feat(notification-outbox): forward site S&F notifications to central

src/ScadaLink.Communication/Actors/SiteCommunicationActor.cs

@@ -8,6 +8,7 @@ using ScadaLink.Commons.Messages.Health;
 using ScadaLink.Commons.Messages.InboundApi;
 using ScadaLink.Commons.Messages.Integration;
 using ScadaLink.Commons.Messages.Lifecycle;
+using ScadaLink.Commons.Messages.Notification;
 using ScadaLink.Commons.Messages.RemoteQuery;
 
 namespace ScadaLink.Communication.Actors;
@@ -165,6 +166,30 @@ public class SiteCommunicationActor : ReceiveActor, IWithTimers
             }
         });
 
+        // Notification Outbox: forward a buffered notification submitted by the site
+        // Store-and-Forward Engine to the central cluster. The original Sender (the
+        // S&F forwarder's Ask) is forwarded as the ClusterClient.Send sender so the
+        // NotificationSubmitAck routes straight back to the waiting Ask, not here.
+        Receive<NotificationSubmit>(msg =>
+        {
+            if (_centralClient == null)
+            {
+                // No ClusterClient registered yet (e.g. central contact points not
+                // configured, or registration not yet completed). A non-accepted ack
+                // makes the S&F forwarder treat this as transient and retry later.
+                _log.Warning(
+                    "Cannot forward NotificationSubmit {0} — no central ClusterClient registered",
+                    msg.NotificationId);
+                Sender.Tell(new NotificationSubmitAck(
+                    msg.NotificationId, Accepted: false, Error: "Central ClusterClient not registered"));
+                return;
+            }
+
+            _log.Debug("Forwarding NotificationSubmit {0} to central", msg.NotificationId);
+            _centralClient.Tell(
+                new ClusterClient.Send("/user/central-communication", msg), Sender);
+        });
+
         // Internal: send heartbeat tick
         Receive<SendHeartbeat>(_ => SendHeartbeatToCentral());
 

src/ScadaLink.Communication/CommunicationOptions.cs

@@ -27,6 +27,14 @@ public class CommunicationOptions
     /// <summary>Timeout for health report acknowledgement (fire-and-forget, but bounded).</summary>
     public TimeSpan HealthReportTimeout { get; set; } = TimeSpan.FromSeconds(10);
 
+    /// <summary>
+    /// Notification Outbox: timeout for forwarding a buffered notification to central
+    /// and awaiting its <c>NotificationSubmitAck</c>. A timeout is treated as a
+    /// transient failure — the Store-and-Forward engine keeps the message buffered
+    /// and retries the forward at the fixed retry interval.
+    /// </summary>
+    public TimeSpan NotificationForwardTimeout { get; set; } = TimeSpan.FromSeconds(30);
+
     /// <summary>
     /// Contact point addresses for the central cluster (e.g. "akka.tcp://scadalink@central-a:8081").
     /// Used by site nodes to create a ClusterClient for reaching central.