From 3d0f4dc168396c48374e98019b8debd4acf49d76 Mon Sep 17 00:00:00 2001
From: Joseph Doherty <dohejw01@gmail.com>
Date: Tue, 26 May 2026 04:31:03 -0400
Subject: [PATCH] feat(cluster): embed Akka HOCON config matching ScadaLink
 tuning

---
 .../ZB.MOM.WW.OtOpcUa.Cluster/HoconLoader.cs  | 15 ++++
 .../Resources/akka.conf                       | 73 +++++++++++++++++++
 .../ZB.MOM.WW.OtOpcUa.Cluster.csproj          |  4 +
 3 files changed, 92 insertions(+)
 create mode 100644 src/Core/ZB.MOM.WW.OtOpcUa.Cluster/HoconLoader.cs
 create mode 100644 src/Core/ZB.MOM.WW.OtOpcUa.Cluster/Resources/akka.conf

diff --git a/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/HoconLoader.cs b/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/HoconLoader.cs
new file mode 100644
index 0000000..23f1b00
--- /dev/null
+++ b/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/HoconLoader.cs
@@ -0,0 +1,15 @@
+namespace ZB.MOM.WW.OtOpcUa.Cluster;
+
+public static class HoconLoader
+{
+    private const string ResourceName = "ZB.MOM.WW.OtOpcUa.Cluster.Resources.akka.conf";
+
+    public static string LoadBaseConfig()
+    {
+        using var stream = typeof(HoconLoader).Assembly.GetManifestResourceStream(ResourceName)
+            ?? throw new InvalidOperationException(
+                $"Embedded resource '{ResourceName}' not found. Verify EmbeddedResource glob in csproj.");
+        using var reader = new StreamReader(stream);
+        return reader.ReadToEnd();
+    }
+}
diff --git a/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/Resources/akka.conf b/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/Resources/akka.conf
new file mode 100644
index 0000000..46b9711
--- /dev/null
+++ b/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/Resources/akka.conf
@@ -0,0 +1,73 @@
+# Base Akka.NET cluster configuration for OtOpcUa fused-host nodes.
+#
+# Roles, seed nodes, public hostname/port, and the actor system name are overlaid
+# at runtime by AkkaHostedService — see ZB.MOM.WW.OtOpcUa.Cluster/AkkaHostedService.cs.
+# Everything else here is the cluster-wide tuning that should match across nodes.
+#
+# Tuning sourced from ScadaLink (ScadaLink.Host/Actors/AkkaHostedService.BuildHocon);
+# any divergence must be deliberate and recorded in docs/v2/Architecture.md.
+
+akka {
+    extensions = [
+        "Akka.Cluster.Tools.PublishSubscribe.DistributedPubSubExtensionProvider, Akka.Cluster.Tools"
+    ]
+
+    actor {
+        provider = cluster
+    }
+
+    remote {
+        dot-netty.tcp {
+            hostname = "0.0.0.0"
+            port = 4053
+        }
+        transport-failure-detector {
+            heartbeat-interval = 2s
+            acceptable-heartbeat-pause = 10s
+        }
+    }
+
+    cluster {
+        seed-nodes = []
+        roles = []
+        min-nr-of-members = 1
+
+        split-brain-resolver {
+            active-strategy = "keep-oldest"
+            stable-after = 15s
+            keep-oldest {
+                down-if-alone = on
+            }
+        }
+
+        failure-detector {
+            heartbeat-interval = 2s
+            threshold = 10.0
+            acceptable-heartbeat-pause = 10s
+        }
+
+        down-removal-margin = 15s
+        run-coordinated-shutdown-when-down = on
+
+        singleton {
+            singleton-name = "singleton"
+        }
+        singleton-proxy {
+            singleton-identification-interval = 1s
+        }
+    }
+
+    coordinated-shutdown {
+        run-by-clr-shutdown-hook = on
+        default-phase-timeout = 30s
+    }
+}
+
+# Pinned dispatcher used by OpcUaPublishActor (Task 44) so the OPC UA SDK sees
+# only one thread per actor instance — its session/subscription locks expect
+# strict single-threaded access.
+opcua-synchronized-dispatcher {
+    type = "PinnedDispatcher"
+    executor = "thread-pool-executor"
+    throughput = 1
+}
diff --git a/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/ZB.MOM.WW.OtOpcUa.Cluster.csproj b/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/ZB.MOM.WW.OtOpcUa.Cluster.csproj
index 942f1bd..234de21 100644
--- a/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/ZB.MOM.WW.OtOpcUa.Cluster.csproj
+++ b/src/Core/ZB.MOM.WW.OtOpcUa.Cluster/ZB.MOM.WW.OtOpcUa.Cluster.csproj
@@ -19,6 +19,10 @@
         <ProjectReference Include="..\ZB.MOM.WW.OtOpcUa.Commons\ZB.MOM.WW.OtOpcUa.Commons.csproj"/>
     </ItemGroup>
 
+    <ItemGroup>
+        <EmbeddedResource Include="Resources\akka.conf"/>
+    </ItemGroup>
+
     <ItemGroup>
         <!-- OpenTelemetry.Api 1.9.0 reaches this project transitively from Akka.Cluster.Hosting.
              Bump arrives when Akka updates its OTel dependency; tracked separately. -->