fix(dotnet-client): no ack retry, caller-owned channels, safe session dispose, typed diagnostics, AttachSession

clients/dotnet/ZB.MOM.WW.MxGateway.Client/MxGatewaySession.cs

@@ -1,3 +1,4 @@
+using Grpc.Core;
 using ZB.MOM.WW.MxGateway.Contracts.Proto;
 
 namespace ZB.MOM.WW.MxGateway.Client;
@@ -1452,6 +1453,106 @@ public sealed class MxGatewaySession : IAsyncDisposable
         return _client.InvokeAsync(request, cancellationToken);
     }
 
+    /// <summary>
+    /// Sends a PING diagnostic command to the worker and throws if the reply is a failure.
+    /// </summary>
+    /// <param name="message">Optional message echoed to the worker; defaults to empty.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that completes when the worker acknowledges the ping.</returns>
+    public async Task PingAsync(
+        string? message = null,
+        CancellationToken cancellationToken = default)
+    {
+        MxCommandReply reply = await InvokeCommandAsync(
+                new MxCommand
+                {
+                    Kind = MxCommandKind.Ping,
+                    Ping = new PingCommand { Message = message ?? string.Empty },
+                },
+                cancellationToken)
+            .ConfigureAwait(false);
+        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
+    }
+
+    /// <summary>
+    /// Gets the gateway's lifecycle state for this session.
+    /// </summary>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The current session state.</returns>
+    public async Task<SessionState> GetSessionStateAsync(CancellationToken cancellationToken = default)
+    {
+        MxCommandReply reply = await InvokeCommandAsync(
+                new MxCommand
+                {
+                    Kind = MxCommandKind.GetSessionState,
+                    GetSessionState = new GetSessionStateCommand(),
+                },
+                cancellationToken)
+            .ConfigureAwait(false);
+        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
+
+        return reply.SessionState?.State
+            ?? throw CreateMalformed(reply, "GetSessionState");
+    }
+
+    /// <summary>
+    /// Gets diagnostic information about the worker process serving this session.
+    /// </summary>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The worker process id, version, and MXAccess COM identifiers.</returns>
+    public async Task<WorkerInfoReply> GetWorkerInfoAsync(CancellationToken cancellationToken = default)
+    {
+        MxCommandReply reply = await InvokeCommandAsync(
+                new MxCommand
+                {
+                    Kind = MxCommandKind.GetWorkerInfo,
+                    GetWorkerInfo = new GetWorkerInfoCommand(),
+                },
+                cancellationToken)
+            .ConfigureAwait(false);
+        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
+
+        return reply.WorkerInfo
+            ?? throw CreateMalformed(reply, "GetWorkerInfo");
+    }
+
+    /// <summary>
+    /// Drains events queued in the worker through the diagnostic command path. This removes
+    /// events from the worker queue; it is not a substitute for <see cref="StreamEventsAsync"/>
+    /// and is not retried automatically. The reply is bounded by server-side caps, so call
+    /// repeatedly until it returns an empty list.
+    /// </summary>
+    /// <param name="maxEvents">Maximum events to return; 0 lets the server choose.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The drained events, possibly empty.</returns>
+    public async Task<IReadOnlyList<MxEvent>> DrainEventsAsync(
+        uint maxEvents = 0,
+        CancellationToken cancellationToken = default)
+    {
+        MxCommandReply reply = await InvokeCommandAsync(
+                new MxCommand
+                {
+                    Kind = MxCommandKind.DrainEvents,
+                    DrainEvents = new DrainEventsCommand { MaxEvents = maxEvents },
+                },
+                cancellationToken)
+            .ConfigureAwait(false);
+        reply.EnsureProtocolSuccess().EnsureMxAccessSuccess();
+
+        return reply.DrainEvents?.Events.ToArray() ?? [];
+    }
+
+    private static MxGatewayMalformedReplyException CreateMalformed(MxCommandReply reply, string operation)
+    {
+        return new MxGatewayMalformedReplyException(
+            $"{operation} returned a malformed reply: OK reply carried no typed payload",
+            reply.SessionId,
+            reply.CorrelationId,
+            reply.ProtocolStatus,
+            reply.HasHresult ? reply.Hresult : null,
+            reply.Statuses.ToArray());
+    }
+
     /// <summary>
     /// Streams events from the worker for this session, optionally starting after a given sequence number.
     /// </summary>
@@ -1505,8 +1606,20 @@ public sealed class MxGatewaySession : IAsyncDisposable
     /// <returns>A task that represents the asynchronous operation.</returns>
     public async ValueTask DisposeAsync()
     {
-        await CloseAsync().ConfigureAwait(false);
-        _closeLock.Dispose();
+        try
+        {
+            await CloseAsync().ConfigureAwait(false);
+        }
+        catch (Exception ex) when (ex is MxGatewayException or ObjectDisposedException or RpcException)
+        {
+            // Best-effort close: the gateway may be unreachable or the owning client
+            // already disposed. Disposal must not throw or leak the lock; the gateway
+            // reaps the session on its own idle/detach timers.
+        }
+        finally
+        {
+            _closeLock.Dispose();
+        }
     }
 
     private Task<MxCommandReply> InvokeCommandAsync(