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

Closes #282

src/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient/OpcUaClientDriverOptions.cs

@@ -225,6 +225,34 @@ public sealed class OpcUaClientDriverOptions
     ///     </para>
     /// </remarks>
     public bool MirrorTypeDefinitions { get; init; } = false;
+
+    /// <summary>
+    ///     When <c>true</c> (default), the driver subscribes to
+    ///     <c>BaseModelChangeEventType</c> + <c>GeneralModelChangeEventType</c> on the
+    ///     upstream <c>Server</c> node (<c>i=2253</c>) at the end of <see cref="OpcUaClientDriver.InitializeAsync"/>.
+    ///     When the upstream advertises a topology change, the driver coalesces events over
+    ///     <see cref="ModelChangeDebounce"/> and triggers a re-import (equivalent to calling
+    ///     <c>ReinitializeAsync</c>) so the locally-mirrored address space tracks the upstream.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         The re-import path acquires the same <c>_gate</c> that read / write / browse /
+    ///         subscribe paths use, which means there's a brief browse-gap (≈ the upstream
+    ///         <c>DiscoverAsync</c> duration) during which downstream calls block on the
+    ///         driver's gate. Operators can disable the watch when the upstream topology is
+    ///         known-static and the gap isn't acceptable.
+    ///     </para>
+    /// </remarks>
+    public bool WatchModelChanges { get; init; } = true;
+
+    /// <summary>
+    ///     Coalescing window for upstream <c>ModelChangeEvent</c> notifications. The first
+    ///     event in a window starts the timer; further events extend it; when the timer
+    ///     fires the driver runs one re-import regardless of how many events arrived. Default
+    ///     5 seconds — long enough to absorb a bulk topology edit on the upstream server,
+    ///     short enough that single-node adds re-import promptly.
+    /// </summary>
+    public TimeSpan ModelChangeDebounce { get; init; } = TimeSpan.FromSeconds(5);
 }
 
 /// <summary>