This will make @DHowett happy

src/cascadia/TerminalApp/Resources/en-US/Resources.resw

@@ -588,9 +588,13 @@
   <data name="CommandPalette_MoreOptions.[using:Windows.UI.Xaml.Automation]AutomationProperties.HelpText" xml:space="preserve">
     <value>More options</value>
   </data>
-  <data name="WindowIdPrefix" xml:space="preserve">
-    <value>Window: {}</value>
-    <comment>{} will be replaced with a number identifying this window</comment>
+  <data name="WindowIdLabel" xml:space="preserve">
+    <value>Window</value>
+    <comment>This is displayed as a label for a number, like "Window: 10"</comment>
+  </data>
+  <data name="UnnamedWindowName" xml:space="preserve">
+    <value>unnamed window</value>
+    <comment>text used to identify when a window hasn't been assigned a name by the user</comment>
   </data>
   <data name="WindowMaximizeButtonToolTip" xml:space="preserve">
     <value>Maximize</value>

src/cascadia/TerminalApp/TerminalAppLib.vcxproj

@@ -78,10 +78,6 @@
     <ClInclude Include="MinMaxCloseControl.h">
       <DependentUpon>MinMaxCloseControl.xaml</DependentUpon>
     </ClInclude>
-    <ClInclude Include="WindowNameConverter.h">
-      <DependentUpon>TerminalPage.idl</DependentUpon>
-      <SubType>Code</SubType>
-    </ClInclude>
     <ClInclude Include="PaletteItemTemplateSelector.h">
       <DependentUpon>PaletteItemTemplateSelector.idl</DependentUpon>
       <SubType>Code</SubType>
@@ -157,10 +153,6 @@
     <ClCompile Include="MinMaxCloseControl.cpp">
       <DependentUpon>MinMaxCloseControl.xaml</DependentUpon>
     </ClCompile>
-    <ClCompile Include="WindowNameConverter.cpp">
-      <DependentUpon>TerminalPage.idl</DependentUpon>
-      <SubType>Code</SubType>
-    </ClCompile>
     <ClCompile Include="PaletteItemTemplateSelector.cpp">
       <DependentUpon>PaletteItemTemplateSelector.idl</DependentUpon>
       <SubType>Code</SubType>

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -3387,4 +3387,61 @@ namespace winrt::TerminalApp::implementation
         }
     }
 
+    // WindowName is a otherwise generic WINRT_OBSERVABLE_PROPERTY, but it needs
+    // to raise a PropertyChanged for WindowNameForDisplay, instead of
+    // WindowName.
+    winrt::hstring TerminalPage::WindowName() const noexcept
+    {
+        return _WindowName;
+    }
+    void TerminalPage::WindowName(const winrt::hstring& value)
+    {
+        if (_WindowName != value)
+        {
+            _WindowName = value;
+            _PropertyChangedHandlers(*this, Windows::UI::Xaml::Data::PropertyChangedEventArgs{ L"WindowNameForDisplay" });
+        }
+    }
+
+    // WindowId is a otherwise generic WINRT_OBSERVABLE_PROPERTY, but it needs
+    // to raise a PropertyChanged for WindowIdForDisplay, instead of
+    // WindowId.
+    uint64_t TerminalPage::WindowId() const noexcept
+    {
+        return _WindowId;
+    }
+    void TerminalPage::WindowId(const uint64_t& value)
+    {
+        if (_WindowId != value)
+        {
+            _WindowId = value;
+            _PropertyChangedHandlers(*this, Windows::UI::Xaml::Data::PropertyChangedEventArgs{ L"WindowIdForDisplay" });
+        }
+    }
+
+    // Method Description:
+    // - Returns a label like "Window: 1234" for the ID of this window
+    // Arguments:
+    // - <none>
+    // Return Value:
+    // - a string for displaying the name of the window.
+    winrt::hstring TerminalPage::WindowIdForDisplay() const noexcept
+    {
+        return winrt::hstring{ fmt::format(L"{}: {}",
+                                           std::wstring_view(RS_(L"WindowIdLabel")),
+                                           _WindowId) };
+    }
+
+    // Method Description:
+    // - Returns a label like "<unnamed window>" when the window has no name, or the name of the window.
+    // Arguments:
+    // - <none>
+    // Return Value:
+    // - a string for displaying the name of the window.
+    winrt::hstring TerminalPage::WindowNameForDisplay() const noexcept
+    {
+        return _WindowName.empty() ?
+                   winrt::hstring{ fmt::format(L"<{}>", RS_(L"UnnamedWindowName")) } :
+                   _WindowName;
+    }
 }

src/cascadia/TerminalApp/TerminalPage.h

@@ -86,9 +86,17 @@ namespace winrt::TerminalApp::implementation
                                                      const bool initial,
                                                      const winrt::hstring cwd = L"");
 
+        // Normally, WindowName and WindowId would be
+        // WINRT_OBSERVABLE_PROPERTY's, but we want them to raise
+        // WindowNameForDisplay and WindowIdForDisplay instead
+        winrt::hstring WindowName() const noexcept;
+        void WindowName(const winrt::hstring& value);
+        uint64_t WindowId() const noexcept;
+        void WindowId(const uint64_t& value);
+        winrt::hstring WindowIdForDisplay() const noexcept;
+        winrt::hstring WindowNameForDisplay() const noexcept;
+
         WINRT_CALLBACK(PropertyChanged, Windows::UI::Xaml::Data::PropertyChangedEventHandler);
-        WINRT_OBSERVABLE_PROPERTY(winrt::hstring, WindowName, _PropertyChangedHandlers);
-        WINRT_OBSERVABLE_PROPERTY(uint64_t, WindowId, _PropertyChangedHandlers);
 
         // -------------------------------- WinRT Events ---------------------------------
         TYPED_EVENT(TitleChanged, IInspectable, winrt::hstring);
@@ -130,6 +138,8 @@ namespace winrt::TerminalApp::implementation
         bool _isInFocusMode{ false };
         bool _isFullscreen{ false };
         bool _isAlwaysOnTop{ false };
+        winrt::hstring _WindowName{};
+        uint64_t _WindowId{ 0 };
 
         bool _rearranging;
         std::optional<int> _rearrangeFrom;

src/cascadia/TerminalApp/TerminalPage.idl

@@ -10,18 +10,6 @@ namespace TerminalApp
         Windows.Foundation.IAsyncOperation<Windows.UI.Xaml.Controls.ContentDialogResult> ShowDialog(Windows.UI.Xaml.Controls.ContentDialog dialog);
     };
 
-    runtimeclass WindowIdConverter : [default] Windows.UI.Xaml.Data.IValueConverter
-    {
-        WindowIdConverter();
-    };
-
-
-    runtimeclass WindowNameConverter : [default] Windows.UI.Xaml.Data.IValueConverter
-    {
-        WindowNameConverter();
-    };
-
-
     [default_interface] runtimeclass TerminalPage : Windows.UI.Xaml.Controls.Page, Windows.UI.Xaml.Data.INotifyPropertyChanged
     {
         TerminalPage();
@@ -37,6 +25,8 @@ namespace TerminalApp
         void IdentifyWindow();
         String WindowName;
         UInt64 WindowId;
+        String WindowNameForDisplay { get; };
+        String WindowIdForDisplay { get; };
 
         // We cannot use the default XAML APIs because we want to make sure
         // that there's only one application-global dialog visible at a time,

src/cascadia/TerminalApp/TerminalPage.xaml

@@ -10,13 +10,6 @@ the MIT License. See LICENSE in the project root for license information. -->
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     mc:Ignorable="d">
 
-    <Page.Resources>
-        <ResourceDictionary>
-            <local:WindowIdConverter x:Key="WindowIdConverter"/>
-            <local:WindowNameConverter x:Key="WindowNameConverter"/>
-        </ResourceDictionary>
-    </Page.Resources>
-
     <Grid x:Name="Root" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto" />
@@ -146,8 +139,8 @@ the MIT License. See LICENSE in the project root for license information. -->
         <mux:TeachingTip x:Name="WindowIdToast"
                          x:Load="False"
                          IsLightDismissEnabled="True"
-                         Title="{x:Bind WindowId, Mode=OneWay, Converter={StaticResource WindowIdConverter}}"
-                         Subtitle="{x:Bind WindowName, Mode=OneWay, Converter={StaticResource WindowNameConverter}}">
+                         Title="{x:Bind WindowIdForDisplay}"
+                         Subtitle="{x:Bind WindowNameForDisplay}">
         </mux:TeachingTip>
     </Grid>
 </Page>