feat(notification-outbox): add Notification entity

src/ScadaLink.Commons/Entities/Notifications/Notification.cs

@@ -0,0 +1,48 @@
+using ScadaLink.Commons.Types.Enums;
+
+namespace ScadaLink.Commons.Entities.Notifications;
+
+/// <summary>
+/// A single notification queued in the central outbox. Created at a site (where the
+/// <see cref="NotificationId"/> GUID is generated) and forwarded to the central cluster
+/// for delivery, retry, and audit. The lifecycle is tracked by <see cref="Status"/>.
+/// </summary>
+public class Notification
+{
+    /// <summary>GUID primary key, generated at the originating site.</summary>
+    public string NotificationId { get; set; }
+    public NotificationType Type { get; set; }
+    public string ListName { get; set; }
+    public string Subject { get; set; }
+    public string Body { get; set; }
+
+    /// <summary>JSON extensibility hook for channel-specific payload data.</summary>
+    public string? TypeData { get; set; }
+    public NotificationStatus Status { get; set; } = NotificationStatus.Pending;
+    public int RetryCount { get; set; }
+    public string? LastError { get; set; }
+
+    /// <summary>Resolved delivery targets snapshotted at delivery time, for audit.</summary>
+    public string? ResolvedTargets { get; set; }
+    public string SourceSiteId { get; set; }
+    public string? SourceInstanceId { get; set; }
+    public string? SourceScript { get; set; }
+    public DateTimeOffset SiteEnqueuedAt { get; set; }
+
+    /// <summary>Central ingest time.</summary>
+    public DateTimeOffset CreatedAt { get; set; }
+    public DateTimeOffset? LastAttemptAt { get; set; }
+    public DateTimeOffset? NextAttemptAt { get; set; }
+    public DateTimeOffset? DeliveredAt { get; set; }
+
+    public Notification(string notificationId, NotificationType type, string listName,
+        string subject, string body, string sourceSiteId)
+    {
+        NotificationId = notificationId ?? throw new ArgumentNullException(nameof(notificationId));
+        Type = type;
+        ListName = listName ?? throw new ArgumentNullException(nameof(listName));
+        Subject = subject ?? throw new ArgumentNullException(nameof(subject));
+        Body = body ?? throw new ArgumentNullException(nameof(body));
+        SourceSiteId = sourceSiteId ?? throw new ArgumentNullException(nameof(sourceSiteId));
+    }
+}