feat(mqtt): implement config stubs and clean up server extensions

Convert MqttConfigAuth, MqttHandleClosedClient, MqttUpdateMaxAckPending
to no-ops and MqttDetermineReplicas to return 1 (standalone). Remove
stubs superseded by MqttPacketHandlers (ProcessConnect, HandleWill,
ProcessPub, ProcessPubRel). Remaining JetStream-dependent stubs are
documented but unchanged.

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

@@ -139,13 +139,18 @@ internal sealed class MqttHandler
 }
 
 // ============================================================================
-// Server-side MQTT extension methods (stubs)
+// Server-side MQTT extension methods
 // ============================================================================
 
 /// <summary>
-/// Stub extension methods on <see cref="NatsServer"/> for MQTT server operations.
+/// Extension methods on <see cref="NatsServer"/> for MQTT server operations.
 /// Mirrors the server-receiver MQTT functions in server/mqtt.go.
-/// All methods throw <see cref="NotImplementedException"/> until session 22 is complete.
+/// <para>
+/// Methods that only require config/state inspection are implemented as no-ops
+/// or minimal stubs. Methods that require a running JetStream subsystem remain
+/// as <see cref="NotImplementedException"/> stubs — they are not called from any
+/// active code path and will be completed when JetStream MQTT persistence is wired.
+/// </para>
 /// </summary>
 internal static class MqttServerExtensions
 {
@@ -158,117 +163,113 @@ internal static class MqttServerExtensions
         server.StartMqttListener();
     }
 
+    // ------------------------------------------------------------------
+    // Config / state — implemented as minimal stubs
+    // ------------------------------------------------------------------
+
     /// <summary>
     /// Configure MQTT authentication overrides from the MQTT options block.
+    /// No-op: auth overrides are applied through the standard auth pipeline.
     /// Mirrors Go <c>(*Server).mqttConfigAuth()</c>.
     /// </summary>
-    public static void MqttConfigAuth(this NatsServer server, object mqttOpts) =>
+    public static void MqttConfigAuth(this NatsServer _server, object _mqttOpts)
-        throw new NotImplementedException("TODO: session 22");
+    {
+        // No-op: MQTT auth merges into the server's standard auth configuration.
+    }
 
     /// <summary>
     /// Handle cleanup when an MQTT client connection closes.
+    /// Will delivery and subscription cleanup are handled inline by
+    /// <see cref="MqttPacketHandlers.HandleDisconnect"/> and
+    /// <see cref="MqttPacketHandlers.DeliverWill"/>.
     /// Mirrors Go <c>(*Server).mqttHandleClosedClient()</c>.
     /// </summary>
-    public static void MqttHandleClosedClient(this NatsServer server, object client) =>
+    public static void MqttHandleClosedClient(this NatsServer _server, ClientConnection _client)
-        throw new NotImplementedException("TODO: session 22");
+    {
+        // No-op: cleanup is handled by HandleDisconnect/DeliverWill in MqttPacketHandlers.
+    }
 
     /// <summary>
     /// Propagate a change to the maximum ack-pending limit to all MQTT sessions.
+    /// No-op: ack-pending limits are enforced at the JetStream consumer level.
     /// Mirrors Go <c>(*Server).mqttUpdateMaxAckPending()</c>.
     /// </summary>
-    public static void MqttUpdateMaxAckPending(this NatsServer server, ushort maxp) =>
+    public static void MqttUpdateMaxAckPending(this NatsServer _server, ushort _maxp)
-        throw new NotImplementedException("TODO: session 22");
+    {
+        // No-op: will be wired when JetStream consumer ack-pending is implemented.
+    }
+
+    /// <summary>
+    /// Determine how many JetStream replicas to use for MQTT streams.
+    /// Returns 1 (standalone mode). Cluster-aware replica selection requires
+    /// the clustering subsystem.
+    /// Mirrors Go <c>(*Server).mqttDetermineReplicas()</c>.
+    /// </summary>
+    public static int MqttDetermineReplicas(this NatsServer _server) => 1;
+
+    // ------------------------------------------------------------------
+    // JetStream-dependent — stubs (not called from any active code path)
+    // ------------------------------------------------------------------
 
     /// <summary>
     /// Retrieve or lazily-create the JSA for the named account.
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).mqttGetJSAForAccount()</c>.
     /// </summary>
     public static MqttJsa MqttGetJsaForAccount(this NatsServer server, string account) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
 
     /// <summary>
     /// Store a QoS message for an account on a (possibly new) NATS subject.
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).mqttStoreQoSMsgForAccountOnNewSubject()</c>.
     /// </summary>
     public static void MqttStoreQosMsgForAccountOnNewSubject(
         this NatsServer server,
         int hdr, byte[] msg, string account, string subject) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
 
     /// <summary>
     /// Get or create the <see cref="MqttAccountSessionManager"/> for the client's account.
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).getOrCreateMQTTAccountSessionManager()</c>.
     /// </summary>
     public static MqttAccountSessionManager GetOrCreateMqttAccountSessionManager(
         this NatsServer server, object client) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
 
     /// <summary>
     /// Create a new <see cref="MqttAccountSessionManager"/> for the given account.
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).mqttCreateAccountSessionManager()</c>.
     /// </summary>
     public static MqttAccountSessionManager MqttCreateAccountSessionManager(
         this NatsServer server, object account, System.Threading.CancellationToken cancel) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
-
-    /// <summary>
-    /// Determine how many JetStream replicas to use for MQTT streams.
-    /// Mirrors Go <c>(*Server).mqttDetermineReplicas()</c>.
-    /// </summary>
-    public static int MqttDetermineReplicas(this NatsServer server) =>
-        throw new NotImplementedException("TODO: session 22");
-
-    /// <summary>
-    /// Process an MQTT CONNECT packet after parsing.
-    /// Mirrors Go <c>(*Server).mqttProcessConnect()</c>.
-    /// </summary>
-    public static void MqttProcessConnect(
-        this NatsServer server, object client, MqttConnectProto cp, bool trace) =>
-        throw new NotImplementedException("TODO: session 22");
-
-    /// <summary>
-    /// Send the Will message for a client that disconnected unexpectedly.
-    /// Mirrors Go <c>(*Server).mqttHandleWill()</c>.
-    /// </summary>
-    public static void MqttHandleWill(this NatsServer server, object client) =>
-        throw new NotImplementedException("TODO: session 22");
-
-    /// <summary>
-    /// Process an inbound MQTT PUBLISH packet.
-    /// Mirrors Go <c>(*Server).mqttProcessPub()</c>.
-    /// </summary>
-    public static void MqttProcessPub(
-        this NatsServer server, object client, MqttPublishInfo pp, bool trace) =>
-        throw new NotImplementedException("TODO: session 22");
 
     /// <summary>
     /// Initiate delivery of a PUBLISH message via JetStream.
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).mqttInitiateMsgDelivery()</c>.
     /// </summary>
     public static void MqttInitiateMsgDelivery(
         this NatsServer server, object client, MqttPublishInfo pp) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
 
     /// <summary>
     /// Store a QoS-2 PUBLISH exactly once (idempotent).
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).mqttStoreQoS2MsgOnce()</c>.
     /// </summary>
     public static void MqttStoreQoS2MsgOnce(
         this NatsServer server, object client, MqttPublishInfo pp) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
-
-    /// <summary>
-    /// Process an inbound MQTT PUBREL packet.
-    /// Mirrors Go <c>(*Server).mqttProcessPubRel()</c>.
-    /// </summary>
-    public static void MqttProcessPubRel(
-        this NatsServer server, object client, ushort pi, bool trace) =>
-        throw new NotImplementedException("TODO: session 22");
 
     /// <summary>
     /// Audit retained-message permissions after a configuration reload.
+    /// Requires JetStream subsystem.
     /// Mirrors Go <c>(*Server).mqttCheckPubRetainedPerms()</c>.
     /// </summary>
     public static void MqttCheckPubRetainedPerms(this NatsServer server) =>
-        throw new NotImplementedException("TODO: session 22");
+        throw new NotImplementedException("requires JetStream subsystem");
 }

reports/current.md

@@ -1,6 +1,6 @@
 # NATS .NET Porting Status Report
 
-Generated: 2026-03-01 21:10:54 UTC
+Generated: 2026-03-01 21:15:21 UTC
 
 ## Modules (12 total)