fix: preserve history sentinels and alarm SDK metadata

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/AdvertisedAggregateFunctions.cs

@@ -30,8 +30,8 @@ internal static class AdvertisedAggregateFunctions
     private static readonly object SyncGate = new();
     /// <summary>Every standard aggregate-function NodeId the SDK's nodeset knows (<c>ObjectIds.AggregateFunction_*</c>).</summary>
     private static readonly NodeId[] StandardAggregateIds = typeof(ObjectIds)
-        .GetFields(BindingFlags.Public | BindingFlags.Static)
-        .Where(f => f.FieldType == typeof(NodeId) && f.Name.StartsWith("AggregateFunction_", StringComparison.Ordinal))
+        .GetProperties(BindingFlags.Public | BindingFlags.Static)
+        .Where(f => f.PropertyType == typeof(NodeId) && f.Name.StartsWith("AggregateFunction_", StringComparison.Ordinal))
         .Select(f => (NodeId)f.GetValue(null)!)
         .ToArray();
 

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs

@@ -1522,6 +1522,10 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
             var parent = ResolveParentFolder(equipmentNodeId, realm);
 
             AlarmConditionState alarm = CreateAlarmConditionOfType(alarmType, parent);
+            // SDK 2.0 creates optional confirmation nodes only when requested explicitly.
+            // Both are part of the application's existing Part 9 method/state contract.
+            alarm.ConfirmedState = new TwoStateVariableState(alarm);
+            alarm.Confirm = new AddCommentMethodState(alarm);
             alarm.SymbolicName = displayName;
             // HasComponent so the parent folder "owns" the condition (matches the T13 notes' pattern).
             alarm.ReferenceTypeId = ReferenceTypeIds.HasComponent;
@@ -5582,14 +5586,14 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
                     // same HistoryRead authorization as a raw read (above); a backend with no trail ⇒ unsupported.
                     work.Add(() => ServeModifiedPagedAsync(
                         handle, session, nodesToRead, results, errors,
-                        details.StartTime.ToDateTime(), details.EndTime.ToDateTime(), details.NumValuesPerNode,
+                        SdkValueBoundary.ToClrTimestamp(details.StartTime), SdkValueBoundary.ToClrTimestamp(details.EndTime), details.NumValuesPerNode,
                         ct));
                     continue;
                 }
 
                 work.Add(() => ServeRawPagedAsync(
                     handle, session, nodesToRead, results, errors,
-                    details.StartTime.ToDateTime(), details.EndTime.ToDateTime(), details.NumValuesPerNode,
+                    SdkValueBoundary.ToClrTimestamp(details.StartTime), SdkValueBoundary.ToClrTimestamp(details.EndTime), details.NumValuesPerNode,
                     ct, details.ReturnBounds && HonorReturnBounds));
             }
 
@@ -5649,8 +5653,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
                 var agg = aggregate.Value;
                 work.Add(() => ServeNodeAsync(handle, results, errors, (source, tagname, token) => source.ReadProcessedAsync(
                     tagname,
-                    details.StartTime.ToDateTime(),
-                    details.EndTime.ToDateTime(),
+                    SdkValueBoundary.ToClrTimestamp(details.StartTime),
+                    SdkValueBoundary.ToClrTimestamp(details.EndTime),
                     interval,
                     agg,
                     token), ct));
@@ -5827,8 +5831,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         var source = _historianDataSource;
         try
         {
-            var startUtc = details.StartTime.ToDateTime();
-            var endUtc = details.EndTime.ToDateTime();
+            var startUtc = SdkValueBoundary.ToClrTimestamp(details.StartTime);
+            var endUtc = SdkValueBoundary.ToClrTimestamp(details.EndTime);
             var numValuesPerNode = details.NumValuesPerNode;
             var boundarySkip = 0;
             var walkHint = default(ReverseWalkHint); // a walked-back read's width + proven-empty stretch
@@ -6167,8 +6171,8 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
             // Deleting the modified-value trail itself (Part 11 IsDeleteModified) is not supported: the trail is the
             // audit record of every change and is aged out only by retention.
             if (details.IsDeleteModified) return null;
-            var start = details.StartTime.ToDateTime();
-            var end = details.EndTime.ToDateTime();
+            var start = SdkValueBoundary.ToClrTimestamp(details.StartTime);
+            var end = SdkValueBoundary.ToClrTimestamp(details.EndTime);
             // Part 11 requires both bounds of a raw delete; DateTime.MinValue is the wire's "unspecified". Refuse
             // it here rather than let a backend read MinValue as "from the beginning of time".
             if (start == DateTime.MinValue || end == DateTime.MinValue)
@@ -6531,7 +6535,7 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         if (string.IsNullOrWhiteSpace(typeName)) return ObjectTypeIds.AlarmConditionType;
         return s_eventTypesByName.GetOrAdd(typeName, name =>
         {
-            var field = typeof(ObjectTypeIds).GetField(name.EndsWith("Type", StringComparison.Ordinal) ? name : name + "Type",
+            var field = typeof(ObjectTypeIds).GetProperty(name.EndsWith("Type", StringComparison.Ordinal) ? name : name + "Type",
                 System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static);
             return field?.GetValue(null) is NodeId type && Server.TypeTree.IsTypeOf(type, ObjectTypeIds.BaseEventType)
                 ? type
@@ -6838,7 +6842,7 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     ///     synthesised time-based:
     ///     <list type="bullet">
     ///       <item><b>Fresh read</b> (no inbound continuation point): read the window from
-    ///         <c>details.StartTime.ToDateTime()</c> to <paramref name="endUtc"/> capped at
+    ///         <c>SdkValueBoundary.ToClrTimestamp(details.StartTime)</c> to <paramref name="endUtc"/> capped at
     ///         <paramref name="numValuesPerNode"/> <b>+ 1</b> — one lookahead row. If the lookahead row came
     ///         back, return the first N, store a resume cursor and emit a continuation point; otherwise the page is
     ///         the last and carries none (so a total that is an exact multiple of N ends on a full page, not on an

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/SdkValueBoundary.cs

@@ -21,6 +21,10 @@ internal static class SdkValueBoundary
         throw new ArgumentException("Unsupported OPC UA value type.", nameof(value));
     }
 
+    /// <summary>Map the UA zero timestamp to the application's existing unspecified-bound sentinel.</summary>
+    internal static DateTime ToClrTimestamp(DateTimeUtc value) => value == DateTimeUtc.MinValue
+        ? DateTime.SpecifyKind(DateTime.MinValue, DateTimeKind.Utc) : value.ToDateTime();
+
     /// <summary>Restore existing CLR payload types and detach mutable arrays.</summary>
     internal static object? ToClr(Variant value) => value.AsBoxedObject(Variant.BoxingBehavior.Legacy) switch
     {

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/ZB.MOM.WW.OtOpcUa.OpcUaServer.csproj

@@ -23,6 +23,9 @@
 
     <ItemGroup>
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests"/>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests"/>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests"/>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests"/>
         <!-- R2-08 (03/S2): the outage-sim integration test drives the internal static
              OpcUaApplicationHost.HandleImpersonation against the real LDAP library. -->
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Host.IntegrationTests"/>