Add support for "fragment extensions"

.github/actions/spelling/dictionary/apis.txt

@@ -93,6 +93,8 @@ TBPF
 THEMECHANGED
 tmp
 tolower
+TTask
+TVal
 tx
 UPDATEINIFILE
 userenv

src/cascadia/CascadiaPackage/Package-Dev.appxmanifest

@@ -12,7 +12,7 @@
   xmlns:desktop5="http://schemas.microsoft.com/appx/manifest/desktop/windows10/5"
   xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
   xmlns:uap5="http://schemas.microsoft.com/appx/manifest/uap/windows10/5"
-  IgnorableNamespaces="uap mp rescap">
+  IgnorableNamespaces="uap mp rescap uap3">
 
   <Identity
     Name="WindowsTerminalDev"
@@ -69,6 +69,11 @@
             Enabled="false"
             DisplayName="ms-resource:AppNameDev" />
         </uap5:Extension>
+        <uap3:Extension Category="windows.appExtensionHost">
+              <uap3:AppExtensionHost>
+                <uap3:Name>com.microsoft.windows.terminal.settings</uap3:Name>
+              </uap3:AppExtensionHost>
+        </uap3:Extension>
 
         <com:Extension Category="windows.comServer">
             <com:ComServer>

src/cascadia/CascadiaPackage/Package-Pre.appxmanifest

@@ -13,7 +13,7 @@
   xmlns:desktop4="http://schemas.microsoft.com/appx/manifest/desktop/windows10/4"
   xmlns:desktop5="http://schemas.microsoft.com/appx/manifest/desktop/windows10/5"
   xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
-  IgnorableNamespaces="uap mp rescap">
+  IgnorableNamespaces="uap mp rescap uap3">
 
   <Identity
     Name="Microsoft.WindowsTerminalPreview"
@@ -64,6 +64,11 @@
             <desktop:ExecutionAlias Alias="wt.exe" />
           </uap3:AppExecutionAlias>
         </uap3:Extension>
+        <uap3:Extension Category="windows.appExtensionHost">
+          <uap3:AppExtensionHost>
+            <uap3:Name>com.microsoft.windows.terminal.settings</uap3:Name>
+          </uap3:AppExtensionHost>
+        </uap3:Extension>
         <uap5:Extension Category="windows.startupTask">
           <uap5:StartupTask
             TaskId="StartTerminalOnLoginTask"

src/cascadia/CascadiaPackage/Package.appxmanifest

@@ -13,7 +13,7 @@
   xmlns:desktop4="http://schemas.microsoft.com/appx/manifest/desktop/windows10/4"
   xmlns:desktop5="http://schemas.microsoft.com/appx/manifest/desktop/windows10/5"
   xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
-  IgnorableNamespaces="uap mp rescap">
+  IgnorableNamespaces="uap mp rescap uap3">
 
   <Identity
     Name="Microsoft.WindowsTerminal"
@@ -64,6 +64,11 @@
             <desktop:ExecutionAlias Alias="wt.exe" />
           </uap3:AppExecutionAlias>
         </uap3:Extension>
+        <uap3:Extension Category="windows.appExtensionHost">
+          <uap3:AppExtensionHost>
+            <uap3:Name>com.microsoft.windows.terminal.settings</uap3:Name>
+          </uap3:AppExtensionHost>
+        </uap3:Extension>
         <uap5:Extension Category="windows.startupTask">
           <uap5:StartupTask
             TaskId="StartTerminalOnLoginTask"

src/cascadia/LocalTests_TerminalApp/TestHostApp/Package.appxmanifest

@@ -1,5 +1,5 @@
 <?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" IgnorableNamespaces="uap mp">
+<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:uap3="http://schemas.microsoft.com/appx/manifest/uap/windows10/3" IgnorableNamespaces="uap mp uap3">
   <Identity Name="WindowsTerminal.TestHost" Publisher="CN=Windows Terminal Team" Version="1.0.0.0" />
   <mp:PhoneIdentity PhoneProductId="fba054a7-f1a1-4cb7-bb21-4949919af2f5" PhonePublisherId="00000000-0000-0000-0000-000000000000" />
   <Properties>
@@ -22,6 +22,13 @@
         </uap:DefaultTile>
         <uap:SplashScreen Image="taef.png" />
       </uap:VisualElements>
+      <Extensions>
+        <uap3:Extension Category="windows.appExtensionHost">
+              <uap3:AppExtensionHost>
+                <uap3:Name>com.microsoft.windows.terminal.settings</uap3:Name>
+              </uap3:AppExtensionHost>
+        </uap3:Extension>
+      </Extensions>
     </Application>
   </Applications>
 </Package>

src/cascadia/TerminalSettingsModel/CascadiaSettings.h

@@ -117,6 +117,8 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         winrt::com_ptr<implementation::Profile> _FindMatchingProfile(const Json::Value& profileJson);
         std::optional<uint32_t> _FindMatchingProfileIndex(const Json::Value& profileJson);
         void _LayerOrCreateColorScheme(const Json::Value& schemeJson);
+        Json::Value _ParseUtf8JsonString(std::string_view fileData);
+
         winrt::com_ptr<implementation::ColorScheme> _FindMatchingColorScheme(const Json::Value& schemeJson);
         void _ParseJsonString(std::string_view fileData, const bool isDefaultSettings);
         static const Json::Value& _GetProfilesJsonObject(const Json::Value& json);
@@ -129,6 +131,10 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         void _ApplyDefaultsFromUserSettings();
 
         void _LoadDynamicProfiles();
+        void _LoadFragmentExtensions();
+        void _ApplyJsonStubsHelper(const std::wstring_view directory, const std::unordered_set<std::wstring>& ignoredNamespaces);
+        std::unordered_set<std::string> _AccumulateJsonFilesInDirectory(const std::wstring_view directory);
+        void _ParseAndLayerFragmentFiles(const std::unordered_set<std::string> files, const winrt::hstring source);
 
         static bool _IsPackaged();
         static void _WriteSettings(std::string_view content, const hstring filepath);