feat(notification-outbox): add notification message and outbox query contracts

src/ScadaLink.Commons/Messages/Notification/NotificationMessages.cs

@@ -0,0 +1,42 @@
+namespace ScadaLink.Commons.Messages.Notification;
+
+/// <summary>
+/// Site -> Central: submit a notification for central delivery.
+/// Fire-and-forget with ack; the site retries until a <see cref="NotificationSubmitAck"/> is received.
+/// </summary>
+public record NotificationSubmit(
+    string NotificationId,
+    string ListName,
+    string Subject,
+    string Body,
+    string SourceSiteId,
+    string? SourceInstanceId,
+    string? SourceScript,
+    DateTimeOffset SiteEnqueuedAt);
+
+/// <summary>
+/// Central -> Site: ack sent after the notification row is persisted.
+/// Idempotent — safe to re-send for the same <see cref="NotificationId"/>.
+/// </summary>
+public record NotificationSubmitAck(
+    string NotificationId,
+    bool Accepted,
+    string? Error);
+
+/// <summary>
+/// Site -> Central: query the central delivery status for a <see cref="NotificationId"/>.
+/// </summary>
+public record NotificationStatusQuery(
+    string CorrelationId,
+    string NotificationId);
+
+/// <summary>
+/// Central -> Site: response carrying the current delivery status for a queried notification.
+/// </summary>
+public record NotificationStatusResponse(
+    string CorrelationId,
+    bool Found,
+    string Status,
+    int RetryCount,
+    string? LastError,
+    DateTimeOffset? DeliveredAt);

src/ScadaLink.Commons/Messages/Notification/NotificationOutboxQueries.cs

@@ -0,0 +1,92 @@
+namespace ScadaLink.Commons.Messages.Notification;
+
+/// <summary>
+/// Outbox UI -> Central: paginated, filtered query over the notification outbox.
+/// All filter fields are optional; <see cref="StuckOnly"/> restricts results to stuck notifications.
+/// </summary>
+public record NotificationOutboxQueryRequest(
+    string CorrelationId,
+    string? StatusFilter,
+    string? TypeFilter,
+    string? SourceSiteFilter,
+    string? ListNameFilter,
+    bool StuckOnly,
+    string? SubjectKeyword,
+    DateTimeOffset? From,
+    DateTimeOffset? To,
+    int PageNumber,
+    int PageSize);
+
+/// <summary>
+/// A single notification row summarised for outbox UI display.
+/// </summary>
+public record NotificationSummary(
+    string NotificationId,
+    string Type,
+    string ListName,
+    string Subject,
+    string Status,
+    int RetryCount,
+    string? LastError,
+    string SourceSiteId,
+    string? SourceInstanceId,
+    DateTimeOffset CreatedAt,
+    DateTimeOffset? DeliveredAt,
+    bool IsStuck);
+
+/// <summary>
+/// Central -> Outbox UI: paginated response for a <see cref="NotificationOutboxQueryRequest"/>.
+/// </summary>
+public record NotificationOutboxQueryResponse(
+    string CorrelationId,
+    bool Success,
+    string? ErrorMessage,
+    IReadOnlyList<NotificationSummary> Notifications,
+    int TotalCount);
+
+/// <summary>
+/// Outbox UI -> Central: request to immediately retry delivery of a notification.
+/// </summary>
+public record RetryNotificationRequest(
+    string CorrelationId,
+    string NotificationId);
+
+/// <summary>
+/// Central -> Outbox UI: result of a <see cref="RetryNotificationRequest"/>.
+/// </summary>
+public record RetryNotificationResponse(
+    string CorrelationId,
+    bool Success,
+    string? ErrorMessage);
+
+/// <summary>
+/// Outbox UI -> Central: request to discard (cancel) a pending or stuck notification.
+/// </summary>
+public record DiscardNotificationRequest(
+    string CorrelationId,
+    string NotificationId);
+
+/// <summary>
+/// Central -> Outbox UI: result of a <see cref="DiscardNotificationRequest"/>.
+/// </summary>
+public record DiscardNotificationResponse(
+    string CorrelationId,
+    bool Success,
+    string? ErrorMessage);
+
+/// <summary>
+/// Outbox UI -> Central: request for the notification outbox KPI summary.
+/// </summary>
+public record NotificationKpiRequest(
+    string CorrelationId);
+
+/// <summary>
+/// Central -> Outbox UI: KPI summary for the notification outbox dashboard.
+/// </summary>
+public record NotificationKpiResponse(
+    string CorrelationId,
+    int QueueDepth,
+    int StuckCount,
+    int ParkedCount,
+    int DeliveredLastInterval,
+    TimeSpan? OldestPendingAge);