RSVP options.

Wino.Calendar.ViewModels/Data/AccountCalendarViewModel.cs

@@ -66,4 +66,5 @@ public partial class AccountCalendarViewModel : ObservableObject, IAccountCalend
         set => SetProperty(AccountCalendar.RemoteCalendarId, value, AccountCalendar, (u, r) => u.RemoteCalendarId = r);
     }
     public Guid Id { get => ((IAccountCalendar)AccountCalendar).Id; set => ((IAccountCalendar)AccountCalendar).Id = value; }
+    public MailAccount MailAccount { get => MailAccount; set => MailAccount = value; }
 }

Wino.Calendar.ViewModels/EventDetailsPageViewModel.cs

@@ -36,7 +36,10 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
     [NotifyPropertyChangedFor(nameof(CanViewSeries))]
     [NotifyPropertyChangedFor(nameof(CanEditSeries))]
     [NotifyPropertyChangedFor(nameof(IsCurrentUserOrganizer))]
+    [NotifyPropertyChangedFor(nameof(CurrentRsvpText))]
+    [NotifyPropertyChangedFor(nameof(CurrentRsvpStatus))]
     public partial CalendarItemViewModel CurrentEvent { get; set; }
+
     [ObservableProperty]
     public partial CalendarItemViewModel SeriesParent { get; set; }
     [ObservableProperty]
@@ -80,6 +83,45 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
 
     #endregion
 
+    #region RSVP Panel
+
+    [ObservableProperty]
+    public partial bool IsRsvpPanelVisible { get; set; }
+
+    public bool IncludeRsvpMessage => !string.IsNullOrEmpty(RsvpMessage);
+
+    [ObservableProperty]
+    public partial string RsvpMessage { get; set; } = string.Empty;
+
+    public ObservableCollection<RsvpStatusOption> RsvpStatusOptions { get; } = new ObservableCollection<RsvpStatusOption>();
+
+    public CalendarItemStatus CurrentRsvpStatus
+    {
+        get
+        {
+            return CurrentEvent?.CalendarItem?.Status ?? CalendarItemStatus.NotResponded;
+        }
+    }
+
+    public string CurrentRsvpText
+    {
+        get
+        {
+            if (CurrentEvent?.CalendarItem == null) return Translator.CalendarEventResponse_Accept;
+
+            return CurrentEvent.CalendarItem.Status switch
+            {
+                CalendarItemStatus.Accepted => Translator.CalendarEventResponse_AcceptedResponse,
+                CalendarItemStatus.Tentative => Translator.CalendarEventResponse_TentativeResponse,
+                CalendarItemStatus.Cancelled => Translator.CalendarEventResponse_DeclinedResponse,
+                CalendarItemStatus.NotResponded => Translator.CalendarEventResponse_NotResponded,
+                _ => throw new NotImplementedException()
+            };
+        }
+    }
+
+    #endregion
+
     public EventDetailsPageViewModel(ICalendarService calendarService,
                                      INativeAppService nativeAppService,
                                      IPreferencesService preferencesService,
@@ -95,6 +137,11 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
         _navigationService = navigationService;
 
         CurrentSettings = _preferencesService.GetCurrentCalendarSettings();
+
+        // Initialize RSVP status options
+        RsvpStatusOptions.Add(new RsvpStatusOption(CalendarItemStatus.Accepted));
+        RsvpStatusOptions.Add(new RsvpStatusOption(CalendarItemStatus.Tentative));
+        RsvpStatusOptions.Add(new RsvpStatusOption(CalendarItemStatus.Cancelled));
     }
 
     public override async void OnNavigatedTo(NavigationMode mode, object parameters)
@@ -109,6 +156,17 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
         await LoadCalendarItemTargetAsync(args);
     }
 
+    protected override void OnCalendarItemDeleted(CalendarItem calendarItem)
+    {
+        base.OnCalendarItemDeleted(calendarItem);
+
+        // If the current event was deleted, navigate back
+        if (CurrentEvent?.CalendarItem?.Id == calendarItem.Id || CurrentEvent?.CalendarItem.RecurringCalendarItemId == calendarItem.Id)
+        {
+            _navigationService.GoBack();
+        }
+    }
+
     private async Task LoadCalendarItemTargetAsync(CalendarItemTarget target)
     {
         try
@@ -265,11 +323,68 @@ public partial class EventDetailsPageViewModel : CalendarBaseViewModel
     }
 
     [RelayCommand]
-    private async Task RespondAsync(CalendarItemStatus status)
+    private void ToggleRsvpPanel()
+    {
+        IsRsvpPanelVisible = !IsRsvpPanelVisible;
+
+        if (IsRsvpPanelVisible && CurrentEvent?.CalendarItem != null)
+        {
+            // Initialize selection based on current status
+            foreach (var item in RsvpStatusOptions)
+            {
+                item.IsSelected = CurrentEvent?.CalendarItem?.Status == item.Status;
+            }
+        }
+    }
+
+    [RelayCommand]
+    private void CloseRsvpPanel()
+    {
+        IsRsvpPanelVisible = false;
+        RsvpMessage = string.Empty;
+    }
+
+    [RelayCommand]
+    private async Task SendRsvpResponse(AttendeeStatus status)
     {
         if (CurrentEvent == null) return;
 
-        // TODO: Implement response
+        try
+        {
+            // Get the optional response message if user wants to include it
+            var responseMessage = IncludeRsvpMessage ? RsvpMessage : null;
+
+            // Map status to operation
+            CalendarSynchronizerOperation operation = status switch
+            {
+                AttendeeStatus.Accepted => CalendarSynchronizerOperation.AcceptEvent,
+                AttendeeStatus.Tentative => CalendarSynchronizerOperation.TentativeEvent,
+                AttendeeStatus.Declined => CalendarSynchronizerOperation.DeclineEvent,
+                _ => throw new InvalidOperationException($"Invalid RSVP status: {status}")
+            };
+
+            // Create preparation request with the optional message
+            var preparationRequest = new CalendarOperationPreparationRequest(
+                operation,
+                CurrentEvent.CalendarItem,
+                null,
+                responseMessage);
+
+            await _winoRequestDelegator.ExecuteAsync(preparationRequest);
+
+            OnPropertyChanged(nameof(CurrentRsvpText));
+            OnPropertyChanged(nameof(CurrentRsvpStatus));
+
+            CloseRsvpPanel();
+        }
+        catch (Exception ex)
+        {
+            Debug.WriteLine($"Error sending RSVP response: {ex.Message}");
+            _dialogService.InfoBarMessage(
+                Translator.Info_AttachmentSaveFailedTitle,
+                ex.Message,
+                InfoBarMessageType.Error);
+        }
     }
 
     [RelayCommand]
@@ -323,3 +438,30 @@ public partial class ReminderOption : ObservableObject
         IsCustom = isCustom;
     }
 }
+
+public partial class RsvpStatusOption : ObservableObject
+{
+    public CalendarItemStatus Status { get; }
+
+    public string StatusText
+    {
+        get
+        {
+            return Status switch
+            {
+                CalendarItemStatus.Accepted => Translator.CalendarEventResponse_Accept,
+                CalendarItemStatus.Tentative => Translator.CalendarEventResponse_Tentative,
+                CalendarItemStatus.Cancelled => Translator.CalendarEventResponse_Decline,
+                _ => Translator.CalendarEventResponse_Accept
+            };
+        }
+    }
+
+    [ObservableProperty]
+    public partial bool IsSelected { get; set; }
+
+    public RsvpStatusOption(CalendarItemStatus status)
+    {
+        Status = status;
+    }
+}

Wino.Calendar/Views/EventDetailsPage.xaml

@@ -258,18 +258,32 @@
                                             Height="40"
                                             DisplayName="{x:Bind Name}" />
 
-                                        <!--  TODO: Organizer  -->
-                                        <Grid Grid.Column="1">
+                                        <Grid Grid.Column="1" RowSpacing="4">
                                             <Grid.RowDefinitions>
                                                 <RowDefinition Height="Auto" />
                                                 <RowDefinition Height="Auto" />
+                                                <RowDefinition Height="Auto" />
                                             </Grid.RowDefinitions>
 
                                             <TextBlock FontWeight="SemiBold" Text="{x:Bind Name}" />
                                             <TextBlock
                                                 Grid.Row="1"
                                                 FontSize="13"
+                                                Foreground="{ThemeResource TextFillColorSecondaryBrush}"
                                                 Text="{x:Bind Email}" />
+                                            <Border
+                                                Grid.Row="2"
+                                                Padding="6,2"
+                                                HorizontalAlignment="Left"
+                                                Background="{ThemeResource AccentFillColorDefaultBrush}"
+                                                CornerRadius="4"
+                                                Visibility="{x:Bind IsOrganizer}">
+                                                <TextBlock
+                                                    FontSize="11"
+                                                    FontWeight="SemiBold"
+                                                    Foreground="{ThemeResource TextOnAccentFillColorPrimaryBrush}"
+                                                    Text="{x:Bind domain:Translator.CalendarEventDetails_Organizer}" />
+                                            </Border>
                                         </Grid>
                                     </Grid>
                                 </DataTemplate>

Wino.Core.Domain/Entities/Calendar/AccountCalendar.cs

@@ -1,5 +1,6 @@
 using System;
 using SQLite;
+using Wino.Core.Domain.Entities.Shared;
 using Wino.Core.Domain.Interfaces;
 
 namespace Wino.Core.Domain.Entities.Calendar;
@@ -22,4 +23,7 @@ public class AccountCalendar : IAccountCalendar
     public string TextColorHex { get; set; }
     public string BackgroundColorHex { get; set; }
     public string TimeZone { get; set; }
+
+    [Ignore]
+    public MailAccount MailAccount { get; set; }
 }

Wino.Core.Domain/Enums/CalendarItemStatus.cs

@@ -3,7 +3,7 @@
 public enum CalendarItemStatus
 {
     NotResponded,
-    Confirmed,
+    Accepted,
     Tentative,
     Cancelled,
 }

Wino.Core.Domain/Enums/MailOperation.cs

@@ -26,6 +26,9 @@ public enum CalendarSynchronizerOperation
     CreateEvent,
     UpdateEvent,
     DeleteEvent,
+    AcceptEvent,
+    DeclineEvent,
+    TentativeEvent,
 }
 
 // UI requests

Wino.Core.Domain/Interfaces/IAccountCalendar.cs

@@ -1,4 +1,5 @@
 using System;
+using Wino.Core.Domain.Entities.Shared;
 
 namespace Wino.Core.Domain.Interfaces;
 
@@ -12,4 +13,5 @@ public interface IAccountCalendar
     string RemoteCalendarId { get; set; }
     bool IsExtended { get; set; }
     Guid Id { get; set; }
+    MailAccount MailAccount { get; set; }
 }

Wino.Core.Domain/Models/Calendar/CalendarOperationPreparationRequest.cs

@@ -7,7 +7,8 @@ namespace Wino.Core.Domain.Models.Calendar;
 /// <summary>
 /// Encapsulates the options for preparing calendar operation requests.
 /// </summary>
-/// <param name="Operation">Calendar operation to execute (Create, Update, Delete).</param>
+/// <param name="Operation">Calendar operation to execute (Create, Update, Delete, Accept, Decline, Tentative).</param>
 /// <param name="CalendarItem">Calendar item to operate on.</param>
 /// <param name="Attendees">List of attendees for the calendar event.</param>
-public record CalendarOperationPreparationRequest(CalendarSynchronizerOperation Operation, CalendarItem CalendarItem, List<CalendarEventAttendee> Attendees);
+/// <param name="ResponseMessage">Optional message to include with event responses (Accept, Decline, Tentative).</param>
+public record CalendarOperationPreparationRequest(CalendarSynchronizerOperation Operation, CalendarItem CalendarItem, List<CalendarEventAttendee> Attendees, string ResponseMessage = null);

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

@@ -84,14 +84,26 @@
     "CalendarDisplayOptions_Color": "Color",
     "CalendarDisplayOptions_Expand": "Expand",
     "CalendarEventResponse_Accept": "Accept",
+    "CalendarEventResponse_AcceptedResponse": "Accepted",
     "CalendarEventResponse_Decline": "Decline",
+    "CalendarEventResponse_DeclinedResponse": "Declined",
+    "CalendarEventResponse_NotResponded": "Not Responded",
     "CalendarEventResponse_Tentative": "Tentative",
+    "CalendarEventResponse_TentativeResponse": "Tentative",
+    "CalendarEventRsvpPanel_Accept": "Accept",
+    "CalendarEventRsvpPanel_AddMessage": "Add a message to your response... (optional)",
+    "CalendarEventRsvpPanel_Decline": "Decline",
+    "CalendarEventRsvpPanel_Message": "Message",
+    "CalendarEventRsvpPanel_SendReplyMessage": "Send a reply message",
+    "CalendarEventRsvpPanel_Tentative": "Tentative",
+    "CalendarEventRsvpPanel_Title": "Response Options",
     "CalendarEventDetails_Attachments": "Attachments",
     "CalendarEventDetails_Details": "Details",
     "CalendarEventDetails_EditSeries": "Edit Series",
     "CalendarEventDetails_Editing": "Editing",
     "CalendarEventDetails_InviteSomeone": "Invite someone",
     "CalendarEventDetails_JoinOnline": "Join Online",
+    "CalendarEventDetails_Organizer": "Organizer",
     "CalendarEventDetails_People": "People",
     "CalendarEventDetails_ReadOnlyEvent": "Read-only event",
     "CalendarEventDetails_Reminder": "Reminder",

Wino.Core/Integration/Processors/GmailChangeProcessor.cs

@@ -349,10 +349,10 @@ public class GmailChangeProcessor : DefaultChangeProcessor, IGmailChangeProcesso
     {
         return status switch
         {
-            "confirmed" => CalendarItemStatus.Confirmed,
+            "confirmed" => CalendarItemStatus.Accepted,
             "tentative" => CalendarItemStatus.Tentative,
             "cancelled" => CalendarItemStatus.Cancelled,
-            _ => CalendarItemStatus.Confirmed
+            _ => CalendarItemStatus.Accepted
         };
     }
 

Wino.Core/Integration/Processors/OutlookChangeProcessor.cs

@@ -152,7 +152,7 @@ public class OutlookChangeProcessor(IDatabaseService databaseService,
                     break;
                 case ResponseType.Accepted:
                 case ResponseType.Organizer:
-                    savingItem.Status = CalendarItemStatus.Confirmed;
+                    savingItem.Status = CalendarItemStatus.Accepted;
                     break;
                 case ResponseType.Declined:
                     savingItem.Status = CalendarItemStatus.Cancelled;
@@ -164,7 +164,7 @@ public class OutlookChangeProcessor(IDatabaseService databaseService,
         }
         else
         {
-            savingItem.Status = CalendarItemStatus.Confirmed;
+            savingItem.Status = CalendarItemStatus.Accepted;
         }
 
         // Prepare attendees list

Wino.Core/Requests/Calendar/AcceptEventRequest.cs

@@ -0,0 +1,39 @@
+using CommunityToolkit.Mvvm.Messaging;
+using Wino.Core.Domain.Entities.Calendar;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Models.Requests;
+using Wino.Messaging.Client.Calendar;
+
+namespace Wino.Core.Requests.Calendar;
+
+/// <summary>
+/// Request to accept a calendar event invitation on the server.
+/// The calendar item status should be updated locally before queuing this request.
+/// </summary>
+public record AcceptEventRequest(CalendarItem Item, string ResponseMessage = null) : CalendarRequestBase(Item)
+{
+    private readonly CalendarItemStatus _previousStatus = Item.Status;
+
+    public override CalendarSynchronizerOperation Operation => CalendarSynchronizerOperation.AcceptEvent;
+
+    /// <summary>
+    /// After successful acceptance, we need to resync to get updated status.
+    /// </summary>
+    public override int ResynchronizationDelay => 2000;
+
+    public override void ApplyUIChanges()
+    {
+        // Update the item status locally
+        Item.Status = CalendarItemStatus.Accepted;
+        
+        // Notify UI that the event status was updated
+        WeakReferenceMessenger.Default.Send(new CalendarItemUpdated(Item));
+    }
+
+    public override void RevertUIChanges()
+    {
+        // If acceptance fails, revert to the previous status
+        Item.Status = _previousStatus;
+        WeakReferenceMessenger.Default.Send(new CalendarItemUpdated(Item));
+    }
+}

Wino.Core/Requests/Calendar/DeclineEventRequest.cs

@@ -0,0 +1,39 @@
+using CommunityToolkit.Mvvm.Messaging;
+using Wino.Core.Domain.Entities.Calendar;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Models.Requests;
+using Wino.Messaging.Client.Calendar;
+
+namespace Wino.Core.Requests.Calendar;
+
+/// <summary>
+/// Request to decline a calendar event invitation on the server.
+/// The calendar item status should be updated locally before queuing this request.
+/// </summary>
+public record DeclineEventRequest(CalendarItem Item, string ResponseMessage = null) : CalendarRequestBase(Item)
+{
+    private readonly CalendarItemStatus _previousStatus = Item.Status;
+
+    public override CalendarSynchronizerOperation Operation => CalendarSynchronizerOperation.DeclineEvent;
+
+    /// <summary>
+    /// After successful decline, we need to resync to get updated status.
+    /// </summary>
+    public override int ResynchronizationDelay => 2000;
+
+    public override void ApplyUIChanges()
+    {
+        // Update the item status locally
+        Item.Status = CalendarItemStatus.Cancelled;
+
+        // Notify UI that the event status was updated
+        WeakReferenceMessenger.Default.Send(new CalendarItemUpdated(Item));
+    }
+
+    public override void RevertUIChanges()
+    {
+        // If decline fails, revert to the previous status
+        Item.Status = _previousStatus;
+        WeakReferenceMessenger.Default.Send(new CalendarItemUpdated(Item));
+    }
+}

Wino.Core/Requests/Calendar/OutlookDeclineEventRequest.cs

@@ -0,0 +1,38 @@
+using CommunityToolkit.Mvvm.Messaging;
+using Wino.Core.Domain.Entities.Calendar;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Models.Requests;
+using Wino.Messaging.Client.Calendar;
+
+namespace Wino.Core.Requests.Calendar;
+
+/// <summary>
+/// Outlook-specific request to decline a calendar event invitation.
+/// In Outlook, declined events are removed from the calendar by the API after synchronization,
+/// so this request sends a delete notification to remove the event from the UI.
+/// </summary>
+public record OutlookDeclineEventRequest(CalendarItem Item, string ResponseMessage = null) : CalendarRequestBase(Item)
+{
+    private readonly CalendarItemStatus _previousStatus = Item.Status;
+
+    public override CalendarSynchronizerOperation Operation => CalendarSynchronizerOperation.DeclineEvent;
+
+    /// <summary>
+    /// After successful decline, we need to resync to confirm the event is removed.
+    /// </summary>
+    public override int ResynchronizationDelay => 2000;
+
+    public override void ApplyUIChanges()
+    {
+        // In Outlook, declined events are deleted from the calendar after sync
+        // Send deleted message to remove from UI immediately
+        WeakReferenceMessenger.Default.Send(new CalendarItemDeleted(Item));
+    }
+
+    public override void RevertUIChanges()
+    {
+        // If decline fails, restore the previous status and re-add the event
+        Item.Status = _previousStatus;
+        WeakReferenceMessenger.Default.Send(new CalendarItemAdded(Item));
+    }
+}

Wino.Core/Requests/Calendar/TentativeEventRequest.cs

@@ -0,0 +1,39 @@
+using CommunityToolkit.Mvvm.Messaging;
+using Wino.Core.Domain.Entities.Calendar;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Models.Requests;
+using Wino.Messaging.Client.Calendar;
+
+namespace Wino.Core.Requests.Calendar;
+
+/// <summary>
+/// Request to tentatively accept a calendar event invitation on the server.
+/// The calendar item status should be updated locally before queuing this request.
+/// </summary>
+public record TentativeEventRequest(CalendarItem Item, string ResponseMessage = null) : CalendarRequestBase(Item)
+{
+    private readonly CalendarItemStatus _previousStatus = Item.Status;
+
+    public override CalendarSynchronizerOperation Operation => CalendarSynchronizerOperation.TentativeEvent;
+
+    /// <summary>
+    /// After successful tentative acceptance, we need to resync to get updated status.
+    /// </summary>
+    public override int ResynchronizationDelay => 2000;
+
+    public override void ApplyUIChanges()
+    {
+        // Update the item status locally
+        Item.Status = CalendarItemStatus.Tentative;
+        
+        // Notify UI that the event status was updated
+        WeakReferenceMessenger.Default.Send(new CalendarItemUpdated(Item));
+    }
+
+    public override void RevertUIChanges()
+    {
+        // If tentative acceptance fails, revert to the previous status
+        Item.Status = _previousStatus;
+        WeakReferenceMessenger.Default.Send(new CalendarItemUpdated(Item));
+    }
+}

Wino.Core/Services/WinoRequestDelegator.cs

@@ -5,6 +5,7 @@ using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.Messaging;
 using Serilog;
 using Wino.Core.Domain;
+using Wino.Core.Domain.Entities.Calendar;
 using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Exceptions;
 using Wino.Core.Domain.Interfaces;
@@ -141,6 +142,9 @@ public class WinoRequestDelegator : IWinoRequestDelegator
         {
             CalendarSynchronizerOperation.CreateEvent => new CreateCalendarEventRequest(calendarPreparationRequest.CalendarItem, calendarPreparationRequest.Attendees),
             CalendarSynchronizerOperation.DeleteEvent => new DeleteCalendarEventRequest(calendarPreparationRequest.CalendarItem),
+            CalendarSynchronizerOperation.AcceptEvent => new AcceptEventRequest(calendarPreparationRequest.CalendarItem, calendarPreparationRequest.ResponseMessage),
+            CalendarSynchronizerOperation.DeclineEvent => CreateDeclineRequest(calendarPreparationRequest.CalendarItem, calendarPreparationRequest.ResponseMessage),
+            CalendarSynchronizerOperation.TentativeEvent => new TentativeEventRequest(calendarPreparationRequest.CalendarItem, calendarPreparationRequest.ResponseMessage),
             // Future support for update operations
             // CalendarSynchronizerOperation.UpdateEvent => new UpdateCalendarEventRequest(calendarPreparationRequest.CalendarItem, calendarPreparationRequest.Attendees),
             _ => throw new NotImplementedException($"Calendar operation {calendarPreparationRequest.Operation} is not implemented yet.")
@@ -150,6 +154,18 @@ public class WinoRequestDelegator : IWinoRequestDelegator
         await QueueCalendarSynchronizationAsync(calendarPreparationRequest.CalendarItem.AssignedCalendar.AccountId);
     }
 
+    private IRequestBase CreateDeclineRequest(CalendarItem calendarItem, string responseMessage)
+    {
+        // For Outlook accounts, declined events are deleted by the server after synchronization.
+        // Use OutlookDeclineEventRequest to handle UI removal.
+        if (calendarItem.AssignedCalendar?.MailAccount?.ProviderType == MailProviderType.Outlook)
+        {
+            return new OutlookDeclineEventRequest(calendarItem, responseMessage);
+        }
+
+        return new DeclineEventRequest(calendarItem, responseMessage);
+    }
+
     private async Task QueueRequestAsync(IRequestBase request, Guid accountId)
     {
         // Don't trigger synchronization for individual requests - we'll trigger it once for all requests

Wino.Core/Synchronizers/GmailSynchronizer.cs

@@ -8,6 +8,7 @@ using System.Threading.Tasks;
 using System.Web;
 using CommunityToolkit.Mvvm.Messaging;
 using Google;
+using Google.Apis.Calendar.v3;
 using Google.Apis.Calendar.v3.Data;
 using Google.Apis.Gmail.v1;
 using Google.Apis.Gmail.v1.Data;
@@ -1648,7 +1649,7 @@ public class GmailSynchronizer : WinoSynchronizer<IClientServiceRequest, Message
             Summary = calendarItem.Title,
             Description = calendarItem.Description,
             Location = calendarItem.Location,
-            Status = calendarItem.Status == CalendarItemStatus.Confirmed ? "confirmed" : "tentative"
+            Status = calendarItem.Status == CalendarItemStatus.Accepted ? "confirmed" : "tentative"
         };
 
         // Set start and end time
@@ -1696,6 +1697,125 @@ public class GmailSynchronizer : WinoSynchronizer<IClientServiceRequest, Message
         return [new HttpRequestBundle<IClientServiceRequest>(insertRequest, request)];
     }
 
+    public override List<IRequestBundle<IClientServiceRequest>> AcceptEvent(AcceptEventRequest request)
+    {
+        var calendarItem = request.Item;
+        var calendar = calendarItem.AssignedCalendar;
+
+        if (calendar == null)
+        {
+            throw new InvalidOperationException("Calendar item must have an assigned calendar");
+        }
+
+        if (string.IsNullOrEmpty(calendarItem.RemoteEventId))
+        {
+            throw new InvalidOperationException("Cannot accept event without remote event ID");
+        }
+
+        // For Gmail, we need to patch the event with the user's response status
+        // Get the current user's email from the account
+        var userEmail = Account.Address;
+
+        // Create a patch event to update only the attendee response
+        var patchEvent = new Event();
+        
+        // We need to get the event first to update the specific attendee
+        // However, for efficiency, we'll use the patch method with sendUpdates parameter
+        var patchRequest = _calendarService.Events.Patch(new Event
+        {
+            // The API will handle updating the current user's attendee status
+            Attendees = new List<EventAttendee>
+            {
+                new EventAttendee
+                {
+                    Email = userEmail,
+                    ResponseStatus = "accepted"
+                }
+            }
+        }, calendar.RemoteCalendarId, calendarItem.RemoteEventId);
+
+        // Send updates to other attendees if there's a message
+        patchRequest.SendUpdates = !string.IsNullOrEmpty(request.ResponseMessage) 
+            ? Google.Apis.Calendar.v3.EventsResource.PatchRequest.SendUpdatesEnum.All 
+            : Google.Apis.Calendar.v3.EventsResource.PatchRequest.SendUpdatesEnum.None;
+
+        return [new HttpRequestBundle<IClientServiceRequest>(patchRequest, request)];
+    }
+
+    public override List<IRequestBundle<IClientServiceRequest>> DeclineEvent(DeclineEventRequest request)
+    {
+        var calendarItem = request.Item;
+        var calendar = calendarItem.AssignedCalendar;
+
+        if (calendar == null)
+        {
+            throw new InvalidOperationException("Calendar item must have an assigned calendar");
+        }
+
+        if (string.IsNullOrEmpty(calendarItem.RemoteEventId))
+        {
+            throw new InvalidOperationException("Cannot decline event without remote event ID");
+        }
+
+        var userEmail = Account.Address;
+
+        var patchRequest = _calendarService.Events.Patch(new Event
+        {
+            Attendees = new List<EventAttendee>
+            {
+                new EventAttendee
+                {
+                    Email = userEmail,
+                    ResponseStatus = "declined",
+                    Comment = request.ResponseMessage
+                }
+            }
+        }, calendar.RemoteCalendarId, calendarItem.RemoteEventId);
+
+        patchRequest.SendUpdates = !string.IsNullOrEmpty(request.ResponseMessage) 
+            ? Google.Apis.Calendar.v3.EventsResource.PatchRequest.SendUpdatesEnum.All 
+            : Google.Apis.Calendar.v3.EventsResource.PatchRequest.SendUpdatesEnum.None;
+
+        return [new HttpRequestBundle<IClientServiceRequest>(patchRequest, request)];
+    }
+
+    public override List<IRequestBundle<IClientServiceRequest>> TentativeEvent(TentativeEventRequest request)
+    {
+        var calendarItem = request.Item;
+        var calendar = calendarItem.AssignedCalendar;
+
+        if (calendar == null)
+        {
+            throw new InvalidOperationException("Calendar item must have an assigned calendar");
+        }
+
+        if (string.IsNullOrEmpty(calendarItem.RemoteEventId))
+        {
+            throw new InvalidOperationException("Cannot tentatively accept event without remote event ID");
+        }
+
+        var userEmail = Account.Address;
+
+        var patchRequest = _calendarService.Events.Patch(new Event
+        {
+            Attendees = new List<EventAttendee>
+            {
+                new EventAttendee
+                {
+                    Email = userEmail,
+                    ResponseStatus = "tentative",
+                    Comment = request.ResponseMessage
+                }
+            }
+        }, calendar.RemoteCalendarId, calendarItem.RemoteEventId);
+
+        patchRequest.SendUpdates = !string.IsNullOrEmpty(request.ResponseMessage) 
+            ? Google.Apis.Calendar.v3.EventsResource.PatchRequest.SendUpdatesEnum.All 
+            : Google.Apis.Calendar.v3.EventsResource.PatchRequest.SendUpdatesEnum.None;
+
+        return [new HttpRequestBundle<IClientServiceRequest>(patchRequest, request)];
+    }
+
     #endregion
 
     public override async Task KillSynchronizerAsync()

Wino.Core/Synchronizers/OutlookSynchronizer.cs

@@ -1680,6 +1680,9 @@ public class OutlookSynchronizer : WinoSynchronizer<RequestInformation, Message,
 
             foreach (var item in events)
             {
+                // Declined events are returned as Deleted from the API.
+                // There is no way to distinguish unfortunately atm.
+
                 if (IsResourceDeleted(item.AdditionalData))
                 {
                     await _outlookChangeProcessor.DeleteCalendarItemAsync(item.Id, calendar.Id).ConfigureAwait(false);
@@ -1886,6 +1889,80 @@ public class OutlookSynchronizer : WinoSynchronizer<RequestInformation, Message,
         return [new HttpRequestBundle<RequestInformation>(createRequest, request)];
     }
 
+    public override List<IRequestBundle<RequestInformation>> AcceptEvent(AcceptEventRequest request)
+    {
+        var calendarItem = request.Item;
+        var calendar = calendarItem.AssignedCalendar;
+
+        if (calendar == null)
+        {
+            throw new InvalidOperationException("Calendar item must have an assigned calendar");
+        }
+
+        if (string.IsNullOrEmpty(calendarItem.RemoteEventId))
+        {
+            throw new InvalidOperationException("Cannot accept event without remote event ID");
+        }
+
+        var acceptRequestInfo = _graphClient.Me.Calendars[calendar.RemoteCalendarId].Events[calendarItem.RemoteEventId].Accept.ToPostRequestInformation(new Microsoft.Graph.Me.Calendars.Item.Events.Item.Accept.AcceptPostRequestBody
+        {
+            Comment = request.ResponseMessage,
+            SendResponse = !string.IsNullOrEmpty(request.ResponseMessage)
+        });
+
+        return [new HttpRequestBundle<RequestInformation>(acceptRequestInfo, request)];
+    }
+
+    public override List<IRequestBundle<RequestInformation>> OutlookDeclineEvent(OutlookDeclineEventRequest request)
+    {
+        var responseMessage = request.ResponseMessage;
+
+        var calendarItem = request.Item;
+        var calendar = calendarItem.AssignedCalendar;
+
+        if (calendar == null)
+        {
+            throw new InvalidOperationException("Calendar item must have an assigned calendar");
+        }
+
+        if (string.IsNullOrEmpty(calendarItem.RemoteEventId))
+        {
+            throw new InvalidOperationException("Cannot decline event without remote event ID");
+        }
+
+        var declineRequestInfo = _graphClient.Me.Calendars[calendar.RemoteCalendarId].Events[calendarItem.RemoteEventId].Decline.ToPostRequestInformation(new Microsoft.Graph.Me.Calendars.Item.Events.Item.Decline.DeclinePostRequestBody
+        {
+            Comment = responseMessage,
+            SendResponse = !string.IsNullOrEmpty(responseMessage)
+        });
+
+        return [new HttpRequestBundle<RequestInformation>(declineRequestInfo, request)];
+    }
+
+    public override List<IRequestBundle<RequestInformation>> TentativeEvent(TentativeEventRequest request)
+    {
+        var calendarItem = request.Item;
+        var calendar = calendarItem.AssignedCalendar;
+
+        if (calendar == null)
+        {
+            throw new InvalidOperationException("Calendar item must have an assigned calendar");
+        }
+
+        if (string.IsNullOrEmpty(calendarItem.RemoteEventId))
+        {
+            throw new InvalidOperationException("Cannot tentatively accept event without remote event ID");
+        }
+
+        var tentativelyAcceptRequestInfo = _graphClient.Me.Calendars[calendar.RemoteCalendarId].Events[calendarItem.RemoteEventId].TentativelyAccept.ToPostRequestInformation(new Microsoft.Graph.Me.Calendars.Item.Events.Item.TentativelyAccept.TentativelyAcceptPostRequestBody
+        {
+            Comment = request.ResponseMessage,
+            SendResponse = !string.IsNullOrEmpty(request.ResponseMessage)
+        });
+
+        return [new HttpRequestBundle<RequestInformation>(tentativelyAcceptRequestInfo, request)];
+    }
+
     #endregion
 
     public override async Task KillSynchronizerAsync()

Wino.Core/Synchronizers/WinoSynchronizer.cs

@@ -364,6 +364,22 @@ public abstract class WinoSynchronizer<TBaseRequest, TMessageType, TCalendarEven
                         case CalendarSynchronizerOperation.CreateEvent:
                             nativeRequests.AddRange(CreateCalendarEvent(group.ElementAt(0) as CreateCalendarEventRequest));
                             break;
+                        case CalendarSynchronizerOperation.AcceptEvent:
+                            nativeRequests.AddRange(AcceptEvent(group.ElementAt(0) as AcceptEventRequest));
+                            break;
+                        case CalendarSynchronizerOperation.DeclineEvent:
+                            if (Account.ProviderType == MailProviderType.Outlook)
+                            {
+                                nativeRequests.AddRange(OutlookDeclineEvent(group.ElementAt(0) as OutlookDeclineEventRequest));
+                            }
+                            else
+                            {
+                                nativeRequests.AddRange(DeclineEvent(group.ElementAt(0) as DeclineEventRequest));
+                            }
+                            break;
+                        case CalendarSynchronizerOperation.TentativeEvent:
+                            nativeRequests.AddRange(TentativeEvent(group.ElementAt(0) as TentativeEventRequest));
+                            break;
                         case CalendarSynchronizerOperation.UpdateEvent:
                             // TODO: Implement UpdateCalendarEvent
                             break;
@@ -494,6 +510,10 @@ public abstract class WinoSynchronizer<TBaseRequest, TMessageType, TCalendarEven
     #region Calendar Operations
 
     public virtual List<IRequestBundle<TBaseRequest>> CreateCalendarEvent(CreateCalendarEventRequest request) => throw new NotSupportedException(string.Format(Translator.Exception_UnsupportedSynchronizerOperation, this.GetType()));
+    public virtual List<IRequestBundle<TBaseRequest>> AcceptEvent(AcceptEventRequest request) => throw new NotSupportedException(string.Format(Translator.Exception_UnsupportedSynchronizerOperation, this.GetType()));
+    public virtual List<IRequestBundle<TBaseRequest>> DeclineEvent(DeclineEventRequest request) => throw new NotSupportedException(string.Format(Translator.Exception_UnsupportedSynchronizerOperation, this.GetType()));
+    public virtual List<IRequestBundle<TBaseRequest>> OutlookDeclineEvent(OutlookDeclineEventRequest request) => throw new NotSupportedException(string.Format(Translator.Exception_UnsupportedSynchronizerOperation, this.GetType()));
+    public virtual List<IRequestBundle<TBaseRequest>> TentativeEvent(TentativeEventRequest request) => throw new NotSupportedException(string.Format(Translator.Exception_UnsupportedSynchronizerOperation, this.GetType()));
 
     #endregion
 

Wino.Mail.WinUI/Controls/ControlConstants.cs

@@ -100,6 +100,15 @@ public static class ControlConstants
         { WinoIconGlyph.EventJoinOnline, "\uE926" },
         { WinoIconGlyph.ViewMessageSource, "\uE943" },
         { WinoIconGlyph.Apple, "\uE92B" },
-        { WinoIconGlyph.Yahoo, "\uE92C" }
+        { WinoIconGlyph.Yahoo, "\uE92C" },
+        { WinoIconGlyph.People, "\uF007" },
+        { WinoIconGlyph.AttachmentNew, "\uF006" },
+        { WinoIconGlyph.CalendarSettings, "\uF005" },
+        { WinoIconGlyph.SettingsNew, "\uF004" },
+        { WinoIconGlyph.ManageAccounts, "\uF003" },
+        { WinoIconGlyph.SendNew, "\uF002" },
+        { WinoIconGlyph.CalendarShowAs, "\uF001" },
+        { WinoIconGlyph.EventDecline, "\uF000" },
+        { WinoIconGlyph.Dismiss, "\uF008" },
     };
 }

Wino.Mail.WinUI/Controls/WinoFontIcon.cs

@@ -101,7 +101,15 @@ public enum WinoIconGlyph
     EventJoinOnline,
     ViewMessageSource,
     Apple,
-    Yahoo
+    Yahoo,
+    People,
+    AttachmentNew,
+    CalendarSettings,
+    SettingsNew,
+    ManageAccounts,
+    SendNew,
+    CalendarShowAs,
+    Dismiss
 }
 
 public partial class WinoFontIcon : FontIcon

Wino.Mail.WinUI/Selectors/RsvpStatusIconTemplateSelector.cs

@@ -0,0 +1,30 @@
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Mail.WinUI.Selectors;
+
+public partial class RsvpStatusIconTemplateSelector : DataTemplateSelector
+{
+    public DataTemplate NotRespondedTemplate { get; set; }
+    public DataTemplate ConfirmedTemplate { get; set; }
+    public DataTemplate TentativeTemplate { get; set; }
+    public DataTemplate CancelledTemplate { get; set; }
+
+    protected override DataTemplate SelectTemplateCore(object item, DependencyObject container)
+    {
+        if (item is CalendarItemStatus status)
+        {
+            return status switch
+            {
+                CalendarItemStatus.NotResponded => NotRespondedTemplate,
+                CalendarItemStatus.Accepted => ConfirmedTemplate,
+                CalendarItemStatus.Tentative => TentativeTemplate,
+                CalendarItemStatus.Cancelled => CancelledTemplate,
+                _ => NotRespondedTemplate
+            };
+        }
+        
+        return base.SelectTemplateCore(item, container);
+    }
+}

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

@@ -8,16 +8,64 @@
     xmlns:calendarHelpers="using:Wino.Calendar.Helpers"
     xmlns:calendarViewModels="using:Wino.Calendar.ViewModels"
     xmlns:coreControls="using:Wino.Mail.WinUI.Controls"
+    xmlns:ctControls="using:CommunityToolkit.WinUI.Controls"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:domain="using:Wino.Core.Domain"
     xmlns:enums="using:Wino.Core.Domain.Enums"
     xmlns:helpers="using:Wino.Helpers"
     xmlns:local="using:Wino.Calendar.Views"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:selectors="using:Wino.Mail.WinUI.Selectors"
     Style="{StaticResource PageStyle}"
     mc:Ignorable="d">
 
     <Page.Resources>
+        <selectors:RsvpStatusIconTemplateSelector x:Key="RsvpStatusIconSelector">
+            <selectors:RsvpStatusIconTemplateSelector.NotRespondedTemplate>
+                <DataTemplate>
+                    <coreControls:WinoFontIcon
+                        FontSize="20"
+                        Foreground="{ThemeResource SystemAccentColor}"
+                        Icon="EventRespond" />
+                </DataTemplate>
+            </selectors:RsvpStatusIconTemplateSelector.NotRespondedTemplate>
+            <selectors:RsvpStatusIconTemplateSelector.ConfirmedTemplate>
+                <DataTemplate>
+                    <coreControls:WinoFontIcon
+                        FontSize="20"
+                        Foreground="#527257"
+                        Icon="EventAccept" />
+                </DataTemplate>
+            </selectors:RsvpStatusIconTemplateSelector.ConfirmedTemplate>
+            <selectors:RsvpStatusIconTemplateSelector.TentativeTemplate>
+                <DataTemplate>
+                    <coreControls:WinoFontIcon
+                        FontSize="20"
+                        Foreground="#805682"
+                        Icon="EventTentative" />
+                </DataTemplate>
+            </selectors:RsvpStatusIconTemplateSelector.TentativeTemplate>
+            <selectors:RsvpStatusIconTemplateSelector.CancelledTemplate>
+                <DataTemplate>
+                    <coreControls:WinoFontIcon
+                        FontSize="20"
+                        Foreground="{ThemeResource DeleteBrush}"
+                        Icon="EventDecline" />
+                </DataTemplate>
+            </selectors:RsvpStatusIconTemplateSelector.CancelledTemplate>
+        </selectors:RsvpStatusIconTemplateSelector>
+
+        <Style
+            x:Key="TransparentActionButtonStyle"
+            BasedOn="{StaticResource DefaultButtonStyle}"
+            TargetType="Button">
+            <Setter Property="Background" Value="Transparent" />
+            <Setter Property="BorderThickness" Value="0" />
+            <Setter Property="Padding" Value="12,8" />
+            <Setter Property="MinWidth" Value="0" />
+            <Setter Property="MinHeight" Value="0" />
+        </Style>
+
         <Style x:Key="ActionBarElementContainerStackStyle" TargetType="StackPanel">
             <Setter Property="Spacing" Value="6" />
             <Setter Property="Padding" Value="10,0,4,0" />
@@ -25,10 +73,6 @@
             <Setter Property="Orientation" Value="Horizontal" />
         </Style>
 
-        <Style TargetType="AppBarElementContainer">
-            <Setter Property="VerticalAlignment" Value="Center" />
-        </Style>
-
         <Style x:Key="EventDetailsPanelGridStyle" TargetType="Grid">
             <Setter Property="Padding" Value="12,6" />
             <Setter Property="Margin" Value="0,12" />
@@ -46,6 +90,7 @@
     </Page.Resources>
     <Grid Padding="20">
         <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
             <RowDefinition Height="Auto" />
             <RowDefinition Height="*" />
         </Grid.RowDefinitions>
@@ -57,92 +102,100 @@
             BorderBrush="{StaticResource CardStrokeColorDefaultBrush}"
             BorderThickness="1"
             CornerRadius="7">
-            <CommandBar
-                HorizontalAlignment="Left"
-                Background="Transparent"
-                DefaultLabelPosition="Right"
-                IsSticky="True"
-                OverflowButtonVisibility="Auto">
-                <AppBarToggleButton
-                    x:Name="ReadOnlyToggle"
-                    Content="{x:Bind domain:Translator.CalendarEventDetails_ReadOnlyEvent}"
-                    IsChecked="True" />
-                <AppBarButton Command="{x:Bind ViewModel.SaveCommand}" Label="{x:Bind domain:Translator.Buttons_Save}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Icon="Save" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
-                <AppBarButton Command="{x:Bind ViewModel.DeleteCommand}" Label="{x:Bind domain:Translator.Buttons_Delete}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Icon="Delete" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
+            <Grid Padding="8">
+                <ctControls:WrapPanel
+                    x:Name="ActionBarWrapGrid"
+                    HorizontalAlignment="Left"
+                    HorizontalSpacing="4"
+                    VerticalSpacing="4">
 
-                <AppBarSeparator />
+                    <!--  Read Only Toggle  -->
+                    <ToggleButton
+                        x:Name="ReadOnlyToggle"
+                        IsChecked="True"
+                        Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon FontSize="16" Icon="Blocked" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventDetails_ReadOnlyEvent}" />
+                        </StackPanel>
+                    </ToggleButton>
 
-                <!--  Join Online  -->
-                <AppBarButton
-                    Command="{x:Bind ViewModel.JoinOnlineCommand}"
-                    IsEnabled="{x:Bind calendarHelpers:CalendarXamlHelpers.HasOnlineMeetingLink(ViewModel.CurrentEvent), Mode=OneWay}"
-                    Label="{x:Bind domain:Translator.CalendarEventDetails_JoinOnline}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Icon="EventJoinOnline" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
+                    <!--  Save  -->
+                    <Button Command="{x:Bind ViewModel.SaveCommand}" Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon FontSize="16" Icon="Save" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.Buttons_Save}" />
+                        </StackPanel>
+                    </Button>
 
-                <AppBarSeparator />
+                    <!--  Delete  -->
+                    <Button Command="{x:Bind ViewModel.DeleteCommand}" Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon FontSize="16" Icon="Delete" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.Buttons_Delete}" />
+                        </StackPanel>
+                    </Button>
 
-                <!--  Response Options  -->
+                    <Border
+                        Width="1"
+                        Height="24"
+                        Margin="4,0"
+                        VerticalAlignment="Center"
+                        Background="{ThemeResource DividerStrokeColorDefaultBrush}" />
 
-                <AppBarButton
-                    Command="{x:Bind ViewModel.RespondCommand}"
-                    CommandParameter="{x:Bind enums:CalendarItemStatus.Confirmed}"
-                    Label="{x:Bind domain:Translator.CalendarEventResponse_Accept}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Foreground="#527257" Icon="EventAccept" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
+                    <!--  Join Online  -->
+                    <Button
+                        Command="{x:Bind ViewModel.JoinOnlineCommand}"
+                        IsEnabled="{x:Bind calendarHelpers:CalendarXamlHelpers.HasOnlineMeetingLink(ViewModel.CurrentEvent), Mode=OneWay}"
+                        Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon FontSize="16" Icon="EventJoinOnline" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventDetails_JoinOnline}" />
+                        </StackPanel>
+                    </Button>
 
-                <AppBarButton
-                    Command="{x:Bind ViewModel.RespondCommand}"
-                    CommandParameter="{x:Bind enums:CalendarItemStatus.Tentative}"
-                    Label="{x:Bind domain:Translator.CalendarEventResponse_Tentative}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Foreground="#805682" Icon="EventTentative" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
+                    <Border
+                        Width="1"
+                        Height="24"
+                        Margin="4,0"
+                        VerticalAlignment="Center"
+                        Background="{ThemeResource DividerStrokeColorDefaultBrush}" />
 
-                <AppBarButton
-                    Command="{x:Bind ViewModel.RespondCommand}"
-                    CommandParameter="{x:Bind enums:CalendarItemStatus.Cancelled}"
-                    Label="{x:Bind domain:Translator.CalendarEventResponse_Decline}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Foreground="#805682" Icon="EventRespond" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
+                    <!--  RSVP Button  -->
+                    <Button 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}" />
+                        </StackPanel>
+                    </Button>
 
-                <AppBarSeparator />
+                    <Border
+                        Width="1"
+                        Height="24"
+                        Margin="4,0"
+                        VerticalAlignment="Center"
+                        Background="{ThemeResource DividerStrokeColorDefaultBrush}" />
 
-                <!--  Show as  -->
-                <AppBarElementContainer>
-                    <StackPanel Style="{StaticResource ActionBarElementContainerStackStyle}">
-                        <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventDetails_ShowAs}" />
+                    <!--  Show as  -->
+                    <StackPanel
+                        Padding="12,0"
+                        VerticalAlignment="Center"
+                        Orientation="Horizontal"
+                        Spacing="8">
+                        <coreControls:WinoFontIcon FontSize="20" Icon="CalendarShowAs" />
                         <ComboBox
                             Width="150"
+                            VerticalAlignment="Center"
                             ItemsSource="{x:Bind ViewModel.ShowAsOptions}"
                             SelectedItem="{x:Bind ViewModel.SelectedShowAs, Mode=TwoWay}" />
                     </StackPanel>
-                </AppBarElementContainer>
 
-                <!--  Reminder  -->
-                <AppBarElementContainer>
-                    <Button>
-                        <Button.Content>
-                            <StackPanel Orientation="Horizontal" Spacing="8">
-                                <coreControls:WinoFontIcon FontSize="16" Icon="Reminder" />
-                                <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventDetails_Reminder}" />
-                            </StackPanel>
-                        </Button.Content>
+                    <!--  Reminder  -->
+                    <Button Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon FontSize="16" Icon="Reminder" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventDetails_Reminder}" />
+                        </StackPanel>
                         <Button.Flyout>
                             <Flyout>
                                 <ListView
@@ -159,24 +212,124 @@
                             </Flyout>
                         </Button.Flyout>
                     </Button>
-                </AppBarElementContainer>
 
-                <AppBarSeparator Visibility="{x:Bind ViewModel.CanEditSeries, Mode=OneWay}" />
+                    <!--  Edit Series  -->
+                    <Border
+                        Width="1"
+                        Height="24"
+                        Margin="4,0"
+                        VerticalAlignment="Center"
+                        Background="{ThemeResource DividerStrokeColorDefaultBrush}"
+                        Visibility="{x:Bind ViewModel.CanEditSeries, Mode=OneWay}" />
 
-                <!--  Edit Series  -->
-                <AppBarButton
-                    Command="{x:Bind ViewModel.ViewSeriesCommand}"
-                    Label="{x:Bind domain:Translator.CalendarEventDetails_EditSeries}"
-                    Visibility="{x:Bind ViewModel.CanEditSeries, Mode=OneWay}">
-                    <AppBarButton.Icon>
-                        <coreControls:WinoFontIcon Icon="EventEditSeries" />
-                    </AppBarButton.Icon>
-                </AppBarButton>
-            </CommandBar>
+                    <Button
+                        Command="{x:Bind ViewModel.ViewSeriesCommand}"
+                        Style="{StaticResource TransparentActionButtonStyle}"
+                        Visibility="{x:Bind ViewModel.CanEditSeries, Mode=OneWay}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon FontSize="16" Icon="EventEditSeries" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventDetails_EditSeries}" />
+                        </StackPanel>
+                    </Button>
+                </ctControls:WrapPanel>
+            </Grid>
+        </Border>
+
+        <!--  RSVP Panel  -->
+        <Border
+            Grid.Row="1"
+            Margin="0,8,0,0"
+            Padding="16"
+            VerticalAlignment="Top"
+            Background="{ThemeResource CardBackgroundFillColorSecondaryBrush}"
+            BorderBrush="{StaticResource CardStrokeColorDefaultBrush}"
+            BorderThickness="1"
+            CornerRadius="7"
+            Visibility="{x:Bind ViewModel.IsRsvpPanelVisible, Mode=OneWay}">
+            <Grid RowSpacing="6">
+                <Grid.RowDefinitions>
+                    <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
+                </Grid.RowDefinitions>
+
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="*" />
+                    <ColumnDefinition Width="Auto" />
+                </Grid.ColumnDefinitions>
+
+                <!--  Close Button  -->
+                <Button
+                    Grid.Column="1"
+                    HorizontalAlignment="Right"
+                    VerticalAlignment="Top"
+                    Command="{x:Bind ViewModel.CloseRsvpPanelCommand}"
+                    Style="{StaticResource TransparentActionButtonStyle}">
+                    <coreControls:WinoFontIcon FontSize="16" Icon="Dismiss" />
+                </Button>
+
+                <!--  RSVP Buttons  -->
+                <StackPanel Orientation="Horizontal" Spacing="4">
+                    <!--  Accept  -->
+                    <Button
+                        Command="{x:Bind ViewModel.SendRsvpResponseCommand}"
+                        CommandParameter="{x:Bind enums:AttendeeStatus.Accepted}"
+                        Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon
+                                FontSize="20"
+                                Foreground="#527257"
+                                Icon="EventAccept" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventRsvpPanel_Accept, Mode=OneTime}" />
+                        </StackPanel>
+                    </Button>
+
+                    <!--  Tentative  -->
+                    <Button
+                        Command="{x:Bind ViewModel.SendRsvpResponseCommand}"
+                        CommandParameter="{x:Bind enums:AttendeeStatus.Tentative}"
+                        Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon
+                                FontSize="20"
+                                Foreground="#805682"
+                                Icon="EventTentative" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventRsvpPanel_Tentative, Mode=OneTime}" />
+                        </StackPanel>
+                    </Button>
+
+                    <!--  Decline  -->
+                    <Button
+                        Command="{x:Bind ViewModel.SendRsvpResponseCommand}"
+                        CommandParameter="{x:Bind enums:AttendeeStatus.Declined}"
+                        Style="{StaticResource TransparentActionButtonStyle}">
+                        <StackPanel Orientation="Horizontal" Spacing="8">
+                            <coreControls:WinoFontIcon
+                                FontSize="20"
+                                Foreground="{ThemeResource DeleteBrush}"
+                                Icon="EventDecline" />
+                            <TextBlock VerticalAlignment="Center" Text="{x:Bind domain:Translator.CalendarEventRsvpPanel_Decline, Mode=OneTime}" />
+                        </StackPanel>
+                    </Button>
+                </StackPanel>
+
+                <!--  Reply Message TextBox  -->
+                <TextBox
+                    Grid.Row="1"
+                    Grid.ColumnSpan="2"
+                    VerticalAlignment="Center"
+                    AcceptsReturn="True"
+                    PlaceholderText="{x:Bind domain:Translator.CalendarEventRsvpPanel_AddMessage, Mode=OneTime}"
+                    Text="{x:Bind ViewModel.RsvpMessage, Mode=TwoWay}"
+                    TextWrapping="Wrap">
+                    <TextBox.Header>
+                        <StackPanel Orientation="Horizontal" />
+                    </TextBox.Header>
+                </TextBox>
+            </Grid>
         </Border>
 
         <!--  Event details  -->
-        <ScrollViewer Grid.Row="1">
+        <ScrollViewer Grid.Row="2">
             <Grid ColumnSpacing="8">
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="2*" />
@@ -293,18 +446,32 @@
                                             Height="40"
                                             DisplayName="{x:Bind Name}" />
 
-                                        <!--  TODO: Organizer  -->
-                                        <Grid Grid.Column="1">
+                                        <Grid Grid.Column="1" RowSpacing="4">
                                             <Grid.RowDefinitions>
                                                 <RowDefinition Height="Auto" />
                                                 <RowDefinition Height="Auto" />
+                                                <RowDefinition Height="Auto" />
                                             </Grid.RowDefinitions>
 
                                             <TextBlock FontWeight="SemiBold" Text="{x:Bind Name}" />
                                             <TextBlock
                                                 Grid.Row="1"
                                                 FontSize="13"
+                                                Foreground="{ThemeResource TextFillColorSecondaryBrush}"
                                                 Text="{x:Bind Email}" />
+                                            <Border
+                                                Grid.Row="2"
+                                                Padding="6,2"
+                                                HorizontalAlignment="Left"
+                                                Background="{ThemeResource AccentFillColorDefaultBrush}"
+                                                CornerRadius="4"
+                                                Visibility="{x:Bind IsOrganizer}">
+                                                <TextBlock
+                                                    FontSize="11"
+                                                    FontWeight="SemiBold"
+                                                    Foreground="{ThemeResource TextOnAccentFillColorPrimaryBrush}"
+                                                    Text="{x:Bind domain:Translator.CalendarEventDetails_Organizer}" />
+                                            </Border>
                                         </Grid>
                                     </Grid>
                                 </DataTemplate>
@@ -328,5 +495,50 @@
                 </Grid>
             </Grid>
         </ScrollViewer>
+
+        <VisualStateManager.VisualStateGroups>
+            <VisualStateGroup x:Name="WindowWidthStates">
+                <VisualState x:Name="WideState">
+                    <VisualState.StateTriggers>
+                        <AdaptiveTrigger MinWindowWidth="1200" />
+                    </VisualState.StateTriggers>
+                </VisualState>
+                <VisualState x:Name="MediumState">
+                    <VisualState.StateTriggers>
+                        <AdaptiveTrigger MinWindowWidth="800" />
+                    </VisualState.StateTriggers>
+                    <VisualState.Setters>
+                        <!--  Details takes left side (full height), People and Attachments share right side vertically  -->
+                        <Setter Target="DetailsGrid.(Grid.Row)" Value="0" />
+                        <Setter Target="DetailsGrid.(Grid.Column)" Value="0" />
+                        <Setter Target="DetailsGrid.(Grid.RowSpan)" Value="2" />
+                        <Setter Target="DetailsGrid.(Grid.ColumnSpan)" Value="1" />
+                        <Setter Target="PeopleGrid.(Grid.Row)" Value="0" />
+                        <Setter Target="PeopleGrid.(Grid.Column)" Value="1" />
+                        <Setter Target="PeopleGrid.(Grid.ColumnSpan)" Value="2" />
+                        <Setter Target="AttachmentsGrid.(Grid.Row)" Value="1" />
+                        <Setter Target="AttachmentsGrid.(Grid.Column)" Value="1" />
+                        <Setter Target="AttachmentsGrid.(Grid.ColumnSpan)" Value="2" />
+                    </VisualState.Setters>
+                </VisualState>
+                <VisualState x:Name="NarrowState">
+                    <VisualState.StateTriggers>
+                        <AdaptiveTrigger MinWindowWidth="0" />
+                    </VisualState.StateTriggers>
+                    <VisualState.Setters>
+                        <!--  Stack all panels vertically  -->
+                        <Setter Target="DetailsGrid.(Grid.Row)" Value="0" />
+                        <Setter Target="DetailsGrid.(Grid.Column)" Value="0" />
+                        <Setter Target="DetailsGrid.(Grid.ColumnSpan)" Value="3" />
+                        <Setter Target="PeopleGrid.(Grid.Row)" Value="1" />
+                        <Setter Target="PeopleGrid.(Grid.Column)" Value="0" />
+                        <Setter Target="PeopleGrid.(Grid.ColumnSpan)" Value="3" />
+                        <Setter Target="AttachmentsGrid.(Grid.Row)" Value="2" />
+                        <Setter Target="AttachmentsGrid.(Grid.Column)" Value="0" />
+                        <Setter Target="AttachmentsGrid.(Grid.ColumnSpan)" Value="3" />
+                    </VisualState.Setters>
+                </VisualState>
+            </VisualStateGroup>
+        </VisualStateManager.VisualStateGroups>
     </Grid>
 </abstract:EventDetailsPageAbstract>

Wino.Services/CalendarService.cs

@@ -11,6 +11,7 @@ using Itenso.TimePeriod;
 using Serilog;
 using Wino.Core.Domain;
 using Wino.Core.Domain.Entities.Calendar;
+using Wino.Core.Domain.Entities.Shared;
 using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.Calendar;
@@ -253,14 +254,33 @@ public class CalendarService : BaseDatabaseService, ICalendarService
         return result;
     }
 
-    public Task<AccountCalendar> GetAccountCalendarAsync(Guid accountCalendarId)
-        => Connection.GetAsync<AccountCalendar>(accountCalendarId);
-
-    public Task<CalendarItem> GetCalendarItemAsync(Guid id)
+    public async Task<AccountCalendar> GetAccountCalendarAsync(Guid accountCalendarId)
     {
-        return Connection.FindWithQueryAsync<CalendarItem>(
+        var calendar = await Connection.GetAsync<AccountCalendar>(accountCalendarId);
+        if (calendar != null)
+        {
+            calendar.MailAccount = await Connection.GetAsync<MailAccount>(calendar.AccountId);
+        }
+        return calendar;
+    }
+
+    public async Task<CalendarItem> GetCalendarItemAsync(Guid id)
+    {
+        var calendarItem = await Connection.FindWithQueryAsync<CalendarItem>(
             "SELECT * FROM CalendarItem WHERE Id = ?",
             id);
+
+        // Load assigned calendar and account.
+        if (calendarItem != null)
+        {
+            calendarItem.AssignedCalendar = await Connection.GetAsync<AccountCalendar>(calendarItem.CalendarId);
+            if (calendarItem.AssignedCalendar != null)
+            {
+                calendarItem.AssignedCalendar.MailAccount = await Connection.GetAsync<MailAccount>(calendarItem.AssignedCalendar.AccountId);
+            }
+        }
+
+        return calendarItem;
     }
 
     public async Task<CalendarItem> GetCalendarItemAsync(Guid accountCalendarId, string remoteEventId)
@@ -269,10 +289,14 @@ public class CalendarService : BaseDatabaseService, ICalendarService
             "SELECT * FROM CalendarItem WHERE CalendarId = ? AND RemoteEventId = ?",
             accountCalendarId, remoteEventId);
 
-        // Load assigned calendar.
+        // Load assigned calendar and account.
         if (calendarItem != null)
         {
             calendarItem.AssignedCalendar = await Connection.GetAsync<AccountCalendar>(calendarItem.CalendarId);
+            if (calendarItem.AssignedCalendar != null)
+            {
+                calendarItem.AssignedCalendar.MailAccount = await Connection.GetAsync<MailAccount>(calendarItem.AssignedCalendar.AccountId);
+            }
         }
 
         return calendarItem;

WinoMail.slnx

@@ -10,6 +10,7 @@
     <File Path="Directory.Packages.props" />
     <File Path="nuget.config" />
     <File Path="Settings.XamlStyler" />
+    <File Path="WinoFontIcomoon.json" />
   </Folder>
   <Folder Name="/lib/">
     <Project Path="Wino.Authentication/Wino.Authentication.csproj">