feat(drivers): Modbus + S7 implement IBatchSubscribable via PollGroupEngine batch callback

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus/ModbusDriver.cs

@@ -19,7 +19,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus;
 ///     <see cref="PollGroupEngine"/> since Modbus has no native push model.
 /// </remarks>
 public sealed class ModbusDriver
-    : IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, IPerCallHostResolver, ISkippedTagReporter, IDisposable, IAsyncDisposable
+    : IDriver, ITagDiscovery, IReadable, IWritable, IBatchSubscribable, IHostConnectivityProbe, IPerCallHostResolver, ISkippedTagReporter, IDisposable, IAsyncDisposable
 {
     /// <summary>Authored tags this driver could not build into its poll table (Gitea #541).</summary>
     private readonly SkippedTagLedger _skippedTags = new();
@@ -80,6 +80,13 @@ public sealed class ModbusDriver
 
     /// <summary>Occurs when a subscribed tag value changes.</summary>
     public event EventHandler<DataChangeEventArgs>? OnDataChange;
+    /// <summary>
+    ///     Occurs once per poll cycle that produced at least one change, carrying that cycle's
+    ///     changed tags. Both data-change events fire by design — this one once per cycle,
+    ///     <see cref="OnDataChange"/> once per changed tag — so a consumer subscribes to EXACTLY
+    ///     ONE of the two; subscribing both double-delivers.
+    /// </summary>
+    public event EventHandler<DataChangeBatchEventArgs>? OnDataChangeBatch;
     /// <summary>Occurs when host connectivity status changes.</summary>
     public event EventHandler<HostStatusChangedEventArgs>? OnHostStatusChanged;
 
@@ -125,7 +132,8 @@ public sealed class ModbusDriver
                 OnDataChange?.Invoke(this, new DataChangeEventArgs(handle, tagRef, snapshot));
             },
             onError: HandlePollError,
-            backoffCap: PollBackoffCap);
+            backoffCap: PollBackoffCap,
+            onBatch: (handle, items) => OnDataChangeBatch?.Invoke(this, new DataChangeBatchEventArgs(handle, items)));
     }
 
     /// <summary>Upper bound on the poll-loop failure backoff — adopts the S7-proven 30 s cap fleet-wide (05/STAB-8).</summary>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs

@@ -30,7 +30,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.S7;
 ///     </para>
 /// </remarks>
 public sealed class S7Driver
-    : IDriver, ITagDiscovery, IReadable, IWritable, ISubscribable, IHostConnectivityProbe, ISkippedTagReporter, IDisposable, IAsyncDisposable
+    : IDriver, ITagDiscovery, IReadable, IWritable, IBatchSubscribable, IHostConnectivityProbe, ISkippedTagReporter, IDisposable, IAsyncDisposable
 {
     /// <summary>Authored tags this driver could not build into its poll table (Gitea #541).</summary>
     private readonly SkippedTagLedger _skippedTags = new();
@@ -68,7 +68,8 @@ public sealed class S7Driver
                 OnDataChange?.Invoke(this, new DataChangeEventArgs(handle, tagRef, snapshot)),
             minInterval: TimeSpan.FromMilliseconds(100),
             onError: HandlePollError,
-            backoffCap: TimeSpan.FromSeconds(30));
+            backoffCap: TimeSpan.FromSeconds(30),
+            onBatch: (handle, items) => OnDataChangeBatch?.Invoke(this, new DataChangeBatchEventArgs(handle, items)));
     }
     // ---- ISubscribable + IHostConnectivityProbe state ----
 
@@ -93,6 +94,13 @@ public sealed class S7Driver
 
     /// <summary>Occurs when a subscribed tag value or status code changes.</summary>
     public event EventHandler<DataChangeEventArgs>? OnDataChange;
+    /// <summary>
+    ///     Occurs once per poll cycle that produced at least one change, carrying that cycle's
+    ///     changed tags. Both data-change events fire by design — this one once per cycle,
+    ///     <see cref="OnDataChange"/> once per changed tag — so a consumer subscribes to EXACTLY
+    ///     ONE of the two; subscribing both double-delivers.
+    /// </summary>
+    public event EventHandler<DataChangeBatchEventArgs>? OnDataChangeBatch;
     /// <summary>Occurs when host connectivity status changes.</summary>
     public event EventHandler<HostStatusChangedEventArgs>? OnHostStatusChanged;