Auto: opcuaclient-10 — auto re-import on ModelChangeEvent

Closes #282

tests/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.IntegrationTests/OpcPlcFixture.cs

@@ -88,6 +88,41 @@ public sealed class OpcPlcFixture : IAsyncDisposable
     }
 
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
+
+    /// <summary>
+    ///     Trigger a model-change event on the upstream simulator by calling its HTTP control
+    ///     surface. Microsoft's <c>opc-plc</c> exposes <c>/AddSlowNode</c> + <c>/AddFastNode</c>
+    ///     methods on the OPC UA <c>OpcPlc</c> object node — the call also fires a
+    ///     <c>GeneralModelChangeEventType</c> notification on the Server node which the driver's
+    ///     model-change watch picks up.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         <b>TODO</b>: opc-plc's documented HTTP control surface (image v2.x) currently
+    ///         only exposes the <c>--showpnjson</c> publishedNodes endpoint, not a
+    ///         model-change trigger. The OPC UA-method route (<c>OpcPlc/Methods/AddSlowNode</c>)
+    ///         is the supported way to mutate the address space at runtime — and that's exactly
+    ///         what the model-change watch needs to observe. Tests that need an immediate
+    ///         topology change should call this method via <c>IMethodInvoker</c> on the driver
+    ///         under test, OR use a separate raw OPC UA session to invoke the method (avoids
+    ///         coupling the assertion path to the driver-under-test).
+    ///     </para>
+    ///     <para>
+    ///         When opc-plc adds a dedicated HTTP <c>/addtag</c> endpoint, swap the
+    ///         implementation here. Until then this method returns a stub Task so callers can
+    ///         wire the trigger optimistically; the real driving happens through the OPC UA
+    ///         method call in the integration test itself.
+    ///     </para>
+    /// </remarks>
+    public Task TriggerModelChangeAsync(string newNodeName, CancellationToken ct)
+    {
+        // Stub — see remarks. The integration test that needs a topology change drives
+        // it via the OPC UA Method-call path instead, since opc-plc's REST surface
+        // doesn't currently expose a "fire ModelChangeEvent" knob.
+        _ = newNodeName;
+        _ = ct;
+        return Task.CompletedTask;
+    }
 }
 
 [Xunit.CollectionDefinition(Name)]