feat: add stubs and guards for Start() parity

- Add CheckAuthForWarnings() no-op stub (NatsServer.Auth.cs)
- Add StartDelayedApiResponder() no-op stub (NatsServer.JetStreamCore.cs)
- Guard StartMqtt() to warn instead of throwing NotImplementedException

dotnet/src/ZB.MOM.NatsNet.Server/Mqtt/MqttHandler.cs

@@ -133,8 +133,10 @@ internal static class MqttServerExtensions
     /// Start listening for MQTT client connections.
     /// Mirrors Go <c>(*Server).startMQTT()</c>.
     /// </summary>
-    public static void StartMqtt(this NatsServer server) =>
-        throw new NotImplementedException("TODO: session 22");
+    public static void StartMqtt(this NatsServer server)
+    {
+        server.Warnf("MQTT listener not yet implemented; skipping MQTT startup");
+    }
 
     /// <summary>
     /// Configure MQTT authentication overrides from the MQTT options block.

dotnet/src/ZB.MOM.NatsNet.Server/NatsServer.Auth.cs

@@ -362,4 +362,22 @@ public sealed partial class NatsServer
     /// Wraps the synchronous <see cref="Shutdown"/> method.
     /// </summary>
     internal Task ShutdownAsync() => Task.Run(Shutdown);
+
+    // =========================================================================
+    // CheckAuthForWarnings (feature 3049 — Start parity)
+    // =========================================================================
+
+    /// <summary>
+    /// Checks for insecure auth configurations and logs warnings.
+    /// Mirrors Go <c>Server.checkAuthforWarnings()</c> in server/server.go.
+    /// Stub — full implementation deferred.
+    /// </summary>
+    internal void CheckAuthForWarnings()
+    {
+        // No-op stub. Go logs warnings about:
+        // - Password auth without TLS
+        // - Token auth without TLS
+        // - NKey auth without TLS
+        // These are informational warnings only.
+    }
 }

dotnet/src/ZB.MOM.NatsNet.Server/NatsServer.JetStreamCore.cs

@@ -571,4 +571,23 @@ public sealed partial class NatsServer
         _jetStream == null ? null : new JetStreamEngine(_jetStream);
 
     internal JetStream? GetJetStreamState() => _jetStream;
+
+    // =========================================================================
+    // Delayed API responder (feature 3049 — Start parity)
+    // =========================================================================
+
+    /// <summary>
+    /// Starts the delayed JetStream API response handler goroutine.
+    /// Started regardless of JetStream being enabled (can be enabled via config reload).
+    /// Mirrors Go <c>Server.delayedAPIResponder()</c> in server/jetstream_api.go.
+    /// Stub — full implementation deferred.
+    /// </summary>
+    internal void StartDelayedApiResponder()
+    {
+        StartGoRoutine(() =>
+        {
+            // No-op: exits when quit is signaled.
+            _quitCts.Token.WaitHandle.WaitOne();
+        });
+    }
 }

reports/current.md

@@ -1,6 +1,6 @@
 # NATS .NET Porting Status Report
 
-Generated: 2026-03-01 19:52:36 UTC
+Generated: 2026-03-01 20:01:24 UTC
 
 ## Modules (12 total)