feat(localdb): dedicated h2c listener + MapZbLocalDbSync gated on LocalDb:SyncListenPort

src/Server/ZB.MOM.WW.OtOpcUa.Host/Program.cs

@@ -1,7 +1,9 @@
 using Akka.Actor;
 using Akka.Hosting;
+using Microsoft.AspNetCore.Server.Kestrel.Core;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Serilog;
+using ZB.MOM.WW.LocalDb.Replication;
 using Serilog.Events;
 using ZB.MOM.WW.OtOpcUa.AdminUI;
 using ZB.MOM.WW.OtOpcUa.AdminUI.Clients;
@@ -379,6 +381,71 @@ builder.Services.AddOtOpcUaSecrets(builder.Configuration);
 builder.Services.AddOtOpcUaHealth();
 builder.Services.AddOtOpcUaObservability(builder.Configuration);
 
+// ---------------------------------------------------------------------------------------------
+// LocalDb sync listener (default-OFF).
+//
+// DANGER: any explicit Kestrel Listen* call makes Kestrel IGNORE ASPNETCORE_URLS/urls ENTIRELY
+// (it logs "Overriding address(es)"). The host has no ConfigureKestrel today and binds solely via
+// that configuration, so adding a listener naively would silently unbind the AdminUI + deploy API
+// behind Traefik. Everything the host was already asked to serve is therefore re-bound explicitly
+// in the same block.
+//
+// The listener is HTTP/2-ONLY on purpose: the sync client speaks prior-knowledge h2c, which a
+// cleartext Http1AndHttp2 endpoint cannot negotiate (there is no ALPN without TLS). Hence a
+// dedicated port rather than multiplexing onto the main one.
+//
+// When LocalDb:SyncListenPort is 0 (the default) none of this runs and URL binding is untouched.
+// ---------------------------------------------------------------------------------------------
+var syncListenPort = LocalDbRegistration.SyncListenPort(builder.Configuration);
+if (hasDriver && syncListenPort > 0)
+{
+    var configuredUrls = builder.Configuration["urls"]
+                      ?? builder.Configuration["ASPNETCORE_URLS"];
+    var existingBindings = KestrelHttpBinding.Parse(configuredUrls);
+
+    // A driver-only Windows-service node gets NO ASPNETCORE_URLS (Install-Services.ps1 sets it
+    // only under $hasAdmin), so "nothing configured" is a real, supported state — not an error.
+    // Kestrel's own default is localhost:5000; re-state it explicitly, because taking over
+    // configuration means taking over the default too. Health probes hit this port.
+    if (existingBindings.Count == 0)
+    {
+        existingBindings = [new KestrelHttpBinding("localhost", 5000, IsSecure: false)];
+        Log.Information(
+            "LocalDb sync listener enabled with no URLs configured; re-binding Kestrel's default " +
+            "http://localhost:5000 alongside the sync port.");
+    }
+
+    // Re-binding an https endpoint would need its certificate configuration replayed too, which
+    // this host does not model (TLS is terminated at Traefik). Rather than silently serve it
+    // without TLS — or drop it — refuse to take over Kestrel at all and leave the existing
+    // surface exactly as it was. The operator gets a loud, actionable error instead of an
+    // AdminUI that stopped answering.
+    if (existingBindings.Any(b => b.IsSecure))
+    {
+        Log.Error(
+            "LocalDb:SyncListenPort is set to {Port} but this host serves HTTPS endpoint(s) ({Urls}). " +
+            "Binding the sync listener requires re-binding every existing endpoint explicitly, and the " +
+            "HTTPS certificate configuration cannot be replayed safely. The sync listener is DISABLED; " +
+            "terminate TLS upstream (as the docker-dev rig does) or leave replication off on this node.",
+            syncListenPort, configuredUrls);
+        syncListenPort = 0;
+    }
+    else
+    {
+        builder.WebHost.ConfigureKestrel(kestrel =>
+        {
+            foreach (var binding in existingBindings)
+                binding.Apply(kestrel);
+
+            kestrel.ListenAnyIP(syncListenPort, o => o.Protocols = HttpProtocols.Http2);
+        });
+
+        Log.Information(
+            "LocalDb sync listener bound on :{SyncPort} (h2c); re-bound existing endpoint(s) {Urls}.",
+            syncListenPort, configuredUrls ?? "http://localhost:5000 (Kestrel default)");
+    }
+}
+
 var app = builder.Build();
 
 // AddZbSerilog registers Serilog as the MEL logging provider but does NOT assign the static
@@ -409,6 +476,15 @@ if (hasAdmin)
     app.MapOtOpcUaDeployApi(app.Configuration);
 }
 
+// Passive LocalDb sync endpoint. Gated on the same port check that bound the listener, so a
+// default-OFF or admin-only graph carries no sync surface whatsoever. Mapping it would be safe
+// even unauthenticated — LocalDbSyncAuthInterceptor fail-closes with no ApiKey configured — but
+// not mapping it at all is the stronger default.
+if (hasDriver && syncListenPort > 0)
+{
+    app.MapZbLocalDbSync();
+}
+
 app.MapOtOpcUaHealth();
 app.MapOtOpcUaMetrics();