RSVP options.

Wino.Core/Requests/Calendar/TentativeEventRequest.cs

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+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));
+    }
+}