fix(communication): correct audit-ingest timeout-path docs and add timeout test

tests/ScadaLink.Communication.Tests/CentralCommunicationActorAuditTests.cs

@@ -24,7 +24,7 @@ public class CentralCommunicationActorAuditTests : TestKit
 {
     public CentralCommunicationActorAuditTests() : base(@"akka.loglevel = DEBUG") { }
 
-    private IActorRef CreateActor()
+    private IActorRef CreateActor(TimeSpan? auditIngestAskTimeout = null)
     {
         var mockRepo = Substitute.For<ISiteRepository>();
         mockRepo.GetAllSitesAsync(Arg.Any<CancellationToken>())
@@ -35,7 +35,8 @@ public class CentralCommunicationActorAuditTests : TestKit
         var sp = services.BuildServiceProvider();
 
         var mockFactory = Substitute.For<ISiteClientFactory>();
-        return Sys.ActorOf(Props.Create(() => new CentralCommunicationActor(sp, mockFactory)));
+        return Sys.ActorOf(Props.Create(() =>
+            new CentralCommunicationActor(sp, mockFactory, auditIngestAskTimeout)));
     }
 
     private static AuditEvent SampleAuditEvent() => new()
@@ -94,6 +95,28 @@ public class CentralCommunicationActorAuditTests : TestKit
         Assert.Empty(reply.AcceptedEventIds);
     }
 
+    [Fact]
+    public void IngestAuditEventsCommand_WhenProxyNeverReplies_PipesStatusFailureToSender()
+    {
+        // A short test-only Ask timeout (constructor seam) keeps the test fast —
+        // production uses the 30 s default.
+        var actor = CreateActor(auditIngestAskTimeout: TimeSpan.FromMilliseconds(200));
+        var auditProbe = CreateTestProbe();
+        actor.Tell(new RegisterAuditIngest(auditProbe.Ref));
+
+        var cmd = new IngestAuditEventsCommand(new[] { SampleAuditEvent() });
+        actor.Tell(cmd);
+
+        // The proxy receives the command but deliberately never replies.
+        auditProbe.ExpectMsg(cmd);
+
+        // The Ask times out; PipeTo forwards the faulted task as a Status.Failure
+        // to the original sender. This is the real transient signal the site's
+        // own Ask faults on — it is NOT swallowed into an empty ack.
+        var failure = ExpectMsg<Status.Failure>();
+        Assert.IsType<AskTimeoutException>(failure.Cause);
+    }
+
     [Fact]
     public void IngestCachedTelemetryCommand_WithRegisteredProxy_ForwardsAndRoutesReplyToSender()
     {