fix(abcip): thread CIP template-instance-id so discovered-UDT expansion works in production (review)

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/CipSymbolObjectDecoder.cs

@@ -78,12 +78,19 @@ public static class CipSymbolObjectDecoder
             var (programScope, simpleName) = SplitProgramScope(name);
             var dataType = isStruct ? AbCipDataType.Structure : MapTypeCode((byte)typeCode);
 
+            // For a struct symbol the lower 12 bits (typeCode) are NOT a primitive CIP type code —
+            // they are the CIP template instance id (per the bit-15 struct-flag remarks above). Surface
+            // it so the driver can fetch the UDT's Template Object during discovery. Atomic symbols
+            // carry no template id.
+            var templateInstanceId = isStruct ? (uint?)typeCode : null;
+
             yield return new AbCipDiscoveredTag(
                 Name: simpleName,
                 ProgramScope: programScope,
                 DataType: dataType ?? AbCipDataType.Structure, // unknown type code → treat as opaque
                 ReadOnly: false, // Symbol Object doesn't carry write-protection bits; lift via AccessControl Object later
-                IsSystemTag: isSystem);
+                IsSystemTag: isSystem,
+                TemplateInstanceId: templateInstanceId);
 
             _ = instanceId; // retained in the wire format for diagnostics; not surfaced to the driver today
         }

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/IAbCipTagEnumerator.cs

@@ -45,6 +45,9 @@ public interface IAbCipTagEnumeratorFactory
 ///     reported a 1-D array (even of length 1). Surfaces the tag as an OPC UA array node at
 ///     discovery; <see cref="ElementCount"/> alone can't distinguish a scalar from a 1-element
 ///     array.</param>
+/// <param name="TemplateInstanceId">The CIP template instance id for a discovered Structure tag
+///     (<c>null</c> for non-structs / when unknown). Used to fetch the UDT's Template Object shape
+///     during discovery so the struct can be fanned out into addressable member variables.</param>
 public sealed record AbCipDiscoveredTag(
     string Name,
     string? ProgramScope,
@@ -52,7 +55,8 @@ public sealed record AbCipDiscoveredTag(
     bool ReadOnly,
     bool IsSystemTag = false,
     int ElementCount = 1,
-    bool IsArray = false);
+    bool IsArray = false,
+    uint? TemplateInstanceId = null);
 
 /// <summary>
 ///     No-op enumerator returning an empty sequence. Useful for tests + strict-config

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/LibplctagTagEnumerator.cs

@@ -45,6 +45,9 @@ internal sealed class LibplctagTagEnumerator : IAbCipTagEnumerator
         await _tag.ReadAsync(cancellationToken).ConfigureAwait(false);
 
         var buffer = _tag.GetBuffer();
+        // The decoder already surfaces each struct tag's CIP template instance id on
+        // AbCipDiscoveredTag.TemplateInstanceId (from the lower 12 bits of the symbol type), so
+        // re-yielding the decoded records as-is carries it through to DiscoverAsync's UDT fan-out.
         foreach (var tag in CipSymbolObjectDecoder.Decode(buffer))
             yield return tag;
     }