Merge remote-tracking branch 'origin/main' into yuleng/kbm/tsf4

# Conflicts:
#	src/modules/keyboardmanager/KeyboardManagerEditorUI/Controls/UnifiedMappingControl.xaml.cs
#	src/modules/keyboardmanager/KeyboardManagerEditorUI/Helpers/ValidationHelper.cs
#	src/modules/keyboardmanager/KeyboardManagerEditorUI/Pages/MainPage.xaml
#	src/modules/keyboardmanager/KeyboardManagerEditorUI/Pages/MainPage.xaml.cs
#	src/modules/keyboardmanager/KeyboardManagerEditorUI/Strings/en-US/Resources.resw

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

@@ -126,6 +126,7 @@ boxmodel
 BPBF
 bpmf
 bpp
+brb
 Browsable
 BROWSEINFO
 bsd
@@ -750,6 +751,7 @@ KILLFOCUS
 killrunner
 kmph
 Kybd
+Laf
 lastcodeanalysissucceeded
 LASTEXITCODE
 LAYOUTRTL
@@ -941,6 +943,7 @@ mstsc
 msvcp
 MT
 MTND
+Mtnhu
 multimonitor
 MULTIPLEUSE
 multizone
@@ -1470,6 +1473,7 @@ SIZENWSE
 SIZEWE
 SKEXP
 SKIPOWNPROCESS
+skm
 sku
 SLGP
 sln
@@ -1608,6 +1612,7 @@ templatenamespace
 testprocess
 TEXCOORD
 TEXTINCLUDE
+textinputmethod
 tfopen
 tgz
 themeresources
@@ -1716,6 +1721,7 @@ vcruntime
 vcvars
 VDesktop
 vdupq
+VEb
 VERBSONLY
 VERBW
 VERIFYCONTEXT
@@ -1792,6 +1798,7 @@ windowssearch
 windowssettings
 WINDOWSTYLES
 WINDOWSTYLESICON
+windowsupdate
 winerror
 WINEVENT
 winget
@@ -2056,6 +2063,7 @@ framechanged
 FRestore
 fsanitize
 ftps
+FTt
 fuzzingtesting
 fxf
 gameid

CLAUDE.md

@@ -0,0 +1,71 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Communication
+
+Always respond in Chinese (中文).
+
+## Project Overview
+
+PowerToys is a collection of Windows productivity utilities written in C++ and C#. The main solution is `PowerToys.slnx`. Each utility is a "module" loaded by the Runner via a standardized DLL interface.
+
+## Architecture
+
+- **Runner** (`src/runner/`): Main executable (PowerToys.exe). Loads module DLLs, manages hotkeys, shows tray icon, bridges modules to Settings UI via named pipes (JSON IPC).
+- **Settings UI** (`src/settings-ui/`): WinUI/WPF configuration app. Communicates with Runner over named pipes. Changes to IPC contracts must update both sides in the same PR.
+- **Modules** (`src/modules/`): ~30 individual utilities, each implementing the module interface (`src/modules/interface/`). Four module types: simple (self-contained DLL), external app launcher (separate process + IPC), context handler (shell extension), registry-based (preview handlers).
+- **Common** (`src/common/`): Shared libraries — logging, IPC, settings serialization, DPI utilities, telemetry, JSON/string helpers. Changes here affect the entire codebase.
+- **Installer** (`installer/`): WiX-based installer projects. Separate solution at `installer/PowerToysSetup.slnx`.
+
+## Build Commands
+
+Prerequisites: Visual Studio 2022 17.4+ or VS 2026, Windows 10 1803+. Initialize submodules once: `git submodule update --init --recursive`.
+
+| Task | Command |
+|------|---------|
+| First build / NuGet restore | `tools\build\build-essentials.cmd` |
+| Build current folder's project | `cd` to the `.csproj`/`.vcxproj` folder, then `tools\build\build.cmd` |
+| Build with options | `tools\build\build.ps1 -Platform x64 -Configuration Release` |
+| Full installer build | `tools\build\build-installer.ps1 -Platform x64 -Configuration Release -PerUser true -InstallerSuffix wix5` |
+| Format XAML | `.\.pipelines\applyXamlStyling.ps1 -Main` |
+| Format C++ | `src\codeAnalysis\format_sources.ps1` (formats git-modified files) |
+
+Build logs appear next to the solution/project: `build.<config>.<platform>.errors.log` (check first), `.all.log`, `.trace.binlog`.
+
+## Testing
+
+- **Do NOT use `dotnet test`** — use VS Test Explorer (`Ctrl+E, T`) or `vstest.console.exe` with filters.
+- Build the test project first (exit code 0) before running tests.
+- Test projects are named `<Product>*UnitTests` or `<Product>*UITests`, typically sibling folders or 1-2 levels up from the product code.
+- UI Tests require WinAppDriver v1.2.1 and Developer Mode enabled.
+
+## Style and Formatting
+
+- **C++**: `src/.clang-format` — auto-format with `Ctrl+K Ctrl+D` in VS or run `format_sources.ps1`.
+- **C#**: `src/.editorconfig` + StyleCop.Analyzers.
+- **XAML**: XamlStyler — VS extension or `applyXamlStyling.ps1`.
+- Follow existing style in modified files. New code should follow Modern C++ / C++ Core Guidelines.
+
+## Logging
+
+- **C++**: spdlog via `init_logger()`. Include `spdlog.props` in `.vcxproj`. Use `Logger::info/warn/error/debug`.
+- **C#**: `ManagedCommon.Logger`. Call `Logger.InitializeLogger("\\Module\\Logs")` at startup. Use `Logger.LogInfo/LogWarning/LogError/LogDebug`.
+- Log files: `%LOCALAPPDATA%\Microsoft\PowerToys\Logs`. Low-privilege processes use `%USERPROFILE%\AppData\LocalLow\Microsoft\PowerToys`.
+- No logging in hot paths (hooks, tight loops, timers).
+
+## Key Constraints
+
+- Atomic PRs: one logical change per PR, no drive-by refactors.
+- IPC/JSON contract changes must update both `src/runner/` and `src/settings-ui/` together.
+- Changes to `src/common/` public APIs: grep the entire codebase for usages and update all callers.
+- New third-party dependencies must be MIT-licensed (or PM-approved) and added to `NOTICE.md`.
+- Settings schema changes require migration logic and serialization tests.
+- New modules with file I/O or user input must include fuzzing tests.
+
+## Documentation
+
+- [Architecture](doc/devdocs/core/architecture.md), [Runner](doc/devdocs/core/runner.md), [Settings](doc/devdocs/core/settings/readme.md)
+- [Coding Guidelines](doc/devdocs/development/guidelines.md), [Style](doc/devdocs/development/style.md), [Logging](doc/devdocs/development/logging.md)
+- [Build Guidelines](tools/build/BUILD-GUIDELINES.md), [Module Interface](doc/devdocs/modules/interface.md)
+- [AGENTS.md](AGENTS.md) — full AI contributor guide with detailed conventions

src/PackageIdentity/AppxManifest.xml

@@ -68,6 +68,16 @@
         AppListEntry="none">
       </uap:VisualElements>
     </Application>
+    <Application Id="PowerToys.KeyboardManagerEngine" Executable="KeyboardManagerEngine\PowerToys.KeyboardManagerEngine.exe" EntryPoint="Windows.FullTrustApplication">
+      <uap:VisualElements
+        DisplayName="PowerToys.KeyboardManagerEngine"
+        Description="PowerToys Keyboard Manager Engine"
+        BackgroundColor="transparent"
+        Square150x150Logo="Images\Square150x150Logo.png"
+        Square44x44Logo="Images\Square44x44Logo.png"
+        AppListEntry="none">
+      </uap:VisualElements>
+    </Application>
     <Application Id="PowerToys.CmdPalExtension" Executable="Microsoft.CmdPal.Ext.PowerToys.exe" EntryPoint="Windows.FullTrustApplication">
       <uap:VisualElements
         DisplayName="PowerToys.CommandPaletteExtension"

src/common/ManagedCommon/OSVersionHelper.cs

@@ -22,5 +22,14 @@ namespace ManagedCommon
         {
             return Environment.OSVersion.Version.Major >= 10 && Environment.OSVersion.Version.Build > 22000;
         }
+
+        /// <summary>
+        /// TSF4 (Text Services Framework 4) APIs require Windows 11 build 20000+.
+        /// TODO: Confirm the exact minimum build number once finalized.
+        /// </summary>
+        public static bool IsTsf4Supported()
+        {
+            return Environment.OSVersion.Version.Major >= 10 && Environment.OSVersion.Version.Build >= 10000;
+        }
     }
 }

src/modules/keyboardmanager/KeyboardManagerEditorLibraryWrapper/KeyboardManagerEditorLibraryWrapper.cpp

@@ -678,6 +678,50 @@ bool GetShortcutRemapByType(void* config, int operationType, int index, Shortcut
         return false;
     }
 
+    bool AddExpandMapping(void* config, const wchar_t* abbreviation, int triggerKey, const wchar_t* expandedText, const wchar_t* targetApp)
+    {
+        auto mappingConfig = static_cast<MappingConfiguration*>(config);
+        if (!abbreviation || !expandedText)
+        {
+            return false;
+        }
+
+        ExpandMapping mapping;
+        mapping.abbreviation = abbreviation;
+        mapping.triggerKey = static_cast<DWORD>(triggerKey);
+        mapping.expandedText = expandedText;
+        mapping.appName = targetApp ? targetApp : L"";
+
+        mappingConfig->expandMappings.push_back(std::move(mapping));
+        return true;
+    }
+
+    bool DeleteExpandMapping(void* config, const wchar_t* abbreviation, const wchar_t* targetApp)
+    {
+        auto mappingConfig = static_cast<MappingConfiguration*>(config);
+        if (!abbreviation)
+        {
+            return false;
+        }
+
+        std::wstring abbrev = abbreviation;
+        std::wstring app = targetApp ? targetApp : L"";
+
+        auto& mappings = mappingConfig->expandMappings;
+        auto it = std::remove_if(mappings.begin(), mappings.end(), [&](const ExpandMapping& m) {
+            return _wcsicmp(m.abbreviation.c_str(), abbrev.c_str()) == 0 &&
+                   _wcsicmp(m.appName.c_str(), app.c_str()) == 0;
+        });
+
+        if (it != mappings.end())
+        {
+            mappings.erase(it, mappings.end());
+            return true;
+        }
+
+        return false;
+    }
+
     // Function to delete a shortcut remapping
     bool DeleteShortcutRemap(void* config, const wchar_t* originalKeys, const wchar_t* targetApp)
     {

src/modules/keyboardmanager/KeyboardManagerEditorLibraryWrapper/KeyboardManagerEditorLibraryWrapper.h

@@ -79,6 +79,9 @@ extern "C"
     __declspec(dllexport) bool IsShortcutIllegal(const wchar_t* shortcutKeys);
     __declspec(dllexport) bool AreShortcutsEqual(const wchar_t* lShort, const wchar_t* rShort);
 
+    __declspec(dllexport) bool AddExpandMapping(void* config, const wchar_t* abbreviation, int triggerKey, const wchar_t* expandedText, const wchar_t* targetApp);
+    __declspec(dllexport) bool DeleteExpandMapping(void* config, const wchar_t* abbreviation, const wchar_t* targetApp);
+
     __declspec(dllexport) bool DeleteSingleKeyRemap(void* config, int originalKey);
     __declspec(dllexport) bool DeleteSingleKeyToTextRemap(void* config, int originalKey);
     __declspec(dllexport) bool DeleteShortcutRemap(void* config, const wchar_t* originalKeys, const wchar_t* targetApp);

src/modules/keyboardmanager/KeyboardManagerEditorUI/Controls/IconLabelControl.xaml.cs

@@ -81,6 +81,7 @@ namespace KeyboardManagerEditorUI.Controls
                 ActionType.Shortcut => "\uEDA7",
                 ActionType.MouseClick => "\uE962",
                 ActionType.Url => "\uE774",
+                ActionType.Expand => "\uE8C8",
                 _ => "\uE8A5",
             };
         }

src/modules/keyboardmanager/KeyboardManagerEditorUI/Controls/UnifiedMappingControl.xaml

@@ -47,6 +47,12 @@
                         <TextBlock x:Uid="TriggerType_KeyOrShortcut_Text" />
                     </StackPanel>
                 </ComboBoxItem>
+                <ComboBoxItem x:Name="TriggerType_ExpandItem" x:Uid="TriggerType_Expand" Tag="Expand">
+                    <StackPanel Orientation="Horizontal" Spacing="8">
+                        <FontIcon FontSize="14" Glyph="&#xE8C8;" />
+                        <TextBlock x:Uid="TriggerType_Expand_Text" />
+                    </StackPanel>
+                </ComboBoxItem>
                 <!--
                 <ComboBoxItem x:Uid="TriggerType_Mouse" Tag="Mouse">
                     <StackPanel Orientation="Horizontal" Spacing="8">
@@ -113,6 +119,44 @@
                             IsChecked="True" />
                     </StackPanel>
                 </tkcontrols:Case>
+                <!--  Expand Trigger  -->
+                <tkcontrols:Case Value="Expand">
+                    <StackPanel Orientation="Vertical" Spacing="8">
+                        <TextBox
+                            x:Name="ExpandAbbreviationBox"
+                            x:Uid="ExpandAbbreviationBox"
+                            Background="{ThemeResource TextControlBackgroundFocused}"
+                            BorderBrush="{ThemeResource ControlStrokeColorDefaultBrush}"
+                            GotFocus="ExpandAbbreviationBox_GotFocus"
+                            TextChanged="ExpandAbbreviationBox_TextChanged" />
+                        <TextBlock
+                            x:Uid="ExpandTriggerKeyLabel"
+                            Margin="0,8,0,0"
+                            FontWeight="SemiBold" />
+                        <ToggleButton
+                            x:Name="ExpandTriggerKeyToggleBtn"
+                            MinHeight="48"
+                            Padding="8,12,8,12"
+                            HorizontalAlignment="Stretch"
+                            HorizontalContentAlignment="Center"
+                            VerticalContentAlignment="Center"
+                            Checked="ExpandTriggerKeyToggleBtn_Checked"
+                            Style="{StaticResource CustomShortcutToggleButtonStyle}"
+                            Unchecked="ExpandTriggerKeyToggleBtn_Unchecked">
+                            <ToggleButton.Content>
+                                <commoncontrols:KeyVisual
+                                    x:Name="ExpandTriggerKeyVisual"
+                                    Padding="8"
+                                    Background="{ThemeResource ControlFillColorDefaultBrush}"
+                                    BorderThickness="1"
+                                    Content="Space"
+                                    CornerRadius="{StaticResource OverlayCornerRadius}"
+                                    FontSize="16"
+                                    Style="{StaticResource DefaultKeyVisualStyle}" />
+                            </ToggleButton.Content>
+                        </ToggleButton>
+                    </StackPanel>
+                </tkcontrols:Case>
                 <!--  Mouse Button Trigger  -->
                 <tkcontrols:Case Value="Mouse">
                     <ComboBox
@@ -188,10 +232,10 @@
                         <TextBlock x:Uid="ActionType_KeyOrShortcut_Text" />
                     </StackPanel>
                 </ComboBoxItem>
-                <ComboBoxItem x:Uid="ActionType_Text" Tag="Text">
+                <ComboBoxItem x:Name="ActionTypeTextItem" x:Uid="ActionType_Text" Tag="Text">
                     <StackPanel Orientation="Horizontal" Spacing="8">
-                        <FontIcon FontSize="14" Glyph="&#xE8D2;" />
-                        <TextBlock x:Uid="ActionType_Text_Text" />
+                        <FontIcon x:Name="ActionTypeTextIcon" FontSize="14" Glyph="&#xE8D2;" />
+                        <TextBlock x:Name="ActionTypeTextLabel" x:Uid="ActionType_Text_Text" />
                     </StackPanel>
                 </ComboBoxItem>
                 <ComboBoxItem x:Uid="ActionType_OpenUrl" Tag="OpenUrl">
@@ -229,7 +273,7 @@
             <tkcontrols:SwitchPresenter
                 x:Name="ActionSwitchPresenter"
                 TargetType="x:String"
-                Value="{Binding SelectedItem.Tag, ElementName=ActionTypeComboBox}">
+                Value="KeyOrShortcut">
                 <!--  Key or Shortcut Action  -->
                 <tkcontrols:Case Value="KeyOrShortcut">
                     <ToggleButton
@@ -384,6 +428,7 @@
                         </ComboBox>
                     </StackPanel>
                 </tkcontrols:Case>
+                <!--  Replace With uses the Text case above with label override  -->
                 <!--  Mouse Click Action (Placeholder)  -->
                 <tkcontrols:Case Value="MouseClick">
                     <TextBlock

src/modules/keyboardmanager/KeyboardManagerEditorUI/Controls/UnifiedMappingControl.xaml.cs

@@ -43,6 +43,15 @@ namespace KeyboardManagerEditorUI.Controls
         private bool _textContentDirty;
         private bool _urlPathDirty;
         private bool _programPathDirty;
+        private bool _expandAbbreviationDirty;
+
+        // Expand trigger key tracking
+        private string _expandTriggerKey = "Space";
+        private bool _isCapturingExpandTriggerKey;
+
+        // Saved label/icon for restoring "Text" action item after Expand mode
+        private string? _savedTextLabel;
+        private string? _savedTextIconGlyph;
 
         public bool AllowChords { get; set; } = true;
 
@@ -66,6 +75,7 @@ namespace KeyboardManagerEditorUI.Controls
         {
             KeyOrShortcut,
             Mouse,
+            Expand,
         }
 
         /// <summary>
@@ -78,6 +88,7 @@ namespace KeyboardManagerEditorUI.Controls
             OpenUrl,
             OpenApp,
             MouseClick,
+            ReplaceWith,
             Disable,
         }
 
@@ -108,6 +119,7 @@ namespace KeyboardManagerEditorUI.Controls
                     return item.Tag?.ToString() switch
                     {
                         "Mouse" => TriggerType.Mouse,
+                        "Expand" => TriggerType.Expand,
                         _ => TriggerType.KeyOrShortcut,
                     };
                 }
@@ -123,6 +135,12 @@ namespace KeyboardManagerEditorUI.Controls
         {
             get
             {
+                // When in Expand trigger mode, the action is always ReplaceWith
+                if (CurrentTriggerType == TriggerType.Expand)
+                {
+                    return ActionType.ReplaceWith;
+                }
+
                 if (ActionTypeComboBox?.SelectedItem is ComboBoxItem item)
                 {
                     return item.Tag?.ToString() switch
@@ -163,6 +181,12 @@ namespace KeyboardManagerEditorUI.Controls
                 RaiseValidationStateChanged();
             };
 
+            // Disable Text Expand option when TSF4 API is not available on this OS
+            if (!ManagedCommon.OSVersionHelper.IsTsf4Supported())
+            {
+                TriggerType_ExpandItem.IsEnabled = false;
+            }
+
             this.Unloaded += UnifiedMappingControl_Unloaded;
         }
 
@@ -200,13 +224,26 @@ namespace KeyboardManagerEditorUI.Controls
             {
                 string? tag = item.Tag?.ToString();
 
-                // Cleanup keyboard hook when switching to mouse
-                if (tag == "Mouse")
+                // Cleanup keyboard hook when switching to mouse or expand
+                if (tag == "Mouse" || tag == "Expand")
                 {
                     CleanupKeyboardHook();
                     UncheckAllToggleButtons();
                 }
+
+                if (tag == "Expand")
+                {
+                    SwitchActionTypeToReplaceWith();
+                    HideAppSpecific();
+                }
+                else
+                {
+                    RestoreNormalActionTypes();
+                    ShowAppSpecific();
+                }
             }
+
+            RaiseValidationStateChanged();
         }
 
         private void TriggerKeyToggleBtn_Checked(object sender, RoutedEventArgs e)
@@ -248,6 +285,12 @@ namespace KeyboardManagerEditorUI.Controls
             {
                 string? tag = item.Tag?.ToString();
 
+                // Sync SwitchPresenter with the selected action type
+                if (tag != null && ActionSwitchPresenter != null)
+                {
+                    ActionSwitchPresenter.Value = tag;
+                }
+
                 // Cleanup keyboard hook when switching away from key/shortcut
                 if (tag != "KeyOrShortcut")
                 {
@@ -671,6 +714,25 @@ namespace KeyboardManagerEditorUI.Controls
 
         public void OnKeyDown(VirtualKey key, List<string> formattedKeys)
         {
+            // Expand trigger key capture: only accept a single key
+            if (_isCapturingExpandTriggerKey && formattedKeys.Count > 0)
+            {
+                _expandTriggerKey = formattedKeys[0];
+                if (ExpandTriggerKeyVisual != null)
+                {
+                    ExpandTriggerKeyVisual.Content = _expandTriggerKey;
+                }
+
+                // Auto-uncheck the toggle after capturing one key
+                if (ExpandTriggerKeyToggleBtn?.IsChecked == true)
+                {
+                    ExpandTriggerKeyToggleBtn.IsChecked = false;
+                }
+
+                RaiseValidationStateChanged();
+                return;
+            }
+
             if (_currentInputMode == KeyInputMode.OriginalKeys)
             {
                 _triggerKeys.Clear();
@@ -807,7 +869,14 @@ namespace KeyboardManagerEditorUI.Controls
         /// </summary>
         public bool IsInputComplete()
         {
-            // Trigger keys are always required
+            // Expand trigger: abbreviation + expanded text required (no trigger keys needed)
+            if (CurrentTriggerType == TriggerType.Expand)
+            {
+                return !string.IsNullOrWhiteSpace(ExpandAbbreviationBox?.Text)
+                    && !string.IsNullOrWhiteSpace(TextContentBox?.Text);
+            }
+
+            // Trigger keys are always required for other trigger types
             if (_triggerKeys.Count == 0)
             {
                 return false;
@@ -870,6 +939,12 @@ namespace KeyboardManagerEditorUI.Controls
                 return;
             }
 
+            // ReplaceWith is handled by SwitchActionTypeToReplaceWith(), not by index
+            if (actionType == ActionType.ReplaceWith)
+            {
+                return;
+            }
+
             string tag = actionType switch
             {
                 ActionType.Text => "Text",
@@ -1009,6 +1084,11 @@ namespace KeyboardManagerEditorUI.Controls
             {
                 ActionKeyToggleBtn.IsChecked = false;
             }
+
+            if (ExpandTriggerKeyToggleBtn?.IsChecked == true)
+            {
+                ExpandTriggerKeyToggleBtn.IsChecked = false;
+            }
         }
 
         private static void SetDropDownsEnabled(ItemsControl itemsControl, bool enabled)
@@ -1089,6 +1169,21 @@ namespace KeyboardManagerEditorUI.Controls
                         return;
                     }
 
+                    break;
+
+                case ActionType.ReplaceWith:
+                    if (ExpandAbbreviationBox != null && _expandAbbreviationDirty && string.IsNullOrWhiteSpace(ExpandAbbreviationBox.Text))
+                    {
+                        ShowValidationErrorFromType(ValidationErrorType.EmptyExpandAbbreviation);
+                        return;
+                    }
+
+                    if (TextContentBox != null && _textContentDirty && string.IsNullOrWhiteSpace(TextContentBox.Text))
+                    {
+                        ShowValidationErrorFromType(ValidationErrorType.EmptyExpandedText);
+                        return;
+                    }
+
                     break;
             }
 
@@ -1111,6 +1206,24 @@ namespace KeyboardManagerEditorUI.Controls
             _textContentDirty = false;
             _urlPathDirty = false;
             _programPathDirty = false;
+            _expandAbbreviationDirty = false;
+
+            // Reset expand state
+            _expandTriggerKey = "Space";
+            _isCapturingExpandTriggerKey = false;
+
+            if (ExpandAbbreviationBox != null)
+            {
+                ExpandAbbreviationBox.Text = string.Empty;
+            }
+
+            if (ExpandTriggerKeyVisual != null)
+            {
+                ExpandTriggerKeyVisual.Content = "Space";
+            }
+
+            // Restore normal action types if currently in Expand mode
+            RestoreNormalActionTypes();
 
             // Hide any validation messages
             HideValidationMessage();
@@ -1168,6 +1281,7 @@ namespace KeyboardManagerEditorUI.Controls
             {
                 AppSpecificCheckBox.IsChecked = false;
                 AppSpecificCheckBox.IsEnabled = false;
+                AppSpecificCheckBox.Visibility = Visibility.Visible;
             }
 
             // Reset app combo boxes
@@ -1287,6 +1401,167 @@ namespace KeyboardManagerEditorUI.Controls
         {
             AllowChords = AllowChordsCheckBox.IsChecked == true;
         }
+
+        #region Expand Trigger Handling
+
+        private void ExpandAbbreviationBox_GotFocus(object sender, RoutedEventArgs e)
+        {
+            CleanupKeyboardHook();
+            UncheckAllToggleButtons();
+        }
+
+        private void ExpandAbbreviationBox_TextChanged(object sender, TextChangedEventArgs e)
+        {
+            _expandAbbreviationDirty = true;
+            RaiseValidationStateChanged();
+        }
+
+        private void ExpandTriggerKeyToggleBtn_Checked(object sender, RoutedEventArgs e)
+        {
+            if (ExpandTriggerKeyToggleBtn.IsChecked == true)
+            {
+                _isCapturingExpandTriggerKey = true;
+                _currentInputMode = KeyInputMode.OriginalKeys;
+
+                // Uncheck other toggles
+                UncheckAllToggleButtons();
+
+                KeyboardHookHelper.Instance.ActivateHook(this);
+            }
+        }
+
+        private void ExpandTriggerKeyToggleBtn_Unchecked(object sender, RoutedEventArgs e)
+        {
+            if (_isCapturingExpandTriggerKey)
+            {
+                _isCapturingExpandTriggerKey = false;
+                CleanupKeyboardHook();
+            }
+        }
+
+        private void HideAppSpecific()
+        {
+            if (AppSpecificCheckBox != null)
+            {
+                AppSpecificCheckBox.Visibility = Visibility.Collapsed;
+            }
+
+            if (AppNameTextBox != null)
+            {
+                AppNameTextBox.Visibility = Visibility.Collapsed;
+            }
+        }
+
+        private void ShowAppSpecific()
+        {
+            if (AppSpecificCheckBox != null)
+            {
+                AppSpecificCheckBox.Visibility = Visibility.Visible;
+            }
+        }
+
+        private void SwitchActionTypeToReplaceWith()
+        {
+            if (ActionTypeComboBox == null || ActionTypeTextItem == null)
+            {
+                return;
+            }
+
+            // Select the "Text" action item and override its label to "Replace with"
+            ActionTypeComboBox.SelectedItem = ActionTypeTextItem;
+            ActionTypeComboBox.IsEnabled = false;
+
+            if (ActionTypeTextLabel != null)
+            {
+                _savedTextLabel = ActionTypeTextLabel.Text;
+                ActionTypeTextLabel.Text = "Replace with";
+            }
+
+            if (ActionTypeTextIcon != null)
+            {
+                _savedTextIconGlyph = ActionTypeTextIcon.Glyph;
+                ActionTypeTextIcon.Glyph = "\uE8C8";
+            }
+        }
+
+        private void RestoreNormalActionTypes()
+        {
+            if (ActionTypeComboBox == null)
+            {
+                return;
+            }
+
+            // Restore original label and icon on the "Text" action item
+            if (ActionTypeTextLabel != null && _savedTextLabel != null)
+            {
+                ActionTypeTextLabel.Text = _savedTextLabel;
+                _savedTextLabel = null;
+            }
+
+            if (ActionTypeTextIcon != null && _savedTextIconGlyph != null)
+            {
+                ActionTypeTextIcon.Glyph = _savedTextIconGlyph;
+                _savedTextIconGlyph = null;
+            }
+
+            ActionTypeComboBox.SelectedIndex = 0;
+            ActionTypeComboBox.IsEnabled = true;
+        }
+
+        #endregion
+
+        #region Expand Public API - Getters
+
+        public string GetExpandAbbreviation() => ExpandAbbreviationBox?.Text ?? string.Empty;
+
+        public string GetExpandTriggerKey() => _expandTriggerKey;
+
+        public string GetExpandedText() => TextContentBox?.Text ?? string.Empty;
+
+        #endregion
+
+        #region Expand Public API - Setters
+
+        public void SetExpandAbbreviation(string abbreviation)
+        {
+            if (ExpandAbbreviationBox != null)
+            {
+                ExpandAbbreviationBox.Text = abbreviation;
+            }
+        }
+
+        public void SetExpandTriggerKey(string triggerKey)
+        {
+            _expandTriggerKey = triggerKey;
+            if (ExpandTriggerKeyVisual != null)
+            {
+                ExpandTriggerKeyVisual.Content = triggerKey;
+            }
+        }
+
+        public void SetExpandedText(string text)
+        {
+            if (TextContentBox != null)
+            {
+                TextContentBox.Text = text;
+            }
+        }
+
+        public void SetTriggerType(TriggerType triggerType)
+        {
+            int index = triggerType switch
+            {
+                TriggerType.Expand => 1,
+                _ => 0,
+            };
+
+            if (TriggerTypeComboBox != null)
+            {
+                TriggerTypeComboBox.SelectedIndex = index;
+            }
+        }
+
+        #endregion
     }
 }
 

src/modules/keyboardmanager/KeyboardManagerEditorUI/Helpers/ActionType.cs

@@ -11,5 +11,6 @@ namespace KeyboardManagerEditorUI.Helpers
         Shortcut,
         MouseClick,
         Url,
+        Expand,
     }
 }

src/modules/keyboardmanager/KeyboardManagerEditorUI/Helpers/ExpandMapping.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 System.Collections.Generic;
+
+namespace KeyboardManagerEditorUI.Helpers
+{
+    public class ExpandMapping : IToggleableShortcut
+    {
+        public List<string> Shortcut { get; set; } = new List<string>();
+
+        public string Abbreviation { get; set; } = string.Empty;
+
+        public string TriggerKey { get; set; } = "Space";
+
+        public string ExpandedText { get; set; } = string.Empty;
+
+        public bool IsAllApps { get; set; } = true;
+
+        public string AppName { get; set; } = string.Empty;
+
+        public bool IsActive { get; set; } = true;
+
+        public string Id { get; set; } = string.Empty;
+    }
+}

src/modules/keyboardmanager/KeyboardManagerEditorUI/Helpers/ValidationErrorType.cs

@@ -25,5 +25,8 @@ namespace KeyboardManagerEditorUI.Helpers
         EmptyUrl,
         EmptyProgramPath,
         OneKeyMapping,
+        EmptyExpandAbbreviation,
+        EmptyExpandedText,
+        DuplicateExpandAbbreviation,
     }
 }

src/modules/keyboardmanager/KeyboardManagerEditorUI/Helpers/ValidationHelper.cs

@@ -28,6 +28,9 @@ namespace KeyboardManagerEditorUI.Helpers
             { ValidationErrorType.EmptyUrl, (ResourceHelper.GetString("Validation_EmptyUrl_Title"), ResourceHelper.GetString("Validation_EmptyUrl_Message")) },
             { ValidationErrorType.EmptyProgramPath, (ResourceHelper.GetString("Validation_EmptyProgramPath_Title"), ResourceHelper.GetString("Validation_EmptyProgramPath_Message")) },
             { ValidationErrorType.OneKeyMapping, (ResourceHelper.GetString("Validation_OneKeyMapping_Title"), ResourceHelper.GetString("Validation_OneKeyMapping_Message")) },
+            { ValidationErrorType.EmptyExpandAbbreviation, (ResourceHelper.GetString("Validation_EmptyExpandAbbreviation_Title"), ResourceHelper.GetString("Validation_EmptyExpandAbbreviation_Message")) },
+            { ValidationErrorType.EmptyExpandedText, (ResourceHelper.GetString("Validation_EmptyExpandedText_Title"), ResourceHelper.GetString("Validation_EmptyExpandedText_Message")) },
+            { ValidationErrorType.DuplicateExpandAbbreviation, (ResourceHelper.GetString("Validation_DuplicateExpandAbbreviation_Title"), ResourceHelper.GetString("Validation_DuplicateExpandAbbreviation_Message")) },
         };
 
         public static ValidationErrorType ValidateKeyMapping(
@@ -261,6 +264,34 @@ namespace KeyboardManagerEditorUI.Helpers
             return true;
         }
 
+        public static ValidationErrorType ValidateExpandMapping(
+            string abbreviation,
+            string expandedText,
+            List<ExpandMapping> existingMappings,
+            bool isEditMode = false)
+        {
+            if (string.IsNullOrWhiteSpace(abbreviation))
+            {
+                return ValidationErrorType.EmptyExpandAbbreviation;
+            }
+
+            if (string.IsNullOrWhiteSpace(expandedText))
+            {
+                return ValidationErrorType.EmptyExpandedText;
+            }
+
+            int upperLimit = isEditMode ? 1 : 0;
+            int duplicateCount = existingMappings.Count(m =>
+                string.Equals(m.Abbreviation, abbreviation, StringComparison.OrdinalIgnoreCase));
+
+            if (duplicateCount > upperLimit)
+            {
+                return ValidationErrorType.DuplicateExpandAbbreviation;
+            }
+
+            return ValidationErrorType.NoError;
+        }
+
         private static ValidationErrorType ValidateProgramOrUrlMapping(
             List<string> originalKeys,
             bool isAppSpecific,

src/modules/keyboardmanager/KeyboardManagerEditorUI/Interop/KeyboardManagerInterop.cs

@@ -85,6 +85,22 @@ namespace KeyboardManagerEditorUI.Interop
             int ifRunningAction = 0,
             int visibility = 0);
 
+        [DllImport(DllName, CallingConvention = Convention, CharSet = CharSet.Unicode)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        internal static extern bool AddExpandMapping(
+            IntPtr config,
+            [MarshalAs(UnmanagedType.LPWStr)] string abbreviation,
+            int triggerKey,
+            [MarshalAs(UnmanagedType.LPWStr)] string expandedText,
+            [MarshalAs(UnmanagedType.LPWStr)] string targetApp);
+
+        [DllImport(DllName, CallingConvention = Convention, CharSet = CharSet.Unicode)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        internal static extern bool DeleteExpandMapping(
+            IntPtr config,
+            [MarshalAs(UnmanagedType.LPWStr)] string abbreviation,
+            [MarshalAs(UnmanagedType.LPWStr)] string targetApp);
+
         // Delete Mapping Functions
         [DllImport(DllName, CallingConvention = Convention)]
         [return: MarshalAs(UnmanagedType.Bool)]

src/modules/keyboardmanager/KeyboardManagerEditorUI/Interop/KeyboardMappingService.cs

@@ -253,6 +253,16 @@ namespace KeyboardManagerEditorUI.Interop
                 (int)shortcutKeyMapping.OperationType);
         }
 
+        public bool AddExpandMapping(string abbreviation, int triggerKey, string expandedText, string targetApp)
+        {
+            return KeyboardManagerInterop.AddExpandMapping(_configHandle, abbreviation, triggerKey, expandedText, targetApp);
+        }
+
+        public bool DeleteExpandMapping(string abbreviation, string targetApp)
+        {
+            return KeyboardManagerInterop.DeleteExpandMapping(_configHandle, abbreviation, targetApp);
+        }
+
         public bool SaveSettings()
         {
             return KeyboardManagerInterop.SaveMappingSettings(_configHandle);

src/modules/keyboardmanager/KeyboardManagerEditorUI/Interop/ShortcutOperationType.cs

@@ -16,5 +16,6 @@ namespace KeyboardManagerEditorUI.Interop
         RunProgram = 1,
         OpenUri = 2,
         RemapText = 3,
+        ExpandText = 4,
     }
 }

src/modules/keyboardmanager/KeyboardManagerEditorUI/Pages/MainPage.xaml

@@ -540,6 +540,88 @@
                                             </ListView>
                                         </StackPanel>
 
+                                        <!--  Expand Section  -->
+                                        <StackPanel Orientation="Vertical" Visibility="{x:Bind ExpandMappings.Count, Mode=OneWay, Converter={StaticResource CountToVisibilityConverter}}">
+                                            <TextBlock
+                                                x:Uid="ExpandMappingsHeader"
+                                                Margin="16,16,0,8"
+                                                Style="{StaticResource BodyStrongTextBlockStyle}" />
+                                            <Rectangle
+                                                Height="1"
+                                                HorizontalAlignment="Stretch"
+                                                Fill="{ThemeResource CardStrokeColorDefaultBrush}" />
+                                            <ListView
+                                                IsItemClickEnabled="True"
+                                                ItemClick="ExpandMappingsList_ItemClick"
+                                                ItemsSource="{x:Bind ExpandMappings}"
+                                                ScrollViewer.VerticalScrollMode="Disabled"
+                                                SelectionMode="None">
+                                                <ListView.ItemTemplate>
+                                                    <DataTemplate x:DataType="helper:ExpandMapping">
+                                                        <Grid MinHeight="48" Padding="0,8,0,8">
+                                                            <Grid.ColumnDefinitions>
+                                                                <ColumnDefinition Width="*" />
+                                                                <ColumnDefinition Width="Auto" />
+                                                            </Grid.ColumnDefinitions>
+                                                            <Rectangle Style="{StaticResource ItemDividerStyle}" />
+
+                                                            <StackPanel Orientation="Horizontal" Spacing="8">
+                                                                <controls:IconLabelControl ActionType="Text" Label="{x:Bind Abbreviation}" />
+                                                                <TextBlock
+                                                                    x:Uid="ExpandsToText"
+                                                                    VerticalAlignment="Center"
+                                                                    Foreground="{ThemeResource TextFillColorSecondaryBrush}" />
+                                                                <controls:IconLabelControl
+                                                                    ActionType="Expand"
+                                                                    Label="{x:Bind ExpandedText}"
+                                                                    Style="{StaticResource RemappedIconLabelControlStyle}" />
+                                                                <TextBlock
+                                                                    x:Uid="ExpandTriggerKeyText"
+                                                                    VerticalAlignment="Center"
+                                                                    Foreground="{ThemeResource TextFillColorSecondaryBrush}" />
+                                                                <commoncontrols:KeyVisual Content="{x:Bind TriggerKey}" Style="{StaticResource OriginalKeyVisualStyle}" />
+                                                                <StackPanel
+                                                                    Orientation="Horizontal"
+                                                                    Spacing="8"
+                                                                    Visibility="{x:Bind AppName, Converter={StaticResource StringVisibilityConverter}}">
+                                                                    <TextBlock
+                                                                        x:Uid="InText"
+                                                                        VerticalAlignment="Center"
+                                                                        Foreground="{ThemeResource TextFillColorSecondaryBrush}" />
+                                                                    <controls:IconLabelControl ActionType="Program" Label="{x:Bind AppName}" />
+                                                                </StackPanel>
+                                                            </StackPanel>
+                                                            <StackPanel
+                                                                Grid.Column="1"
+                                                                Orientation="Horizontal"
+                                                                Spacing="8">
+                                                                <ToggleSwitch
+                                                                    IsOn="{x:Bind IsActive}"
+                                                                    Style="{StaticResource RightAlignedCompactToggleSwitchStyle}"
+                                                                    Toggled="ToggleSwitch_Toggled" />
+                                                                <Button
+                                                                    VerticalAlignment="Center"
+                                                                    Content="{ui:FontIcon Glyph=&#xE712;,
+                                                                                          FontSize=14}"
+                                                                    Style="{StaticResource SubtleButtonStyle}">
+                                                                    <Button.Flyout>
+                                                                        <MenuFlyout>
+                                                                            <MenuFlyoutItem
+                                                                                x:Uid="DeleteMenuItem"
+                                                                                Click="DeleteMapping_Click"
+                                                                                Icon="{ui:FontIcon Glyph=&#xE74D;,
+                                                                                                   FontSize=14}"
+                                                                                Tag="{x:Bind}" />
+                                                                        </MenuFlyout>
+                                                                    </Button.Flyout>
+                                                                </Button>
+                                                            </StackPanel>
+                                                        </Grid>
+                                                    </DataTemplate>
+                                                </ListView.ItemTemplate>
+                                            </ListView>
+                                        </StackPanel>
+
                                         <!--  Disabled Section  -->
                                         <StackPanel Orientation="Vertical" Visibility="{x:Bind DisabledList.Count, Mode=OneWay, Converter={StaticResource CountToVisibilityConverter}}">
                                             <TextBlock

src/modules/keyboardmanager/KeyboardManagerEditorUI/Pages/MainPage.xaml.cs

@@ -81,6 +81,8 @@ namespace KeyboardManagerEditorUI.Pages
 
         public ObservableCollection<URLShortcut> UrlShortcuts { get; } = new();
 
+        public ObservableCollection<ExpandMapping> ExpandMappings { get; } = new();
+
         [DllImport("PowerToys.KeyboardManagerEditorLibraryWrapper.dll", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Unicode)]
         private static extern void GetKeyDisplayName(int keyCode, [Out] StringBuilder keyName, int maxLength);
 
@@ -92,6 +94,7 @@ namespace KeyboardManagerEditorUI.Pages
                 TextMapping,
                 ProgramShortcut,
                 UrlShortcut,
+                ExpandMapping,
             }
 
             public ItemType Type { get; set; }
@@ -305,6 +308,33 @@ namespace KeyboardManagerEditorUI.Pages
             await ShowRemappingDialog();
         }
 
+        private async void ExpandMappingsList_ItemClick(object sender, ItemClickEventArgs e)
+        {
+            if (e.ClickedItem is not ExpandMapping expandMapping)
+            {
+                return;
+            }
+
+            _isEditMode = true;
+            _editingItem = new EditingItem
+            {
+                Type = EditingItem.ItemType.ExpandMapping,
+                Item = expandMapping,
+                OriginalTriggerKeys = new List<string>(),
+                AppName = expandMapping.AppName,
+                IsAllApps = expandMapping.IsAllApps,
+            };
+
+            UnifiedMappingControl.Reset();
+            UnifiedMappingControl.SetTriggerType(UnifiedMappingControl.TriggerType.Expand);
+            UnifiedMappingControl.SetExpandAbbreviation(expandMapping.Abbreviation);
+            UnifiedMappingControl.SetExpandTriggerKey(expandMapping.TriggerKey);
+            UnifiedMappingControl.SetExpandedText(expandMapping.ExpandedText);
+            UnifiedMappingControl.SetAppSpecific(!expandMapping.IsAllApps, expandMapping.AppName);
+            RemappingDialog.Title = "Edit remapping";
+            await ShowRemappingDialog();
+        }
+
         private async System.Threading.Tasks.Task ShowRemappingDialog()
         {
             RemappingDialog.PrimaryButtonClick += RemappingDialog_PrimaryButtonClick;
@@ -367,7 +397,10 @@ namespace KeyboardManagerEditorUI.Pages
             {
                 List<string> triggerKeys = UnifiedMappingControl.GetTriggerKeys();
 
-                if (triggerKeys == null || triggerKeys.Count == 0)
+                // Expand trigger type does not use traditional trigger keys
+                bool isExpandMode = UnifiedMappingControl.CurrentTriggerType == UnifiedMappingControl.TriggerType.Expand;
+
+                if (!isExpandMode && (triggerKeys == null || triggerKeys.Count == 0))
                 {
                     UnifiedMappingControl.ShowValidationErrorFromType(ValidationErrorType.EmptyOriginalKeys);
                     args.Cancel = true;
@@ -394,6 +427,7 @@ namespace KeyboardManagerEditorUI.Pages
                     UnifiedMappingControl.ActionType.OpenUrl => SaveUrlMapping(triggerKeys),
                     UnifiedMappingControl.ActionType.OpenApp => SaveProgramMapping(triggerKeys),
                     UnifiedMappingControl.ActionType.Disable => SaveDisableMapping(triggerKeys),
+                    UnifiedMappingControl.ActionType.ReplaceWith => SaveExpandMapping(),
                     UnifiedMappingControl.ActionType.MouseClick => throw new NotImplementedException("Mouse click remapping is not yet supported."),
                     _ => false,
                 };
@@ -439,6 +473,8 @@ namespace KeyboardManagerEditorUI.Pages
                     triggerKeys, UnifiedMappingControl.GetProgramPath(), isAppSpecific, appName, _mappingService!, _isEditMode),
                 UnifiedMappingControl.ActionType.Disable => ValidationHelper.ValidateDisableMapping(
                     triggerKeys, isAppSpecific, appName, _mappingService!, _isEditMode, editingRemapping),
+                UnifiedMappingControl.ActionType.ReplaceWith => ValidationHelper.ValidateExpandMapping(
+                    UnifiedMappingControl.GetExpandAbbreviation(), UnifiedMappingControl.GetExpandedText(), ExpandMappings.ToList(), _isEditMode),
                 _ => ValidationErrorType.NoError,
             };
         }
@@ -683,6 +719,44 @@ namespace KeyboardManagerEditorUI.Pages
             return saved;
         }
 
+        private bool SaveExpandMapping()
+        {
+            string abbreviation = UnifiedMappingControl.GetExpandAbbreviation();
+            string triggerKey = UnifiedMappingControl.GetExpandTriggerKey();
+            string expandedText = UnifiedMappingControl.GetExpandedText();
+
+            if (string.IsNullOrWhiteSpace(abbreviation) || string.IsNullOrWhiteSpace(expandedText))
+            {
+                return false;
+            }
+
+            string targetApp = UnifiedMappingControl.GetIsAppSpecific() ? UnifiedMappingControl.GetAppName() : string.Empty;
+
+            var shortcutKeyMapping = new ShortcutKeyMapping
+            {
+                OperationType = ShortcutOperationType.ExpandText,
+                OriginalKeys = abbreviation,
+                TargetKeys = triggerKey,
+                TargetText = expandedText,
+                TargetApp = targetApp,
+            };
+
+            // Resolve trigger key name to VK code (e.g., "Space" → 0x20)
+            int triggerKeyVk = KeyboardManagerInterop.GetKeyCodeFromName(triggerKey);
+            if (triggerKeyVk == 0)
+            {
+                triggerKeyVk = 0x20; // Default to VK_SPACE
+            }
+
+            // Persist to engine config (default.json) via C++ interop
+            _mappingService?.AddExpandMapping(abbreviation, triggerKeyVk, expandedText, targetApp);
+            _mappingService?.SaveSettings();
+
+            // Also persist to editor settings for UI state
+            SettingsManager.AddShortcutKeyMappingToSettings(shortcutKeyMapping);
+            return true;
+        }
+
         #endregion
 
         #region Delete Handlers
@@ -739,6 +813,19 @@ namespace KeyboardManagerEditorUI.Pages
 
         private void HandleShortcutDelete(IToggleableShortcut shortcut)
         {
+            if (shortcut is ExpandMapping)
+            {
+                ShortcutKeyMapping skm = SettingsManager.EditorSettings.ShortcutSettingsDictionary[shortcut.Id].Shortcut;
+                if (shortcut.IsActive)
+                {
+                    _mappingService!.DeleteExpandMapping(skm.OriginalKeys, skm.TargetApp);
+                    _mappingService.SaveSettings();
+                }
+
+                SettingsManager.RemoveShortcutKeyMappingFromSettings(shortcut.Id);
+                return;
+            }
+
             bool deleted = shortcut.Shortcut.Count == 1
                 ? DeleteSingleKeyToTextMapping(shortcut.Shortcut[0]) // Remapping has its own handler, single key will always be text mapping
                 : DeleteMultiKeyShortcut(shortcut);
@@ -804,14 +891,34 @@ namespace KeyboardManagerEditorUI.Pages
                 return;
             }
 
+            if (shortcut is ExpandMapping expandMapping)
+            {
+                ShortcutKeyMapping skm = SettingsManager.EditorSettings.ShortcutSettingsDictionary[shortcut.Id].Shortcut;
+                int triggerKeyVk = KeyboardManagerInterop.GetKeyCodeFromName(skm.TargetKeys);
+                if (triggerKeyVk == 0)
+                {
+                    triggerKeyVk = 0x20;
+                }
+
+                bool saved = _mappingService!.AddExpandMapping(skm.OriginalKeys, triggerKeyVk, skm.TargetText, skm.TargetApp);
+                if (saved)
+                {
+                    shortcut.IsActive = true;
+                    SettingsManager.ToggleShortcutKeyMappingActiveState(shortcut.Id);
+                    _mappingService.SaveSettings();
+                }
+
+                return;
+            }
+
             ShortcutKeyMapping shortcutKeyMapping = SettingsManager.EditorSettings.ShortcutSettingsDictionary[shortcut.Id].Shortcut;
-            bool saved = shortcut.Shortcut.Count == 1
+            bool saved2 = shortcut.Shortcut.Count == 1
                 ? _mappingService!.AddSingleKeyToTextMapping(_mappingService.GetKeyCodeFromName(shortcut.Shortcut[0]), shortcutKeyMapping.TargetText)
                 : shortcutKeyMapping.OperationType == ShortcutOperationType.RemapText
                     ? _mappingService!.AddShortcutMapping(shortcutKeyMapping.OriginalKeys, shortcutKeyMapping.TargetText, operationType: ShortcutOperationType.RemapText)
                     : _mappingService!.AddShortcutMapping(shortcutKeyMapping);
 
-            if (saved)
+            if (saved2)
             {
                 shortcut.IsActive = true;
                 SettingsManager.ToggleShortcutKeyMappingActiveState(shortcut.Id);
@@ -829,11 +936,25 @@ namespace KeyboardManagerEditorUI.Pages
                 return;
             }
 
-            bool deleted = shortcut.Shortcut.Count == 1
+            if (shortcut is ExpandMapping expandMapping)
+            {
+                ShortcutKeyMapping skm = SettingsManager.EditorSettings.ShortcutSettingsDictionary[shortcut.Id].Shortcut;
+                bool deleted = _mappingService!.DeleteExpandMapping(skm.OriginalKeys, skm.TargetApp);
+                if (deleted)
+                {
+                    shortcut.IsActive = false;
+                    SettingsManager.ToggleShortcutKeyMappingActiveState(shortcut.Id);
+                    _mappingService.SaveSettings();
+                }
+
+                return;
+            }
+
+            bool deleted2 = shortcut.Shortcut.Count == 1
                 ? DeleteSingleKeyToTextMapping(shortcut.Shortcut[0])
                 : DeleteMultiKeyMapping(shortcut.Shortcut, shortcut.AppName);
 
-            if (deleted)
+            if (deleted2)
             {
                 shortcut.IsActive = false;
                 SettingsManager.ToggleShortcutKeyMappingActiveState(shortcut.Id);
@@ -882,12 +1003,13 @@ namespace KeyboardManagerEditorUI.Pages
             LoadTextMappings();
             LoadProgramShortcuts();
             LoadUrlShortcuts();
+            LoadExpandMappings();
             UpdateHasAnyMappings();
         }
 
         private void UpdateHasAnyMappings()
         {
-            bool hasAny = RemappingList.Count > 0 || DisabledList.Count > 0 || TextMappings.Count > 0 || ProgramShortcuts.Count > 0 || UrlShortcuts.Count > 0;
+            bool hasAny = RemappingList.Count > 0 || DisabledList.Count > 0 || TextMappings.Count > 0 || ProgramShortcuts.Count > 0 || UrlShortcuts.Count > 0 || ExpandMappings.Count > 0;
             MappingState = hasAny ? "HasMappings" : "Empty";
         }
 
@@ -1024,6 +1146,35 @@ namespace KeyboardManagerEditorUI.Pages
             }
         }
 
+        private void LoadExpandMappings()
+        {
+            SettingsManager.EditorSettings.ShortcutsByOperationType.TryGetValue(ShortcutOperationType.ExpandText, out var expandIds);
+
+            if (expandIds == null)
+            {
+                return;
+            }
+
+            ExpandMappings.Clear();
+
+            foreach (var id in expandIds)
+            {
+                ShortcutSettings shortcutSettings = SettingsManager.EditorSettings.ShortcutSettingsDictionary[id];
+                ShortcutKeyMapping mapping = shortcutSettings.Shortcut;
+
+                ExpandMappings.Add(new ExpandMapping
+                {
+                    Abbreviation = mapping.OriginalKeys,
+                    TriggerKey = mapping.TargetKeys,
+                    ExpandedText = mapping.TargetText,
+                    IsAllApps = string.IsNullOrEmpty(mapping.TargetApp),
+                    AppName = mapping.TargetApp ?? string.Empty,
+                    Id = shortcutSettings.Id,
+                    IsActive = shortcutSettings.IsActive,
+                });
+            }
+        }
+
         private List<string> ParseKeyCodes(string keyCodesString)
         {
             return keyCodesString.Split(';')

src/modules/keyboardmanager/KeyboardManagerEditorUI/Strings/en-US/Resources.resw

@@ -378,6 +378,42 @@
   <data name="MouseClickPlaceholder.Text" xml:space="preserve">
     <value>Mouse click action - coming soon</value>
   </data>
+  <data name="TriggerType_Expand.AutomationProperties.Name" xml:space="preserve">
+    <value>Text expand</value>
+  </data>
+  <data name="TriggerType_Expand_Text.Text" xml:space="preserve">
+    <value>Text expand</value>
+  </data>
+  <data name="ExpandAbbreviationBox.Header" xml:space="preserve">
+    <value>Abbreviation</value>
+  </data>
+  <data name="ExpandAbbreviationBox.PlaceholderText" xml:space="preserve">
+    <value>e.g. brb</value>
+  </data>
+  <data name="ExpandTriggerKeyLabel.Text" xml:space="preserve">
+    <value>Trigger key</value>
+  </data>
+  <data name="ActionType_ReplaceWith.AutomationProperties.Name" xml:space="preserve">
+    <value>Replace with</value>
+  </data>
+  <data name="ActionType_ReplaceWith_Text.Text" xml:space="preserve">
+    <value>Replace with</value>
+  </data>
+  <data name="ExpandedTextBox.Header" xml:space="preserve">
+    <value>Expanded text</value>
+  </data>
+  <data name="ExpandedTextBox.PlaceholderText" xml:space="preserve">
+    <value>e.g. be right back</value>
+  </data>
+  <data name="ExpandMappingsHeader.Text" xml:space="preserve">
+    <value>Text expansions</value>
+  </data>
+  <data name="ExpandsToText.Text" xml:space="preserve">
+    <value>expands to</value>
+  </data>
+  <data name="ExpandTriggerKeyText.Text" xml:space="preserve">
+    <value>via</value>
+  </data>
   <data name="Validation_EmptyOriginalKeys_Title" xml:space="preserve">
     <value>Missing original keys</value>
   </data>
@@ -450,6 +486,24 @@
   <data name="Validation_OneKeyMapping_Message" xml:space="preserve">
     <value>A single key cannot be remapped to a Program or URL shortcut. Please choose a combination of keys.</value>
   </data>
+  <data name="Validation_EmptyExpandAbbreviation_Title" xml:space="preserve">
+    <value>Missing abbreviation</value>
+  </data>
+  <data name="Validation_EmptyExpandAbbreviation_Message" xml:space="preserve">
+    <value>Please enter the abbreviation text that will trigger the expansion.</value>
+  </data>
+  <data name="Validation_EmptyExpandedText_Title" xml:space="preserve">
+    <value>Missing expanded text</value>
+  </data>
+  <data name="Validation_EmptyExpandedText_Message" xml:space="preserve">
+    <value>Please enter the text that the abbreviation will expand to.</value>
+  </data>
+  <data name="Validation_DuplicateExpandAbbreviation_Title" xml:space="preserve">
+    <value>Duplicate abbreviation</value>
+  </data>
+  <data name="Validation_DuplicateExpandAbbreviation_Message" xml:space="preserve">
+    <value>This abbreviation is already used by another text expansion.</value>
+  </data>
   <data name="Warning_ShortcutStartWithModifier" xml:space="preserve">
     <value>Shortcuts must start with a modifier key (Ctrl, Alt, Shift, or Win).</value>
   </data>
@@ -501,4 +555,4 @@
   <data name="CheckServiceBtn.Content" xml:space="preserve">
     <value>Check service status</value>
   </data>
-</root>
+</root>

src/modules/keyboardmanager/KeyboardManagerEngine/main.cpp

@@ -9,6 +9,7 @@
 #include <common/utils/gpo.h>
 #include <keyboardmanager/common/KeyboardManagerConstants.h>
 #include <keyboardmanager/KeyboardManagerEngineLibrary/KeyboardManager.h>
+#include <keyboardmanager/KeyboardManagerEngineLibrary/Tsf4TextReplacer.h>
 #include <keyboardmanager/KeyboardManagerEngineLibrary/trace.h>
 #include <common/interop/shared_constants.h>
 
@@ -73,6 +74,9 @@ int WINAPI wWinMain(_In_ HINSTANCE /*hInstance*/,
         });
     }
 
+    // Initialize TSF4 text input provider on the main thread (before the message loop).
+    Tsf4TextReplacer::Initialize();
+
     auto kbm = KeyboardManager();
     if (kbm.HasRegisteredRemappings())
         kbm.StartLowlevelKeyboardHook();
@@ -84,6 +88,7 @@ int WINAPI wWinMain(_In_ HINSTANCE /*hInstance*/,
     run_message_loop({}, {}, { { KeyboardManager::StartHookMessageID, StartHookFunc } });
 
     kbm.StopLowlevelKeyboardHook();
+    Tsf4TextReplacer::Shutdown();
     Trace::UnregisterProvider();
 
     trace.Flush();

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/KeyboardEventHandlers.cpp

@@ -8,6 +8,7 @@
 #include <keyboardmanager/common/InputInterface.h>
 #include <keyboardmanager/common/Helpers.h>
 #include <keyboardmanager/KeyboardManagerEngineLibrary/trace.h>
+#include "Tsf4TextReplacer.h"
 
 #include <TlHelp32.h>
 #include <thread>
@@ -1803,4 +1804,63 @@ namespace KeyboardEventHandlers
 
         return 1;
     }
+
+    // Function to handle text expansion (abbreviation → expanded text) via TSF4.
+    // When the trigger key is pressed, reads the last N characters from the focused
+    // text box. If they match an abbreviation, replaces them with the expanded text.
+    intptr_t HandleExpandTextEvent(LowlevelKeyboardEvent* data, State& state)
+    {
+        if (GeneratedByKBM(data))
+        {
+            return 0;
+        }
+
+        if (data->wParam != WM_KEYDOWN)
+        {
+            return 0;
+        }
+
+        if (!Tsf4TextReplacer::IsAvailable())
+        {
+            return 0;
+        }
+
+        DWORD vkCode = data->lParam->vkCode;
+
+        // Check if this key is a trigger key for any expand mapping.
+        // Also filter by the current application if app-specific.
+        std::wstring currentApp;
+        bool currentAppResolved = false;
+
+        for (const auto& mapping : state.expandMappings)
+        {
+            if (mapping.triggerKey != vkCode)
+            {
+                continue;
+            }
+
+            // Check app-specific filter
+            if (!mapping.appName.empty())
+            {
+                if (!currentAppResolved)
+                {
+                    currentApp = Helpers::GetCurrentApplication(false);
+                    currentAppResolved = true;
+                }
+
+                // Case-insensitive comparison
+                if (_wcsicmp(currentApp.c_str(), mapping.appName.c_str()) != 0)
+                {
+                    continue;
+                }
+            }
+
+            if (Tsf4TextReplacer::TryExpand(mapping.abbreviation, mapping.expandedText))
+            {
+                return 1; // Swallow the trigger key
+            }
+        }
+
+        return 0;
+    }
 }

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/KeyboardEventHandlers.h

@@ -82,6 +82,9 @@ namespace KeyboardEventHandlers
     // Function to generate a unicode string in response to a single keypress
     intptr_t HandleSingleKeyToTextRemapEvent(KeyboardManagerInput::InputInterface& ii, LowlevelKeyboardEvent* data, State& state);
 
+    // Function to handle text expansion (abbreviation → expanded text) via TSF4
+    intptr_t HandleExpandTextEvent(LowlevelKeyboardEvent* data, State& state);
+
     // Function to ensure Ctrl/Shift/Alt modifier key state is not detected as pressed down by applications which detect keys at a lower level than hooks when it is remapped for scenarios where its required
     void ResetIfModifierKeyForLowerLevelKeyHandlers(KeyboardManagerInput::InputInterface& ii, DWORD key, DWORD target);
 };

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/KeyboardManager.cpp

@@ -181,7 +181,7 @@ bool KeyboardManager::HasRegisteredRemappings() const
 
 bool KeyboardManager::HasRegisteredRemappingsUnchecked() const
 {
-    return !(state.appSpecificShortcutReMap.empty() && state.appSpecificShortcutReMapSortedKeys.empty() && state.osLevelShortcutReMap.empty() && state.osLevelShortcutReMapSortedKeys.empty() && state.singleKeyReMap.empty() && state.singleKeyToTextReMap.empty());
+    return !(state.appSpecificShortcutReMap.empty() && state.appSpecificShortcutReMapSortedKeys.empty() && state.osLevelShortcutReMap.empty() && state.osLevelShortcutReMapSortedKeys.empty() && state.singleKeyReMap.empty() && state.singleKeyToTextReMap.empty() && state.expandMappings.empty());
 }
 
 intptr_t KeyboardManager::HandleKeyboardHookEvent(LowlevelKeyboardEvent* data) noexcept
@@ -233,6 +233,14 @@ intptr_t KeyboardManager::HandleKeyboardHookEvent(LowlevelKeyboardEvent* data) n
         return 1;
     }
 
+    // Handle text expansion (abbreviation + trigger key → expanded text via TSF4)
+    intptr_t ExpandTextResult = KeyboardEventHandlers::HandleExpandTextEvent(data, state);
+
+    if (ExpandTextResult == 1)
+    {
+        return 1;
+    }
+
     // Handle an os-level shortcut remapping
     return KeyboardEventHandlers::HandleOSLevelShortcutRemapEvent(inputHandler, data, state);
 }

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/KeyboardManagerEngineLibrary.vcxproj

@@ -38,10 +38,12 @@
     <ClInclude Include="pch.h" />
     <ClInclude Include="State.h" />
     <ClInclude Include="trace.h" />
+    <ClInclude Include="Tsf4TextReplacer.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="KeyboardEventHandlers.cpp" />
     <ClCompile Include="KeyboardManager.cpp" />
+    <ClCompile Include="Tsf4TextReplacer.cpp" />
     <ClCompile Include="pch.cpp">
       <PrecompiledHeader Condition="'$(UsePrecompiledHeaders)' != 'false'">Create</PrecompiledHeader>
     </ClCompile>
@@ -56,6 +58,14 @@
   <ItemGroup>
     <None Include="packages.config" />
   </ItemGroup>
+  <!-- TSF4 (Text Services Framework 4) WinMD for C++/WinRT projection generation -->
+  <ItemGroup>
+    <Reference Include="Windows.UI.Input.Preview.Text.PreviewTextContract">
+      <HintPath>$(WindowsSdkDir)References\10.0.26100.0\Windows.UI.Input.Preview.Text.PreviewTextContract\1.0.0.0\Windows.UI.Input.Preview.Text.PreviewTextContract.winmd</HintPath>
+      <IsWinMDFile>true</IsWinMDFile>
+      <Private>false</Private>
+    </Reference>
+  </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <Import Project="$(RepoRoot)deps\spdlog.props" />
   <ImportGroup Label="ExtensionTargets">

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/Tsf4TextReplacer.cpp

@@ -0,0 +1,164 @@
+#include "pch.h"
+#include "Tsf4TextReplacer.h"
+
+#include <winrt/Windows.ApplicationModel.h>
+#include <winrt/Windows.UI.Input.Preview.Text.h>
+#include <winrt/Windows.UI.Text.Core.h>
+
+using namespace winrt::Windows::UI::Input::Preview::Text;
+using namespace winrt::Windows::UI::Text::Core;
+
+namespace
+{
+    TextInputProvider s_provider{ nullptr };
+    bool s_initialized = false;
+    bool s_available = false;
+
+    // LAF token computed for PFN: Microsoft.PowerToys.SparseApp_8wekyb3d8bbwe
+    constexpr wchar_t LafFeatureId[] = L"com.microsoft.windows.textinputmethod";
+    constexpr wchar_t LafToken[] = L"fs0FTtO4rVEbMtnhuNmCNA==";
+    constexpr wchar_t LafPublisherId[] = L"8wekyb3d8bbwe";
+
+    void UnlockTextInputMethodFeature() noexcept
+    {
+        try
+        {
+            std::wstring attestation = std::wstring(LafPublisherId) + L" has registered their use of " + LafFeatureId + L" with Microsoft and agrees to the terms of use.";
+
+            auto result = winrt::Windows::ApplicationModel::LimitedAccessFeatures::TryUnlockFeature(
+                LafFeatureId, LafToken, attestation);
+
+            Logger::info(L"TSF4 LAF unlock status: {}", static_cast<int>(result.Status()));
+        }
+        catch (const winrt::hresult_error& ex)
+        {
+            Logger::warn(L"TSF4 LAF unlock failed: {}", ex.message().c_str());
+        }
+        catch (...)
+        {
+            Logger::warn(L"TSF4 LAF unlock failed (no package identity?)");
+        }
+    }
+}
+
+namespace Tsf4TextReplacer
+{
+    void Initialize() noexcept
+    {
+        if (s_initialized)
+        {
+            return;
+        }
+
+        s_initialized = true;
+
+        UnlockTextInputMethodFeature();
+
+        try
+        {
+            auto service = TextInputService::GetForCurrentThread();
+            if (!service)
+            {
+                Logger::warn(L"TSF4: TextInputService not available on this thread");
+                return;
+            }
+
+            s_provider = service.CreateTextInputProvider(L"");
+            if (!s_provider)
+            {
+                Logger::warn(L"TSF4: Failed to create TextInputProvider");
+                return;
+            }
+
+            TextInputServiceSubscription subscription{};
+            subscription.requiredEnabledFeatures = TextBoxFeatures::None;
+            s_provider.SetSubscription(subscription);
+
+            s_available = true;
+            Logger::info(L"TSF4: Text input provider initialized successfully");
+        }
+        catch (const winrt::hresult_error& ex)
+        {
+            Logger::warn(L"TSF4: Initialization failed: {}", ex.message().c_str());
+        }
+        catch (...)
+        {
+            Logger::warn(L"TSF4: Initialization failed with unknown exception");
+        }
+    }
+
+    bool IsAvailable() noexcept
+    {
+        return s_available && s_provider;
+    }
+
+    bool TryExpand(const std::wstring& abbreviation, const std::wstring& expandedText) noexcept
+    {
+        if (!s_available || !s_provider)
+        {
+            return false;
+        }
+
+        try
+        {
+            if (!s_provider.HasFocusedTextBox())
+            {
+                return false;
+            }
+
+            auto session = s_provider.CreateEditSession();
+            if (!session)
+            {
+                return false;
+            }
+
+            int textLength = session.TextLength();
+            int abbrevLen = static_cast<int>(abbreviation.length());
+
+            if (textLength < abbrevLen)
+            {
+                session.SubmitPayload();
+                return false;
+            }
+
+            // Read the last N characters (where N = abbreviation length)
+            CoreTextRange range{};
+            range.StartCaretPosition = textLength - abbrevLen;
+            range.EndCaretPosition = textLength;
+
+            winrt::hstring tail = session.GetText(range);
+
+            // Case-insensitive comparison
+            if (_wcsicmp(tail.c_str(), abbreviation.c_str()) == 0)
+            {
+                session.ReplaceText(range, expandedText);
+                session.SubmitPayload();
+                return true;
+            }
+
+            session.SubmitPayload();
+            return false;
+        }
+        catch (const winrt::hresult_error&)
+        {
+            return false;
+        }
+        catch (...)
+        {
+            return false;
+        }
+    }
+
+    void Shutdown() noexcept
+    {
+        try
+        {
+            s_provider = nullptr;
+            s_available = false;
+            s_initialized = false;
+        }
+        catch (...)
+        {
+        }
+    }
+}

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/Tsf4TextReplacer.h

@@ -0,0 +1,24 @@
+#pragma once
+
+// TSF4 (Text Services Framework 4) text expansion utilities.
+// Uses Windows.UI.Input.Preview.Text APIs to read/replace text in the
+// currently focused text box for the Expand (abbreviation expansion) feature.
+
+namespace Tsf4TextReplacer
+{
+    // Initialize the TSF4 provider on the current thread.
+    // Must be called on a thread that has a message pump (typically the main thread).
+    void Initialize() noexcept;
+
+    // Whether TSF4 was initialized and is available.
+    bool IsAvailable() noexcept;
+
+    // Try to expand an abbreviation in the focused text box.
+    // Reads the last |abbreviation.length()| characters before the cursor.
+    // If they match |abbreviation| (case-insensitive), replaces them with |expandedText|.
+    // Returns true if expansion occurred, false otherwise.
+    bool TryExpand(const std::wstring& abbreviation, const std::wstring& expandedText) noexcept;
+
+    // Release TSF4 resources. Called on shutdown.
+    void Shutdown() noexcept;
+}

src/modules/keyboardmanager/KeyboardManagerEngineLibrary/pch.h

@@ -6,6 +6,7 @@
 #include <stdexcept>
 #include <unordered_set>
 #include <winrt/base.h>
+#include <winrt/Windows.Foundation.h>
 #include <filesystem>
 #include <common/SettingsAPI/settings_helpers.h>
 #include <common/logger/logger.h>

src/modules/keyboardmanager/common/KeyboardManagerConstants.h

@@ -76,6 +76,15 @@ namespace KeyboardManagerConstants
     // Name of the property use to store the target application.
     inline const std::wstring TargetAppSettingName = L"targetApp";
 
+    // Name of the property used to store expand (abbreviation) mappings.
+    inline const std::wstring ExpandMappingsSettingName = L"expandMappings";
+
+    // Name of the property used to store the trigger key for expand mappings.
+    inline const std::wstring ExpandTriggerKeySettingName = L"triggerKey";
+
+    // Name of the property used to store the expanded text for expand mappings.
+    inline const std::wstring ExpandedTextSettingName = L"expandedText";
+
     // Name of the default configuration.
     inline const std::wstring DefaultConfiguration = L"default";
 

src/modules/keyboardmanager/common/MappingConfiguration.cpp

@@ -407,6 +407,60 @@ bool MappingConfiguration::LoadShortcutRemaps(const json::JsonObject& jsonData,
     return result;
 }
 
+bool MappingConfiguration::LoadExpandMappings(const json::JsonObject& jsonData)
+{
+    bool result = true;
+
+    try
+    {
+        expandMappings.clear();
+
+        if (!jsonData.HasKey(KeyboardManagerConstants::ExpandMappingsSettingName))
+        {
+            return result;
+        }
+
+        auto expandArray = jsonData.GetNamedArray(KeyboardManagerConstants::ExpandMappingsSettingName);
+        for (const auto& it : expandArray)
+        {
+            try
+            {
+                auto obj = it.GetObjectW();
+                ExpandMapping mapping;
+                mapping.abbreviation = obj.GetNamedString(KeyboardManagerConstants::OriginalKeysSettingName).c_str();
+                mapping.expandedText = obj.GetNamedString(KeyboardManagerConstants::ExpandedTextSettingName).c_str();
+
+                if (obj.HasKey(KeyboardManagerConstants::ExpandTriggerKeySettingName))
+                {
+                    mapping.triggerKey = static_cast<DWORD>(obj.GetNamedNumber(KeyboardManagerConstants::ExpandTriggerKeySettingName));
+                }
+
+                if (obj.HasKey(KeyboardManagerConstants::TargetAppSettingName))
+                {
+                    mapping.appName = obj.GetNamedString(KeyboardManagerConstants::TargetAppSettingName).c_str();
+                }
+
+                if (!mapping.abbreviation.empty() && !mapping.expandedText.empty())
+                {
+                    expandMappings.push_back(std::move(mapping));
+                }
+            }
+            catch (...)
+            {
+                Logger::error(L"Improper expand mapping JSON. Try the next mapping.");
+                result = false;
+            }
+        }
+    }
+    catch (...)
+    {
+        Logger::error(L"Improper JSON format for expand mappings. Skip.");
+        result = false;
+    }
+
+    return result;
+}
+
 bool MappingConfiguration::LoadSettings()
 {
     Logger::trace(L"SettingsHelper::LoadSettings()");
@@ -435,6 +489,7 @@ bool MappingConfiguration::LoadSettings()
         result = LoadShortcutRemaps(*configFile, KeyboardManagerConstants::RemapShortcutsSettingName) && result;
         result = LoadShortcutRemaps(*configFile, KeyboardManagerConstants::RemapShortcutsToTextSettingName) && result;
         result = LoadSingleKeyToTextRemaps(*configFile) && result;
+        result = LoadExpandMappings(*configFile) && result;
 
         return result;
     }
@@ -632,10 +687,25 @@ bool MappingConfiguration::SaveSettingsToFile()
 
     remapKeys.SetNamedValue(KeyboardManagerConstants::InProcessRemapKeysSettingName, inProcessRemapKeysArray);
     remapKeysToText.SetNamedValue(KeyboardManagerConstants::InProcessRemapKeysSettingName, inProcessRemapKeysToTextArray);
+    json::JsonArray expandMappingsArray;
+    for (const auto& em : expandMappings)
+    {
+        json::JsonObject obj;
+        obj.SetNamedValue(KeyboardManagerConstants::OriginalKeysSettingName, json::value(em.abbreviation));
+        obj.SetNamedValue(KeyboardManagerConstants::ExpandedTextSettingName, json::value(em.expandedText));
+        obj.SetNamedValue(KeyboardManagerConstants::ExpandTriggerKeySettingName, json::JsonValue::CreateNumberValue(static_cast<double>(em.triggerKey)));
+        if (!em.appName.empty())
+        {
+            obj.SetNamedValue(KeyboardManagerConstants::TargetAppSettingName, json::value(em.appName));
+        }
+        expandMappingsArray.Append(obj);
+    }
+
     configJson.SetNamedValue(KeyboardManagerConstants::RemapKeysSettingName, remapKeys);
     configJson.SetNamedValue(KeyboardManagerConstants::RemapKeysToTextSettingName, remapKeysToText);
     configJson.SetNamedValue(KeyboardManagerConstants::RemapShortcutsSettingName, remapShortcuts);
     configJson.SetNamedValue(KeyboardManagerConstants::RemapShortcutsToTextSettingName, remapShortcutsToText);
+    configJson.SetNamedValue(KeyboardManagerConstants::ExpandMappingsSettingName, expandMappingsArray);
 
     try
     {

src/modules/keyboardmanager/common/MappingConfiguration.h

@@ -11,6 +11,17 @@ using SingleKeyToTextRemapTable = SingleKeyRemapTable;
 using ShortcutRemapTable = std::map<Shortcut, RemapShortcut>;
 using AppSpecificShortcutRemapTable = std::map<std::wstring, ShortcutRemapTable>;
 
+// A single expand mapping: abbreviation + trigger key → expanded text
+struct ExpandMapping
+{
+    std::wstring abbreviation;
+    DWORD triggerKey = VK_SPACE; // Virtual key code of the trigger key
+    std::wstring expandedText;
+    std::wstring appName; // Empty = all apps
+};
+
+using ExpandMappingTable = std::vector<ExpandMapping>;
+
 class MappingConfiguration
 {
 public:
@@ -66,6 +77,9 @@ public:
     AppSpecificShortcutRemapTable appSpecificShortcutReMap;
     std::map<std::wstring, std::vector<Shortcut>> appSpecificShortcutReMapSortedKeys;
 
+    // Stores expand (abbreviation → text) mappings
+    ExpandMappingTable expandMappings;
+
     // Stores the current configuration name.
     std::wstring currentConfig = KeyboardManagerConstants::DefaultConfiguration;
 
@@ -74,4 +88,5 @@ private:
     bool LoadSingleKeyToTextRemaps(const json::JsonObject& jsonData);
     bool LoadShortcutRemaps(const json::JsonObject& jsonData, const std::wstring& objectName);
     bool LoadAppSpecificShortcutRemaps(const json::JsonObject& remapShortcutsData);
+    bool LoadExpandMappings(const json::JsonObject& jsonData);
 };

src/settings-ui/Settings.UI/SettingsXAML/Views/KeyboardManagerPage.xaml

@@ -269,6 +269,52 @@
                         </controls:SettingsGroup>
                     </tkcontrols:Case>
                 </tkcontrols:SwitchPresenter>
+
+                <!--  TSF4 (Text Expand) API support status  -->
+                <controls:SettingsGroup x:Uid="KeyboardManager_Tsf4Status" IsEnabled="{x:Bind ViewModel.Enabled, Mode=OneWay}">
+                    <tkcontrols:SettingsCard
+                        x:Uid="KeyboardManager_Tsf4Api"
+                        HeaderIcon="{ui:FontIcon Glyph=&#xE8C8;}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <!--  Supported  -->
+                            <FontIcon
+                                VerticalAlignment="Center"
+                                Foreground="{ThemeResource SystemFillColorSuccessBrush}"
+                                Glyph="&#xEC61;"
+                                Visibility="{x:Bind ViewModel.IsTsf4Supported, Converter={StaticResource BoolToVisibilityConverter}}" />
+                            <TextBlock
+                                x:Uid="KeyboardManager_Tsf4Api_Supported"
+                                VerticalAlignment="Center"
+                                Visibility="{x:Bind ViewModel.IsTsf4Supported, Converter={StaticResource BoolToVisibilityConverter}}" />
+                            <!--  Not supported: info button with flyout + update button  -->
+                            <Button
+                                x:Uid="KeyboardManager_Tsf4Api_InfoButton"
+                                Content="&#xE946;"
+                                FontFamily="{ThemeResource SymbolThemeFontFamily}"
+                                Style="{StaticResource SubtleButtonStyle}"
+                                Visibility="{x:Bind ViewModel.IsTsf4Supported, Converter={StaticResource ReverseBoolToVisibilityConverter}}">
+                                <Button.Flyout>
+                                    <Flyout ShouldConstrainToRootBounds="False">
+                                        <StackPanel Width="360" Spacing="12">
+                                            <TextBlock
+                                                x:Uid="KeyboardManager_Tsf4Api_Unsupported_Title"
+                                                FontWeight="SemiBold"
+                                                TextWrapping="Wrap" />
+                                            <TextBlock
+                                                x:Uid="KeyboardManager_Tsf4Api_Unsupported_Description"
+                                                Foreground="{ThemeResource TextFillColorSecondaryBrush}"
+                                                TextWrapping="Wrap" />
+                                        </StackPanel>
+                                    </Flyout>
+                                </Button.Flyout>
+                            </Button>
+                            <Button
+                                x:Uid="KeyboardManager_Tsf4Api_Update"
+                                Command="{x:Bind ViewModel.OpenWindowsUpdateCommand}"
+                                Visibility="{x:Bind ViewModel.IsTsf4Supported, Converter={StaticResource ReverseBoolToVisibilityConverter}}" />
+                        </StackPanel>
+                    </tkcontrols:SettingsCard>
+                </controls:SettingsGroup>
             </StackPanel>
         </controls:SettingsPageControl.ModuleContent>
         <controls:SettingsPageControl.PrimaryLinks>

src/settings-ui/Settings.UI/Strings/en-us/Resources.resw

@@ -566,6 +566,38 @@ opera.exe</value>
     <value>Keys</value>
     <comment>Keyboard Manager remap keyboard header</comment>
   </data>
+  <data name="KeyboardManager_Tsf4Status.Header" xml:space="preserve">
+    <value>Text Expand</value>
+    <comment>Keyboard Manager TSF4 status section header</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api.Header" xml:space="preserve">
+    <value>Text Services Framework 4 (TSF4) API</value>
+    <comment>TSF4 API availability status card header</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api.Description" xml:space="preserve">
+    <value>Text Expand requires TSF4 API support from the operating system</value>
+    <comment>TSF4 API availability status card description</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api_Supported.Text" xml:space="preserve">
+    <value>Supported</value>
+    <comment>TSF4 API is supported on this OS version</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api_InfoButton.ToolTipService.ToolTip" xml:space="preserve">
+    <value>View requirements</value>
+    <comment>Tooltip for the TSF4 unsupported info button</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api_Unsupported_Title.Text" xml:space="preserve">
+    <value>Windows update required</value>
+    <comment>Title shown in TSF4 unsupported flyout</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api_Unsupported_Description.Text" xml:space="preserve">
+    <value>Text Expand requires Windows 11 build 20099 or higher. This update may not yet be available on your device due to your update rollout schedule.</value>
+    <comment>Description shown in TSF4 unsupported flyout explaining the OS requirement</comment>
+  </data>
+  <data name="KeyboardManager_Tsf4Api_Update.Content" xml:space="preserve">
+    <value>Update Windows</value>
+    <comment>Button to open Windows Update when TSF4 is not supported</comment>
+  </data>
   <data name="KeyboardManager_RemapShortcutsButton.Header" xml:space="preserve">
     <value>Remap a shortcut</value>
     <comment>Keyboard Manager remap shortcuts button</comment>

src/settings-ui/Settings.UI/ViewModels/KeyboardManagerViewModel.cs

@@ -280,6 +280,13 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             }
         }
 
+        public bool IsTsf4Supported => OSVersionHelper.IsTsf4Supported();
+
+        public ICommand OpenWindowsUpdateCommand => new RelayCommand(() =>
+        {
+            Process.Start(new ProcessStartInfo("ms-settings:windowsupdate") { UseShellExecute = true });
+        });
+
         public ICommand RemapKeyboardCommand => _remapKeyboardCommand ?? (_remapKeyboardCommand = new RelayCommand(OnRemapKeyboard));
 
         public ICommand EditShortcutCommand => _editShortcutCommand ?? (_editShortcutCommand = new RelayCommand(OnEditShortcut));