Calendar invitations for Mail part of the app.

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

@@ -140,6 +140,12 @@ public class CalendarItem : ICalendarItem
     public string HtmlLink { get; set; }
     public CalendarItemStatus Status { get; set; }
     public CalendarItemVisibility Visibility { get; set; }
+    
+    /// <summary>
+    /// Indicates how the event should be shown in the calendar (Free, Busy, Tentative, etc.).
+    /// </summary>
+    public CalendarItemShowAs ShowAs { get; set; } = CalendarItemShowAs.Busy;
+    
     public DateTimeOffset CreatedAt { get; set; }
     public DateTimeOffset UpdatedAt { get; set; }
     public Guid CalendarId { get; set; }

Wino.Core.Domain/Entities/Mail/MailCopy.cs

@@ -103,6 +103,11 @@ public class MailCopy
     /// </summary>
     public bool HasAttachments { get; set; }
 
+    /// <summary>
+    /// Type of mail item (regular mail, calendar invitation, calendar response, etc.).
+    /// </summary>
+    public MailItemType ItemType { get; set; } = MailItemType.Mail;
+
     /// <summary>
     /// Assigned draft id.
     /// </summary>

Wino.Core.Domain/Entities/Shared/MailAccount.cs

@@ -78,6 +78,14 @@ public class MailAccount
     /// </summary>
     public SpecialImapProvider SpecialImapProvider { get; set; }
 
+    /// <summary>
+    /// Gets or sets whether calendar access is granted for this account.
+    /// When false, synchronizers will not process EventMessages or calendar invitations.
+    /// Default is false for existing accounts to prevent scope issues.
+    /// New accounts created after this feature will have this set to true.
+    /// </summary>
+    public bool IsCalendarAccessGranted { get; set; }
+
     /// <summary>
     /// Contains the merged inbox this account belongs to.
     /// Ignored for all SQLite operations.

Wino.Core.Domain/Enums/MailItemType.cs

@@ -0,0 +1,27 @@
+namespace Wino.Core.Domain.Enums;
+
+/// <summary>
+/// Represents the type of mail item.
+/// </summary>
+public enum MailItemType
+{
+    /// <summary>
+    /// Regular mail message.
+    /// </summary>
+    Mail = 0,
+
+    /// <summary>
+    /// Calendar invitation (meeting request).
+    /// </summary>
+    CalendarInvitation = 1,
+
+    /// <summary>
+    /// Calendar response (meeting accepted, tentatively accepted, or declined).
+    /// </summary>
+    CalendarResponse = 2,
+
+    /// <summary>
+    /// Calendar cancellation (meeting cancelled).
+    /// </summary>
+    CalendarCancellation = 3
+}

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

@@ -11,4 +11,12 @@ namespace Wino.Core.Domain.Models.Calendar;
 /// <param name="CalendarItem">Calendar item to operate on.</param>
 /// <param name="Attendees">List of attendees for the calendar event.</param>
 /// <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);
+/// <param name="OriginalItem">Original calendar item state before update (for revert capability).</param>
+/// <param name="OriginalAttendees">Original attendees list before update (for revert capability).</param>
+public record CalendarOperationPreparationRequest(
+    CalendarSynchronizerOperation Operation,
+    CalendarItem CalendarItem,
+    List<CalendarEventAttendee> Attendees,
+    string ResponseMessage = null,
+    CalendarItem OriginalItem = null,
+    List<CalendarEventAttendee> OriginalAttendees = null);