fix(dcl): cancel old event loop + dispose old MxGateway client on reconnect (S1)

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayDataConnection.cs

@@ -67,6 +67,27 @@ public class MxGatewayDataConnection : IDataConnection, IBrowsableDataConnection
     public async Task ConnectAsync(IDictionary<string, string> connectionDetails, CancellationToken cancellationToken = default)
     {
         var cfg = MxGatewayEndpointConfigSerializer.FromFlatDict(connectionDetails);
+
+        // Reconnect reuses this adapter: cancel the previous event loop and dispose
+        // the previous client so a flapping gateway cannot accumulate orphaned
+        // streams/sockets, and the old loop's fault path cannot signal Disconnected
+        // against the new session after the guard resets below. Keep this BEFORE the
+        // _disconnectFired reset so a fault raised by the dying loop during teardown
+        // is absorbed by the old guard cycle. Dispose is best-effort fire-and-forget.
+        if (_eventLoopCts is { } previousLoopCts)
+        {
+            previousLoopCts.Cancel();
+            previousLoopCts.Dispose();
+            _eventLoopCts = null;
+        }
+        if (_client is { } previousClient)
+        {
+            _ = previousClient.DisposeAsync().AsTask().ContinueWith(
+                t => _logger.LogWarning(t.Exception?.GetBaseException(),
+                    "Disposing previous MxGateway client failed"),
+                TaskContinuationOptions.OnlyOnFaulted);
+        }
+
         Interlocked.Exchange(ref _disconnectFired, 0); // reset guard on (re)connect, like OPC UA
         _client = _clientFactory.Create();