel();
+        _fetchItemsCancellationTokenSource?.Dispose();
+        _fetchItemsCancellationTokenSource = null;
     }
 
     protected override void UnsafeCleanup()
@@ -570,6 +623,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
         EmptyContent = new(new(null), PageContext); // necessary?
 
         _cancellationTokenSource?.Cancel();
+        _fetchItemsCancellationTokenSource?.Cancel();
 
         lock (_listLock)
         {
@@ -588,7 +642,7 @@ public partial class ListViewModel : PageViewModel, IDisposable
         }
 
         var model = _model.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.ItemsChanged -= Model_ItemsChanged;
         }

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

@@ -22,7 +22,7 @@ public partial class LogMessageViewModel : ExtensionObjectViewModel
     public override void InitializeProperties()
     {
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }

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

@@ -5,6 +5,7 @@
 using System.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using Microsoft.CmdPal.Common.Helpers;
 using Microsoft.CmdPal.Core.ViewModels.Models;
 using Microsoft.CommandPalette.Extensions;
 
@@ -45,7 +46,7 @@ public partial class PageViewModel : ExtensionObjectViewModel, IPageContext
     [ObservableProperty]
     public partial AppExtensionHost ExtensionHost { get; private set; }
 
-    public bool HasStatusMessage => MostRecentStatusMessage != null;
+    public bool HasStatusMessage => MostRecentStatusMessage is not null;
 
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(HasStatusMessage))]
@@ -132,7 +133,7 @@ public partial class PageViewModel : ExtensionObjectViewModel, IPageContext
     public override void InitializeProperties()
     {
         var page = _pageModel.Unsafe;
-        if (page == null)
+        if (page is null)
         {
             return; // throw?
         }
@@ -177,7 +178,7 @@ public partial class PageViewModel : ExtensionObjectViewModel, IPageContext
     protected virtual void FetchProperty(string propertyName)
     {
         var model = this._pageModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -223,9 +224,10 @@ public partial class PageViewModel : ExtensionObjectViewModel, IPageContext
         extensionHint ??= ExtensionHost.GetExtensionDisplayName() ?? Title;
         Task.Factory.StartNew(
             () =>
-        {
-            ErrorMessage += $"A bug occurred in {$"the \"{extensionHint}\"" ?? "an unknown's"} extension's code:\n{ex.Message}\n{ex.Source}\n{ex.StackTrace}\n\n";
-        },
+            {
+                var message = DiagnosticsHelper.BuildExceptionMessage(ex, extensionHint);
+                ErrorMessage += message;
+            },
             CancellationToken.None,
             TaskCreationOptions.None,
             Scheduler);
@@ -240,7 +242,7 @@ public partial class PageViewModel : ExtensionObjectViewModel, IPageContext
         ExtensionHost.StatusMessages.CollectionChanged -= StatusMessages_CollectionChanged;
 
         var model = _pageModel.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.PropChanged -= Model_PropChanged;
         }

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

@@ -24,7 +24,7 @@ public partial class ProgressViewModel : ExtensionObjectViewModel
     public override void InitializeProperties()
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -50,7 +50,7 @@ public partial class ProgressViewModel : ExtensionObjectViewModel
     protected virtual void FetchProperty(string propertyName)
     {
         var model = this.Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }

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

@@ -120,7 +120,7 @@ public partial class ShellViewModel : ObservableObject,
 
         ////LoadedState = ViewModelLoadedState.Loading;
         if (!viewModel.IsInitialized
-            && viewModel.InitializeCommand != null)
+            && viewModel.InitializeCommand is not null)
         {
             _ = Task.Run(async () =>
             {
@@ -185,7 +185,7 @@ public partial class ShellViewModel : ObservableObject,
     private void PerformCommand(PerformCommandMessage message)
     {
         var command = message.Command.Unsafe;
-        if (command == null)
+        if (command is null)
         {
             return;
         }
@@ -205,7 +205,7 @@ public partial class ShellViewModel : ObservableObject,
 
                 // Construct our ViewModel of the appropriate type and pass it the UI Thread context.
                 var pageViewModel = _pageViewModelFactory.TryCreatePageViewModel(page, _isNested, host);
-                if (pageViewModel == null)
+                if (pageViewModel is null)
                 {
                     Logger.LogError($"Failed to create ViewModel for page {page.GetType().Name}");
                     throw new NotSupportedException();
@@ -240,7 +240,7 @@ public partial class ShellViewModel : ObservableObject,
         // TODO GH #525 This needs more better locking.
         lock (_invokeLock)
         {
-            if (_handleInvokeTask != null)
+            if (_handleInvokeTask is not null)
             {
                 // do nothing - a command is already doing a thing
             }
@@ -280,7 +280,7 @@ public partial class ShellViewModel : ObservableObject,
 
     private void UnsafeHandleCommandResult(ICommandResult? result)
     {
-        if (result == null)
+        if (result is null)
         {
             // No result, nothing to do.
             return;

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

@@ -17,7 +17,7 @@ public partial class StatusMessageViewModel : ExtensionObjectViewModel
 
     public ProgressViewModel? Progress { get; private set; }
 
-    public bool HasProgress => Progress != null;
+    public bool HasProgress => Progress is not null;
 
     public StatusMessageViewModel(IStatusMessage message, WeakReference<IPageContext> context)
         : base(context)
@@ -28,7 +28,7 @@ public partial class StatusMessageViewModel : ExtensionObjectViewModel
     public override void InitializeProperties()
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -36,7 +36,7 @@ public partial class StatusMessageViewModel : ExtensionObjectViewModel
         Message = model.Message;
         State = model.State;
         var modelProgress = model.Progress;
-        if (modelProgress != null)
+        if (modelProgress is not null)
         {
             Progress = new(modelProgress, this.PageContext);
             Progress.InitializeProperties();
@@ -61,7 +61,7 @@ public partial class StatusMessageViewModel : ExtensionObjectViewModel
     protected virtual void FetchProperty(string propertyName)
     {
         var model = this.Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -76,7 +76,7 @@ public partial class StatusMessageViewModel : ExtensionObjectViewModel
                 break;
             case nameof(Progress):
                 var modelProgress = model.Progress;
-                if (modelProgress != null)
+                if (modelProgress is not null)
                 {
                     Progress = new(modelProgress, this.PageContext);
                     Progress.InitializeProperties();

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

@@ -28,7 +28,7 @@ public partial class TagViewModel(ITag _tag, WeakReference<IPageContext> context
     public override void InitializeProperties()
     {
         var model = _tagModel.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }

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

@@ -35,7 +35,7 @@ public partial class AliasManager : ObservableObject
             try
             {
                 var topLevelCommand = _topLevelCommandManager.LookupCommand(alias.CommandId);
-                if (topLevelCommand != null)
+                if (topLevelCommand is not null)
                 {
                     WeakReferenceMessenger.Default.Send<ClearSearchMessage>();
 
@@ -88,7 +88,7 @@ public partial class AliasManager : ObservableObject
         }
 
         // If we already have _this exact alias_, do nothing
-        if (newAlias != null &&
+        if (newAlias is not null &&
             _aliases.TryGetValue(newAlias.SearchPrefix, out var existingAlias))
         {
             if (existingAlias.CommandId == commandId)
@@ -113,7 +113,7 @@ public partial class AliasManager : ObservableObject
             _aliases.Remove(alias.SearchPrefix);
         }
 
-        if (newAlias != null)
+        if (newAlias is not null)
         {
             AddAlias(newAlias);
         }

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

@@ -55,7 +55,7 @@ public partial class AppStateModel : ObservableObject
 
             var loaded = JsonSerializer.Deserialize<AppStateModel>(jsonContent, JsonSerializationContext.Default.AppStateModel);
 
-            Debug.WriteLine(loaded != null ? "Loaded settings file" : "Failed to parse");
+            Debug.WriteLine(loaded is not null ? "Loaded settings file" : "Failed to parse");
 
             return loaded ?? new();
         }

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

@@ -15,7 +15,7 @@ namespace Microsoft.CmdPal.UI.ViewModels;
 
 public sealed class CommandProviderWrapper
 {
-    public bool IsExtension => Extension != null;
+    public bool IsExtension => Extension is not null;
 
     private readonly bool isValid;
 
@@ -188,14 +188,14 @@ public sealed class CommandProviderWrapper
 
             return topLevelViewModel;
         };
-        if (commands != null)
+        if (commands is not null)
         {
             TopLevelItems = commands
                 .Select(c => makeAndAdd(c, false))
                 .ToArray();
         }
 
-        if (fallbacks != null)
+        if (fallbacks is not null)
         {
             FallbackItems = fallbacks
                 .Select(c => makeAndAdd(c, true))

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

@@ -18,18 +18,18 @@ public partial class CommandSettingsViewModel(ICommandSettings? _unsafeSettings,
     public bool Initialized { get; private set; }
 
     public bool HasSettings =>
-        _model.Unsafe != null && // We have a settings model AND
-        (!Initialized || SettingsPage != null); // we weren't initialized, OR we were, and we do have a settings page
+        _model.Unsafe is not null && // We have a settings model AND
+        (!Initialized || SettingsPage is not null); // we weren't initialized, OR we were, and we do have a settings page
 
     private void UnsafeInitializeProperties()
     {
         var model = _model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
 
-        if (model.SettingsPage != null)
+        if (model.SettingsPage is not null)
         {
             SettingsPage = new CommandPaletteContentPageViewModel(model.SettingsPage, mainThread, provider.ExtensionHost);
             SettingsPage.InitializeProperties();

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Commands/CreatedExtensionForm.cs

@@ -30,7 +30,7 @@ internal sealed partial class CreatedExtensionForm : NewExtensionFormBase
     public override ICommandResult SubmitForm(string inputs, string data)
     {
         var dataInput = JsonNode.Parse(data)?.AsObject();
-        if (dataInput == null)
+        if (dataInput is null)
         {
             return CommandResult.KeepOpen();
         }

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Commands/LogMessagesPage.cs

@@ -23,7 +23,7 @@ public partial class LogMessagesPage : ListPage
 
     private void LogMessages_CollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
     {
-        if (e.Action == NotifyCollectionChangedAction.Add && e.NewItems != null)
+        if (e.Action == NotifyCollectionChangedAction.Add && e.NewItems is not null)
         {
             foreach (var item in e.NewItems)
             {

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Commands/MainListPage.cs

@@ -203,7 +203,7 @@ public partial class MainListPage : DynamicListPage,
 
             // If we don't have any previous filter results to work with, start
             // with a list of all our commands & apps.
-            if (_filteredItems == null)
+            if (_filteredItems is null)
             {
                 _filteredItems = commands;
                 _filteredItemsIncludesApps = _includeApps;

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Commands/NewExtensionForm.cs

@@ -98,7 +98,7 @@ internal sealed partial class NewExtensionForm : NewExtensionFormBase
     public override CommandResult SubmitForm(string payload)
     {
         var formInput = JsonNode.Parse(payload)?.AsObject();
-        if (formInput == null)
+        if (formInput is null)
         {
             return CommandResult.KeepOpen();
         }

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Commands/NewExtensionPage.cs

@@ -14,7 +14,7 @@ public partial class NewExtensionPage : ContentPage
 
     public override IContent[] GetContent()
     {
-        return _resultForm != null ? [_resultForm] : [_inputForm];
+        return _resultForm is not null ? [_resultForm] : [_inputForm];
     }
 
     public NewExtensionPage()
@@ -28,13 +28,13 @@ public partial class NewExtensionPage : ContentPage
 
     private void FormSubmitted(NewExtensionFormBase sender, NewExtensionFormBase? args)
     {
-        if (_resultForm != null)
+        if (_resultForm is not null)
         {
             _resultForm.FormSubmitted -= FormSubmitted;
         }
 
         _resultForm = args;
-        if (_resultForm != null)
+        if (_resultForm is not null)
         {
             _resultForm.FormSubmitted += FormSubmitted;
         }

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

@@ -2,6 +2,7 @@
 // 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.Text.Json;
 using AdaptiveCards.ObjectModel.WinUI3;
 using AdaptiveCards.Templating;
@@ -96,109 +97,40 @@ public partial class ContentFormViewModel(IFormContent _form, WeakReference<IPag
         UpdateProperty(nameof(Card));
     }
 
+    [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(AdaptiveOpenUrlAction))]
+    [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(AdaptiveSubmitAction))]
+    [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(AdaptiveExecuteAction))]
     public void HandleSubmit(IAdaptiveActionElement action, JsonObject inputs)
     {
-        // BODGY circa GH #40979
-        // Usually, you're supposed to try to cast the action to a specific
-        // type, and use those objects to get the data you need.
-        // However, there's something weird with AdaptiveCards and the way it
-        // works when we consume it when built in Release, with AOT (and
-        // trimming) enabled. Any sort of `action.As<IAdaptiveSubmitAction>()`
-        // or similar will throw a System.InvalidCastException.
-        //
-        // Instead we have this horror show.
-        //
-        // The `action.ToJson()` blob ACTUALLY CONTAINS THE `type` field, which
-        // we can use to determine what kind of action it is. Then we can parse
-        // the JSON manually based on the type.
-        var actionJson = action.ToJson();
-
-        if (actionJson.TryGetValue("type", out var actionTypeValue))
+        if (action is AdaptiveOpenUrlAction openUrlAction)
         {
-            var actionTypeString = actionTypeValue.GetString();
-            Logger.LogTrace($"atString={actionTypeString}");
-
-            var actionType = actionTypeString switch
-            {
-                "Action.Submit" => ActionType.Submit,
-                "Action.Execute" => ActionType.Execute,
-                "Action.OpenUrl" => ActionType.OpenUrl,
-                _ => ActionType.Unsupported,
-            };
-
-            Logger.LogDebug($"{actionTypeString}->{actionType}");
-
-            switch (actionType)
-            {
-                case ActionType.OpenUrl:
-                    {
-                        HandleOpenUrlAction(action, actionJson);
-                    }
-
-                    break;
-                case ActionType.Submit:
-                case ActionType.Execute:
-                    {
-                        HandleSubmitAction(action, actionJson, inputs);
-                    }
-
-                    break;
-                default:
-                    Logger.LogError($"{actionType} was an unexpected action `type`");
-                    break;
-            }
-        }
-        else
-        {
-            Logger.LogError($"actionJson.TryGetValue(type) failed");
-        }
-    }
-
-    private void HandleOpenUrlAction(IAdaptiveActionElement action, JsonObject actionJson)
-    {
-        if (actionJson.TryGetValue("url", out var actionUrlValue))
-        {
-            var actionUrl = actionUrlValue.GetString() ?? string.Empty;
-            if (Uri.TryCreate(actionUrl, default(UriCreationOptions), out var uri))
-            {
-                WeakReferenceMessenger.Default.Send<LaunchUriMessage>(new(uri));
-            }
-            else
-            {
-                Logger.LogError($"Failed to produce URI for {actionUrlValue}");
-            }
-        }
-    }
-
-    private void HandleSubmitAction(
-        IAdaptiveActionElement action,
-        JsonObject actionJson,
-        JsonObject inputs)
-    {
-        var dataString = string.Empty;
-        if (actionJson.TryGetValue("data", out var actionDataValue))
-        {
-            dataString = actionDataValue.Stringify() ?? string.Empty;
+            WeakReferenceMessenger.Default.Send<LaunchUriMessage>(new(openUrlAction.Url));
+            return;
         }
 
-        var inputString = inputs.Stringify();
-        _ = Task.Run(() =>
+        if (action is AdaptiveSubmitAction or AdaptiveExecuteAction)
         {
-            try
+            // Get the data and inputs
+            var dataString = (action as AdaptiveSubmitAction)?.DataJson.Stringify() ?? string.Empty;
+            var inputString = inputs.Stringify();
+
+            _ = Task.Run(() =>
             {
-                var model = _formModel.Unsafe!;
-                if (model != null)
+                try
                 {
-                    var result = model.SubmitForm(inputString, dataString);
-                    Logger.LogDebug($"SubmitForm() returned {result}");
-                    WeakReferenceMessenger.Default.Send<HandleCommandResultMessage>(new(new(result)));
+                    var model = _formModel.Unsafe!;
+                    if (model != null)
+                    {
+                        var result = model.SubmitForm(inputString, dataString);
+                        WeakReferenceMessenger.Default.Send<HandleCommandResultMessage>(new(new(result)));
+                    }
                 }
-            }
-            catch (Exception ex)
-            {
-                ShowException(ex);
-            }
-        });
+                catch (Exception ex)
+                {
+                    ShowException(ex);
+                }
+            });
+        }
     }
 
     private static readonly string ErrorCardJson = """

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

@@ -20,7 +20,7 @@ public partial class ContentMarkdownViewModel(IMarkdownContent _markdown, WeakRe
     public override void InitializeProperties()
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
@@ -47,7 +47,7 @@ public partial class ContentMarkdownViewModel(IMarkdownContent _markdown, WeakRe
     protected void FetchProperty(string propertyName)
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -66,7 +66,7 @@ public partial class ContentMarkdownViewModel(IMarkdownContent _markdown, WeakRe
     {
         base.UnsafeCleanup();
         var model = Model.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.PropChanged -= Model_PropChanged;
         }

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

@@ -30,13 +30,13 @@ public partial class ContentTreeViewModel(ITreeContent _tree, WeakReference<IPag
     public override void InitializeProperties()
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return;
         }
 
         var root = model.RootContent;
-        if (root != null)
+        if (root is not null)
         {
             RootContent = ViewModelFromContent(root, PageContext);
             RootContent?.InitializeProperties();
@@ -82,7 +82,7 @@ public partial class ContentTreeViewModel(ITreeContent _tree, WeakReference<IPag
     protected void FetchProperty(string propertyName)
     {
         var model = Model.Unsafe;
-        if (model == null)
+        if (model is null)
         {
             return; // throw?
         }
@@ -91,7 +91,7 @@ public partial class ContentTreeViewModel(ITreeContent _tree, WeakReference<IPag
         {
             case nameof(RootContent):
                 var root = model.RootContent;
-                if (root != null)
+                if (root is not null)
                 {
                     RootContent = ViewModelFromContent(root, PageContext);
                 }
@@ -119,7 +119,7 @@ public partial class ContentTreeViewModel(ITreeContent _tree, WeakReference<IPag
             foreach (var item in newItems)
             {
                 var viewModel = ViewModelFromContent(item, PageContext);
-                if (viewModel != null)
+                if (viewModel is not null)
                 {
                     viewModel.InitializeProperties();
                     newContent.Add(viewModel);
@@ -153,7 +153,7 @@ public partial class ContentTreeViewModel(ITreeContent _tree, WeakReference<IPag
 
         Children.Clear();
         var model = Model.Unsafe;
-        if (model != null)
+        if (model is not null)
         {
             model.PropChanged -= Model_PropChanged;
             model.ItemsChanged -= Model_ItemsChanged;

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

@@ -29,7 +29,7 @@ public partial class HotkeyManager : ObservableObject
             }
         }
 
-        _commandHotkeys.RemoveAll(item => item.Hotkey == null);
+        _commandHotkeys.RemoveAll(item => item.Hotkey is null);
 
         foreach (var item in _commandHotkeys)
         {

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Models/ExtensionService.cs

@@ -90,7 +90,7 @@ public partial class ExtensionService : IExtensionService, IDisposable
         }).Result;
         var isExtension = isCmdPalExtensionResult.IsExtension;
         var extension = isCmdPalExtensionResult.Extension;
-        if (isExtension && extension != null)
+        if (isExtension && extension is not null)
         {
             CommandPaletteHost.Instance.DebugLog($"Installed new extension app {extension.DisplayName}");
 
@@ -152,7 +152,7 @@ public partial class ExtensionService : IExtensionService, IDisposable
             {
                 var (cmdPalProvider, classId) = await GetCmdPalExtensionPropertiesAsync(extension);
 
-                return new(cmdPalProvider != null && classId.Count != 0, extension);
+                return new(cmdPalProvider is not null && classId.Count != 0, extension);
             }
         }
 
@@ -237,7 +237,7 @@ public partial class ExtensionService : IExtensionService, IDisposable
     {
         var (cmdPalProvider, classIds) = await GetCmdPalExtensionPropertiesAsync(extension);
 
-        if (cmdPalProvider == null || classIds.Count == 0)
+        if (cmdPalProvider is null || classIds.Count == 0)
         {
             return [];
         }
@@ -352,12 +352,12 @@ public partial class ExtensionService : IExtensionService, IDisposable
     {
         var propSetList = new List<string>();
         var singlePropertySet = GetSubPropertySet(activationPropSet, CreateInstanceProperty);
-        if (singlePropertySet != null)
+        if (singlePropertySet is not null)
         {
             var classId = GetProperty(singlePropertySet, ClassIdProperty);
 
             // If the instance has a classId as a single string, then it's only supporting a single instance.
-            if (classId != null)
+            if (classId is not null)
             {
                 propSetList.Add(classId);
             }
@@ -365,7 +365,7 @@ public partial class ExtensionService : IExtensionService, IDisposable
         else
         {
             var propertySetArray = GetSubPropertySetArray(activationPropSet, CreateInstanceProperty);
-            if (propertySetArray != null)
+            if (propertySetArray is not null)
             {
                 foreach (var prop in propertySetArray)
                 {
@@ -375,7 +375,7 @@ public partial class ExtensionService : IExtensionService, IDisposable
                     }
 
                     var classId = GetProperty(propertySet, ClassIdProperty);
-                    if (classId != null)
+                    if (classId is not null)
                     {
                         propSetList.Add(classId);
                     }

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

@@ -35,7 +35,7 @@ public class ProviderSettings
     public void Connect(CommandProviderWrapper wrapper)
     {
         ProviderId = wrapper.ProviderId;
-        IsBuiltin = wrapper.Extension == null;
+        IsBuiltin = wrapper.Extension is null;
 
         ProviderDisplayName = wrapper.DisplayName;
 

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

@@ -33,7 +33,7 @@ public partial class ProviderSettingsViewModel(
         Resources.builtin_disabled_extension;
 
     [MemberNotNullWhen(true, nameof(Extension))]
-    public bool IsFromExtension => _provider.Extension != null;
+    public bool IsFromExtension => _provider.Extension is not null;
 
     public IExtensionWrapper? Extension => _provider.Extension;
 
@@ -76,7 +76,7 @@ public partial class ProviderSettingsViewModel(
     {
         get
         {
-            if (_provider.Settings == null)
+            if (_provider.Settings is null)
             {
                 return false;
             }
@@ -100,7 +100,7 @@ public partial class ProviderSettingsViewModel(
     {
         get
         {
-            if (_provider.Settings == null)
+            if (_provider.Settings is null)
             {
                 return null;
             }
@@ -126,7 +126,7 @@ public partial class ProviderSettingsViewModel(
     {
         get
         {
-            if (field == null)
+            if (field is null)
             {
                 field = BuildTopLevelViewModels();
             }
@@ -149,7 +149,7 @@ public partial class ProviderSettingsViewModel(
     {
         get
         {
-            if (field == null)
+            if (field is null)
             {
                 field = BuildFallbackViewModels();
             }
@@ -173,7 +173,7 @@ public partial class ProviderSettingsViewModel(
 
     private void InitializeSettingsPage()
     {
-        if (_provider.Settings == null)
+        if (_provider.Settings is null)
         {
             return;
         }

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

@@ -30,7 +30,7 @@ public partial class RecentCommandsManager : ObservableObject
             // These numbers are vaguely scaled so that "VS" will make "Visual Studio" the
             // match after one use.
             // Usually it has a weight of 84, compared to 109 for the VS cmd prompt
-            if (entry.Item != null)
+            if (entry.Item is not null)
             {
                 var index = entry.Index;
 
@@ -61,7 +61,7 @@ public partial class RecentCommandsManager : ObservableObject
             var entry = History
             .Where(item => item.CommandId == commandId)
             .FirstOrDefault();
-            if (entry == null)
+            if (entry is null)
             {
                 var newitem = new HistoryItem() { CommandId = commandId, Uses = 1 };
                 History.Insert(0, newitem);

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

@@ -95,7 +95,7 @@ public partial class SettingsModel : ObservableObject
 
             var loaded = JsonSerializer.Deserialize<SettingsModel>(jsonContent, JsonSerializationContext.Default.SettingsModel);
 
-            Debug.WriteLine(loaded != null ? "Loaded settings file" : "Failed to parse");
+            Debug.WriteLine(loaded is not null ? "Loaded settings file" : "Failed to parse");
 
             return loaded ?? new();
         }

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

@@ -170,20 +170,29 @@ public partial class TopLevelCommandManager : ObservableObject,
             // TODO: just added a lock around all of this anyway, but keeping the clone
             // while looking on some other ways to improve this; can be removed later.
             List<TopLevelViewModel> clone = [.. TopLevelCommands];
-            var startIndex = -1;
 
+            var startIndex = FindIndexForFirstProviderItem(clone, sender.ProviderId);
+            clone.RemoveAll(item => item.CommandProviderId == sender.ProviderId);
+            clone.InsertRange(startIndex, newItems);
+
+            ListHelpers.InPlaceUpdateList(TopLevelCommands, clone);
+        }
+
+        return;
+
+        static int FindIndexForFirstProviderItem(List<TopLevelViewModel> topLevelItems, string providerId)
+        {
             // Tricky: all Commands from a single provider get added to the
             // top-level list all together, in a row. So if we find just the first
             // one, we can slice it out and insert the new ones there.
-            for (var i = 0; i < clone.Count; i++)
+            for (var i = 0; i < topLevelItems.Count; i++)
             {
-                var wrapper = clone[i];
+                var wrapper = topLevelItems[i];
                 try
                 {
-                    if (sender.ProviderId == wrapper.CommandProviderId)
+                    if (providerId == wrapper.CommandProviderId)
                     {
-                        startIndex = i;
-                        break;
+                        return i;
                     }
                 }
                 catch
@@ -191,9 +200,8 @@ public partial class TopLevelCommandManager : ObservableObject,
                 }
             }
 
-            clone.RemoveAll(item => item.CommandProviderId == sender.ProviderId);
-            clone.InsertRange(startIndex, newItems);
-            ListHelpers.InPlaceUpdateList(TopLevelCommands, clone);
+            // If we didn't find any, then we just append the new commands to the end of the list.
+            return topLevelItems.Count;
         }
     }
 
@@ -241,7 +249,7 @@ public partial class TopLevelCommandManager : ObservableObject,
             _extensionCommandProviders.Clear();
         }
 
-        if (extensions != null)
+        if (extensions is not null)
         {
             await StartExtensionsAndGetCommands(extensions);
         }
@@ -275,7 +283,7 @@ public partial class TopLevelCommandManager : ObservableObject,
         var startTasks = extensions.Select(StartExtensionWithTimeoutAsync);
 
         // Wait for all extensions to start
-        var wrappers = (await Task.WhenAll(startTasks)).Where(wrapper => wrapper != null).Select(w => w!).ToList();
+        var wrappers = (await Task.WhenAll(startTasks)).Where(wrapper => wrapper is not null).Select(w => w!).ToList();
 
         lock (_commandProvidersLock)
         {
@@ -285,7 +293,7 @@ public partial class TopLevelCommandManager : ObservableObject,
         // Load the commands from the providers in parallel
         var loadTasks = wrappers.Select(LoadCommandsWithTimeoutAsync);
 
-        var commandSets = (await Task.WhenAll(loadTasks)).Where(results => results != null).Select(r => r!).ToList();
+        var commandSets = (await Task.WhenAll(loadTasks)).Where(results => results is not null).Select(r => r!).ToList();
 
         lock (TopLevelCommands)
         {
@@ -402,8 +410,8 @@ public partial class TopLevelCommandManager : ObservableObject,
 
     void IPageContext.ShowException(Exception ex, string? extensionHint)
     {
-        var errorMessage = $"A bug occurred in {$"the \"{extensionHint}\"" ?? "an unknown's"} extension's code:\n{ex.Message}\n{ex.Source}\n{ex.StackTrace}\n\n";
-        CommandPaletteHost.Instance.Log(errorMessage);
+        var message = DiagnosticsHelper.BuildExceptionMessage(ex, extensionHint ?? "TopLevelCommandManager");
+        CommandPaletteHost.Instance.Log(message);
     }
 
     internal bool IsProviderActive(string id)

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

@@ -240,7 +240,7 @@ public sealed partial class TopLevelViewModel : ObservableObject, IListItem
     private void FetchAliasFromAliasManager()
     {
         var am = _serviceProvider.GetService<AliasManager>();
-        if (am != null)
+        if (am is not null)
         {
             var commandAlias = am.AliasFromId(Id);
             if (commandAlias is not null)
@@ -254,7 +254,7 @@ public sealed partial class TopLevelViewModel : ObservableObject, IListItem
     private void UpdateHotkey()
     {
         var hotkey = _settings.CommandHotkeys.Where(hk => hk.CommandId == Id).FirstOrDefault();
-        if (hotkey != null)
+        if (hotkey is not null)
         {
             _hotkey = hotkey.Hotkey;
         }
@@ -264,12 +264,12 @@ public sealed partial class TopLevelViewModel : ObservableObject, IListItem
     {
         List<Tag> tags = [];
 
-        if (Hotkey != null)
+        if (Hotkey is not null)
         {
             tags.Add(new Tag() { Text = Hotkey.ToString() });
         }
 
-        if (Alias != null)
+        if (Alias is not null)
         {
             tags.Add(new Tag() { Text = Alias.SearchPrefix });
         }

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/CommandBar.xaml

@@ -47,7 +47,8 @@
             <Flyout
                 x:Name="ContextMenuFlyout"
                 FlyoutPresenterStyle="{StaticResource ContextMenuFlyoutStyle}"
-                Opened="ContextMenuFlyout_Opened">
+                Opened="ContextMenuFlyout_Opened"
+                ShouldConstrainToRootBounds="False">
                 <cpcontrols:ContextMenu x:Name="ContextControl" />
             </Flyout>
 

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

@@ -10,7 +10,6 @@ using Microsoft.CmdPal.UI.Views;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Controls.Primitives;
-using Microsoft.UI.Xaml.Input;
 using Windows.System;
 
 namespace Microsoft.CmdPal.UI.Controls;
@@ -50,7 +49,7 @@ public sealed partial class CommandBar : UserControl,
             return;
         }
 
-        if (message.Element == null)
+        if (message.Element is null)
         {
             _ = DispatcherQueue.TryEnqueue(
                 () =>

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

@@ -44,7 +44,7 @@ public sealed partial class ContentFormControl : UserControl
         // 5% BODGY: if we set this multiple times over the lifetime of the app,
         // then the second call will explode, because "CardOverrideStyles is already the child of another element".
         // SO only set this once.
-        if (_renderer.OverrideStyles == null)
+        if (_renderer.OverrideStyles is null)
         {
             _renderer.OverrideStyles = CardOverrideStyles;
         }
@@ -55,19 +55,19 @@ public sealed partial class ContentFormControl : UserControl
 
     private void AttachViewModel(ContentFormViewModel? vm)
     {
-        if (_viewModel != null)
+        if (_viewModel is not null)
         {
             _viewModel.PropertyChanged -= ViewModel_PropertyChanged;
         }
 
         _viewModel = vm;
 
-        if (_viewModel != null)
+        if (_viewModel is not null)
         {
             _viewModel.PropertyChanged += ViewModel_PropertyChanged;
 
             var c = _viewModel.Card;
-            if (c != null)
+            if (c is not null)
             {
                 DisplayCard(c);
             }
@@ -76,7 +76,7 @@ public sealed partial class ContentFormControl : UserControl
 
     private void ViewModel_PropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
     {
-        if (ViewModel == null)
+        if (ViewModel is null)
         {
             return;
         }
@@ -84,7 +84,7 @@ public sealed partial class ContentFormControl : UserControl
         if (e.PropertyName == nameof(ViewModel.Card))
         {
             var c = ViewModel.Card;
-            if (c != null)
+            if (c is not null)
             {
                 DisplayCard(c);
             }
@@ -95,7 +95,7 @@ public sealed partial class ContentFormControl : UserControl
     {
         _renderedCard = _renderer.RenderAdaptiveCard(result.AdaptiveCard);
         ContentGrid.Children.Clear();
-        if (_renderedCard.FrameworkElement != null)
+        if (_renderedCard.FrameworkElement is not null)
         {
             ContentGrid.Children.Add(_renderedCard.FrameworkElement);
 
@@ -148,7 +148,7 @@ public sealed partial class ContentFormControl : UserControl
 
             // Recursively check children
             var result = FindFirstFocusableElement(child);
-            if (result != null)
+            if (result is not null)
             {
                 return result;
             }

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ContentIcon.cs

@@ -2,6 +2,7 @@
 // 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;
 using CommunityToolkit.WinUI;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
@@ -35,6 +36,17 @@ public partial class ContentIcon : FontIcon
     {
         if (this.FindDescendants().OfType<Grid>().FirstOrDefault() is Grid grid && Content is not null)
         {
+            if (grid.Children.Contains(Content))
+            {
+                return;
+            }
+
+            if (Content is FrameworkElement element && element.Parent is not null)
+            {
+                Debug.Assert(false, $"IconBoxElement Content is already parented to {element.Parent.GetType().Name}");
+                return;
+            }
+
             grid.Children.Add(Content);
         }
     }

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ContextMenu.xaml

@@ -112,7 +112,7 @@
                 <Rectangle
                     Height="1"
                     Margin="-16,-12,-12,-12"
-                    Fill="{ThemeResource MenuFlyoutSeparatorThemeBrush}" />
+                    Fill="{ThemeResource MenuFlyoutSeparatorBackground}" />
             </DataTemplate>
         </ResourceDictionary>
     </UserControl.Resources>

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

@@ -31,7 +31,7 @@ public sealed partial class ContextMenu : UserControl,
         WeakReferenceMessenger.Default.Register<UpdateCommandBarMessage>(this);
         WeakReferenceMessenger.Default.Register<TryCommandKeybindingMessage>(this);
 
-        if (ViewModel != null)
+        if (ViewModel is not null)
         {
             ViewModel.PropertyChanged += ViewModel_PropertyChanged;
         }

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/IconBox.cs

@@ -91,7 +91,7 @@ public partial class IconBox : ContentControl
     {
         if (d is IconBox @this)
         {
-            if (e.NewValue == null)
+            if (e.NewValue is null)
             {
                 @this.Source = null;
             }
@@ -104,7 +104,7 @@ public partial class IconBox : ContentControl
                     var requestedTheme = @this.ActualTheme;
                     var eventArgs = new SourceRequestedEventArgs(e.NewValue, requestedTheme);
 
-                    if (@this.SourceRequested != null)
+                    if (@this.SourceRequested is not null)
                     {
                         await @this.SourceRequested.InvokeAsync(@this, eventArgs);
 
@@ -142,7 +142,7 @@ public partial class IconBox : ContentControl
                             iconData = requestedTheme == ElementTheme.Light ? info.Light : info.Dark;
                         }
 
-                        if (iconData != null &&
+                        if (iconData is not null &&
                             @this.Source is FontIconSource)
                         {
                             if (!string.IsNullOrEmpty(iconData.Icon) && iconData.Icon.Length <= 2)

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/KeyVisual/KeyVisual.cs

@@ -2,7 +2,6 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using Microsoft.CmdPal.UI;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Markup;
@@ -80,12 +79,12 @@ public sealed partial class KeyVisual : Control
 
     private void Update()
     {
-        if (_keyVisual == null)
+        if (_keyVisual is null)
         {
             return;
         }
 
-        if (_keyVisual.Content != null)
+        if (_keyVisual.Content is not null)
         {
             if (_keyVisual.Content.GetType() == typeof(string))
             {

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

@@ -51,13 +51,13 @@ public sealed partial class SearchBar : UserControl,
         //// TODO: If the Debounce timer hasn't fired, we may want to store the current Filter in the OldValue/prior VM, but we don't want that to go actually do work...
         var @this = (SearchBar)d;
 
-        if (@this != null
+        if (@this is not null
             && e.OldValue is PageViewModel old)
         {
             old.PropertyChanged -= @this.Page_PropertyChanged;
         }
 
-        if (@this != null
+        if (@this is not null
             && e.NewValue is PageViewModel page)
         {
             // TODO: In some cases we probably want commands to clear a filter
@@ -85,7 +85,7 @@ public sealed partial class SearchBar : UserControl,
         {
             this.FilterBox.Text = string.Empty;
 
-            if (CurrentPageViewModel != null)
+            if (CurrentPageViewModel is not null)
             {
                 CurrentPageViewModel.Filter = string.Empty;
             }
@@ -143,7 +143,7 @@ public sealed partial class SearchBar : UserControl,
                 FilterBox.Text = string.Empty;
 
                 // hack TODO GH #245
-                if (CurrentPageViewModel != null)
+                if (CurrentPageViewModel is not null)
                 {
                     CurrentPageViewModel.Filter = FilterBox.Text;
                 }
@@ -154,7 +154,7 @@ public sealed partial class SearchBar : UserControl,
         else if (e.Key == VirtualKey.Back)
         {
             // hack TODO GH #245
-            if (CurrentPageViewModel != null)
+            if (CurrentPageViewModel is not null)
             {
                 CurrentPageViewModel.Filter = FilterBox.Text;
             }
@@ -318,7 +318,7 @@ public sealed partial class SearchBar : UserControl,
         }
 
         // Actually plumb Filtering to the view model
-        if (CurrentPageViewModel != null)
+        if (CurrentPageViewModel is not null)
         {
             CurrentPageViewModel.Filter = FilterBox.Text;
         }

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

@@ -39,13 +39,13 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
     private static void OnAllowDisableChanged(DependencyObject d, DependencyPropertyChangedEventArgs? e)
     {
         var me = d as ShortcutControl;
-        if (me == null)
+        if (me is null)
         {
             return;
         }
 
         var description = me.c?.FindDescendant<TextBlock>();
-        if (description == null)
+        if (description is null)
         {
             return;
         }
@@ -431,7 +431,7 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
 
     private void ShortcutDialog_PrimaryButtonClick(ContentDialog sender, ContentDialogButtonClickEventArgs args)
     {
-        if (lastValidSettings != null && ComboIsValid(lastValidSettings))
+        if (lastValidSettings is not null && ComboIsValid(lastValidSettings))
         {
             HotkeySettings = lastValidSettings with { };
         }
@@ -458,7 +458,7 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
 
     private static bool ComboIsValid(HotkeySettings? settings)
     {
-        return settings != null && (settings.IsValid() || settings.IsEmpty());
+        return settings is not null && (settings.IsValid() || settings.IsEmpty());
     }
 
     public void Receive(WindowActivatedEventArgs message) => DoWindowActivated(message);
@@ -466,12 +466,12 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
     private void DoWindowActivated(WindowActivatedEventArgs args)
     {
         args.Handled = true;
-        if (args.WindowActivationState != WindowActivationState.Deactivated && (hook == null || hook.GetDisposedState() == true))
+        if (args.WindowActivationState != WindowActivationState.Deactivated && (hook is null || hook.GetDisposedState() == true))
         {
             // If the PT settings window gets focussed/activated again, we enable the keyboard hook to catch the keyboard input.
             hook = new HotkeySettingsControlHook(Hotkey_KeyDown, Hotkey_KeyUp, Hotkey_IsActive, FilterAccessibleKeyboardEvents);
         }
-        else if (args.WindowActivationState == WindowActivationState.Deactivated && hook != null && hook.GetDisposedState() == false)
+        else if (args.WindowActivationState == WindowActivationState.Deactivated && hook is not null && hook.GetDisposedState() == false)
         {
             // If the PT settings window lost focus/activation, we disable the keyboard hook to allow keyboard input on other windows.
             hook.Dispose();
@@ -490,7 +490,7 @@ public sealed partial class ShortcutControl : UserControl, IDisposable, IRecipie
         {
             if (disposing)
             {
-                if (hook != null)
+                if (hook is not null)
                 {
                     hook.Dispose();
                 }

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

@@ -84,7 +84,7 @@ public partial class Tag : Control
             return;
         }
 
-        if (tag.ForegroundColor != null &&
+        if (tag.ForegroundColor is not null &&
             OptionalColorBrushCacheProvider.Convert(tag.ForegroundColor.Value) is SolidColorBrush brush)
         {
             tag.Foreground = brush;
@@ -114,7 +114,7 @@ public partial class Tag : Control
             return;
         }
 
-        if (tag.BackgroundColor != null &&
+        if (tag.BackgroundColor is not null &&
             OptionalColorBrushCacheProvider.Convert(tag.BackgroundColor.Value) is SolidColorBrush brush)
         {
             tag.Background = brush;

src/modules/cmdpal/Microsoft.CmdPal.UI/ExtViews/ContentPage.xaml.cs

@@ -34,8 +34,14 @@ public sealed partial class ContentPage : Page,
     public ContentPage()
     {
         this.InitializeComponent();
-        WeakReferenceMessenger.Default.Register<ActivateSelectedListItemMessage>(this);
-        WeakReferenceMessenger.Default.Register<ActivateSecondaryCommandMessage>(this);
+        this.Unloaded += OnUnloaded;
+    }
+
+    private void OnUnloaded(object sender, RoutedEventArgs e)
+    {
+        // Unhook from everything to ensure nothing can reach us
+        // between this point and our complete and utter destruction.
+        WeakReferenceMessenger.Default.UnregisterAll(this);
     }
 
     protected override void OnNavigatedTo(NavigationEventArgs e)
@@ -45,6 +51,16 @@ public sealed partial class ContentPage : Page,
             ViewModel = vm;
         }
 
+        if (!WeakReferenceMessenger.Default.IsRegistered<ActivateSelectedListItemMessage>(this))
+        {
+            WeakReferenceMessenger.Default.Register<ActivateSelectedListItemMessage>(this);
+        }
+
+        if (!WeakReferenceMessenger.Default.IsRegistered<ActivateSecondaryCommandMessage>(this))
+        {
+            WeakReferenceMessenger.Default.Register<ActivateSecondaryCommandMessage>(this);
+        }
+
         base.OnNavigatedTo(e);
     }
 

src/modules/cmdpal/Microsoft.CmdPal.UI/ExtViews/ListPage.xaml.cs

@@ -15,6 +15,7 @@ using Microsoft.UI.Xaml.Controls;
 using Microsoft.UI.Xaml.Input;
 using Microsoft.UI.Xaml.Media;
 using Microsoft.UI.Xaml.Navigation;
+using Windows.System;
 
 namespace Microsoft.CmdPal.UI;
 
@@ -24,6 +25,8 @@ public sealed partial class ListPage : Page,
     IRecipient<ActivateSelectedListItemMessage>,
     IRecipient<ActivateSecondaryCommandMessage>
 {
+    private InputSource _lastInputSource;
+
     private ListViewModel? ViewModel
     {
         get => (ListViewModel?)GetValue(ViewModelProperty);
@@ -39,6 +42,8 @@ public sealed partial class ListPage : Page,
         this.InitializeComponent();
         this.NavigationCacheMode = NavigationCacheMode.Disabled;
         this.ItemsList.Loaded += ItemsList_Loaded;
+        this.ItemsList.PreviewKeyDown += ItemsList_PreviewKeyDown;
+        this.ItemsList.PointerPressed += ItemsList_PointerPressed;
     }
 
     protected override void OnNavigatedTo(NavigationEventArgs e)
@@ -74,7 +79,7 @@ public sealed partial class ListPage : Page,
         WeakReferenceMessenger.Default.Unregister<ActivateSelectedListItemMessage>(this);
         WeakReferenceMessenger.Default.Unregister<ActivateSecondaryCommandMessage>(this);
 
-        if (ViewModel != null)
+        if (ViewModel is not null)
         {
             ViewModel.PropertyChanged -= ViewModel_PropertyChanged;
             ViewModel.ItemsUpdated -= Page_ItemsUpdated;
@@ -98,6 +103,12 @@ public sealed partial class ListPage : Page,
     {
         if (e.ClickedItem is ListItemViewModel item)
         {
+            if (_lastInputSource == InputSource.Keyboard)
+            {
+                ViewModel?.InvokeItemCommand.Execute(item);
+                return;
+            }
+
             var settings = App.Current.Services.GetService<SettingsModel>()!;
             if (settings.SingleClickActivates)
             {
@@ -142,13 +153,13 @@ public sealed partial class ListPage : Page,
         // here, then in Page_ItemsUpdated trying to select that cached item if
         // it's in the list (otherwise, clear the cache), but that seems
         // aggressively BODGY for something that mostly just works today.
-        if (ItemsList.SelectedItem != null)
+        if (ItemsList.SelectedItem is not null)
         {
             ItemsList.ScrollIntoView(ItemsList.SelectedItem);
 
             // Automation notification for screen readers
             var listViewPeer = Microsoft.UI.Xaml.Automation.Peers.ListViewAutomationPeer.CreatePeerForElement(ItemsList);
-            if (listViewPeer != null && li != null)
+            if (listViewPeer is not null && li is not null)
             {
                 var notificationText = li.Title;
                 listViewPeer.RaiseNotificationEvent(
@@ -165,7 +176,7 @@ public sealed partial class ListPage : Page,
         // Find the ScrollViewer in the ListView
         var listViewScrollViewer = FindScrollViewer(this.ItemsList);
 
-        if (listViewScrollViewer != null)
+        if (listViewScrollViewer is not null)
         {
             listViewScrollViewer.ViewChanged += ListViewScrollViewer_ViewChanged;
         }
@@ -174,7 +185,7 @@ public sealed partial class ListPage : Page,
     private void ListViewScrollViewer_ViewChanged(object? sender, ScrollViewerViewChangedEventArgs e)
     {
         var scrollView = sender as ScrollViewer;
-        if (scrollView == null)
+        if (scrollView is null)
         {
             return;
         }
@@ -256,7 +267,7 @@ public sealed partial class ListPage : Page,
                 page.PropertyChanged += @this.ViewModel_PropertyChanged;
                 page.ItemsUpdated += @this.Page_ItemsUpdated;
             }
-            else if (e.NewValue == null)
+            else if (e.NewValue is null)
             {
                 Logger.LogDebug("cleared view model");
             }
@@ -274,7 +285,7 @@ public sealed partial class ListPage : Page,
         // ItemsList_SelectionChanged again to give us another chance to change
         // the selection from null -> something. Better to just update the
         // selection once, at the end of all the updating.
-        if (ItemsList.SelectedItem == null)
+        if (ItemsList.SelectedItem is null)
         {
             ItemsList.SelectedIndex = 0;
         }
@@ -307,7 +318,7 @@ public sealed partial class ListPage : Page,
         {
             var child = VisualTreeHelper.GetChild(parent, i);
             var result = FindScrollViewer(child);
-            if (result != null)
+            if (result is not null)
             {
                 return result;
             }
@@ -329,7 +340,7 @@ public sealed partial class ListPage : Page,
             _ => (null, null),
         };
 
-        if (item == null || element == null)
+        if (item is null || element is null)
         {
             return;
         }
@@ -363,4 +374,21 @@ public sealed partial class ListPage : Page,
     {
         _ = DispatcherQueue.TryEnqueue(() => WeakReferenceMessenger.Default.Send<CloseContextMenuMessage>());
     }
+
+    private void ItemsList_PointerPressed(object sender, PointerRoutedEventArgs e) => _lastInputSource = InputSource.Pointer;
+
+    private void ItemsList_PreviewKeyDown(object sender, KeyRoutedEventArgs e)
+    {
+        if (e.Key is VirtualKey.Enter or VirtualKey.Space)
+        {
+            _lastInputSource = InputSource.Keyboard;
+        }
+    }
+
+    private enum InputSource
+    {
+        None,
+        Keyboard,
+        Pointer,
+    }
 }

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

@@ -2,13 +2,6 @@
 // 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;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Microsoft.CmdPal.Ext.Bookmarks;
-using Microsoft.UI.Xaml.Documents;
 using Microsoft.Win32;
 
 namespace Microsoft.CmdPal.UI.Helpers;
@@ -63,7 +56,7 @@ internal static class GpoValueChecker
     {
         using (RegistryKey? key = rootKey.OpenSubKey(subKeyPath, false))
         {
-            if (key == null)
+            if (key is null)
             {
                 return null;
             }

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

@@ -4,7 +4,6 @@
 
 using Microsoft.CmdPal.Core.ViewModels;
 using Microsoft.CmdPal.UI.Controls;
-using Microsoft.CmdPal.UI.Helpers;
 
 namespace Microsoft.CmdPal.UI.Helpers;
 
@@ -19,7 +18,7 @@ public static partial class IconCacheProvider
     public static async void SourceRequested(IconBox sender, SourceRequestedEventArgs args)
 #pragma warning restore IDE0060 // Remove unused parameter
     {
-        if (args.Key == null)
+        if (args.Key is null)
         {
             return;
         }

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

@@ -28,7 +28,7 @@ public sealed class IconCacheService(DispatcherQueue dispatcherQueue)
                 var source = IconPathConverter.IconSourceMUX(icon.Icon, false);
                 return source;
             }
-            else if (icon.Data != null)
+            else if (icon.Data is not null)
             {
                 try
                 {
@@ -49,7 +49,7 @@ public sealed class IconCacheService(DispatcherQueue dispatcherQueue)
 
     private async Task<IconSource?> StreamToIconSource(IRandomAccessStreamReference iconStreamRef)
     {
-        if (iconStreamRef == null)
+        if (iconStreamRef is null)
         {
             return null;
         }

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

@@ -0,0 +1,157 @@
+// 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 ManagedCommon;
+
+using Windows.System;
+using Windows.Win32;
+using Windows.Win32.Foundation;
+using Windows.Win32.UI.WindowsAndMessaging;
+
+namespace Microsoft.CmdPal.UI.Helpers;
+
+/// <summary>
+/// A class that listens for local keyboard events using a Windows hook.
+/// </summary>
+internal sealed class LocalKeyboardListener : IDisposable
+{
+    /// <summary>
+    /// Event that is raised when a key is pressed down.
+    /// </summary>
+    public event EventHandler<LocalKeyboardListenerKeyPressedEventArgs>? KeyPressed;
+
+    private bool _disposed;
+    private UnhookWindowsHookExSafeHandle? _handle;
+    private HOOKPROC? _hookProc; // Keep reference to prevent GC collection
+
+    /// <summary>
+    /// Registers a global keyboard hook to listen for key down events.
+    /// </summary>
+    /// <exception cref="InvalidOperationException">
+    /// Throws if the hook could not be registered, which may happen if the system is unable to set the hook.
+    /// </exception>
+    public void RegisterKeyboardHook()
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+
+        if (_handle is not null && !_handle.IsInvalid)
+        {
+            // Hook is already set
+            return;
+        }
+
+        _hookProc = KeyEventHook;
+        if (!SetWindowKeyHook(_hookProc))
+        {
+            throw new InvalidOperationException("Failed to register keyboard hook.");
+        }
+    }
+
+    /// <summary>
+    /// Attempts to register a global keyboard hook to listen for key down events.
+    /// </summary>
+    /// <returns>
+    /// <see langword="true"/> if the keyboard hook was successfully registered; otherwise, <see langword="false"/>.
+    /// </returns>
+    public bool Start()
+    {
+        if (_disposed)
+        {
+            return false;
+        }
+
+        try
+        {
+            RegisterKeyboardHook();
+            return true;
+        }
+        catch (Exception ex)
+        {
+            Logger.LogError("Failed to register hook", ex);
+            return false;
+        }
+    }
+
+    private void UnregisterKeyboardHook()
+    {
+        if (_handle is not null && !_handle.IsInvalid)
+        {
+            // The SafeHandle should automatically call UnhookWindowsHookEx when disposed
+            _handle.Dispose();
+            _handle = null;
+        }
+
+        _hookProc = null;
+    }
+
+    private bool SetWindowKeyHook(HOOKPROC hookProc)
+    {
+        if (_handle is not null && !_handle.IsInvalid)
+        {
+            // Hook is already set
+            return false;
+        }
+
+        _handle = PInvoke.SetWindowsHookEx(
+            WINDOWS_HOOK_ID.WH_KEYBOARD,
+            hookProc,
+            PInvoke.GetModuleHandle(null),
+            PInvoke.GetCurrentThreadId());
+
+        // Check if the hook was successfully set
+        return _handle is not null && !_handle.IsInvalid;
+    }
+
+    private static bool IsKeyDownHook(LPARAM lParam)
+    {
+        // The 30th bit tells what the previous key state is with 0 being the "UP" state
+        // For more info see https://learn.microsoft.com/windows/win32/winmsg/keyboardproc#lparam-in
+        return ((lParam.Value >> 30) & 1) == 0;
+    }
+
+    private LRESULT KeyEventHook(int nCode, WPARAM wParam, LPARAM lParam)
+    {
+        try
+        {
+            if (nCode >= 0 && IsKeyDownHook(lParam))
+            {
+                InvokeKeyDown((VirtualKey)wParam.Value);
+            }
+        }
+        catch (Exception ex)
+        {
+            Logger.LogError("Failed when invoking key down keyboard hook event", ex);
+        }
+
+        // Call next hook in chain - pass null as first parameter for current hook
+        return PInvoke.CallNextHookEx(null, nCode, wParam, lParam);
+    }
+
+    private void InvokeKeyDown(VirtualKey virtualKey)
+    {
+        if (!_disposed)
+        {
+            KeyPressed?.Invoke(this, new LocalKeyboardListenerKeyPressedEventArgs(virtualKey));
+        }
+    }
+
+    public void Dispose()
+    {
+        Dispose(true);
+        GC.SuppressFinalize(this);
+    }
+
+    private void Dispose(bool disposing)
+    {
+        if (!_disposed)
+        {
+            if (disposing)
+            {
+                UnregisterKeyboardHook();
+            }
+
+            _disposed = true;
+        }
+    }
+}

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

@@ -0,0 +1,12 @@
+// 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 Windows.System;
+
+namespace Microsoft.CmdPal.UI.Helpers;
+
+public class LocalKeyboardListenerKeyPressedEventArgs(VirtualKey key) : EventArgs
+{
+    public VirtualKey Key { get; } = key;
+}

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

@@ -50,7 +50,7 @@ internal sealed partial class TrayIconService
     {
         if (showSystemTrayIcon ?? _settingsModel.ShowSystemTrayIcon)
         {
-            if (_window == null)
+            if (_window is null)
             {
                 _window = new Window();
                 _hwnd = new HWND(WindowNative.GetWindowHandle(_window));
@@ -64,7 +64,7 @@ internal sealed partial class TrayIconService
                 _originalWndProc = Marshal.GetDelegateForFunctionPointer<WNDPROC>(PInvoke.SetWindowLongPtr(_hwnd, WINDOW_LONG_PTR_INDEX.GWL_WNDPROC, hotKeyPrcPointer));
             }
 
-            if (_trayIconData == null)
+            if (_trayIconData is null)
             {
                 // We need to stash this handle, so it doesn't clean itself up. If
                 // explorer restarts, we'll come back through here, and we don't
@@ -88,7 +88,7 @@ internal sealed partial class TrayIconService
             // Add the notification icon
             PInvoke.Shell_NotifyIcon(NOTIFY_ICON_MESSAGE.NIM_ADD, in d);
 
-            if (_popupMenu == null)
+            if (_popupMenu is null)
             {
                 _popupMenu = PInvoke.CreatePopupMenu_SafeHandle();
                 PInvoke.InsertMenu(_popupMenu, 0, MENU_ITEM_FLAGS.MF_BYPOSITION | MENU_ITEM_FLAGS.MF_STRING, PInvoke.WM_USER + 1, RS_.GetString("TrayMenu_Settings"));
@@ -103,7 +103,7 @@ internal sealed partial class TrayIconService
 
     public void Destroy()
     {
-        if (_trayIconData != null)
+        if (_trayIconData is not null)
         {
             var d = (NOTIFYICONDATAW)_trayIconData;
             if (PInvoke.Shell_NotifyIcon(NOTIFY_ICON_MESSAGE.NIM_DELETE, in d))
@@ -112,19 +112,19 @@ internal sealed partial class TrayIconService
             }
         }
 
-        if (_popupMenu != null)
+        if (_popupMenu is not null)
         {
             _popupMenu.Close();
             _popupMenu = null;
         }
 
-        if (_largeIcon != null)
+        if (_largeIcon is not null)
         {
             _largeIcon.Close();
             _largeIcon = null;
         }
 
-        if (_window != null)
+        if (_window is not null)
         {
             _window.Close();
             _window = null;
@@ -167,7 +167,7 @@ internal sealed partial class TrayIconService
             // WM_WINDOWPOSCHANGING which is always received on explorer startup sequence.
             case PInvoke.WM_WINDOWPOSCHANGING:
                 {
-                    if (_trayIconData == null)
+                    if (_trayIconData is null)
                     {
                         SetupTrayIcon();
                     }
@@ -189,7 +189,7 @@ internal sealed partial class TrayIconService
                     {
                         case PInvoke.WM_RBUTTONUP:
                             {
-                                if (_popupMenu != null)
+                                if (_popupMenu is not null)
                                 {
                                     PInvoke.GetCursorPos(out var cursorPos);
                                     PInvoke.SetForegroundWindow(_hwnd);

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

@@ -46,7 +46,7 @@ public static class TypedEventHandlerExtensions
 #pragma warning restore CA1715 // Identifiers should have correct prefix
         where R : DeferredEventArgs
     {
-        if (eventHandler == null)
+        if (eventHandler is null)
         {
             return Task.CompletedTask;
         }

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

@@ -13,7 +13,7 @@ internal sealed partial class WindowHelper
         UserNotificationState state;
 
         // https://learn.microsoft.com/en-us/windows/win32/api/shellapi/ne-shellapi-query_user_notification_state
-        if (Marshal.GetExceptionForHR(NativeMethods.SHQueryUserNotificationState(out state)) == null)
+        if (Marshal.GetExceptionForHR(NativeMethods.SHQueryUserNotificationState(out state)) is null)
         {
             if (state == UserNotificationState.QUNS_RUNNING_D3D_FULL_SCREEN ||
                 state == UserNotificationState.QUNS_BUSY ||

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

@@ -27,6 +27,7 @@ using Microsoft.Windows.AppLifecycle;
 using Windows.ApplicationModel.Activation;
 using Windows.Foundation;
 using Windows.Graphics;
+using Windows.System;
 using Windows.UI;
 using Windows.UI.WindowManagement;
 using Windows.Win32;
@@ -44,7 +45,8 @@ public sealed partial class MainWindow : WindowEx,
     IRecipient<DismissMessage>,
     IRecipient<ShowWindowMessage>,
     IRecipient<HideWindowMessage>,
-    IRecipient<QuitMessage>
+    IRecipient<QuitMessage>,
+    IDisposable
 {
     [System.Diagnostics.CodeAnalysis.SuppressMessage("StyleCop.CSharp.NamingRules", "SA1310:Field names should not contain underscore", Justification = "Stylistically, window messages are WM_")]
     [System.Diagnostics.CodeAnalysis.SuppressMessage("StyleCop.CSharp.NamingRules", "SA1306:Field names should begin with lower-case letter", Justification = "Stylistically, window messages are WM_")]
@@ -54,6 +56,7 @@ public sealed partial class MainWindow : WindowEx,
     private readonly WNDPROC? _originalWndProc;
     private readonly List<TopLevelHotkey> _hotkeys = [];
     private readonly KeyboardListener _keyboardListener;
+    private readonly LocalKeyboardListener _localKeyboardListener;
     private bool _ignoreHotKeyWhenFullScreen = true;
 
     private DesktopAcrylicController? _acrylicController;
@@ -116,6 +119,18 @@ public sealed partial class MainWindow : WindowEx,
         {
             Summon(string.Empty);
         });
+
+        _localKeyboardListener = new LocalKeyboardListener();
+        _localKeyboardListener.KeyPressed += LocalKeyboardListener_OnKeyPressed;
+        _localKeyboardListener.Start();
+    }
+
+    private static void LocalKeyboardListener_OnKeyPressed(object? sender, LocalKeyboardListenerKeyPressedEventArgs e)
+    {
+        if (e.Key == VirtualKey.GoBack)
+        {
+            WeakReferenceMessenger.Default.Send(new GoBackMessage());
+        }
     }
 
     private void SettingsChangedHandler(SettingsModel sender, object? args) => HotReloadSettings();
@@ -376,6 +391,7 @@ public sealed partial class MainWindow : WindowEx,
         // WinUI bug is causing a crash on shutdown when FailFastOnErrors is set to true (#51773592).
         // Workaround by turning it off before shutdown.
         App.Current.DebugSettings.FailFastOnErrors = false;
+        _localKeyboardListener.Dispose();
         DisposeAcrylic();
 
         _keyboardListener.Stop();
@@ -384,7 +400,7 @@ public sealed partial class MainWindow : WindowEx,
 
     private void DisposeAcrylic()
     {
-        if (_acrylicController != null)
+        if (_acrylicController is not null)
         {
             _acrylicController.Dispose();
             _acrylicController = null!;
@@ -459,7 +475,7 @@ public sealed partial class MainWindow : WindowEx,
             PowerToysTelemetry.Log.WriteEvent(new CmdPalDismissedOnLostFocus());
         }
 
-        if (_configurationSource != null)
+        if (_configurationSource is not null)
         {
             _configurationSource.IsInputActive = args.WindowActivationState != WindowActivationState.Deactivated;
         }
@@ -467,7 +483,7 @@ public sealed partial class MainWindow : WindowEx,
 
     public void HandleLaunch(AppActivationArguments? activatedEventArgs)
     {
-        if (activatedEventArgs == null)
+        if (activatedEventArgs is null)
         {
             Summon(string.Empty);
             return;
@@ -535,7 +551,7 @@ public sealed partial class MainWindow : WindowEx,
         UnregisterHotkeys();
 
         var globalHotkey = settings.Hotkey;
-        if (globalHotkey != null)
+        if (globalHotkey is not null)
         {
             if (settings.UseLowLevelGlobalHotkey)
             {
@@ -565,7 +581,7 @@ public sealed partial class MainWindow : WindowEx,
         {
             var key = commandHotkey.Hotkey;
 
-            if (key != null)
+            if (key is not null)
             {
                 if (settings.UseLowLevelGlobalHotkey)
                 {
@@ -682,4 +698,10 @@ public sealed partial class MainWindow : WindowEx,
 
         return PInvoke.CallWindowProc(_originalWndProc, hwnd, uMsg, wParam, lParam);
     }
+
+    public void Dispose()
+    {
+        _localKeyboardListener.Dispose();
+        DisposeAcrylic();
+    }
 }

src/modules/cmdpal/Microsoft.CmdPal.UI/NativeMethods.txt

@@ -47,4 +47,10 @@ DWM_CLOAKED_APP
 
 CoWaitForMultipleObjects
 INFINITE
-CWMO_FLAGS 
+CWMO_FLAGS
+
+GetCurrentThreadId
+SetWindowsHookEx
+UnhookWindowsHookEx
+CallNextHookEx
+GetModuleHandle

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

@@ -24,7 +24,7 @@ public sealed partial class LoadingPage : Page
     protected override void OnNavigatedTo(NavigationEventArgs e)
     {
         if (e.Parameter is ShellViewModel shellVM
-            && shellVM.LoadCommand != null)
+            && shellVM.LoadCommand is not null)
         {
             // This will load the built-in commands, then navigate to the main page.
             // Once the mainpage loads, we'll start loading extensions.

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

@@ -171,7 +171,7 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
     // This gets called from the UI thread
     private async Task HandleConfirmArgsOnUiThread(IConfirmationArgs? args)
     {
-        if (args == null)
+        if (args is null)
         {
             return;
         }
@@ -236,7 +236,7 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
 
     public void OpenSettings()
     {
-        if (_settingsWindow == null)
+        if (_settingsWindow is null)
         {
             _settingsWindow = new SettingsWindow();
         }
@@ -324,7 +324,7 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
                 // command from our list of toplevel commands.
                 var tlcManager = App.Current.Services.GetService<TopLevelCommandManager>()!;
                 var topLevelCommand = tlcManager.LookupCommand(commandId);
-                if (topLevelCommand != null)
+                if (topLevelCommand is not null)
                 {
                     var command = topLevelCommand.CommandViewModel.Model.Unsafe;
                     var isPage = command is not IInvokableCommand;

src/modules/cmdpal/Microsoft.CmdPal.UI/PowerToysRootPageService.cs

@@ -100,7 +100,7 @@ internal sealed class PowerToysRootPageService : IRootPageService
             _activeExtension = extension;
 
             var extensionWinRtObject = _activeExtension?.GetExtensionObject();
-            if (extensionWinRtObject != null)
+            if (extensionWinRtObject is not null)
             {
                 try
                 {

src/modules/cmdpal/Microsoft.CmdPal.UI/Settings/SettingsWindow.xaml.cs

@@ -105,6 +105,8 @@ public sealed partial class SettingsWindow : WindowEx,
     private void Window_Closed(object sender, WindowEventArgs args)
     {
         WeakReferenceMessenger.Default.Send<SettingsWindowClosedMessage>();
+
+        WeakReferenceMessenger.Default.UnregisterAll(this);
     }
 
     private void PaneToggleBtn_Click(object sender, RoutedEventArgs e)

src/modules/cmdpal/Tests/Microsoft.CmdPal.Ext.Apps.UnitTests/AllAppsCommandProviderTests.cs

@@ -0,0 +1,119 @@
+// 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;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Microsoft.CmdPal.Ext.Apps.UnitTests;
+
+[TestClass]
+public class AllAppsCommandProviderTests : AppsTestBase
+{
+    [TestMethod]
+    public void ProviderHasDisplayName()
+    {
+        // Setup
+        var provider = new AllAppsCommandProvider();
+
+        // Assert
+        Assert.IsNotNull(provider.DisplayName);
+        Assert.IsTrue(provider.DisplayName.Length > 0);
+    }
+
+    [TestMethod]
+    public void ProviderHasIcon()
+    {
+        // Setup
+        var provider = new AllAppsCommandProvider();
+
+        // Assert
+        Assert.IsNotNull(provider.Icon);
+    }
+
+    [TestMethod]
+    public void TopLevelCommandsNotEmpty()
+    {
+        // Setup
+        var provider = new AllAppsCommandProvider();
+
+        // Act
+        var commands = provider.TopLevelCommands();
+
+        // Assert
+        Assert.IsNotNull(commands);
+        Assert.IsTrue(commands.Length > 0);
+    }
+
+    [TestMethod]
+    public void LookupAppWithEmptyNameReturnsNotNull()
+    {
+        // Setup
+        var mockApp = TestDataHelper.CreateTestWin32Program("Notepad", "C:\\Windows\\System32\\notepad.exe");
+        MockCache.AddWin32Program(mockApp);
+        var page = new AllAppsPage(MockCache);
+
+        var provider = new AllAppsCommandProvider(page);
+
+        // Act
+        var result = provider.LookupApp(string.Empty);
+
+        // Assert
+        Assert.IsNotNull(result);
+    }
+
+    [TestMethod]
+    public async Task ProviderWithMockData_LookupApp_ReturnsCorrectApp()
+    {
+        // Arrange
+        var testApp = TestDataHelper.CreateTestWin32Program("TestApp", "C:\\TestApp.exe");
+        MockCache.AddWin32Program(testApp);
+
+        var provider = new AllAppsCommandProvider(Page);
+
+        // Wait for initialization to complete
+        await WaitForPageInitializationAsync();
+
+        // Act
+        var result = provider.LookupApp("TestApp");
+
+        // Assert
+        Assert.IsNotNull(result);
+        Assert.AreEqual("TestApp", result.Title);
+    }
+
+    [TestMethod]
+    public async Task ProviderWithMockData_LookupApp_ReturnsNullForNonExistentApp()
+    {
+        // Arrange
+        var testApp = TestDataHelper.CreateTestWin32Program("TestApp", "C:\\TestApp.exe");
+        MockCache.AddWin32Program(testApp);
+
+        var provider = new AllAppsCommandProvider(Page);
+
+        // Wait for initialization to complete
+        await WaitForPageInitializationAsync();
+
+        // Act
+        var result = provider.LookupApp("NonExistentApp");
+
+        // Assert
+        Assert.IsNull(result);
+    }
+
+    [TestMethod]
+    public void ProviderWithMockData_TopLevelCommands_IncludesListItem()
+    {
+        // Arrange
+        var provider = new AllAppsCommandProvider(Page);
+
+        // Act
+        var commands = provider.TopLevelCommands();
+
+        // Assert
+        Assert.IsNotNull(commands);
+        Assert.IsTrue(commands.Length >= 1); // At least the list item should be present
+    }
+}

src/modules/cmdpal/Tests/Microsoft.CmdPal.Ext.Apps.UnitTests/AllAppsPageTests.cs

@@ -0,0 +1,97 @@
+// 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;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Microsoft.CmdPal.Ext.Apps.UnitTests;
+
+[TestClass]
+public class AllAppsPageTests : AppsTestBase
+{
+    [TestMethod]
+    public void AllAppsPage_Constructor_ThrowsOnNullAppCache()
+    {
+        // Act & Assert
+        Assert.ThrowsException<ArgumentNullException>(() => new AllAppsPage(null!));
+    }
+
+    [TestMethod]
+    public void AllAppsPage_WithMockCache_InitializesSuccessfully()
+    {
+        // Arrange
+        var mockCache = new MockAppCache();
+
+        // Act
+        var page = new AllAppsPage(mockCache);
+
+        // Assert
+        Assert.IsNotNull(page);
+        Assert.IsNotNull(page.Name);
+        Assert.IsNotNull(page.Icon);
+    }
+
+    [TestMethod]
+    public async Task AllAppsPage_GetItems_ReturnsEmptyWithEmptyCache()
+    {
+        // Act - Wait for initialization to complete
+        await WaitForPageInitializationAsync();
+        var items = Page.GetItems();
+
+        // Assert
+        Assert.IsNotNull(items);
+        Assert.AreEqual(0, items.Length);
+    }
+
+    [TestMethod]
+    public async Task AllAppsPage_GetItems_ReturnsAppsFromCacheAsync()
+    {
+        // Arrange
+        var mockCache = new MockAppCache();
+        var win32App = TestDataHelper.CreateTestWin32Program("Notepad", "C:\\Windows\\System32\\notepad.exe");
+        var uwpApp = TestDataHelper.CreateTestUWPApplication("Calculator");
+
+        mockCache.AddWin32Program(win32App);
+        mockCache.AddUWPApplication(uwpApp);
+
+        var page = new AllAppsPage(mockCache);
+
+        // Wait a bit for initialization to complete
+        await Task.Delay(100);
+
+        // Act
+        var items = page.GetItems();
+
+        // Assert
+        Assert.IsNotNull(items);
+        Assert.AreEqual(2, items.Length);
+
+        // we need to loop the items to ensure we got the correct ones
+        Assert.IsTrue(items.Any(i => i.Title == "Notepad"));
+        Assert.IsTrue(items.Any(i => i.Title == "Calculator"));
+    }
+
+    [TestMethod]
+    public async Task AllAppsPage_GetPinnedApps_ReturnsEmptyWhenNoAppsArePinned()
+    {
+        // Arrange
+        var mockCache = new MockAppCache();
+        var app = TestDataHelper.CreateTestWin32Program("TestApp", "C:\\TestApp.exe");
+        mockCache.AddWin32Program(app);
+
+        var page = new AllAppsPage(mockCache);
+
+        // Wait a bit for initialization to complete
+        await Task.Delay(100);
+
+        // Act
+        var pinnedApps = page.GetPinnedApps();
+
+        // Assert
+        Assert.IsNotNull(pinnedApps);
+        Assert.AreEqual(0, pinnedApps.Length);
+    }
+}