Some changes.

Wino.Calendar.ViewModels/EventDetailsPageViewModel.cs

@@ -27,8 +27,19 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
     private readonly IMailDialogService _dialogService;
     private readonly IWinoRequestDelegator _winoRequestDelegator;
     private readonly INavigationService _navigationService;
+    private readonly IUnderlyingThemeService _underlyingThemeService;
 
     public CalendarSettings CurrentSettings { get; }
+    public INativeAppService NativeAppService => _nativeAppService;
+
+    [ObservableProperty]
+    public partial bool IsDarkWebviewRenderer { get; set; }
+
+    /// <summary>
+    /// Returns true if the current event has attachments.
+    /// Currently always returns false until attachments are implemented.
+    /// </summary>
+    public bool HasAttachments => false; // TODO: Implement when CalendarItem attachments are added
 
     #region Details
 
@@ -40,6 +51,12 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
     [NotifyPropertyChangedFor(nameof(CurrentRsvpStatus))]
     public partial CalendarItemViewModel CurrentEvent { get; set; }
 
+    partial void OnCurrentEventChanged(CalendarItemViewModel value)
+    {
+        // Notify the view to re-render the description
+        Messenger.Send(new CalendarDescriptionRenderingRequested());
+    }
+
     [ObservableProperty]
     public partial CalendarItemViewModel SeriesParent { get; set; }
     [ObservableProperty]
@@ -127,7 +144,8 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
                                      IPreferencesService preferencesService,
                                      IMailDialogService dialogService,
                                      IWinoRequestDelegator winoRequestDelegator,
-                                     INavigationService navigationService)
+                                     INavigationService navigationService,
+                                     IUnderlyingThemeService underlyingThemeService)
     {
         _calendarService = calendarService;
         _nativeAppService = nativeAppService;
@@ -135,8 +153,10 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
         _dialogService = dialogService;
         _winoRequestDelegator = winoRequestDelegator;
         _navigationService = navigationService;
+        _underlyingThemeService = underlyingThemeService;
 
         CurrentSettings = _preferencesService.GetCurrentCalendarSettings();
+        IsDarkWebviewRenderer = _underlyingThemeService.IsUnderlyingThemeDark();
 
         // Initialize RSVP status options
         RsvpStatusOptions.Add(new RsvpStatusOption(CalendarItemStatus.Accepted));

Wino.Core.Domain/Translations/en_US/resources.json

@@ -97,6 +97,10 @@
     "CalendarEventRsvpPanel_SendReplyMessage": "Send a reply message",
     "CalendarEventRsvpPanel_Tentative": "Tentative",
     "CalendarEventRsvpPanel_Title": "Response Options",
+    "CalendarAttendeeStatus_Accepted": "Accepted",
+    "CalendarAttendeeStatus_Declined": "Declined",
+    "CalendarAttendeeStatus_NeedsAction": "Needs Action",
+    "CalendarAttendeeStatus_Tentative": "Tentative",
     "CalendarEventDetails_Attachments": "Attachments",
     "CalendarEventDetails_Details": "Details",
     "CalendarEventDetails_EditSeries": "Edit Series",

Wino.Mail.WinUI/Helpers/CalendarXamlHelpers.cs

@@ -110,4 +110,31 @@ public static class CalendarXamlHelpers
     /// </summary>
     public static bool HasOnlineMeetingLink(CalendarItemViewModel calendarItemViewModel)
         => calendarItemViewModel != null && !string.IsNullOrEmpty(calendarItemViewModel.CalendarItem?.HtmlLink);
+
+    /// <summary>
+    /// Returns the text representation of an attendee's status.
+    /// </summary>
+    public static string GetAttendeeStatusText(AttendeeStatus status)
+    {
+        return status switch
+        {
+            AttendeeStatus.Accepted => Translator.CalendarAttendeeStatus_Accepted,
+            AttendeeStatus.Declined => Translator.CalendarAttendeeStatus_Declined,
+            AttendeeStatus.Tentative => Translator.CalendarAttendeeStatus_Tentative,
+            AttendeeStatus.NeedsAction => Translator.CalendarAttendeeStatus_NeedsAction,
+            _ => string.Empty
+        };
+    }
+
+    /// <summary>
+    /// Returns visibility for attendee status badge.
+    /// Only shows status for non-organizers and when status is not NeedsAction.
+    /// </summary>
+    public static Microsoft.UI.Xaml.Visibility GetAttendeeStatusVisibility(AttendeeStatus status)
+    {
+        // Don't show "Needs Action" status as it's the default
+        return status == AttendeeStatus.NeedsAction 
+            ? Microsoft.UI.Xaml.Visibility.Collapsed 
+            : Microsoft.UI.Xaml.Visibility.Visible;
+    }
 }

Wino.Mail.WinUI/Views/Calendar/EventDetailsPage.xaml

@@ -162,7 +162,10 @@
                         Background="{ThemeResource DividerStrokeColorDefaultBrush}" />
 
                     <!--  RSVP Button  -->
-                    <Button Command="{x:Bind ViewModel.ToggleRsvpPanelCommand}" Style="{StaticResource TransparentActionButtonStyle}">
+                    <Button
+                        Background="{ThemeResource CardBackgroundFillColorDefault}"
+                        Command="{x:Bind ViewModel.ToggleRsvpPanelCommand}"
+                        Style="{StaticResource TransparentActionButtonStyle}">
                         <StackPanel Orientation="Horizontal" Spacing="8">
                             <ContentControl Content="{x:Bind ViewModel.CurrentRsvpStatus, Mode=OneWay}" ContentTemplateSelector="{StaticResource RsvpStatusIconSelector}" />
                             <TextBlock VerticalAlignment="Center" Text="{x:Bind ViewModel.CurrentRsvpText, Mode=OneWay}" />
@@ -360,9 +363,9 @@
                             Visibility="{x:Bind ReadOnlyToggle.IsChecked, Mode=OneWay}">
                             <Grid.RowDefinitions>
                                 <RowDefinition Height="Auto" />
-                                <RowDefinition Height="16" />
                                 <RowDefinition Height="Auto" />
                                 <RowDefinition Height="Auto" />
+                                <RowDefinition Height="*" />
                             </Grid.RowDefinitions>
 
                             <!--  Title  -->
@@ -373,13 +376,13 @@
 
                             <!--  Date and Duration  -->
                             <TextBlock
-                                Grid.Row="2"
+                                Grid.Row="1"
                                 Text="{x:Bind calendarHelpers:CalendarXamlHelpers.GetEventDetailsDateString(ViewModel.CurrentEvent, ViewModel.CurrentSettings), Mode=OneWay}"
                                 TextWrapping="Wrap" />
 
                             <!--  Recurrence Info  -->
                             <Grid
-                                Grid.Row="3"
+                                Grid.Row="2"
                                 ColumnSpacing="6"
                                 Visibility="{x:Bind ViewModel.CurrentEvent.IsRecurringParent, Mode=OneWay}">
                                 <Grid.ColumnDefinitions>
@@ -395,6 +398,8 @@
                                     TextWrapping="Wrap" />
                             </Grid>
 
+                            <!--  WebView  -->
+                            <WebView2 x:Name="EventDetailsWebView" Grid.Row="3" />
                         </Grid>
 
                         <!--  Editable Event  -->
@@ -459,10 +464,9 @@
                                                 FontSize="13"
                                                 Foreground="{ThemeResource TextFillColorSecondaryBrush}"
                                                 Text="{x:Bind Email}" />
+                                            <StackPanel Grid.Row="2" Orientation="Horizontal" Spacing="6">
                                                 <Border
-                                                Grid.Row="2"
                                                     Padding="6,2"
-                                                HorizontalAlignment="Left"
                                                     Background="{ThemeResource AccentFillColorDefaultBrush}"
                                                     CornerRadius="4"
                                                     Visibility="{x:Bind IsOrganizer}">
@@ -472,6 +476,17 @@
                                                         Foreground="{ThemeResource TextOnAccentFillColorPrimaryBrush}"
                                                         Text="{x:Bind domain:Translator.CalendarEventDetails_Organizer}" />
                                                 </Border>
+                                                <Border
+                                                    Padding="6,2"
+                                                    Background="{ThemeResource CardStrokeColorDefaultBrush}"
+                                                    CornerRadius="4"
+                                                    Visibility="{x:Bind calendarHelpers:CalendarXamlHelpers.GetAttendeeStatusVisibility(AttendenceStatus)}">
+                                                    <TextBlock
+                                                        FontSize="11"
+                                                        Foreground="{ThemeResource TextFillColorSecondaryBrush}"
+                                                        Text="{x:Bind calendarHelpers:CalendarXamlHelpers.GetAttendeeStatusText(AttendenceStatus)}" />
+                                                </Border>
+                                            </StackPanel>
                                         </Grid>
                                     </Grid>
                                 </DataTemplate>
@@ -484,7 +499,8 @@
                 <Grid
                     x:Name="AttachmentsGrid"
                     Grid.Column="2"
-                    Style="{StaticResource EventDetailsPanelGridStyle}">
+                    Style="{StaticResource EventDetailsPanelGridStyle}"
+                    Visibility="{x:Bind ViewModel.HasAttachments, Mode=OneWay}">
                     <Grid.RowDefinitions>
                         <RowDefinition Height="Auto" />
                         <RowDefinition Height="*" />
@@ -516,6 +532,8 @@
                         <Setter Target="PeopleGrid.(Grid.Row)" Value="0" />
                         <Setter Target="PeopleGrid.(Grid.Column)" Value="1" />
                         <Setter Target="PeopleGrid.(Grid.ColumnSpan)" Value="2" />
+                        <!--  People grid spans both rows when attachments are hidden  -->
+                        <Setter Target="PeopleGrid.(Grid.RowSpan)" Value="2" />
                         <Setter Target="AttachmentsGrid.(Grid.Row)" Value="1" />
                         <Setter Target="AttachmentsGrid.(Grid.Column)" Value="1" />
                         <Setter Target="AttachmentsGrid.(Grid.ColumnSpan)" Value="2" />

Wino.Mail.WinUI/Views/Calendar/EventDetailsPage.xaml.cs

@@ -1,11 +1,206 @@
+using System;
+using System.Text.Json;
+using System.Threading.Tasks;
+using CommunityToolkit.Mvvm.Messaging;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Navigation;
+using Microsoft.Web.WebView2.Core;
+using Windows.System;
+using Wino.Core.Domain;
+using Wino.Core.Domain.Interfaces;
+using Wino.Mail.WinUI;
+using Wino.Mail.WinUI.Extensions;
 using Wino.Mail.WinUI.Views.Abstract;
+using Wino.Messaging.Client.Calendar;
+using Wino.Messaging.Client.Shell;
 
 namespace Wino.Calendar.Views;
 
-public sealed partial class EventDetailsPage : EventDetailsPageAbstract
+public sealed partial class EventDetailsPage : EventDetailsPageAbstract,
+    IRecipient<ApplicationThemeChanged>,
+    IRecipient<CalendarDescriptionRenderingRequested>
 {
+    private readonly IPreferencesService _preferencesService = App.Current.Services.GetService<IPreferencesService>()!;
+    private TaskCompletionSource<bool> DOMLoadedTask = new TaskCompletionSource<bool>();
+    private bool isChromiumDisposed = false;
+
     public EventDetailsPage()
     {
-        this.InitializeComponent();
+        InitializeComponent();
+
+        Environment.SetEnvironmentVariable("WEBVIEW2_DEFAULT_BACKGROUND_COLOR", "00FFFFFF");
+        Environment.SetEnvironmentVariable("WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS", "--enable-features=OverlayScrollbar,msOverlayScrollbarWinStyle,msOverlayScrollbarWinStyleAnimation,msWebView2CodeCache");
+    }
+
+    protected override void OnNavigatedTo(NavigationEventArgs e)
+    {
+        base.OnNavigatedTo(e);
+
+        EventDetailsWebView.CoreWebView2Initialized -= CoreWebViewInitialized;
+        EventDetailsWebView.CoreWebView2Initialized += CoreWebViewInitialized;
+
+        _ = EventDetailsWebView.EnsureCoreWebView2Async();
+    }
+
+    protected override void OnNavigatedFrom(NavigationEventArgs e)
+    {
+        base.OnNavigatedFrom(e);
+
+        DisposeWebView2();
+    }
+
+    private async void CoreWebViewInitialized(Microsoft.UI.Xaml.Controls.WebView2 sender, CoreWebView2InitializedEventArgs args)
+    {
+        if (EventDetailsWebView.CoreWebView2 == null) return;
+
+        var editorBundlePath = (await ViewModel.NativeAppService.GetEditorBundlePathAsync()).Replace("editor.html", string.Empty);
+
+        EventDetailsWebView.CoreWebView2.SetVirtualHostNameToFolderMapping("wino.mail", editorBundlePath, CoreWebView2HostResourceAccessKind.Allow);
+
+        EventDetailsWebView.CoreWebView2.DOMContentLoaded -= DOMContentLoaded;
+        EventDetailsWebView.CoreWebView2.DOMContentLoaded += DOMContentLoaded;
+
+        EventDetailsWebView.CoreWebView2.NewWindowRequested -= WindowRequested;
+        EventDetailsWebView.CoreWebView2.NewWindowRequested += WindowRequested;
+
+        EventDetailsWebView.NavigationStarting -= WebViewNavigationStarting;
+        EventDetailsWebView.NavigationStarting += WebViewNavigationStarting;
+
+        EventDetailsWebView.Source = new Uri("https://wino.mail/reader.html");
+    }
+
+    private void DOMContentLoaded(CoreWebView2 sender, CoreWebView2DOMContentLoadedEventArgs args)
+    {
+        DOMLoadedTask.TrySetResult(true);
+        _ = RenderDescriptionAsync();
+    }
+
+    private async Task RenderDescriptionAsync()
+    {
+        if (ViewModel?.CurrentEvent?.CalendarItem == null)
+            return;
+
+        await DOMLoadedTask.Task;
+
+        await UpdateEditorThemeAsync();
+        await UpdateReaderFontPropertiesAsync();
+
+        var description = ViewModel.CurrentEvent.CalendarItem.Description ?? string.Empty;
+
+        if (string.IsNullOrEmpty(description))
+        {
+            await EventDetailsWebView.ExecuteScriptFunctionAsync("RenderHTML", isChromiumDisposed, JsonSerializer.Serialize(" ", BasicTypesJsonContext.Default.String));
+        }
+        else
+        {
+            await EventDetailsWebView.ExecuteScriptFunctionAsync("RenderHTML", isChromiumDisposed,
+                JsonSerializer.Serialize(description, BasicTypesJsonContext.Default.String),
+                JsonSerializer.Serialize(true, BasicTypesJsonContext.Default.Boolean));
+        }
+    }
+
+    private async void WindowRequested(CoreWebView2 sender, CoreWebView2NewWindowRequestedEventArgs args)
+    {
+        args.Handled = true;
+
+        try
+        {
+            await Launcher.LaunchUriAsync(new Uri(args.Uri));
+        }
+        catch (Exception) { }
+    }
+
+    private async void WebViewNavigationStarting(Microsoft.UI.Xaml.Controls.WebView2 sender, CoreWebView2NavigationStartingEventArgs args)
+    {
+        if (args.Uri == "https://wino.mail/reader.html")
+            return;
+
+        args.Cancel = !args.Uri.StartsWith("data:text/html");
+
+        if (args.Cancel && Uri.TryCreate(args.Uri, UriKind.Absolute, out Uri? newUri) && newUri != null)
+        {
+            await Launcher.LaunchUriAsync(newUri);
+        }
+    }
+
+    private void DisposeWebView2()
+    {
+        if (EventDetailsWebView == null) return;
+
+        EventDetailsWebView.CoreWebView2Initialized -= CoreWebViewInitialized;
+        EventDetailsWebView.NavigationStarting -= WebViewNavigationStarting;
+
+        if (EventDetailsWebView.CoreWebView2 != null)
+        {
+            EventDetailsWebView.CoreWebView2.DOMContentLoaded -= DOMContentLoaded;
+            EventDetailsWebView.CoreWebView2.NewWindowRequested -= WindowRequested;
+        }
+
+        isChromiumDisposed = true;
+
+        EventDetailsWebView.Close();
+    }
+
+    private async Task UpdateEditorThemeAsync()
+    {
+        await DOMLoadedTask.Task;
+
+        if (ViewModel.IsDarkWebviewRenderer)
+        {
+            EventDetailsWebView.CoreWebView2.Profile.PreferredColorScheme = CoreWebView2PreferredColorScheme.Dark;
+            await InvokeScriptSafeAsync("SetDarkEditor();");
+        }
+        else
+        {
+            EventDetailsWebView.CoreWebView2.Profile.PreferredColorScheme = CoreWebView2PreferredColorScheme.Light;
+            await InvokeScriptSafeAsync("SetLightEditor();");
+        }
+    }
+
+    private async Task UpdateReaderFontPropertiesAsync()
+    {
+        await EventDetailsWebView.ExecuteScriptFunctionAsync("ChangeFontSize", isChromiumDisposed, JsonSerializer.Serialize(_preferencesService.ReaderFontSize, BasicTypesJsonContext.Default.Int32));
+
+        var fontName = _preferencesService.ReaderFont;
+        fontName += ", sans-serif";
+
+        await EventDetailsWebView.ExecuteScriptFunctionAsync("ChangeFontFamily", isChromiumDisposed, JsonSerializer.Serialize(fontName, BasicTypesJsonContext.Default.String));
+    }
+
+    private async Task<string> InvokeScriptSafeAsync(string function)
+    {
+        try
+        {
+            return await EventDetailsWebView.ExecuteScriptAsync(function);
+        }
+        catch (Exception) { }
+
+        return string.Empty;
+    }
+
+    void IRecipient<ApplicationThemeChanged>.Receive(ApplicationThemeChanged message)
+    {
+        ViewModel.IsDarkWebviewRenderer = message.IsUnderlyingThemeDark;
+        _ = UpdateEditorThemeAsync();
+    }
+
+    async void IRecipient<CalendarDescriptionRenderingRequested>.Receive(CalendarDescriptionRenderingRequested message)
+    {
+        await RenderDescriptionAsync();
+    }
+
+    protected override void RegisterRecipients()
+    {
+        base.RegisterRecipients();
+        WeakReferenceMessenger.Default.Register<ApplicationThemeChanged>(this);
+        WeakReferenceMessenger.Default.Register<CalendarDescriptionRenderingRequested>(this);
+    }
+
+    protected override void UnregisterRecipients()
+    {
+        base.UnregisterRecipients();
+        WeakReferenceMessenger.Default.Unregister<ApplicationThemeChanged>(this);
+        WeakReferenceMessenger.Default.Unregister<CalendarDescriptionRenderingRequested>(this);
     }
 }

Wino.Messages/Client/Calendar/CalendarDescriptionRenderingRequested.cs

@@ -0,0 +1,6 @@
+namespace Wino.Messaging.Client.Calendar;
+
+/// <summary>
+/// Message to trigger rendering of calendar event description in WebView2.
+/// </summary>
+public record CalendarDescriptionRenderingRequested();