Merge hw5-592 (#592)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport/Cip/CipConnection.cs

@@ -221,7 +221,9 @@ public sealed class CipConnection : ICipChannel, IAsyncDisposable
             _o.RpiMicros, size, _route);
         var frame = ConnectionManagerServices.ForwardOpen(p);
         _diagnostics.CountForwardOpen();
-        return CipReply.Parse(await client.SendRRDataAsync(frame, _o.Timeout, ct).ConfigureAwait(false));
+        var raw = await client.SendRRDataAsync(frame, _o.Timeout, ct).ConfigureAwait(false);
+        _diagnostics.NotifyExchange(frame, raw);   // evidence tap: the granted RPIs / connection ids (#566 gate)
+        return CipReply.Parse(raw);
     }
 
     private ushort NextConnectionSerial()

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport/Cip/ConnectionDiagnostics.cs

@@ -92,8 +92,8 @@ internal sealed class ConnectionDiagnostics
     }
 
     /// <summary>
-    /// Evidence tap for the gate harness (#582 / #572): sees the CIP request and the raw CIP reply of every
-    /// completed exchange. Null in production; set only by the read-only differential harness. A throwing
+    /// Evidence tap for the gate harness (#582 / #572 / #566): sees the CIP request and the raw CIP reply of every
+    /// completed exchange, Forward Opens included (their replies carry the granted RPIs). Null in production; set only by the read-only differential harness. A throwing
     /// observer is swallowed so it can never affect a request.
     /// </summary>
     internal Action<ReadOnlyMemory<byte>, ReadOnlyMemory<byte>>? ExchangeObserver { get; set; }