fix(communication): resolve Communication-009,010,011 — atomic site-cache refresh, XML doc correction, test coverage

src/ScadaLink.Communication/Actors/CentralCommunicationActor.cs

@@ -50,7 +50,7 @@ public class CentralCommunicationActor : ReceiveActor
     /// Maps SiteIdentifier → (ClusterClient actor, set of contact address strings).
     /// Refreshed periodically via RefreshSiteAddresses.
     /// </summary>
-    private Dictionary<string, (IActorRef Client, ImmutableHashSet<string> ContactAddresses)> _siteClients = new();
+    private readonly Dictionary<string, (IActorRef Client, ImmutableHashSet<string> ContactAddresses)> _siteClients = new();
 
     /// <summary>
     /// Tracks active debug view subscriptions: correlationId → (siteId, subscriber).
@@ -262,9 +262,23 @@ public class CentralCommunicationActor : ReceiveActor
         // Add or update
         foreach (var (siteId, addresses) in msg.SiteContacts)
         {
-            var contactPaths = addresses
-                .Select(a => ActorPath.Parse($"{a}/system/receptionist"))
-                .ToImmutableHashSet();
+            // Communication-009: parse all addresses up front inside a try/catch so a
+            // single malformed site row cannot abort the whole refresh loop and leave
+            // the cache half-updated. A bad site is logged and skipped; others proceed.
+            ImmutableHashSet<ActorPath> contactPaths;
+            try
+            {
+                contactPaths = addresses
+                    .Select(a => ActorPath.Parse($"{a}/system/receptionist"))
+                    .ToImmutableHashSet();
+            }
+            catch (Exception ex)
+            {
+                _log.Warning(ex,
+                    "Malformed contact address for site {0}; skipping this site in the refresh "
+                    + "(other sites are unaffected)", siteId);
+                continue;
+            }
 
             var contactStrings = addresses.ToImmutableHashSet();
 

src/ScadaLink.Communication/Actors/DebugStreamBridgeActor.cs

@@ -7,7 +7,9 @@ using ScadaLink.Communication.Grpc;
 namespace ScadaLink.Communication.Actors;
 
 /// <summary>
-/// Persistent actor (one per active debug session) on the central side.
+/// Long-lived (one per active debug session) actor on the central side. Debug sessions
+/// are session-based and temporary — this actor holds no persisted state and does not
+/// derive from an Akka.Persistence base class; its state does not survive a restart.
 /// Sends SubscribeDebugViewRequest to the site via CentralCommunicationActor (with THIS actor
 /// as the Sender) to get the initial snapshot. After receiving the snapshot, opens a gRPC
 /// server-streaming subscription via SiteStreamGrpcClient for ongoing events.