fix: preserve SDK 2.0 client value and lifetime contracts

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/Commands/HistoryReadCommand.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using System.Globalization;
 using CliFx.Attributes;
 using CliFx.Exceptions;
@@ -210,7 +211,7 @@ public class HistoryReadCommand : CommandBase
                         : StatusCode.IsBad(dv.StatusCode) ? "Bad"
                         : "Uncertain";
                     await console.Output.WriteLineAsync(
-                        $"{dv.SourceTimestamp.ToString("O"),-35} {dv.Value?.ToString() ?? "(none)",-15} {status,-10} " +
+                        $"{dv.SourceTimestamp.ToString("O"),-35} {ValueConverter.ToClrObject(dv.WrappedValue)?.ToString() ?? "(none)",-15} {status,-10} " +
                         $"{e.UpdateType,-8} {e.UserName ?? "",-20} {e.ModificationTime:O}");
                 }
 
@@ -244,7 +245,7 @@ public class HistoryReadCommand : CommandBase
                     : StatusCode.IsBad(dv.StatusCode) ? "Bad"
                     : "Uncertain";
                 await console.Output.WriteLineAsync(
-                    $"{dv.SourceTimestamp.ToString("O"),-35} {dv.Value,-15} {status}");
+                    $"{dv.SourceTimestamp.ToString("O"),-35} {ValueConverter.ToClrObject(dv.WrappedValue),-15} {status}");
             }
 
             await console.Output.WriteLineAsync();
@@ -276,23 +277,25 @@ public class HistoryReadCommand : CommandBase
     internal static EventFilter BuildEventFilter(IReadOnlyList<string> fields, NodeId? ofType)
     {
         var filter = new EventFilter();
+        var clauses = new List<SimpleAttributeOperand>();
         foreach (var field in fields)
         {
             var type = string.Equals(field, "ConditionName", StringComparison.Ordinal)
                 ? ObjectTypeIds.ConditionType
                 : ObjectTypeIds.BaseEventType;
-            filter.SelectClauses.Add(new SimpleAttributeOperand(type, new QualifiedName(field)) { AttributeId = Attributes.Value });
+            clauses.Add(new SimpleAttributeOperand(type, new QualifiedName(field)) { AttributeId = Attributes.Value });
         }
 
+        filter.SelectClauses = clauses.ToArrayOf();
         if (ofType is not null)
-            filter.WhereClause.Push(FilterOperator.OfType, new LiteralOperand(new Variant(ofType)));
+            filter.WhereClause.Push(FilterOperator.OfType, Variant.From(ofType.Value));
         return filter;
     }
 
     /// <summary>Formats one projected event field for the console: byte strings as hex, times as ISO 8601, null as <c>-</c>.</summary>
     /// <param name="field">The field value.</param>
     /// <returns>Its display text.</returns>
-    private static string FormatEventField(Variant field) => field.Value switch
+    private static string FormatEventField(Variant field) => ValueConverter.ToClrObject(field) switch
     {
         null => "-",
         byte[] bytes => Convert.ToHexString(bytes),

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/Commands/HistoryUpdateCommand.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using System.Globalization;
 using CliFx.Attributes;
 using CliFx.Exceptions;
@@ -89,11 +90,11 @@ public class HistoryUpdateCommand : CommandBase
                     throw new CommandException(
                         $"--value and --time must be supplied in pairs ({values.Count} value(s), {times.Count} time(s)).");
 
-                var updates = new DataValueCollection();
+                var updates = new List<DataValue>();
                 for (var i = 0; i < values.Count; i++)
                 {
                     var ts = ParseTime(times[i], "--time");
-                    updates.Add(new DataValue(new Variant(ParseValue(values[i], Type)), StatusCodes.Good, ts, ts));
+                    updates.Add(new DataValue(ValueConverter.ToVariant(ParseValue(values[i], Type)), StatusCodes.Good, ts, ts));
                 }
 
                 return new UpdateDataDetails
@@ -105,7 +106,7 @@ public class HistoryUpdateCommand : CommandBase
                         "replace" => PerformUpdateType.Replace,
                         _ => PerformUpdateType.Update
                     },
-                    UpdateValues = updates
+                    UpdateValues = updates.ToArrayOf()
                 };
             }
             case "delete-raw":
@@ -134,9 +135,9 @@ public class HistoryUpdateCommand : CommandBase
                     throw new CommandException("--mode delete-at-time takes --time only; --value is not allowed.");
                 if (times.Count == 0)
                     throw new CommandException("--mode delete-at-time requires at least one --time.");
-                var req = new DateTimeCollection();
+                var req = new List<DateTimeUtc>();
                 foreach (var t in times) req.Add(ParseTime(t, "--time"));
-                return new DeleteAtTimeDetails { NodeId = nodeId, ReqTimes = req };
+                return new DeleteAtTimeDetails { NodeId = nodeId, ReqTimes = req.ToArrayOf() };
             }
         }
     }
@@ -238,8 +239,8 @@ public class HistoryUpdateCommand : CommandBase
     /// <returns>The status name, or <c>0xXXXXXXXX</c>.</returns>
     private static string StatusName(StatusCode code)
     {
-        var name = StatusCodes.GetBrowseName(code.Code);
+        var name = code.SymbolicId;
-        if (string.IsNullOrEmpty(name)) name = StatusCodes.GetBrowseName(code.Code & 0xFFFF0000u);
+        if (string.IsNullOrEmpty(name)) name = new StatusCode(code.Code & 0xFFFF0000u).SymbolicId;
         return string.IsNullOrEmpty(name) ? $"0x{code.Code:X8}" : name;
     }
 
@@ -247,8 +248,8 @@ public class HistoryUpdateCommand : CommandBase
     {
         return details switch
         {
-            UpdateDataDetails u => u.UpdateValues.Select(v => v.SourceTimestamp.ToString("O")).ToList(),
+            UpdateDataDetails u => (u.UpdateValues.ToArray() ?? []).Select(v => v.SourceTimestamp.ToString("O")).ToList(),
-            DeleteAtTimeDetails d => d.ReqTimes.Select(t => t.ToString("O")).ToList(),
+            DeleteAtTimeDetails d => (d.ReqTimes.ToArray() ?? []).Select(t => t.ToString("O")).ToList(),
             DeleteRawModifiedDetails r => [$"{r.StartTime:O}..{r.EndTime:O}"],
             _ => []
         };

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/Commands/ReadCommand.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using CliFx.Attributes;
 using CliFx.Exceptions;
 using CliFx.Infrastructure;
@@ -59,12 +60,12 @@ public class ReadCommand : CommandBase
                 // not crash with a stack trace — session-level failures still propagate.
                 await console.Output.WriteLineAsync($"Node:        {NodeId}");
                 await console.Output.WriteLineAsync($"Value:       ");
-                await console.Output.WriteLineAsync($"Status:      {(StatusCode)ex.StatusCode} ({StatusCodes.GetBrowseName(ex.StatusCode)})");
+                await console.Output.WriteLineAsync($"Status:      {(StatusCode)ex.StatusCode} ({ex.StatusCode.SymbolicId})");
                 return;
             }
 
             await console.Output.WriteLineAsync($"Node:        {NodeId}");
-            await console.Output.WriteLineAsync($"Value:       {value.Value}");
+            await console.Output.WriteLineAsync($"Value:       {ValueConverter.ToClrObject(value.WrappedValue)}");
             await console.Output.WriteLineAsync($"Status:      {value.StatusCode}");
             await console.Output.WriteLineAsync($"Source Time: {value.SourceTimestamp:O}");
             await console.Output.WriteLineAsync($"Server Time: {value.ServerTimestamp:O}");

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/Commands/SubscribeCommand.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using System.Collections.Concurrent;
 using System.Threading.Channels;
 using CliFx.Attributes;
@@ -123,14 +124,14 @@ public class SubscribeCommand : CommandBase
                 try
                 {
                     var key = e.NodeId.ToString();
-                    lastStatus[key] = (e.Value.StatusCode, DateTime.UtcNow, e.Value.Value);
+                    lastStatus[key] = (e.Value.StatusCode, DateTime.UtcNow, ValueConverter.ToClrObject(e.Value.WrappedValue));
                     updateCount.AddOrUpdate(key, 1, (_, v) => v + 1);
                     if (!StatusCode.IsGood(e.Value.StatusCode))
                         everBad.TryAdd(key, 0);
                     if (!Quiet)
                     {
                         var line =
-                            $"[{e.Value.SourceTimestamp:O}] {displayNameByNodeId.GetValueOrDefault(key, key)} = {e.Value.Value} ({e.Value.StatusCode})";
+                            $"[{e.Value.SourceTimestamp:O}] {displayNameByNodeId.GetValueOrDefault(key, key)} = {ValueConverter.ToClrObject(e.Value.WrappedValue)} ({e.Value.StatusCode})";
                         outputChannel.Writer.TryWrite(line);
                     }
                 }
@@ -271,7 +272,7 @@ public class SubscribeCommand : CommandBase
             var childPath = $"{parentPath}/{child.DisplayName}";
             if (child.NodeClass == "Variable")
             {
-                into.Add((nodeId, childPath));
+                into.Add((nodeId.Value, childPath));
             }
             if (child.HasChildren)
             {

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/Commands/WriteCommand.cs

@@ -54,7 +54,7 @@ public class WriteCommand : CommandBase
 
             // Read current value to determine type for conversion
             var currentValue = await service.ReadValueAsync(nodeId, ct);
-            var typedValue = ValueConverter.ConvertValue(Value, currentValue.Value);
+            var typedValue = ValueConverter.ConvertValue(Value, ValueConverter.ToClrObject(currentValue.WrappedValue));
 
             var statusCode = await service.WriteValueAsync(nodeId, typedValue, ct);
 

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/Helpers/NodeIdParser.cs

@@ -52,6 +52,6 @@ public static class NodeIdParser
         var result = Parse(nodeIdString);
         if (result == null)
             throw new ArgumentException("Node ID is required but was not provided.");
-        return result;
+        return result.Value;
     }
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultApplicationConfigurationFactory.cs

@@ -58,20 +58,26 @@ internal sealed class DefaultApplicationConfigurationFactory : IApplicationConfi
             }
         };
 
-        await config.ValidateAsync(ApplicationType.Client, ct);
+        try
-
-        if (settings.AutoAcceptCertificates)
-            config.CertificateValidator.CertificateValidation += (_, e) => e.Accept = true;
-
-        if (settings.SecurityMode != SecurityMode.None)
         {
-            var app = new ApplicationInstance(ClientTelemetry.Context)
+            await config.ValidateAsync(ApplicationType.Client, ct);
+
+            if (settings.SecurityMode != SecurityMode.None)
             {
-                ApplicationName = "OtOpcUaClient",
+                var app = new ApplicationInstance(ClientTelemetry.Context)
-                ApplicationType = ApplicationType.Client,
+                {
-                ApplicationConfiguration = config
+                    ApplicationName = "OtOpcUaClient",
-            };
+                    ApplicationType = ApplicationType.Client,
-            await app.CheckApplicationInstanceCertificatesAsync(false, 2048);
+                    ApplicationConfiguration = config
+                };
+                await app.CheckApplicationInstanceCertificatesAsync(false, lifeTimeInMonths: 2048, ct: ct);
+            }
+        }
+        catch
+        {
+            try { (config.CertificateManager as IDisposable)?.Dispose(); }
+            catch (Exception ex) { Logger.Warning(ex, "Disposing certificate manager after configuration failure"); }
+            throw;
         }
 
         Logger.Debug("ApplicationConfiguration created for {EndpointUrl}", settings.EndpointUrl);

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultEndpointDiscovery.cs

@@ -19,9 +19,9 @@ internal sealed class DefaultEndpointDiscovery : IEndpointDiscovery
         // obsolete synchronous CoreClientUtils.SelectEndpoint, which does the same filter + rewrite.)
         using var client = await DiscoveryClient.CreateAsync(
             config, new Uri(endpointUrl), DiagnosticsMasks.None, ct).ConfigureAwait(false);
-        var allEndpoints = await client.GetEndpointsAsync(null, ct).ConfigureAwait(false);
+        var allEndpoints = await client.GetEndpointsAsync(default, ct).ConfigureAwait(false);
 
-        return EndpointSelector.SelectBest(allEndpoints, endpointUrl, requestedMode);
+        return EndpointSelector.SelectBest(allEndpoints.ToArray() ?? [], endpointUrl, requestedMode);
     }
 }
 
@@ -90,7 +90,7 @@ internal static class EndpointSelector
         // advertises its own host:port (docker-dev containers all say :4840); following that would
         // open the session on a different server and fail the secure-channel certificate check.
         // Only when the scheme matches: a different scheme (https vs opc.tcp) is a different transport.
-        var serverUri = new Uri(best.EndpointUrl);
+        var serverUri = new Uri(best.EndpointUrl ?? throw new InvalidOperationException("Endpoint has no URL."));
         var requestedUri = new Uri(endpointUrl);
         // A URL typed without a port (opc.tcp has no registered default, so Port is -1) keeps the advertised port.
         var port = requestedUri.Port > 0 ? requestedUri.Port : serverUri.Port;

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultSessionAdapter.cs

@@ -12,21 +12,25 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
 {
     private static readonly ILogger Logger = Log.ForContext<DefaultSessionAdapter>();
     private readonly Session _session;
+    private readonly IDisposable? _certificateManager;
+    private int _disposed;
 
     /// <summary>
     /// Wraps a live OPC UA session so the shared client can issue runtime operations through a testable adapter surface.
     /// </summary>
     /// <param name="session">The connected OPC UA session used for browsing, reads, writes, history, and subscriptions.</param>
-    public DefaultSessionAdapter(Session session)
+    /// <param name="certificateManager">The per-connection certificate manager owned until session disposal.</param>
+    public DefaultSessionAdapter(Session session, IDisposable? certificateManager = null)
     {
         _session = session;
+        _certificateManager = certificateManager;
     }
 
     /// <inheritdoc />
     public bool Connected => _session.Connected;
 
     /// <inheritdoc />
-    public string SessionId => _session.SessionId?.ToString() ?? string.Empty;
+    public string SessionId => _session.SessionId.IsNull ? string.Empty : _session.SessionId.ToString();
 
     /// <inheritdoc />
     public string SessionName => _session.SessionName ?? string.Empty;
@@ -35,7 +39,7 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
     public string EndpointUrl => _session.Endpoint?.EndpointUrl ?? string.Empty;
 
     /// <inheritdoc />
-    public string ServerName => _session.Endpoint?.Server?.ApplicationName?.Text ?? string.Empty;
+    public string ServerName => _session.Endpoint?.Server?.ApplicationName.Text ?? string.Empty;
 
     /// <inheritdoc />
     public string SecurityMode => _session.Endpoint?.SecurityMode.ToString() ?? string.Empty;
@@ -72,13 +76,13 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
             Value = value
         };
 
-        var writeCollection = new WriteValueCollection { writeValue };
+        ArrayOf<WriteValue> writeCollection = [writeValue];
         var response = await _session.WriteAsync(null, writeCollection, ct);
         // A malformed or service-level-faulted response can come back with an empty
         // Results collection alongside a service fault. Surface the service result
         // (or BadUnexpectedError) rather than letting Results[0] throw
         // IndexOutOfRangeException upstream.
-        if (response.Results == null || response.Results.Count == 0)
+        if (response.Results.Count == 0)
         {
             var serviceResult = response.ResponseHeader?.ServiceResult.Code ?? StatusCodes.BadUnexpectedError;
             throw new ServiceResultException(serviceResult,
@@ -89,7 +93,7 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
     }
 
     /// <inheritdoc />
-    public async Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseAsync(
+    public async Task<(byte[]? ContinuationPoint, ArrayOf<ReferenceDescription> References)> BrowseAsync(
         NodeId nodeId, uint nodeClassMask, CancellationToken ct)
     {
         var (_, continuationPoint, references) = await _session.BrowseAsync(
@@ -100,19 +104,25 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
             BrowseDirection.Forward,
             ReferenceTypeIds.HierarchicalReferences,
             true,
-            nodeClassMask);
+            nodeClassMask, ct);
 
-        return (continuationPoint, references ?? []);
+        return (continuationPoint.IsNull ? null : continuationPoint.ToArray(), references);
     }
 
     /// <inheritdoc />
-    public async Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseNextAsync(
+    public async Task<(byte[]? ContinuationPoint, ArrayOf<ReferenceDescription> References)> BrowseNextAsync(
         byte[] continuationPoint, CancellationToken ct)
     {
         // Pass the caller's token so a cancelled browse does not block on the continuation
         // round-trip.
-        var (_, nextCp, nextRefs) = await _session.BrowseNextAsync(null, false, continuationPoint, ct);
+        var (_, nextCp, nextRefs) = await _session.BrowseNextAsync(null, false, ByteString.From(continuationPoint), ct);
-        return (nextCp, nextRefs ?? []);
+        return (nextCp.IsNull ? null : nextCp.ToArray(), nextRefs);
+    }
+
+    /// <inheritdoc />
+    public async Task ReleaseBrowseContinuationPointAsync(byte[] continuationPoint, CancellationToken ct)
+    {
+        await _session.BrowseNextAsync(null, true, ByteString.From(continuationPoint), ct).ConfigureAwait(false);
     }
 
     /// <inheritdoc />
@@ -120,16 +130,16 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
     {
         var response = await _session.HistoryUpdateAsync(
             null,
-            new ExtensionObjectCollection { new ExtensionObject(details) },
+            [new ExtensionObject(details)],
             ct).ConfigureAwait(false);
 
         var statuses = new List<StatusCode>();
         var ops = new List<IReadOnlyList<StatusCode>>();
-        if (response.Results != null)
+        if (!response.Results.IsEmpty)
             foreach (var r in response.Results)
             {
                 statuses.Add(r.StatusCode);
-                ops.Add(r.OperationResults?.ToArray() ?? Array.Empty<StatusCode>());
+                ops.Add(r.OperationResults.ToArray() ?? []);
             }
 
         return new Models.HistoryUpdateOutcome(response.ResponseHeader.ServiceResult, statuses, ops);
@@ -152,10 +162,10 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
         // by the cap releases the server's cursor (HistoryReadPaging). This path used to pass
         // `releaseContinuationPoints: continuationPoint != null`, which RELEASED the second page instead of reading it,
         // silently truncating every raw read to its first server page.
-        return await HistoryReadPaging.ReadAllAsync(
+        return await HistoryReadPaging.ReadAllAsync<DataValue>(
             (cp, release, token) => ReadHistoryPageAsync(details, nodeId, cp, release, TimestampsToReturn.Source, token),
-            result => result.HistoryData is ExtensionObject { Body: HistoryData historyData }
+            result => result.HistoryData.TryGetValue(out HistoryData? historyData)
-                ? historyData.DataValues
+                ? historyData.DataValues.ToArray() ?? []
                 : [],
             maxValues, nodeId, ct).ConfigureAwait(false);
     }
@@ -193,21 +203,21 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
 
         return await HistoryReadPaging.ReadAllAsync(
             (cp, release, token) => ReadHistoryPageAsync(details, nodeId, cp, release, TimestampsToReturn.Both, token),
-            result => result.HistoryData is ExtensionObject { Body: HistoryEvent historyEvent }
+            result => result.HistoryData.TryGetValue(out HistoryEvent? historyEvent)
-                ? historyEvent.Events.Select(e => new Models.HistoryEventEntry(e.EventFields?.ToArray() ?? []))
+                ? (historyEvent.Events.ToArray() ?? []).Select(e => new Models.HistoryEventEntry(e.EventFields.ToArray() ?? []))
                 : [],
             maxEvents, nodeId, ct).ConfigureAwait(false);
     }
 
     private static IEnumerable<Models.HistoryModifiedEntry> ToModifiedEntries(HistoryReadResult result)
     {
-        if (result.HistoryData is not ExtensionObject { Body: HistoryModifiedData modified }) yield break;
+        if (!result.HistoryData.TryGetValue(out HistoryModifiedData? modified)) yield break;
         for (var i = 0; i < modified.DataValues.Count; i++)
         {
             var info = i < modified.ModificationInfos.Count ? modified.ModificationInfos[i] : null;
             yield return new Models.HistoryModifiedEntry(
                 modified.DataValues[i],
-                info?.ModificationTime ?? DateTime.MinValue,
+                info?.ModificationTime.ToDateTime() ?? DateTime.MinValue,
                 info?.UpdateType ?? default,
                 info?.UserName);
         }
@@ -218,10 +228,10 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
         HistoryReadDetails details, NodeId nodeId, byte[]? continuationPoint, bool release,
         TimestampsToReturn timestamps, CancellationToken ct)
     {
-        var nodesToRead = new HistoryReadValueIdCollection
+        ArrayOf<HistoryReadValueId> nodesToRead =
-        {
+        [
-            new HistoryReadValueId { NodeId = nodeId, ContinuationPoint = continuationPoint }
+            new HistoryReadValueId { NodeId = nodeId, ContinuationPoint = ByteString.From(continuationPoint) }
-        };
+        ];
 
         // The async overload honours the token and does not block the caller's thread (the UI dispatcher for
         // client.ui consumers).
@@ -244,10 +254,7 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
             AggregateType = [aggregateId]
         };
 
-        var nodesToRead = new HistoryReadValueIdCollection
+        ArrayOf<HistoryReadValueId> nodesToRead = [new HistoryReadValueId { NodeId = nodeId }];
-        {
-            new HistoryReadValueId { NodeId = nodeId }
-        };
 
         // Use the async overload so the method honors the cancellation token and
         // does not block on a synchronous service round-trip.
@@ -262,13 +269,23 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
         var results = response.Results;
         var allValues = new List<DataValue>();
 
-        if (results != null && results.Count > 0)
+        if (results.Count > 0)
         {
             var result = results[0];
-            HistoryReadStatus.ThrowIfRefused(result.StatusCode, nodeId);
+            try
-            if (result.HistoryData is ExtensionObject ext &&
+            {
-                ext.Body is HistoryData historyData)
+                HistoryReadStatus.ThrowIfRefused(result.StatusCode, nodeId);
-                allValues.AddRange(historyData.DataValues);
+                if (result.HistoryData.TryGetValue(out HistoryData? historyData))
+                    allValues.AddRange(historyData.DataValues);
+            }
+            finally
+            {
+                // Keep the existing one-shot processed read; it owns no outstanding server cursor on return.
+                if (!result.ContinuationPoint.IsEmpty)
+                    await HistoryReadPaging.ReleaseAsync(
+                        (cp, release, token) => ReadHistoryPageAsync(details, nodeId, cp, release, TimestampsToReturn.Source, token),
+                        result.ContinuationPoint.ToArray(), nodeId).ConfigureAwait(false);
+            }
         }
 
         return allValues;
@@ -322,6 +339,7 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
     /// </summary>
     public void Dispose()
     {
+        if (Interlocked.Exchange(ref _disposed, 1) != 0) return;
         try
         {
             if (_session.Connected) DisposeBridge.Run(ct => _session.CloseAsync(ct));
@@ -330,7 +348,8 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
         {
         }
 
-        _session.Dispose();
+        try { _session.Dispose(); }
+        finally { _certificateManager?.Dispose(); }
     }
 
     /// <inheritdoc />
@@ -339,20 +358,20 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
     {
         var result = await _session.CallAsync(
             null,
-            new CallMethodRequestCollection
+            new CallMethodRequest[]
             {
                 new()
                 {
                     ObjectId = objectId,
                     MethodId = methodId,
-                    InputArguments = new VariantCollection(inputArguments.Select(a => new Variant(a)))
+                    InputArguments = inputArguments.Select(ValueConverter.ToVariant).ToArrayOf()
                 }
             },
             ct);
 
         // An empty Results collection paired with a service fault must surface as
         // a ServiceResultException, not an IndexOutOfRangeException from Results[0].
-        if (result.Results == null || result.Results.Count == 0)
+        if (result.Results.Count == 0)
         {
             var serviceResult = result.ResponseHeader?.ServiceResult.Code ?? StatusCodes.BadUnexpectedError;
             throw new ServiceResultException(serviceResult,
@@ -363,6 +382,7 @@ internal sealed class DefaultSessionAdapter : ISessionAdapter
         if (StatusCode.IsBad(callResult.StatusCode))
             throw new ServiceResultException(callResult.StatusCode);
 
-        return callResult.OutputArguments?.Select(v => v.Value).ToList();
+        return callResult.OutputArguments.IsNull ? null
+            : (callResult.OutputArguments.ToArray() ?? []).Select(v => ValueConverter.ToClrObject(v)!).ToList();
     }
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultSessionFactory.cs

@@ -30,13 +30,13 @@ internal sealed class DefaultSessionFactory : ISessionFactory
             sessionName,
             sessionTimeoutMs,
             identity,
-            null,
+            default,
             ct);
         var session = created as Session
             ?? throw new InvalidOperationException(
                 $"Session factory returned {created.GetType().Name}, expected {nameof(Session)}.");
 
         Logger.Information("Session created: {SessionName} -> {EndpointUrl}", sessionName, endpoint.EndpointUrl);
-        return new DefaultSessionAdapter(session);
+        return new DefaultSessionAdapter(session, config.CertificateManager as IDisposable);
     }
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultSubscriptionAdapter.cs

@@ -14,6 +14,8 @@ internal sealed class DefaultSubscriptionAdapter : ISubscriptionAdapter
     private readonly Subscription _subscription;
     private readonly Func<Subscription, CancellationToken, Task>? _detach;
     private int _detached;
+    private int _finishing;
+    private readonly TaskCompletionSource _finished = new(TaskCreationOptions.RunContinuationsAsynchronously);
 
     /// <summary>
     /// Wraps a live OPC UA subscription so client code can manage monitored items through a testable abstraction.
@@ -47,7 +49,7 @@ internal sealed class DefaultSubscriptionAdapter : ISubscriptionAdapter
 
         item.Notification += (_, e) =>
         {
-            if (e.NotificationValue is MonitoredItemNotification notification)
+            if (Volatile.Read(ref _finishing) == 0 && e.NotificationValue is MonitoredItemNotification notification)
                 onDataChange(nodeId.ToString(), notification.Value);
         };
 
@@ -90,7 +92,7 @@ internal sealed class DefaultSubscriptionAdapter : ISubscriptionAdapter
 
         item.Notification += (_, e) =>
         {
-            if (e.NotificationValue is EventFieldList eventFields) onEvent(eventFields);
+            if (Volatile.Read(ref _finishing) == 0 && e.NotificationValue is EventFieldList eventFields) onEvent(eventFields);
         };
 
         _subscription.AddItem(item);
@@ -112,19 +114,28 @@ internal sealed class DefaultSubscriptionAdapter : ISubscriptionAdapter
     /// <inheritdoc />
     public async Task DeleteAsync(CancellationToken ct)
     {
+        if (Interlocked.Exchange(ref _finishing, 1) != 0)
+        {
+            await _finished.Task.WaitAsync(ct).ConfigureAwait(false);
+            return;
+        }
         try
         {
-            // Forward the caller's token so the delete can be cancelled.
+            try { await _subscription.DeleteAsync(true, ct).ConfigureAwait(false); }
-            await _subscription.DeleteAsync(true, ct);
+            catch (Exception ex) { Logger.Warning(ex, "Error deleting subscription"); }
-        }
-        catch (Exception ex)
-        {
-            Logger.Warning(ex, "Error deleting subscription");
-        }
 
-        // Detach whether or not the server-side delete succeeded: the adapter is finished with it either way.
+            // A cancelled delete still has local resources to release. Cleanup gets its own bounded token.
-        await DetachAsync(ct);
+            using var cleanup = new CancellationTokenSource(TimeSpan.FromSeconds(5));
-        _monitoredItems.Clear();
+            try { await DetachAsync(cleanup.Token).WaitAsync(cleanup.Token).ConfigureAwait(false); }
+            catch (Exception ex) { Logger.Warning(ex, "Error detaching subscription"); }
+            finally
+            {
+                _monitoredItems.Clear();
+                try { await Task.Run(_subscription.Dispose).WaitAsync(cleanup.Token).ConfigureAwait(false); }
+                catch (Exception ex) { Logger.Warning(ex, "Error disposing subscription resources"); }
+            }
+        }
+        finally { _finished.TrySetResult(); }
     }
 
     private async Task DetachAsync(CancellationToken ct)
@@ -145,21 +156,6 @@ internal sealed class DefaultSubscriptionAdapter : ISubscriptionAdapter
     /// </summary>
     public void Dispose()
     {
-        // One bounded bridge (5 s) for delete + detach, so a dispose never blocks longer than before (review m6).
+        DisposeBridge.Run(DeleteAsync);
-        // DetachAsync swallows its own failures; a failed delete must not skip the detach.
-        try
-        {
-            DisposeBridge.Run(async ct =>
-            {
-                try { await _subscription.DeleteAsync(true, ct); }
-                catch (Exception ex) { Logger.Warning(ex, "Error deleting subscription"); }
-                await DetachAsync(ct);
-            });
-        }
-        catch
-        {
-        }
-
-        _monitoredItems.Clear();
     }
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/ISessionAdapter.cs

@@ -78,7 +78,7 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="nodeClassMask">The node classes that should be returned to the caller.</param>
     /// <param name="ct">The cancellation token that aborts the browse request.</param>
     /// <returns>A continuation point (or <c>null</c> when complete) and the references found.</returns>
-    Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseAsync(
+    Task<(byte[]? ContinuationPoint, ArrayOf<ReferenceDescription> References)> BrowseAsync(
         NodeId nodeId, uint nodeClassMask = 0, CancellationToken ct = default);
 
     /// <summary>
@@ -87,9 +87,15 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="continuationPoint">The continuation token returned by a prior browse result page.</param>
     /// <param name="ct">The cancellation token that aborts the browse-next request.</param>
     /// <returns>The next continuation point (or <c>null</c> when exhausted) and the additional references.</returns>
-    Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseNextAsync(
+    Task<(byte[]? ContinuationPoint, ArrayOf<ReferenceDescription> References)> BrowseNextAsync(
         byte[] continuationPoint, CancellationToken ct = default);
 
+    /// <summary>Releases a browse cursor that the caller stops following.</summary>
+    /// <param name="continuationPoint">The cursor owned by this session.</param>
+    /// <param name="ct">A bounded cleanup token independent of the cancelled browse.</param>
+    /// <returns>The completion of the release request.</returns>
+    Task ReleaseBrowseContinuationPointAsync(byte[] continuationPoint, CancellationToken ct);
+
     /// <summary>
     ///     Reads raw historical data.
     /// </summary>

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Helpers/HistoryReadPaging.cs

@@ -56,15 +56,15 @@ internal static class HistoryReadPaging
                 HistoryReadStatus.ThrowIfRefused(result.StatusCode, nodeId);
                 all.AddRange(extract(result));
 
-                continuationPoint = result.ContinuationPoint;
+                continuationPoint = result.ContinuationPoint.IsNull ? null : result.ContinuationPoint.ToArray();
                 if (continuationPoint is not { Length: > 0 }) return Trim(all, maxValues);
                 if (all.Count >= maxValues) break;
             }
         }
-        catch (OperationCanceledException)
+        catch
         {
-            // Cancelled between pages (or during page N+1) with a cursor outstanding: release it rather than leave it
+            // A refused/failed/cancelled continuation still leaves the last cursor owned by this read.
-            // occupying one of the session's continuation-point slots, then surface the cancellation.
+            // Best-effort release must preserve the original operation failure.
             if (continuationPoint is { Length: > 0 }) await ReleaseAsync(readPage, continuationPoint, nodeId);
             throw;
         }
@@ -81,12 +81,12 @@ internal static class HistoryReadPaging
         return all;
     }
 
-    private static async Task ReleaseAsync(PageReader readPage, byte[] continuationPoint, NodeId nodeId)
+    internal static async Task ReleaseAsync(PageReader readPage, byte[] continuationPoint, NodeId nodeId)
     {
         try
         {
             using var cts = new CancellationTokenSource(ReleaseTimeout);
-            await readPage(continuationPoint, true, cts.Token).ConfigureAwait(false);
+            await readPage(continuationPoint, true, cts.Token).WaitAsync(cts.Token).ConfigureAwait(false);
         }
         catch (Exception ex)
         {

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Helpers/HistoryReadStatus.cs

@@ -19,6 +19,6 @@ internal static class HistoryReadStatus
     {
         if (!StatusCode.IsBad(status) || status.Code == StatusCodes.BadNoData) return;
         throw new ServiceResultException(status.Code,
-            $"HistoryRead of {nodeId} failed: {StatusCodes.GetBrowseName(status.Code)} (0x{status.Code:X8}).");
+            $"HistoryRead of {nodeId} failed: {status.ToString()} (0x{status.Code:X8}).");
     }
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Helpers/ValueConverter.cs

@@ -1,3 +1,5 @@
+using Opc.Ua;
+
 namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 
 /// <summary>
@@ -6,6 +8,49 @@ namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 /// </summary>
 public static class ValueConverter
 {
+    /// <summary>Converts a supported client payload to an SDK value, detaching caller-owned buffers.</summary>
+    /// <param name="value">The existing CLR or SDK payload.</param>
+    /// <returns>The corresponding OPC UA value.</returns>
+    /// <exception cref="ServiceResultException">The payload shape is unsupported.</exception>
+    public static Variant ToVariant(object? value)
+    {
+        // Historically a CLR byte[] supplied to a client write/method was a scalar ByteString.
+        if (value is byte[] bytes && bytes.GetType() == typeof(byte[])) return Variant.From(ByteString.From(bytes.AsSpan()));
+        if (value is ByteString byteString) return Variant.From(byteString.IsNull ? default : byteString.Copy());
+        if (!VariantHelper.TryCastFrom(value, out Variant variant))
+            throw new ServiceResultException(StatusCodes.BadTypeMismatch, "Unsupported client value type or shape.");
+        if (variant.TypeInfo.IsMatrix)
+            throw new ServiceResultException(StatusCodes.BadTypeMismatch, "Unsupported client matrix shape.");
+        if (variant.TypeInfo.IsArray && variant.TryGetValue(out ArrayOf<ByteString> buffers))
+            return Variant.From(buffers.IsNull ? default : buffers.ConvertAll(b => b.IsNull ? default : b.Copy()));
+        // ArrayOf is read-only, but can wrap externally owned ReadOnlyMemory. Detach it too.
+        if (value is not Array && variant.TypeInfo.IsArray && variant.AsBoxedObject(Variant.BoxingBehavior.Legacy) is Array array)
+        {
+            if (!VariantHelper.TryCastFrom(array, out variant))
+                throw new ServiceResultException(StatusCodes.BadTypeMismatch, "Unsupported client array type.");
+        }
+        else if (variant.TypeInfo.IsScalar && variant.TryGetValue(out ByteString retainedBytes))
+            variant = Variant.From(retainedBytes.IsNull ? default : retainedBytes.Copy());
+        return variant;
+    }
+
+    /// <summary>Returns the CLR representation expected by existing client object consumers.</summary>
+    /// <param name="value">The SDK value to inspect.</param>
+    /// <returns>A CLR scalar or array, preserving null versus empty values.</returns>
+    public static object? ToClrObject(Variant value)
+    {
+        return value.AsBoxedObject(Variant.BoxingBehavior.Legacy) switch
+        {
+            ByteString bytes => bytes.IsNull ? null : bytes.ToArray(),
+            DateTimeUtc timestamp => timestamp.ToDateTime(),
+            Uuid guid => (Guid)guid,
+            DateTimeUtc[] timestamps => timestamps.Select(t => t.ToDateTime()).ToArray(),
+            Uuid[] guids => guids.Select(g => (Guid)g).ToArray(),
+            ByteString[] buffers => buffers.Select(b => b.IsNull ? null : b.ToArray()).ToArray(),
+            var payload => payload
+        };
+    }
+
     /// <summary>
     ///     Converts a raw string value into the runtime type expected by the target node.
     /// </summary>

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/OpcUaClientService.cs

@@ -221,13 +221,13 @@ public sealed class OpcUaClientService : IOpcUaClientService
         if (value is string rawString)
         {
             var currentDataValue = await _session!.ReadValueAsync(nodeId, ct);
-            if (!StatusCode.IsGood(currentDataValue.StatusCode) || currentDataValue.Value == null)
+            if (!StatusCode.IsGood(currentDataValue.StatusCode) || ValueConverter.ToClrObject(currentDataValue.WrappedValue) == null)
                 throw new InvalidOperationException(
                     $"Cannot infer target type for node {nodeId}: read returned status {currentDataValue.StatusCode} with no value. Provide a typed value instead of a string.");
-            typedValue = ValueConverter.ConvertValue(rawString, currentDataValue.Value);
+            typedValue = ValueConverter.ConvertValue(rawString, ValueConverter.ToClrObject(currentDataValue.WrappedValue));
         }
 
-        var dataValue = new DataValue(new Variant(typedValue));
+        var dataValue = new DataValue(ValueConverter.ToVariant(typedValue));
         return await _session!.WriteValueAsync(nodeId, dataValue, ct);
     }
 
@@ -242,22 +242,39 @@ public sealed class OpcUaClientService : IOpcUaClientService
         var nodeClassMask = (uint)NodeClass.Object | (uint)NodeClass.Variable | (uint)NodeClass.Method;
         var results = new List<BrowseResult>();
 
-        var (continuationPoint, references) = await _session!.BrowseAsync(startNode, nodeClassMask, ct);
+        // A cursor belongs to the session that issued it, including while failover swaps _session.
-
+        var session = _session!;
-        while (references.Count > 0)
+        byte[]? continuationPoint = null;
+        try
         {
-            // Child detection is lazy: an Object MAY have children and is confirmed when the caller expands or
+            ArrayOf<ReferenceDescription> references;
-            // recurses into it. Probing each Object child with its own Browse made one level of N folders cost N + 1
+            (continuationPoint, references) = await session.BrowseAsync(startNode, nodeClassMask, ct);
-            // round trips, and a recursive subscribe over a 50k-node tree ~50k extra Browse calls.
+            while (references.Count > 0)
-            foreach (var reference in references)
+            {
-                results.Add(new BrowseResult(
+                foreach (var reference in references)
-                    reference.NodeId.ToString(),
+                    results.Add(new BrowseResult(
-                    reference.DisplayName?.Text ?? string.Empty,
+                        reference.NodeId.ToString(),
-                    reference.NodeClass.ToString(),
+                        reference.DisplayName.Text ?? string.Empty,
-                    reference.NodeClass == NodeClass.Object));
+                        reference.NodeClass.ToString(),
+                        reference.NodeClass == NodeClass.Object));
 
-            if (continuationPoint is not { Length: > 0 } pending) break;
+                if (continuationPoint is not { Length: > 0 } pending) break;
-            (continuationPoint, references) = await _session.BrowseNextAsync(pending, ct);
+                ct.ThrowIfCancellationRequested();
+                (continuationPoint, references) = await session.BrowseNextAsync(pending, ct);
+            }
+        }
+        finally
+        {
+            if (continuationPoint is { Length: > 0 })
+            {
+                try
+                {
+                    using var release = new CancellationTokenSource(HistoryReadPaging.ReleaseTimeout);
+                    await session.ReleaseBrowseContinuationPointAsync(continuationPoint, release.Token)
+                        .WaitAsync(release.Token).ConfigureAwait(false);
+                }
+                catch (Exception ex) { Logger.Warning(ex, "Releasing browse continuation point failed"); }
+            }
         }
 
         return results;
@@ -293,7 +310,7 @@ public sealed class OpcUaClientService : IOpcUaClientService
             }
 
             var handle = await subscription.AddDataChangeMonitoredItemAsync(
-                nodeId, intervalMs, OnDataChangeNotification, ct);
+                nodeId, intervalMs, DataCallback(session, subscription), ct);
 
             lock (_subscriptionLock)
             {
@@ -377,7 +394,7 @@ public sealed class OpcUaClientService : IOpcUaClientService
 
             var filter = CreateAlarmEventFilter();
             await subscription.AddEventMonitoredItemAsync(
-                monitorNode, intervalMs, filter, OnAlarmEventNotification, ct);
+                monitorNode, intervalMs, filter, AlarmCallback(session, subscription), ct);
 
             lock (_subscriptionLock)
             {
@@ -683,15 +700,15 @@ public sealed class OpcUaClientService : IOpcUaClientService
         var redundancySupportValue =
             await _session!.ReadValueAsync(VariableIds.Server_ServerRedundancy_RedundancySupport, ct);
         RedundancySupport redundancySupport;
-        if (StatusCode.IsGood(redundancySupportValue.StatusCode) && redundancySupportValue.Value != null)
+        if (StatusCode.IsGood(redundancySupportValue.StatusCode) && ValueConverter.ToClrObject(redundancySupportValue.WrappedValue) != null)
-            redundancySupport = (RedundancySupport)Convert.ToInt32(redundancySupportValue.Value);
+            redundancySupport = (RedundancySupport)Convert.ToInt32(ValueConverter.ToClrObject(redundancySupportValue.WrappedValue));
         else
             redundancySupport = RedundancySupport.None;
         var redundancyMode = redundancySupport.ToString();
 
         var serviceLevelValue = await _session.ReadValueAsync(VariableIds.Server_ServiceLevel, ct);
-        var serviceLevel = StatusCode.IsGood(serviceLevelValue.StatusCode) && serviceLevelValue.Value != null
+        var serviceLevel = StatusCode.IsGood(serviceLevelValue.StatusCode) && ValueConverter.ToClrObject(serviceLevelValue.WrappedValue) != null
-            ? Convert.ToByte(serviceLevelValue.Value)
+            ? Convert.ToByte(ValueConverter.ToClrObject(serviceLevelValue.WrappedValue))
             : (byte)0;
 
         string[] serverUris = [];
@@ -699,7 +716,7 @@ public sealed class OpcUaClientService : IOpcUaClientService
         {
             var serverUriArrayValue =
                 await _session.ReadValueAsync(VariableIds.Server_ServerRedundancy_ServerUriArray, ct);
-            if (serverUriArrayValue.Value is string[] uris)
+            if (ValueConverter.ToClrObject(serverUriArrayValue.WrappedValue) is string[] uris)
                 serverUris = uris;
         }
         catch
@@ -711,7 +728,7 @@ public sealed class OpcUaClientService : IOpcUaClientService
         try
         {
             var serverArrayValue = await _session.ReadValueAsync(VariableIds.Server_ServerArray, ct);
-            if (serverArrayValue.Value is string[] serverArray && serverArray.Length > 0)
+            if (ValueConverter.ToClrObject(serverArrayValue.WrappedValue) is string[] serverArray && serverArray.Length > 0)
                 applicationUri = serverArray[0];
         }
         catch
@@ -766,16 +783,26 @@ public sealed class OpcUaClientService : IOpcUaClientService
         };
 
         var config = await _configFactory.CreateAsync(effectiveSettings, ct);
-        var requestedMode = SecurityModeMapper.ToMessageSecurityMode(settings.SecurityMode);
+        try
-        var endpoint = await _endpointDiscovery.SelectEndpointAsync(config, endpointUrl, requestedMode, ct);
+        {
+            var requestedMode = SecurityModeMapper.ToMessageSecurityMode(settings.SecurityMode);
+            var endpoint = await _endpointDiscovery.SelectEndpointAsync(config, endpointUrl, requestedMode, ct);
 
-        var identity = settings.Username != null
+            var identity = settings.Username != null
-            ? new UserIdentity(settings.Username, Encoding.UTF8.GetBytes(settings.Password ?? ""))
+                ? new UserIdentity(settings.Username, Encoding.UTF8.GetBytes(settings.Password ?? ""))
-            : new UserIdentity();
+                : new UserIdentity();
 
-        var sessionTimeoutMs = (uint)(settings.SessionTimeoutSeconds * 1000);
+            var sessionTimeoutMs = (uint)(settings.SessionTimeoutSeconds * 1000);
-        return await _sessionFactory.CreateSessionAsync(config, endpoint, "OtOpcUaClient", sessionTimeoutMs, identity,
+            return await _sessionFactory.CreateSessionAsync(config, endpoint, "OtOpcUaClient", sessionTimeoutMs, identity,
-            ct);
+                ct);
+        }
+        catch
+        {
+            // The session adapter owns it after successful creation; a failed attempt has no adapter owner.
+            try { (config.CertificateManager as IDisposable)?.Dispose(); }
+            catch (Exception ex) { Logger.Warning(ex, "Disposing certificate manager after connection failure"); }
+            throw;
+        }
     }
 
     /// <summary>A bad keep-alive from the session of connection <paramref name="epoch"/>.</summary>
@@ -962,7 +989,7 @@ public sealed class OpcUaClientService : IOpcUaClientService
                 }
 
                 var handle = await dataSubscription.AddDataChangeMonitoredItemAsync(
-                    nodeId, intervalMs, OnDataChangeNotification, CancellationToken.None);
+                    nodeId, intervalMs, DataCallback(session, dataSubscription), CancellationToken.None);
 
                 lock (_subscriptionLock)
                 {
@@ -985,7 +1012,7 @@ public sealed class OpcUaClientService : IOpcUaClientService
                 lock (_subscriptionLock) _alarmSubscription = replayedAlarms;
                 var filter = CreateAlarmEventFilter();
                 await replayedAlarms.AddEventMonitoredItemAsync(
-                    monitorNode, intervalMs, filter, OnAlarmEventNotification, CancellationToken.None);
+                    monitorNode, intervalMs, filter, AlarmCallback(session, replayedAlarms), CancellationToken.None);
 
                 lock (_subscriptionLock)
                 {
@@ -999,6 +1026,25 @@ public sealed class OpcUaClientService : IOpcUaClientService
         }
     }
 
+    private bool IsCurrentNotification(ISessionAdapter session, ISubscriptionAdapter subscription, bool alarm)
+    {
+        lock (_subscriptionLock)
+            return !_disposed && _state == ConnectionState.Connected && ReferenceEquals(_session, session)
+                && ReferenceEquals(alarm ? _alarmSubscription : _dataSubscription, subscription);
+    }
+
+    private Action<string, DataValue> DataCallback(ISessionAdapter session, ISubscriptionAdapter subscription) =>
+        (nodeId, value) =>
+        {
+            if (IsCurrentNotification(session, subscription, false)) OnDataChangeNotification(nodeId, value);
+        };
+
+    private Action<EventFieldList> AlarmCallback(ISessionAdapter session, ISubscriptionAdapter subscription) =>
+        fields =>
+        {
+            if (IsCurrentNotification(session, subscription, true)) OnAlarmEventNotification(fields);
+        };
+
     private void OnDataChangeNotification(string nodeId, DataValue value)
     {
         DataChanged?.Invoke(this, new DataChangedEventArgs(nodeId, value));
@@ -1007,28 +1053,28 @@ public sealed class OpcUaClientService : IOpcUaClientService
     private void OnAlarmEventNotification(EventFieldList eventFields)
     {
         var fields = eventFields.EventFields;
-        if (fields == null || fields.Count < 1)
+        if (fields.Count < 1)
             return;
 
-        var eventId = fields.Count > 0 ? fields[0].Value as byte[] : null;
+        var eventId = fields.Count > 0 ? ValueConverter.ToClrObject(fields[0]) as byte[] : null;
-        var sourceName = fields.Count > 2 ? fields[2].Value as string ?? string.Empty : string.Empty;
+        var sourceName = fields.Count > 2 ? ValueConverter.ToClrObject(fields[2]) as string ?? string.Empty : string.Empty;
         var time = DateTime.MinValue;
-        if (fields.Count > 3 && fields[3].Value != null)
+        if (fields.Count > 3 && ValueConverter.ToClrObject(fields[3]) != null)
         {
-            if (fields[3].Value is DateTime dt)
+            if (ValueConverter.ToClrObject(fields[3]) is DateTime dt)
                 time = dt;
-            else if (DateTime.TryParse(fields[3].Value.ToString(), out var parsed))
+            else if (DateTime.TryParse(ValueConverter.ToClrObject(fields[3])?.ToString(), out var parsed))
                 time = parsed;
         }
-        var message = fields.Count > 4 ? (fields[4].Value as LocalizedText)?.Text ?? string.Empty : string.Empty;
+        var message = fields.Count > 4 ? (fields[4].TryGetValue(out LocalizedText text) ? text.Text : null) ?? string.Empty : string.Empty;
-        var severity = fields.Count > 5 ? Convert.ToUInt16(fields[5].Value) : (ushort)0;
+        var severity = fields.Count > 5 ? Convert.ToUInt16(ValueConverter.ToClrObject(fields[5])) : (ushort)0;
-        var conditionName = fields.Count > 6 ? fields[6].Value as string ?? string.Empty : string.Empty;
+        var conditionName = fields.Count > 6 ? ValueConverter.ToClrObject(fields[6]) as string ?? string.Empty : string.Empty;
-        var retain = fields.Count > 7 && ParseBool(fields[7].Value);
+        var retain = fields.Count > 7 && ParseBool(ValueConverter.ToClrObject(fields[7]));
-        var conditionNodeId = fields.Count > 12 ? fields[12].Value?.ToString() : null;
+        var conditionNodeId = fields.Count > 12 ? ValueConverter.ToClrObject(fields[12])?.ToString() : null;
 
         // Try standard OPC UA ActiveState/AckedState fields first
-        bool? ackedField = fields.Count > 8 && fields[8].Value != null ? ParseBool(fields[8].Value) : null;
+        bool? ackedField = fields.Count > 8 && ValueConverter.ToClrObject(fields[8]) != null ? ParseBool(ValueConverter.ToClrObject(fields[8])) : null;
-        bool? activeField = fields.Count > 9 && fields[9].Value != null ? ParseBool(fields[9].Value) : null;
+        bool? activeField = fields.Count > 9 && ValueConverter.ToClrObject(fields[9]) != null ? ParseBool(ValueConverter.ToClrObject(fields[9])) : null;
 
         var ackedState = ackedField ?? false;
         var activeState = activeField ?? false;
@@ -1053,39 +1099,25 @@ public sealed class OpcUaClientService : IOpcUaClientService
     /// <returns>The populated <see cref="EventFilter"/>.</returns>
     internal static EventFilter CreateAlarmEventFilter()
     {
-        var filter = new EventFilter();
+        var filter = new EventFilter
-        // 0: EventId
+        {
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.EventId);
+            SelectClauses =
-        // 1: EventType
+            [
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.EventType);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("EventId")] },
-        // 2: SourceName
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("EventType")] },
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.SourceName);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("SourceName")] },
-        // 3: Time
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("Time")] },
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.Time);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("Message")] },
-        // 4: Message
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("Severity")] },
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.Message);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.ConditionType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("ConditionName")] },
-        // 5: Severity
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.ConditionType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("Retain")] },
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.Severity);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.AcknowledgeableConditionType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("AckedState"), new QualifiedName("Id")] },
-        // 6: ConditionName
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.AlarmConditionType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("ActiveState"), new QualifiedName("Id")] },
-        filter.AddSelectClause(ObjectTypeIds.ConditionType, BrowseNames.ConditionName);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.ConditionType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("EnabledState"), new QualifiedName("Id")] },
-        // 7: Retain
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.AlarmConditionType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("SuppressedOrShelved")] },
-        filter.AddSelectClause(ObjectTypeIds.ConditionType, BrowseNames.Retain);
+                new SimpleAttributeOperand { TypeDefinitionId = ObjectTypeIds.BaseEventType, AttributeId = Attributes.Value, BrowsePath = [new QualifiedName("SourceNode")] },
-        // 8-10: the two-state /Id booleans. Each browse path is TWO QualifiedNames. Passing "AckedState/Id" as a
+            ]
-        // string to AddSelectClause does not split it — it selects one element NAMED "AckedState/Id", which no
+        };
-        // event carries, so all three arrived null and every alarm read inactive + unacknowledged.
-        // 8: AckedState/Id
-        filter.SelectClauses.Add(new SimpleAttributeOperand(
-            ObjectTypeIds.AcknowledgeableConditionType, [BrowseNames.AckedState, BrowseNames.Id]));
-        // 9: ActiveState/Id
-        filter.SelectClauses.Add(new SimpleAttributeOperand(
-            ObjectTypeIds.AlarmConditionType, [BrowseNames.ActiveState, BrowseNames.Id]));
-        // 10: EnabledState/Id
-        filter.SelectClauses.Add(new SimpleAttributeOperand(
-            ObjectTypeIds.ConditionType, [BrowseNames.EnabledState, BrowseNames.Id]));
-        // 11: SuppressedOrShelved
-        filter.AddSelectClause(ObjectTypeIds.AlarmConditionType, "SuppressedOrShelved");
-        // 12: SourceNode (ConditionId for acknowledgment)
-        filter.AddSelectClause(ObjectTypeIds.BaseEventType, BrowseNames.SourceNode);
         return filter;
     }
 

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/ZB.MOM.WW.OtOpcUa.Client.Shared.csproj

@@ -8,7 +8,6 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="OPCFoundation.NetStandard.Opc.Ua.MigrationAnalyzer" PrivateAssets="all" IncludeAssets="analyzers;build;buildtransitive" />
         <PackageReference Include="OPCFoundation.NetStandard.Opc.Ua.Client"/>
         <PackageReference Include="Serilog"/>
     </ItemGroup>

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/Helpers/StatusCodeFormatter.cs

@@ -16,7 +16,7 @@ internal static class StatusCodeFormatter
         var hex = $"0x{code:X8}";
 
         // Try the SDK's browse name lookup first
-        var name = StatusCodes.GetBrowseName(code);
+        var name = statusCode.SymbolicId;
         if (!string.IsNullOrEmpty(name))
             return $"{hex} ({name})";
 
@@ -24,7 +24,7 @@ internal static class StatusCodeFormatter
         var mainCode = code & 0xFFFF0000;
         if (mainCode != code)
         {
-            name = StatusCodes.GetBrowseName(mainCode);
+            name = new StatusCode(mainCode).SymbolicId;
             if (!string.IsNullOrEmpty(name))
                 return $"{hex} ({name})";
         }

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/AlarmsViewModel.cs

@@ -109,7 +109,7 @@ public partial class AlarmsViewModel : ObservableObject
     {
         try
         {
-            var sourceNodeId = string.IsNullOrWhiteSpace(MonitoredNodeIdText)
+            NodeId? sourceNodeId = string.IsNullOrWhiteSpace(MonitoredNodeIdText)
                 ? null
                 : NodeId.Parse(MonitoredNodeIdText);
 
@@ -275,7 +275,7 @@ public partial class AlarmsViewModel : ObservableObject
 
         try
         {
-            var nodeId = string.IsNullOrWhiteSpace(sourceNodeId)
+            NodeId? nodeId = string.IsNullOrWhiteSpace(sourceNodeId)
                 ? null
                 : NodeId.Parse(sourceNodeId);
 

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/HistoryViewModel.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using System.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
@@ -97,7 +98,7 @@ public partial class HistoryViewModel : ObservableObject
             {
                 foreach (var dv in values)
                     Results.Add(new HistoryValueViewModel(
-                        Helpers.ValueFormatter.Format(dv.Value),
+                        Helpers.ValueFormatter.Format(ValueConverter.ToClrObject(dv.WrappedValue)),
                         Helpers.StatusCodeFormatter.Format(dv.StatusCode),
                         dv.SourceTimestamp.ToString("O"),
                         dv.ServerTimestamp.ToString("O")));

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/ReadWriteViewModel.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using Opc.Ua;
@@ -76,7 +77,7 @@ public partial class ReadWriteViewModel : ObservableObject
 
             _dispatcher.Post(() =>
             {
-                CurrentValue = Helpers.ValueFormatter.Format(dataValue.Value);
+                CurrentValue = Helpers.ValueFormatter.Format(ValueConverter.ToClrObject(dataValue.WrappedValue));
                 CurrentStatus = Helpers.StatusCodeFormatter.Format(dataValue.StatusCode);
                 SourceTimestamp = dataValue.SourceTimestamp.ToString("O");
                 ServerTimestamp = dataValue.ServerTimestamp.ToString("O");

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/SubscriptionsViewModel.cs

@@ -1,3 +1,4 @@
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using CommunityToolkit.Mvvm.ComponentModel;
@@ -75,7 +76,7 @@ public partial class SubscriptionsViewModel : ObservableObject
             if (!_rowsByNodeId.TryGetValue(e.NodeId, out var rows)) return;
             foreach (var item in rows)
             {
-                item.Value = Helpers.ValueFormatter.Format(e.Value.Value);
+                item.Value = Helpers.ValueFormatter.Format(ValueConverter.ToClrObject(e.Value.WrappedValue));
                 item.Status = Helpers.StatusCodeFormatter.Format(e.Value.StatusCode);
                 item.Timestamp = e.Value.SourceTimestamp.ToString("O");
             }
@@ -281,7 +282,7 @@ public partial class SubscriptionsViewModel : ObservableObject
 
             // Read current value to determine target type
             var currentDataValue = await _service.ReadValueAsync(nodeId);
-            var currentValue = currentDataValue.Value;
+            var currentValue = ValueConverter.ToClrObject(currentDataValue.WrappedValue);
 
             // Try parsing to the target type before writing
             try

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/AlarmsCommandTests.cs

@@ -54,7 +54,7 @@ public class AlarmsCommandTests
 
         fakeService.SubscribeAlarmsCalls.Count.ShouldBe(1);
         fakeService.SubscribeAlarmsCalls[0].SourceNodeId.ShouldNotBeNull();
-        fakeService.SubscribeAlarmsCalls[0].SourceNodeId!.Identifier.ShouldBe("AlarmSource");
+        fakeService.SubscribeAlarmsCalls[0].SourceNodeId!.Value.IdentifierAsString.ShouldBe("AlarmSource");
     }
 
     /// <summary>Verifies that Execute with refresh requests condition refresh.</summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/BrowseCommandTests.cs

@@ -56,7 +56,7 @@ public class BrowseCommandTests
 
         fakeService.BrowseNodeIds.Count.ShouldBe(1);
         fakeService.BrowseNodeIds[0].ShouldNotBeNull();
-        fakeService.BrowseNodeIds[0]!.Identifier.ShouldBe("StartNode");
+        fakeService.BrowseNodeIds[0]!.Value.IdentifierAsString.ShouldBe("StartNode");
     }
 
     /// <summary>Verifies that Execute browses from null node when not specified.</summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/HistoryReadCommandTests.cs

@@ -61,7 +61,7 @@ public class HistoryReadCommandTests
 
         fakeService.HistoryReadRawCalls.Count.ShouldBe(1);
         fakeService.HistoryReadRawCalls[0].MaxValues.ShouldBe(500);
-        fakeService.HistoryReadRawCalls[0].NodeId.Identifier.ShouldBe("HistNode");
+        fakeService.HistoryReadRawCalls[0].NodeId.IdentifierAsString.ShouldBe("HistNode");
     }
 
     /// <summary>Verifies AggregateRead execution calls HistoryReadAggregate.</summary>
@@ -211,11 +211,11 @@ public class HistoryReadCommandTests
 
         var call = fakeService.HistoryReadEventsCalls.ShouldHaveSingleItem();
         call.MaxEvents.ShouldBe(25);
-        call.Filter.SelectClauses.Select(c => c.BrowsePath.ShouldHaveSingleItem().Name)
+        call.Filter.SelectClauses.ToArray()!.Select(c => c.BrowsePath.ToArray()!.ShouldHaveSingleItem().Name)
             .ShouldBe(["EventId", "EventType", "Time", "SourceName", "Severity", "Message", "ConditionName", "SourceNode"]);
-        call.Filter.SelectClauses.Single(c => c.BrowsePath[0].Name == "ConditionName").TypeDefinitionId
+        call.Filter.SelectClauses.ToArray()!.Single(c => c.BrowsePath[0].Name == "ConditionName").TypeDefinitionId
             .ShouldBe(ObjectTypeIds.ConditionType);
-        call.Filter.WhereClause.Elements.ShouldBeEmpty("no --of-type, no where-clause");
+        call.Filter.WhereClause.Elements.ToArray()!.ShouldBeEmpty("no --of-type, no where-clause");
         fakeService.HistoryReadRawCalls.ShouldBeEmpty();
 
         var output = TestConsoleHelper.GetOutput(console);
@@ -243,10 +243,10 @@ public class HistoryReadCommandTests
         await command.ExecuteAsync(console);
 
         var filter = fakeService.HistoryReadEventsCalls.ShouldHaveSingleItem().Filter;
-        filter.SelectClauses.Select(c => c.BrowsePath[0].Name).ShouldBe(["EventType", "Severity"]);
+        filter.SelectClauses.ToArray()!.Select(c => c.BrowsePath[0].Name).ShouldBe(["EventType", "Severity"]);
-        var element = filter.WhereClause.Elements.ShouldHaveSingleItem();
+        var element = filter.WhereClause.Elements.ToArray()!.ShouldHaveSingleItem();
         element.FilterOperator.ShouldBe(FilterOperator.OfType);
-        ((LiteralOperand)ExtensionObject.ToEncodeable(element.FilterOperands[0])).Value.Value
+        (element.FilterOperands[0].TryGetValue(out LiteralOperand? literal) ? literal.Value : Variant.Null)
             .ShouldBe(ObjectTypeIds.LimitAlarmType);
         TestConsoleHelper.GetOutput(console).ShouldContain("0 events returned.");
     }

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/HistoryUpdateCommandTests.cs

@@ -33,9 +33,9 @@ public class HistoryUpdateCommandTests
             .BuildDetails().ShouldBeOfType<UpdateDataDetails>();
         d.PerformInsertReplace.ShouldBe(PerformUpdateType.Insert);
         d.UpdateValues.Count.ShouldBe(2);
-        d.UpdateValues[1].Value.ShouldBe(2.5);
+        d.UpdateValues[1].WrappedValue.ShouldBe(Variant.From(2.5));
         d.UpdateValues[0].SourceTimestamp.ShouldBe(new DateTime(2026, 1, 15, 8, 0, 0, DateTimeKind.Utc));
-        d.NodeId.Identifier.ShouldBe("HistNode");
+        d.NodeId.IdentifierAsString.ShouldBe("HistNode");
     }
 
     /// <summary>Replace and update map to their update types.</summary>
@@ -60,7 +60,7 @@ public class HistoryUpdateCommandTests
     {
         var d = Make(values: [value], times: ["2026-01-15T08:00:00Z"], type: type)
             .BuildDetails().ShouldBeOfType<UpdateDataDetails>();
-        d.UpdateValues[0].Value.ShouldBeOfType(expected);
+        ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers.ValueConverter.ToClrObject(d.UpdateValues[0].WrappedValue).ShouldBeOfType(expected);
     }
 
     /// <summary>delete-raw builds DeleteRawModifiedDetails with IsDeleteModified=false.</summary>
@@ -211,7 +211,7 @@ public class HistoryUpdateCommandTests
     public async Task Execute_UnnamedStatus_PrintsHex()
     {
         const uint unnamed = 0x8FFF0000u;
-        StatusCodes.GetBrowseName(unnamed).ShouldBeNullOrEmpty(); // precondition: genuinely unnamed
+        new StatusCode(unnamed).SymbolicId.ShouldBeNullOrEmpty(); // precondition: genuinely unnamed
         var svc = new FakeOpcUaClientService
         {
             HistoryUpdateResult = new HistoryUpdateOutcome(StatusCodes.Good, [StatusCodes.Good],

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/NodeIdParserTests.cs

@@ -34,8 +34,8 @@ public class NodeIdParserTests
     {
         var result = NodeIdParser.Parse("ns=2;s=MyNode");
         result.ShouldNotBeNull();
-        result.NamespaceIndex.ShouldBe((ushort)2);
+        result.Value.NamespaceIndex.ShouldBe((ushort)2);
-        result.Identifier.ShouldBe("MyNode");
+        result.Value.IdentifierAsString.ShouldBe("MyNode");
     }
 
     /// <summary>Verifies that Parse correctly parses numeric NodeId format (i=85).</summary>
@@ -44,7 +44,7 @@ public class NodeIdParserTests
     {
         var result = NodeIdParser.Parse("i=85");
         result.ShouldNotBeNull();
-        result.IdType.ShouldBe(IdType.Numeric);
+        result.Value.IdType.ShouldBe(IdType.Numeric);
     }
 
     /// <summary>Verifies that Parse treats bare numeric input as namespace 0 numeric NodeId.</summary>
@@ -53,8 +53,9 @@ public class NodeIdParserTests
     {
         var result = NodeIdParser.Parse("85");
         result.ShouldNotBeNull();
-        result.NamespaceIndex.ShouldBe((ushort)0);
+        result.Value.NamespaceIndex.ShouldBe((ushort)0);
-        result.Identifier.ShouldBe((uint)85);
+        result.Value.TryGetValue(out uint identifier).ShouldBeTrue();
+        identifier.ShouldBe(85u);
     }
 
     /// <summary>Verifies that Parse trims whitespace padding from input.</summary>
@@ -63,7 +64,7 @@ public class NodeIdParserTests
     {
         var result = NodeIdParser.Parse("  ns=2;s=MyNode  ");
         result.ShouldNotBeNull();
-        result.Identifier.ShouldBe("MyNode");
+        result.Value.IdentifierAsString.ShouldBe("MyNode");
     }
 
     /// <summary>Verifies that Parse throws FormatException for invalid input.</summary>
@@ -92,7 +93,36 @@ public class NodeIdParserTests
     public void ParseRequired_ValidInput_ReturnsNodeId()
     {
         var result = NodeIdParser.ParseRequired("ns=2;s=TestNode");
-        result.ShouldNotBeNull();
+        result.IsNull.ShouldBeFalse();
-        result.Identifier.ShouldBe("TestNode");
+        result.IdentifierAsString.ShouldBe("TestNode");
+    }
+
+    [Fact]
+    public void Parse_OpaqueIdentifier_PreservesBytes()
+    {
+        var node = NodeIdParser.ParseRequired("ns=3;b=AQID");
+        node.IdType.ShouldBe(IdType.Opaque);
+        node.NamespaceIndex.ShouldBe((ushort)3);
+        node.TryGetValue(out ByteString bytes).ShouldBeTrue();
+        bytes.ToArray().ShouldBe(new byte[] { 1, 2, 3 });
+    }
+
+    [Fact]
+    public void Parse_StringIdentifierContainingEncodedText_StaysLiteral()
+    {
+        var node = NodeIdParser.ParseRequired("ns=4;s=ns=2;b=AQID");
+        node.IdType.ShouldBe(IdType.String);
+        node.NamespaceIndex.ShouldBe((ushort)4);
+        node.TryGetValue(out string? identifier).ShouldBeTrue();
+        identifier.ShouldBe("ns=2;b=AQID");
+    }
+
+    [Theory]
+    [InlineData("ns=bad;i=1")]
+    [InlineData("ns=2;b=invalid!")]
+    [InlineData("ns=2;i=invalid")]
+    public void Parse_InvalidEncodedIdentifier_IsRejected(string input)
+    {
+        Should.Throw<FormatException>(() => NodeIdParser.ParseRequired(input));
     }
 }

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/ReadCommandTests.cs

@@ -56,7 +56,7 @@ public class ReadCommandTests
         await command.ExecuteAsync(console);
 
         fakeService.ReadNodeIds.Count.ShouldBe(1);
-        fakeService.ReadNodeIds[0].Identifier.ShouldBe("MyVariable");
+        fakeService.ReadNodeIds[0].IdentifierAsString.ShouldBe("MyVariable");
     }
 
     /// <summary>Verifies that execute disconnects in finally.</summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/SubscribeCommandSummaryTests.cs

@@ -222,8 +222,8 @@ public class SubscribeCommandSummaryTests
 
         // Both Variables (depth 1 + depth 2) should have been subscribed.
         fakeService.SubscribeCalls.Count.ShouldBeGreaterThanOrEqualTo(2);
-        fakeService.SubscribeCalls.ShouldContain(c => c.NodeId.Identifier.ToString() == "Tag1");
+        fakeService.SubscribeCalls.ShouldContain(c => c.NodeId.IdentifierAsString.ToString() == "Tag1");
-        fakeService.SubscribeCalls.ShouldContain(c => c.NodeId.Identifier.ToString() == "Tag2");
+        fakeService.SubscribeCalls.ShouldContain(c => c.NodeId.IdentifierAsString.ToString() == "Tag2");
 
         var output = TestConsoleHelper.GetOutput(console);
         output.ShouldContain("Browsing subtree of ns=2;s=Root");

tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/SubscribeCommandTests.cs

@@ -33,7 +33,7 @@ public class SubscribeCommandTests
 
         fakeService.SubscribeCalls.Count.ShouldBe(1);
         fakeService.SubscribeCalls[0].IntervalMs.ShouldBe(500);
-        fakeService.SubscribeCalls[0].NodeId.Identifier.ShouldBe("TestVar");
+        fakeService.SubscribeCalls[0].NodeId.IdentifierAsString.ShouldBe("TestVar");
     }
 
     /// <summary>Verifies that ExecuteAsync unsubscribes when cancellation is requested.</summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Adapters/DefaultSubscriptionAdapterTests.cs

@@ -11,6 +11,48 @@ namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Adapters;
 /// </summary>
 public class DefaultSubscriptionAdapterTests
 {
+    private sealed class CountingSubscription() : Subscription(ClientTelemetry.Context)
+    {
+        public int DisposeCount;
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing) Interlocked.Increment(ref DisposeCount);
+            base.Dispose(disposing);
+        }
+    }
+
+    [Fact]
+    public async Task DeleteAndDispose_ReleaseSdkResourcesExactlyOnce()
+    {
+        var subscription = new CountingSubscription();
+        var detached = 0;
+        var adapter = new DefaultSubscriptionAdapter(subscription, (_, _) =>
+        {
+            Interlocked.Increment(ref detached);
+            return Task.CompletedTask;
+        });
+        await adapter.DeleteAsync(TestContext.Current.CancellationToken);
+        adapter.Dispose();
+        adapter.Dispose();
+        detached.ShouldBe(1);
+        subscription.DisposeCount.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task ConcurrentTeardown_HasOneSdkResourceOwner()
+    {
+        var subscription = new CountingSubscription();
+        var detached = 0;
+        var adapter = new DefaultSubscriptionAdapter(subscription, (_, _) =>
+        {
+            Interlocked.Increment(ref detached);
+            return Task.CompletedTask;
+        });
+        await Task.WhenAll(Task.Run(adapter.Dispose, TestContext.Current.CancellationToken), adapter.DeleteAsync(TestContext.Current.CancellationToken));
+        detached.ShouldBe(1);
+        subscription.DisposeCount.ShouldBe(1);
+    }
+
     /// <summary>DeleteAsync detaches the wrapped subscription exactly once, even when Dispose follows.</summary>
     [Fact]
     public async Task DeleteAsync_detaches_the_subscription_from_its_session_once()

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Adapters/EndpointSelectorTests.cs

@@ -117,7 +117,7 @@ public class EndpointSelectorTests
         var best = EndpointSelector.SelectBest(endpoints, "opc.tcp://external-host:4840",
             MessageSecurityMode.Sign);
 
-        new Uri(best.EndpointUrl).Host.ShouldBe("external-host");
+        new Uri(best.EndpointUrl.ShouldNotBeNull()).Host.ShouldBe("external-host");
     }
 
     /// <summary>
@@ -169,7 +169,7 @@ public class EndpointSelectorTests
 
         var best = EndpointSelector.SelectBest(endpoints, "opc.tcp://localhost:4841", MessageSecurityMode.None);
 
-        var uri = new Uri(best.EndpointUrl);
+        var uri = new Uri(best.EndpointUrl.ShouldNotBeNull());
         uri.Host.ShouldBe("localhost");
         uri.Port.ShouldBe(4841);
         uri.AbsolutePath.ShouldBe("/OtOpcUa");
@@ -183,8 +183,8 @@ public class EndpointSelectorTests
 
         var best = EndpointSelector.SelectBest(endpoints, "opc.tcp://localhost:4841", MessageSecurityMode.None);
 
-        new Uri(best.EndpointUrl).Host.ShouldBe("internal-host");
+        new Uri(best.EndpointUrl.ShouldNotBeNull()).Host.ShouldBe("internal-host");
-        new Uri(best.EndpointUrl).Port.ShouldBe(4843);
+        new Uri(best.EndpointUrl.ShouldNotBeNull()).Port.ShouldBe(4843);
     }
 
     /// <summary>Identical host, port and scheme: nothing to rewrite.</summary>
@@ -206,7 +206,7 @@ public class EndpointSelectorTests
 
         var best = EndpointSelector.SelectBest(endpoints, "opc.tcp://localhost", MessageSecurityMode.None);
 
-        var uri = new Uri(best.EndpointUrl);
+        var uri = new Uri(best.EndpointUrl.ShouldNotBeNull());
         uri.Host.ShouldBe("localhost");
         uri.Port.ShouldBe(4840);
     }
@@ -219,7 +219,7 @@ public class EndpointSelectorTests
 
         var best = EndpointSelector.SelectBest(endpoints, "opc.tcp://[::1]:4841", MessageSecurityMode.None);
 
-        var uri = new Uri(best.EndpointUrl);
+        var uri = new Uri(best.EndpointUrl.ShouldNotBeNull());
         uri.Host.ShouldBe("[::1]");
         uri.Port.ShouldBe(4841);
     }

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/AlarmEventFilterTests.cs

@@ -18,7 +18,7 @@ public sealed class AlarmEventFilterTests
     {
         var filter = OpcUaClientService.CreateAlarmEventFilter();
 
-        filter.SelectClauses.SelectMany(c => c.BrowsePath).ShouldAllBe(q => !q.Name.Contains('/'));
+        filter.SelectClauses.ToArray()!.SelectMany(c => c.BrowsePath.ToArray()!).ShouldAllBe(q => !(q.Name ?? "").Contains('/'));
     }
 
     /// <summary>The two-state ids are selected by their two-element browse paths, at the indices the parser reads.</summary>
@@ -27,7 +27,7 @@ public sealed class AlarmEventFilterTests
     {
         var clauses = OpcUaClientService.CreateAlarmEventFilter().SelectClauses;
 
-        string Path(int i) => string.Join("/", clauses[i].BrowsePath.Select(q => q.Name));
+        string Path(int i) => string.Join("/", clauses[i].BrowsePath.ToArray()!.Select(q => q.Name));
         Path(8).ShouldBe("AckedState/Id");
         clauses[8].BrowsePath.Count.ShouldBe(2);
         Path(9).ShouldBe("ActiveState/Id");

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/FailoverEpochTests.cs

@@ -164,7 +164,7 @@ public sealed class FailoverEpochTests : IDisposable
         var sub = new FakeSubscriptionAdapter();
         _factory.EnqueueSession(new FakeSessionAdapter { NextSubscription = sub });
         await _service.ConnectAsync(Settings(), TestContext.Current.CancellationToken);
-        var node = new Opc.Ua.NodeId("ns=2;s=X");
+        var node = Opc.Ua.NodeId.Parse("ns=2;s=X");
         await _service.SubscribeAsync(node, ct: TestContext.Current.CancellationToken);
 
         sub.ThrowOnRemove = true;

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeEndpointDiscovery.cs

@@ -35,7 +35,7 @@ internal sealed class FakeEndpointDiscovery : IEndpointDiscovery
                 : SecurityPolicies.Basic256Sha256,
             Server = new ApplicationDescription
             {
-                ApplicationName = "FakeServer",
+                ApplicationName = new LocalizedText("FakeServer"),
                 ApplicationUri = "urn:localhost:FakeServer"
             }
         });

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeSessionAdapter.cs

@@ -48,11 +48,15 @@ internal sealed class FakeSessionAdapter : ISessionAdapter
     public bool ThrowOnBrowse { get; set; }
 
     /// <summary>Gets or sets the browse references returned by browse operations.</summary>
-    public ReferenceDescriptionCollection BrowseResponse { get; set; } = [];
+    public ArrayOf<ReferenceDescription> BrowseResponse { get; set; } = [];
     /// <summary>Gets or sets the continuation point for browse operations.</summary>
     public byte[]? BrowseContinuationPoint { get; set; }
+    public Func<CancellationToken, Task>? BeforeBrowseNext { get; set; }
+    public List<(byte[] Point, bool Cancelled)> BrowseReleases { get; } = [];
+    public bool ThrowOnBrowseRelease { get; set; }
+
     /// <summary>Gets or sets the browse references returned by browse-next operations.</summary>
-    public ReferenceDescriptionCollection BrowseNextResponse { get; set; } = [];
+    public ArrayOf<ReferenceDescription> BrowseNextResponse { get; set; } = [];
     /// <summary>Gets or sets the continuation point for browse-next operations.</summary>
     public byte[]? BrowseNextContinuationPoint { get; set; }
 
@@ -129,7 +133,7 @@ internal sealed class FakeSessionAdapter : ISessionAdapter
     }
 
     /// <inheritdoc />
-    public Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseAsync(
+    public Task<(byte[]? ContinuationPoint, ArrayOf<ReferenceDescription> References)> BrowseAsync(
         NodeId nodeId, uint nodeClassMask, CancellationToken ct)
     {
         BrowseCount++;
@@ -139,11 +143,19 @@ internal sealed class FakeSessionAdapter : ISessionAdapter
     }
 
     /// <inheritdoc />
-    public Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseNextAsync(
+    public async Task<(byte[]? ContinuationPoint, ArrayOf<ReferenceDescription> References)> BrowseNextAsync(
         byte[] continuationPoint, CancellationToken ct)
     {
         BrowseNextCount++;
-        return Task.FromResult((BrowseNextContinuationPoint, BrowseNextResponse));
+        if (BeforeBrowseNext != null) await BeforeBrowseNext(ct);
+        return (BrowseNextContinuationPoint, BrowseNextResponse);
+    }
+
+    public Task ReleaseBrowseContinuationPointAsync(byte[] continuationPoint, CancellationToken ct)
+    {
+        BrowseReleases.Add((continuationPoint, ct.IsCancellationRequested));
+        if (ThrowOnBrowseRelease) throw new ServiceResultException(StatusCodes.BadSessionClosed);
+        return Task.CompletedTask;
     }
 
     /// <inheritdoc />

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeSessionFactory.cs

@@ -40,7 +40,7 @@ internal sealed class FakeSessionFactory : ISessionFactory
         uint sessionTimeoutMs, UserIdentity identity, CancellationToken ct)
     {
         CreateCallCount++;
-        LastEndpointUrl = endpoint.EndpointUrl;
+        LastEndpointUrl = endpoint.EndpointUrl ?? string.Empty;
 
         // One-shot: the gate holds only the call that observed it, so a later call (e.g. a user's Connect while a
         // failover is held) runs freely.
@@ -60,14 +60,14 @@ internal sealed class FakeSessionFactory : ISessionFactory
         else
             session = new FakeSessionAdapter
             {
-                EndpointUrl = endpoint.EndpointUrl,
+                EndpointUrl = endpoint.EndpointUrl ?? string.Empty,
-                ServerName = endpoint.Server?.ApplicationName?.Text ?? "FakeServer",
+                ServerName = endpoint.Server?.ApplicationName.Text ?? "FakeServer",
                 SecurityMode = endpoint.SecurityMode.ToString(),
                 SecurityPolicyUri = endpoint.SecurityPolicyUri ?? string.Empty
             };
 
         // Ensure endpoint URL matches
-        session.EndpointUrl = endpoint.EndpointUrl;
+        session.EndpointUrl = endpoint.EndpointUrl ?? string.Empty;
         _createdSessions.Add(session);
         return session;
     }

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeSubscriptionAdapter.cs

@@ -129,6 +129,16 @@ internal sealed class FakeSubscriptionAdapter : ISubscriptionAdapter
         lock (_itemsLock) _items.Clear();
     }
 
+    public Action<string, DataValue> CaptureDataCallback(uint handle)
+    {
+        lock (_itemsLock) return _items[handle].DataCallback!;
+    }
+
+    public Action<EventFieldList> CaptureEventCallback(uint handle)
+    {
+        lock (_itemsLock) return _items[handle].EventCallback!;
+    }
+
     /// <summary>
     ///     Simulates a data change notification for testing.
     /// </summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Helpers/AggregateTypeMapperTests.cs

@@ -26,8 +26,7 @@ public class AggregateTypeMapperTests
     public void ToNodeId_ReturnsNonNullForAllValues(AggregateType aggregate)
     {
         var nodeId = AggregateTypeMapper.ToNodeId(aggregate);
-        nodeId.ShouldNotBeNull();
+        nodeId.IsNull.ShouldBeFalse();
-        nodeId.IsNullNodeId.ShouldBeFalse();
     }
 
     /// <summary>Verifies that Average aggregate type maps to the correct OPC UA node ID.</summary>
@@ -109,9 +108,9 @@ public class AggregateTypeMapperTests
     [MemberData(nameof(AllAggregates))]
     public void ToNodeId_maps_to_the_same_named_AggregateFunction(AggregateType aggregate)
     {
-        var field = typeof(ObjectIds).GetField("AggregateFunction_" + aggregate);
+        var property = typeof(ObjectIds).GetProperty("AggregateFunction_" + aggregate);
-        field.ShouldNotBeNull();
+        property.ShouldNotBeNull();
-        AggregateTypeMapper.ToNodeId(aggregate).ShouldBe((NodeId)field.GetValue(null)!);
+        AggregateTypeMapper.ToNodeId(aggregate).ShouldBe((NodeId)property.GetValue(null)!);
     }
 
     /// <summary>Every client aggregate.</summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Helpers/HistoryReadPagingTests.cs

@@ -29,19 +29,18 @@ public class HistoryReadPagingTests
             Calls.Add(new Call(cp, release));
             if (release) return Task.FromResult<HistoryReadResult?>(new HistoryReadResult { StatusCode = StatusCodes.Good });
             var (count, next) = _pages.Dequeue();
-            var data = new HistoryData();
+            var data = new HistoryData { DataValues = Enumerable.Range(0, count).Select(i => new DataValue(Variant.From(i))).ToArrayOf() };
-            for (var i = 0; i < count; i++) data.DataValues.Add(new DataValue(new Variant(i)));
             return Task.FromResult<HistoryReadResult?>(new HistoryReadResult
             {
                 StatusCode = StatusCodes.Good,
-                ContinuationPoint = next,
+                ContinuationPoint = ByteString.From(next),
                 HistoryData = new ExtensionObject(data)
             });
         }
     }
 
     private static IEnumerable<DataValue> Values(HistoryReadResult r) =>
-        r.HistoryData?.Body is HistoryData d ? d.DataValues : [];
+        r.HistoryData.TryGetValue(out HistoryData? d) ? d.DataValues.ToArray() ?? [] : [];
 
     /// <summary>
     /// A server page limit below the caller's cap hands back a continuation point: the follow-up must READ the next
@@ -136,8 +135,7 @@ public class HistoryReadPagingTests
             calls.Add((cp, release, ct.IsCancellationRequested));
             if (release) return Task.FromResult<HistoryReadResult?>(new HistoryReadResult { StatusCode = StatusCodes.Good });
             if (cp != null) { cts.Cancel(); ct.ThrowIfCancellationRequested(); }
-            var data = new HistoryData();
+            var data = new HistoryData { DataValues = [new DataValue(Variant.From(1))] };
-            data.DataValues.Add(new DataValue(new Variant(1)));
             return Task.FromResult<HistoryReadResult?>(new HistoryReadResult
             {
                 StatusCode = StatusCodes.Good, ContinuationPoint = [5], HistoryData = new ExtensionObject(data)
@@ -165,8 +163,7 @@ public class HistoryReadPagingTests
                 releaseSawCancelled = ct.IsCancellationRequested;
                 return Task.FromResult<HistoryReadResult?>(new HistoryReadResult { StatusCode = StatusCodes.Good });
             }
-            var data = new HistoryData();
+            var data = new HistoryData { DataValues = [new DataValue(Variant.From(1))] };
-            data.DataValues.Add(new DataValue(new Variant(1)));
             cts.Cancel(); // the caller gives up right as the capped page arrives
             return Task.FromResult<HistoryReadResult?>(new HistoryReadResult
             {
@@ -189,8 +186,7 @@ public class HistoryReadPagingTests
         {
             calls++;
             if (release) throw new ServiceResultException(StatusCodes.BadSessionClosed);
-            var data = new HistoryData();
+            var data = new HistoryData { DataValues = [new DataValue(Variant.From(1))] };
-            data.DataValues.Add(new DataValue(new Variant(1)));
             return Task.FromResult<HistoryReadResult?>(new HistoryReadResult
             {
                 StatusCode = StatusCodes.Good, ContinuationPoint = [9], HistoryData = new ExtensionObject(data)
@@ -216,4 +212,24 @@ public class HistoryReadPagingTests
         await Should.ThrowAsync<ServiceResultException>(() =>
             HistoryReadPaging.ReadAllAsync(Read, Values, maxValues: 10, Node, CancellationToken.None));
     }
+    [Fact]
+    public async Task RefusedContinuationPage_ReleasesCursorAndPreservesStatus()
+    {
+        var releases = new List<byte[]>();
+        Task<HistoryReadResult?> Read(byte[]? cp, bool release, CancellationToken ct)
+        {
+            if (release)
+            {
+                releases.Add(cp!);
+                throw new ServiceResultException(StatusCodes.BadSessionClosed);
+            }
+            return Task.FromResult<HistoryReadResult?>(cp == null
+                ? new HistoryReadResult { StatusCode = StatusCodes.Good, ContinuationPoint = [7] }
+                : new HistoryReadResult { StatusCode = StatusCodes.BadUserAccessDenied });
+        }
+        var exception = await Should.ThrowAsync<ServiceResultException>(() =>
+            HistoryReadPaging.ReadAllAsync(Read, Values, 10, Node, TestContext.Current.CancellationToken));
+        exception.StatusCode.ShouldBe(StatusCodes.BadUserAccessDenied);
+        releases.ShouldHaveSingleItem().ShouldBe(new byte[] { 7 });
+    }
 }

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Helpers/HistoryReadStatusTests.cs

@@ -7,32 +7,29 @@ namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Helpers;
 
 public class HistoryReadStatusTests
 {
+    public static IEnumerable<object[]> Refusals() => new[] { StatusCodes.BadHistoryOperationUnsupported,
+        StatusCodes.BadUserAccessDenied, StatusCodes.BadNodeIdUnknown, StatusCodes.BadTimeout }.Select(s => new object[] { s });
+    public static IEnumerable<object[]> NonRefusals() => new[] { StatusCodes.Good, StatusCodes.GoodNoData,
+        StatusCodes.GoodMoreData, StatusCodes.UncertainNoCommunicationLastUsableValue, StatusCodes.BadNoData }.Select(s => new object[] { s });
     /// <summary>A refused read must surface, carrying the status code, rather than read as an empty result.</summary>
     /// <param name="code">The Bad per-node status code.</param>
     [Theory]
-    [InlineData(StatusCodes.BadHistoryOperationUnsupported)]
+    [MemberData(nameof(Refusals))]
-    [InlineData(StatusCodes.BadUserAccessDenied)]
+    public void Bad_status_throws_ServiceResultException_with_the_code(StatusCode code)
-    [InlineData(StatusCodes.BadNodeIdUnknown)]
-    [InlineData(StatusCodes.BadTimeout)]
-    public void Bad_status_throws_ServiceResultException_with_the_code(uint code)
     {
         var ex = Should.Throw<ServiceResultException>(
-            () => HistoryReadStatus.ThrowIfRefused(new StatusCode(code), new NodeId("n", 2)));
+            () => HistoryReadStatus.ThrowIfRefused(code, new NodeId("n", 2)));
 
-        ex.StatusCode.ShouldBe(code);
+        ex.StatusCode.ShouldBe(code.Code);
         ex.Message.ShouldContain("ns=2;s=n");
     }
 
     /// <summary>Good, GoodNoData, Uncertain and BadNoData are all non-refusals (the window may simply be empty).</summary>
     /// <param name="code">The non-refusal status code.</param>
     [Theory]
-    [InlineData(StatusCodes.Good)]
+    [MemberData(nameof(NonRefusals))]
-    [InlineData(StatusCodes.GoodNoData)]
+    public void Non_refusal_status_does_not_throw(StatusCode code)
-    [InlineData(StatusCodes.GoodMoreData)]
-    [InlineData(StatusCodes.UncertainNoCommunicationLastUsableValue)]
-    [InlineData(StatusCodes.BadNoData)]
-    public void Non_refusal_status_does_not_throw(uint code)
     {
-        Should.NotThrow(() => HistoryReadStatus.ThrowIfRefused(new StatusCode(code), new NodeId("n", 2)));
+        Should.NotThrow(() => HistoryReadStatus.ThrowIfRefused(code, new NodeId("n", 2)));
     }
 }

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Helpers/VariantBoundaryTests.cs

@@ -0,0 +1,126 @@
+using Opc.Ua;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Helpers;
+
+public class VariantBoundaryTests
+{
+    public static IEnumerable<object?[]> Payloads()
+    {
+        foreach (var value in new object?[] { null, true, (sbyte)-1, (byte)1, (short)-2, (ushort)2,
+                     -3, 3u, -4L, 4UL, 1.25f, 2.5, "", "text", Guid.Parse("de305d54-75b4-431b-adb2-eb6b9e546014"),
+                     new DateTime(2026, 11, 10, 0, 0, 0, DateTimeKind.Utc), Array.Empty<byte>(), new byte[] { 1, 2 },
+                     Array.Empty<int>(), new[] { 1 }, new[] { 1, 2 }, Array.Empty<string>(), new[] { "", "text" } })
+            yield return [value];
+        foreach (var value in new object[] { true, (sbyte)-1, (byte)1, (short)-2, (ushort)2,
+                     -3, 3u, -4L, 4UL, 1.25f, 2.5, "text", Guid.Empty,
+                     new DateTime(2026, 11, 10, 0, 0, 0, DateTimeKind.Utc) })
+        {
+            foreach (var count in new[] { 0, 1, 3 })
+            {
+                var array = Array.CreateInstance(value.GetType(), count);
+                for (var i = 0; i < count; i++) array.SetValue(value, i);
+                yield return [array];
+            }
+        }
+    }
+
+    [Theory]
+    [MemberData(nameof(Payloads))]
+    public void RoundTrip_PreservesClrTypeAndValue(object? expected)
+    {
+        var actual = ValueConverter.ToClrObject(ValueConverter.ToVariant(expected));
+        if (expected == null) actual.ShouldBeNull();
+        else
+        {
+            actual.ShouldNotBeNull();
+            actual.GetType().ShouldBe(expected.GetType());
+            actual.ShouldBe(expected);
+        }
+    }
+
+    [Fact]
+    public void RetainedArrays_AreDetachedFromCaller()
+    {
+        var bytes = new byte[] { 1, 2 };
+        var numbers = new[] { 3, 4 };
+        var byteValue = ValueConverter.ToVariant(bytes);
+        var numericValue = ValueConverter.ToVariant(numbers);
+        bytes[0] = 99;
+        numbers[0] = 99;
+        ValueConverter.ToClrObject(byteValue).ShouldBe(new byte[] { 1, 2 });
+        ValueConverter.ToClrObject(numericValue).ShouldBe(new[] { 3, 4 });
+    }
+
+    [Fact]
+    public void ByteString_NullAndEmptyRemainDistinct()
+    {
+        ValueConverter.ToClrObject(Variant.From(default(ByteString))).ShouldBeNull();
+        ValueConverter.ToClrObject(Variant.From(ByteString.Empty)).ShouldBe(Array.Empty<byte>());
+        ValueConverter.ToClrObject(Variant.Null).ShouldBeNull();
+        ValueConverter.ToClrObject(Variant.From(0)).ShouldBe(0);
+    }
+
+    [Fact]
+    public void NullWrapperInputs_RemainNullAfterRetention()
+    {
+        ValueConverter.ToClrObject(ValueConverter.ToVariant(default(ByteString))).ShouldBeNull();
+        ValueConverter.ToClrObject(ValueConverter.ToVariant(default(ArrayOf<int>))).ShouldBeNull();
+        ValueConverter.ToVariant(default(ArrayOf<byte>)).TypeInfo.ValueRank.ShouldBe(ValueRanks.OneDimension);
+        ValueConverter.ToClrObject(ValueConverter.ToVariant(Variant.From(default(ByteString)))).ShouldBeNull();
+    }
+
+    [Fact]
+    public void ReadOnlyWrappers_AreDetachedFromMutableBackingBuffers()
+    {
+        var bytes = new byte[] { 1, 2 };
+        var numbers = new[] { 3, 4 };
+        var retainedBytes = ValueConverter.ToVariant(new ByteString(bytes));
+        var retainedNumbers = ValueConverter.ToVariant(new ArrayOf<int>(numbers));
+        bytes[0] = 99;
+        numbers[0] = 99;
+        ValueConverter.ToClrObject(retainedBytes).ShouldBe(new byte[] { 1, 2 });
+        ValueConverter.ToClrObject(retainedNumbers).ShouldBe(new[] { 3, 4 });
+    }
+
+    [Fact]
+    public void RetainedByteStringArray_CopiesElementBuffersAndPreservesNullEmpty()
+    {
+        var bytes = new byte[] { 1, 2 };
+        var value = ValueConverter.ToVariant(new ByteString[] { default, ByteString.Empty, new(bytes) });
+        bytes[0] = 99;
+        var actual = ValueConverter.ToClrObject(value).ShouldBeOfType<byte[][]>();
+        actual[0].ShouldBeNull();
+        actual[1].ShouldBeEmpty();
+        actual[2].ShouldBe(new byte[] { 1, 2 });
+    }
+
+    [Fact]
+    public void ByteArrayAndByteString_KeepWireRank()
+    {
+        ValueConverter.ToVariant(new byte[] { 1 }).TypeInfo.BuiltInType.ShouldBe(BuiltInType.ByteString);
+        ValueConverter.ToVariant(new ArrayOf<byte>(new byte[] { 1 })).TypeInfo.BuiltInType.ShouldBe(BuiltInType.Byte);
+        ValueConverter.ToVariant(new ArrayOf<byte>(new byte[] { 1 })).TypeInfo.ValueRank.ShouldBe(ValueRanks.OneDimension);
+    }
+
+    [Fact]
+    public void NodeIds_KeepOpaqueBytesAndLiteralStringIdentifiers()
+    {
+        var opaque = NodeId.Parse("ns=2;b=AQID");
+        ValueConverter.ToClrObject(ValueConverter.ToVariant(opaque)).ShouldBe(opaque);
+        var literal = new NodeId("ns=2;s=literal", 4);
+        var result = ValueConverter.ToClrObject(ValueConverter.ToVariant(literal)).ShouldBeOfType<NodeId>();
+        result.NamespaceIndex.ShouldBe((ushort)4);
+        result.TryGetValue(out string? identifier).ShouldBeTrue();
+        identifier.ShouldBe("ns=2;s=literal");
+    }
+
+    [Fact]
+    public void UnsupportedShape_IsRejected()
+    {
+        Should.Throw<ServiceResultException>(() => ValueConverter.ToVariant(new int[2, 2]));
+        Should.Throw<ServiceResultException>(() => ValueConverter.ToVariant(new object()));
+    }
+}

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Models/ModelConstructionTests.cs

@@ -76,7 +76,7 @@ public class ModelConstructionTests
 
         args.NodeId.ShouldBe("ns=2;s=Temp");
         args.Value.ShouldBe(value);
-        args.Value.Value.ShouldBe(42);
+        args.Value.WrappedValue.ShouldBe(Variant.From(42));
     }
 
     /// <summary>Verifies that ConnectionStateChangedEventArgs constructs correctly with all properties.</summary>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/OpcUaClientServiceTests.cs

@@ -197,9 +197,9 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        var result = await _service.ReadValueAsync(new NodeId("ns=2;s=MyNode"), TestContext.Current.CancellationToken);
+        var result = await _service.ReadValueAsync(NodeId.Parse("ns=2;s=MyNode"), TestContext.Current.CancellationToken);
 
-        result.Value.ShouldBe(42);
+        result.WrappedValue.ShouldBe(Variant.From(42));
         session.ReadCount.ShouldBe(1);
     }
 
@@ -210,7 +210,7 @@ public class OpcUaClientServiceTests : IDisposable
     public async Task ReadValueAsync_WhenDisconnected_Throws()
     {
         await Should.ThrowAsync<InvalidOperationException>(() =>
-            _service.ReadValueAsync(new NodeId("ns=2;s=MyNode")));
+            _service.ReadValueAsync(NodeId.Parse("ns=2;s=MyNode")));
     }
 
     /// <summary>
@@ -224,7 +224,7 @@ public class OpcUaClientServiceTests : IDisposable
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
         await Should.ThrowAsync<ServiceResultException>(() =>
-            _service.ReadValueAsync(new NodeId("ns=2;s=MyNode")));
+            _service.ReadValueAsync(NodeId.Parse("ns=2;s=MyNode")));
     }
 
     // --- Write tests ---
@@ -243,7 +243,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        var result = await _service.WriteValueAsync(new NodeId("ns=2;s=MyNode"), 42, TestContext.Current.CancellationToken);
+        var result = await _service.WriteValueAsync(NodeId.Parse("ns=2;s=MyNode"), 42, TestContext.Current.CancellationToken);
 
         result.ShouldBe(StatusCodes.Good);
         session.WriteCount.ShouldBe(1);
@@ -262,7 +262,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        await _service.WriteValueAsync(new NodeId("ns=2;s=MyNode"), "42", TestContext.Current.CancellationToken);
+        await _service.WriteValueAsync(NodeId.Parse("ns=2;s=MyNode"), "42", TestContext.Current.CancellationToken);
 
         session.WriteCount.ShouldBe(1);
         session.ReadCount.ShouldBe(1); // Read for type inference
@@ -278,7 +278,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        await _service.WriteValueAsync(new NodeId("ns=2;s=MyNode"), 42, TestContext.Current.CancellationToken);
+        await _service.WriteValueAsync(NodeId.Parse("ns=2;s=MyNode"), 42, TestContext.Current.CancellationToken);
 
         session.WriteCount.ShouldBe(1);
         session.ReadCount.ShouldBe(0); // No read for non-string values
@@ -291,7 +291,7 @@ public class OpcUaClientServiceTests : IDisposable
     public async Task WriteValueAsync_WhenDisconnected_Throws()
     {
         await Should.ThrowAsync<InvalidOperationException>(() =>
-            _service.WriteValueAsync(new NodeId("ns=2;s=MyNode"), 42));
+            _service.WriteValueAsync(NodeId.Parse("ns=2;s=MyNode"), 42));
     }
 
     /// <summary>
@@ -303,13 +303,13 @@ public class OpcUaClientServiceTests : IDisposable
     {
         var session = new FakeSessionAdapter
         {
-            ReadResponse = new DataValue(StatusCodes.BadNodeIdUnknown) // Bad status, null Value
+            ReadResponse = DataValue.FromStatusCode(StatusCodes.BadNodeIdUnknown) // Bad status, null Value
         };
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
         var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
-            _service.WriteValueAsync(new NodeId("ns=2;s=MyNode"), "42"));
+            _service.WriteValueAsync(NodeId.Parse("ns=2;s=MyNode"), "42"));
 
         ex.Message.ShouldContain("Cannot infer target type");
     }
@@ -323,17 +323,90 @@ public class OpcUaClientServiceTests : IDisposable
     {
         var session = new FakeSessionAdapter
         {
-            ReadResponse = new DataValue(StatusCodes.BadNotReadable)
+            ReadResponse = DataValue.FromStatusCode(StatusCodes.BadNotReadable)
         };
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
         var ex = await Should.ThrowAsync<InvalidOperationException>(() =>
-            _service.WriteValueAsync(new NodeId("ns=2;s=MyNode"), "42"));
+            _service.WriteValueAsync(NodeId.Parse("ns=2;s=MyNode"), "42"));
 
         ex.Message.ShouldContain("ns=2;s=MyNode");
     }
 
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public async Task BrowseCancellation_ReleasesOwnedCursor_WithoutMaskingCancellation(bool releaseFails)
+    {
+        using var cts = new CancellationTokenSource();
+        var session = new FakeSessionAdapter
+        {
+            BrowseResponse = [new ReferenceDescription { NodeId = new ExpandedNodeId("child", 2) }],
+            BrowseContinuationPoint = [7],
+            ThrowOnBrowseRelease = releaseFails,
+            BeforeBrowseNext = token => { cts.Cancel(); token.ThrowIfCancellationRequested(); return Task.CompletedTask; }
+        };
+        _sessionFactory.EnqueueSession(session);
+        await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
+        await Should.ThrowAsync<OperationCanceledException>(() => _service.BrowseAsync(ct: cts.Token));
+        var release = session.BrowseReleases.ShouldHaveSingleItem();
+        release.Point.ShouldBe(new byte[] { 7 });
+        release.Cancelled.ShouldBeFalse();
+    }
+
+    [Fact]
+    public async Task BrowseEmptyPage_ReleasesRemainingCursor()
+    {
+        var session = new FakeSessionAdapter { BrowseContinuationPoint = [8] };
+        _sessionFactory.EnqueueSession(session);
+        await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
+        (await _service.BrowseAsync(ct: TestContext.Current.CancellationToken)).ShouldBeEmpty();
+        session.BrowseReleases.ShouldHaveSingleItem().Point.ShouldBe(new byte[] { 8 });
+    }
+
+    [Fact]
+    public async Task ReadValue_PreservesSdkStatusTimestampsAndPicoseconds()
+    {
+        var source = new DateTime(2026, 11, 10, 12, 0, 0, DateTimeKind.Utc);
+        var value = new DataValue(Variant.From(12.5), StatusCodes.UncertainLastUsableValue,
+            source, source.AddSeconds(1), 12, 34);
+        var session = new FakeSessionAdapter { ReadResponse = value };
+        _sessionFactory.EnqueueSession(session);
+        await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
+        var actual = await _service.ReadValueAsync(new NodeId("tag", 2), TestContext.Current.CancellationToken);
+        actual.ShouldBe(value);
+        actual.StatusCode.ShouldBe(StatusCodes.UncertainLastUsableValue);
+        actual.SourcePicoseconds.ShouldBe((ushort)12);
+        actual.ServerPicoseconds.ShouldBe((ushort)34);
+    }
+
+    [Fact]
+    public async Task AlarmMapping_PreservesTimeEmptyTextAndRetainedEventId()
+    {
+        var session = new FakeSessionAdapter();
+        _sessionFactory.EnqueueSession(session);
+        await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
+        await _service.SubscribeAlarmsAsync(ct: TestContext.Current.CancellationToken);
+        var timestamp = new DateTime(2026, 11, 10, 12, 0, 0, DateTimeKind.Utc);
+        var bytes = new byte[] { 1, 2, 3 };
+        AlarmEventArgs? received = null;
+        _service.AlarmEvent += (_, e) => received = e;
+        var subscription = session.CreatedSubscriptions.Single();
+        subscription.SimulateEvent(subscription.ActiveHandles.Single(), new EventFieldList
+        {
+            EventFields = [Variant.From(new ByteString(bytes)), Variant.From(ObjectTypeIds.AlarmConditionType),
+                Variant.From("source"), Variant.From((DateTimeUtc)timestamp), Variant.From(LocalizedText.Null),
+                Variant.From((ushort)321), Variant.From("condition"), Variant.From(true)]
+        });
+        bytes[0] = 99;
+        received.ShouldNotBeNull();
+        received.Time.ShouldBe(timestamp);
+        received.Message.ShouldBe("");
+        received.EventId.ShouldBe(new byte[] { 1, 2, 3 });
+        received.Severity.ShouldBe((ushort)321);
+    }
+
     // --- Browse tests ---
 
     /// <summary>
@@ -348,7 +421,7 @@ public class OpcUaClientServiceTests : IDisposable
             [
                 new ReferenceDescription
                 {
-                    NodeId = new ExpandedNodeId("ns=2;s=Child1"),
+                    NodeId = ExpandedNodeId.Parse("ns=2;s=Child1"),
                     DisplayName = new LocalizedText("Child1"),
                     NodeClass = NodeClass.Variable
                 }
@@ -397,19 +470,19 @@ public class OpcUaClientServiceTests : IDisposable
             [
                 new ReferenceDescription
                 {
-                    NodeId = new ExpandedNodeId("ns=2;s=Folder1"),
+                    NodeId = ExpandedNodeId.Parse("ns=2;s=Folder1"),
                     DisplayName = new LocalizedText("Folder1"),
                     NodeClass = NodeClass.Object
                 },
                 new ReferenceDescription
                 {
-                    NodeId = new ExpandedNodeId("ns=2;s=Folder2"),
+                    NodeId = ExpandedNodeId.Parse("ns=2;s=Folder2"),
                     DisplayName = new LocalizedText("Folder2"),
                     NodeClass = NodeClass.Object
                 },
                 new ReferenceDescription
                 {
-                    NodeId = new ExpandedNodeId("ns=2;s=Tag"),
+                    NodeId = ExpandedNodeId.Parse("ns=2;s=Tag"),
                     DisplayName = new LocalizedText("Tag"),
                     NodeClass = NodeClass.Variable
                 }
@@ -437,7 +510,7 @@ public class OpcUaClientServiceTests : IDisposable
             [
                 new ReferenceDescription
                 {
-                    NodeId = new ExpandedNodeId("ns=2;s=A"),
+                    NodeId = ExpandedNodeId.Parse("ns=2;s=A"),
                     DisplayName = new LocalizedText("A"),
                     NodeClass = NodeClass.Variable
                 }
@@ -447,7 +520,7 @@ public class OpcUaClientServiceTests : IDisposable
             [
                 new ReferenceDescription
                 {
-                    NodeId = new ExpandedNodeId("ns=2;s=B"),
+                    NodeId = ExpandedNodeId.Parse("ns=2;s=B"),
                     DisplayName = new LocalizedText("B"),
                     NodeClass = NodeClass.Variable
                 }
@@ -484,7 +557,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        await _service.SubscribeAsync(new NodeId("ns=2;s=MyNode"), 500, TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(NodeId.Parse("ns=2;s=MyNode"), 500, TestContext.Current.CancellationToken);
 
         session.CreatedSubscriptions.Count.ShouldBe(1);
         session.CreatedSubscriptions[0].AddDataChangeCount.ShouldBe(1);
@@ -500,8 +573,8 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        await _service.SubscribeAsync(new NodeId("ns=2;s=MyNode"), ct: TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(NodeId.Parse("ns=2;s=MyNode"), ct: TestContext.Current.CancellationToken);
-        await _service.SubscribeAsync(new NodeId("ns=2;s=MyNode"), ct: TestContext.Current.CancellationToken); // duplicate
+        await _service.SubscribeAsync(NodeId.Parse("ns=2;s=MyNode"), ct: TestContext.Current.CancellationToken); // duplicate
 
         session.CreatedSubscriptions[0].AddDataChangeCount.ShouldBe(1);
     }
@@ -520,7 +593,7 @@ public class OpcUaClientServiceTests : IDisposable
         DataChangedEventArgs? received = null;
         _service.DataChanged += (_, e) => received = e;
 
-        await _service.SubscribeAsync(new NodeId("ns=2;s=MyNode"), 500, TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(NodeId.Parse("ns=2;s=MyNode"), 500, TestContext.Current.CancellationToken);
 
         // Simulate data change
         var handle = fakeSub.ActiveHandles.First();
@@ -528,7 +601,7 @@ public class OpcUaClientServiceTests : IDisposable
 
         received.ShouldNotBeNull();
         received!.NodeId.ShouldBe("ns=2;s=MyNode");
-        received.Value.Value.ShouldBe(99);
+        received.Value.WrappedValue.ShouldBe(Variant.From(99));
     }
 
     /// <summary>
@@ -542,8 +615,8 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        await _service.SubscribeAsync(new NodeId("ns=2;s=MyNode"), ct: TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(NodeId.Parse("ns=2;s=MyNode"), ct: TestContext.Current.CancellationToken);
-        await _service.UnsubscribeAsync(new NodeId("ns=2;s=MyNode"), TestContext.Current.CancellationToken);
+        await _service.UnsubscribeAsync(NodeId.Parse("ns=2;s=MyNode"), TestContext.Current.CancellationToken);
 
         fakeSub.RemoveCount.ShouldBe(1);
     }
@@ -558,7 +631,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        await _service.UnsubscribeAsync(new NodeId("ns=2;s=NotSubscribed"), TestContext.Current.CancellationToken);
+        await _service.UnsubscribeAsync(NodeId.Parse("ns=2;s=NotSubscribed"), TestContext.Current.CancellationToken);
         // Should not throw
     }
 
@@ -569,7 +642,7 @@ public class OpcUaClientServiceTests : IDisposable
     public async Task SubscribeAsync_WhenDisconnected_Throws()
     {
         await Should.ThrowAsync<InvalidOperationException>(() =>
-            _service.SubscribeAsync(new NodeId("ns=2;s=MyNode")));
+            _service.SubscribeAsync(NodeId.Parse("ns=2;s=MyNode")));
     }
 
     // --- Alarm subscription tests ---
@@ -742,7 +815,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        var results = await _service.HistoryReadRawAsync(new NodeId("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow, ct: TestContext.Current.CancellationToken);
+        var results = await _service.HistoryReadRawAsync(NodeId.Parse("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow, ct: TestContext.Current.CancellationToken);
 
         results.Count.ShouldBe(2);
         session.HistoryReadRawCount.ShouldBe(1);
@@ -755,7 +828,7 @@ public class OpcUaClientServiceTests : IDisposable
     public async Task HistoryReadRawAsync_WhenDisconnected_Throws()
     {
         await Should.ThrowAsync<InvalidOperationException>(() =>
-            _service.HistoryReadRawAsync(new NodeId("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow));
+            _service.HistoryReadRawAsync(NodeId.Parse("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow));
     }
 
     /// <summary>
@@ -769,7 +842,7 @@ public class OpcUaClientServiceTests : IDisposable
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
         await Should.ThrowAsync<ServiceResultException>(() =>
-            _service.HistoryReadRawAsync(new NodeId("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow));
+            _service.HistoryReadRawAsync(NodeId.Parse("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow));
     }
 
     /// <summary>
@@ -786,7 +859,7 @@ public class OpcUaClientServiceTests : IDisposable
         _sessionFactory.EnqueueSession(session);
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
-        var results = await _service.HistoryReadAggregateAsync(new NodeId("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow, AggregateType.Average, ct: TestContext.Current.CancellationToken);
+        var results = await _service.HistoryReadAggregateAsync(NodeId.Parse("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow, AggregateType.Average, ct: TestContext.Current.CancellationToken);
 
         results.Count.ShouldBe(1);
         session.HistoryReadAggregateCount.ShouldBe(1);
@@ -800,7 +873,7 @@ public class OpcUaClientServiceTests : IDisposable
     {
         await Should.ThrowAsync<InvalidOperationException>(() =>
             _service.HistoryReadAggregateAsync(
-                new NodeId("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow,
+                NodeId.Parse("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow,
                 AggregateType.Average));
     }
 
@@ -816,7 +889,7 @@ public class OpcUaClientServiceTests : IDisposable
 
         await Should.ThrowAsync<ServiceResultException>(() =>
             _service.HistoryReadAggregateAsync(
-                new NodeId("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow,
+                NodeId.Parse("ns=2;s=Temp"), DateTime.UtcNow.AddHours(-1), DateTime.UtcNow,
                 AggregateType.Average));
     }
 
@@ -840,7 +913,7 @@ public class OpcUaClientServiceTests : IDisposable
                     return new DataValue(new Variant(["urn:server1", "urn:server2"]), StatusCodes.Good);
                 if (nodeId == VariableIds.Server_ServerArray)
                     return new DataValue(new Variant(["urn:server1"]), StatusCodes.Good);
-                return new DataValue(StatusCodes.BadNodeIdUnknown);
+                return DataValue.FromStatusCode(StatusCodes.BadNodeIdUnknown);
             }
         };
         _sessionFactory.EnqueueSession(session);
@@ -933,9 +1006,9 @@ public class OpcUaClientServiceTests : IDisposable
             ReadResponseFunc = nodeId =>
             {
                 if (nodeId == VariableIds.Server_ServerRedundancy_RedundancySupport)
-                    return new DataValue(StatusCodes.BadNotReadable); // bad status, null Value
+                    return DataValue.FromStatusCode(StatusCodes.BadNotReadable); // bad status, null Value
                 if (nodeId == VariableIds.Server_ServiceLevel)
-                    return new DataValue(StatusCodes.BadNotReadable);
+                    return DataValue.FromStatusCode(StatusCodes.BadNotReadable);
                 throw new ServiceResultException(StatusCodes.BadNodeIdUnknown);
             }
         };
@@ -1046,7 +1119,7 @@ public class OpcUaClientServiceTests : IDisposable
         var result = await _service.AcknowledgeAlarmAsync("ns=2;s=Cond", new byte[] { 1, 2 }, "acked", TestContext.Current.CancellationToken);
 
         StatusCode.IsBad(result).ShouldBeTrue();
-        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyEnabled);
+        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyEnabled.Code);
     }
 
     /// <summary>
@@ -1105,7 +1178,7 @@ public class OpcUaClientServiceTests : IDisposable
         var result = await _service.ConfirmAlarmAsync("ns=2;s=Cond", new byte[] { 1, 2 }, "confirmed", TestContext.Current.CancellationToken);
 
         StatusCode.IsBad(result).ShouldBeTrue();
-        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyEnabled);
+        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyEnabled.Code);
     }
 
     // --- ShelveAlarm tests ---
@@ -1186,7 +1259,7 @@ public class OpcUaClientServiceTests : IDisposable
         var result = await _service.ShelveAlarmAsync("ns=2;s=Cond", ShelveKind.OneShot, ct: TestContext.Current.CancellationToken);
 
         StatusCode.IsBad(result).ShouldBeTrue();
-        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyShelved);
+        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyShelved.Code);
     }
 
     // --- Enable / Disable tests (H4 client path) ---
@@ -1249,7 +1322,7 @@ public class OpcUaClientServiceTests : IDisposable
         var result = await _service.EnableAsync("ns=2;s=Cond", TestContext.Current.CancellationToken);
 
         StatusCode.IsBad(result).ShouldBeTrue();
-        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyEnabled);
+        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyEnabled.Code);
     }
 
     /// <summary>
@@ -1270,7 +1343,7 @@ public class OpcUaClientServiceTests : IDisposable
         var result = await _service.DisableAsync("ns=2;s=Cond", TestContext.Current.CancellationToken);
 
         StatusCode.IsBad(result).ShouldBeTrue();
-        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyDisabled);
+        result.Code.ShouldBe(StatusCodes.BadConditionAlreadyDisabled.Code);
     }
 
     // --- Missing standard alarm fields (#598: the Galaxy-era supplemental reads are gone) ---
@@ -1484,7 +1557,7 @@ public class OpcUaClientServiceTests : IDisposable
 
         var gate = new TaskCompletionSource();
         session1.CreateSubscriptionGate = gate;
-        var subscribe = _service.SubscribeAsync(new NodeId("ns=2;s=Racer"), 1000, TestContext.Current.CancellationToken);
+        var subscribe = _service.SubscribeAsync(NodeId.Parse("ns=2;s=Racer"), 1000, TestContext.Current.CancellationToken);
         await session1.CreateSubscriptionEntered.Task.WaitAsync(TimeSpan.FromSeconds(10), TestContext.Current.CancellationToken);
 
         session1.SimulateKeepAlive(false);
@@ -1499,7 +1572,7 @@ public class OpcUaClientServiceTests : IDisposable
         replayed.AddDataChangeCount.ShouldBe(1);
 
         // And it is the live subscription: unsubscribing removes it from session2's subscription, not session1's.
-        await _service.UnsubscribeAsync(new NodeId("ns=2;s=Racer"), TestContext.Current.CancellationToken);
+        await _service.UnsubscribeAsync(NodeId.Parse("ns=2;s=Racer"), TestContext.Current.CancellationToken);
         replayed.RemoveCount.ShouldBe(1);
         replayed.ActiveHandles.ShouldBeEmpty();
     }
@@ -1548,7 +1621,7 @@ public class OpcUaClientServiceTests : IDisposable
         var tasks = new List<Task>();
         for (var i = 0; i < 50; i++)
         {
-            var nodeId = new NodeId($"ns=2;s=Node{i}");
+            var nodeId = NodeId.Parse($"ns=2;s=Node{i}");
             tasks.Add(Task.Run(async () =>
             {
                 await _service.SubscribeAsync(nodeId);
@@ -1560,6 +1633,55 @@ public class OpcUaClientServiceTests : IDisposable
         await Should.NotThrowAsync(() => Task.WhenAll(tasks));
     }
 
+    [Fact]
+    public async Task QueuedCallbacks_AfterDisposal_AreIgnored()
+    {
+        var session = new FakeSessionAdapter();
+        _sessionFactory.EnqueueSession(session);
+        await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(new NodeId("tag", 2), ct: TestContext.Current.CancellationToken);
+        await _service.SubscribeAlarmsAsync(ct: TestContext.Current.CancellationToken);
+        var data = session.CreatedSubscriptions[0];
+        var alarm = session.CreatedSubscriptions[1];
+        var queuedData = data.CaptureDataCallback(data.ActiveHandles.Single());
+        var queuedAlarm = alarm.CaptureEventCallback(alarm.ActiveHandles.Single());
+        var dataCount = 0;
+        var alarmCount = 0;
+        _service.DataChanged += (_, _) => dataCount++;
+        _service.AlarmEvent += (_, _) => alarmCount++;
+        queuedData("ns=2;s=tag", new DataValue(Variant.From(1)));
+        queuedAlarm(new EventFieldList { EventFields = [Variant.From(ByteString.Empty)] });
+        dataCount.ShouldBe(1);
+        alarmCount.ShouldBe(1);
+        _service.Dispose();
+        queuedData("ns=2;s=tag", new DataValue(Variant.From(2)));
+        queuedAlarm(new EventFieldList { EventFields = [Variant.From(ByteString.Empty)] });
+        dataCount.ShouldBe(1);
+        alarmCount.ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task QueuedCallbacks_FromPreviousSession_AreIgnoredAfterFailover()
+    {
+        var first = new FakeSessionAdapter();
+        var second = new FakeSessionAdapter();
+        _sessionFactory.EnqueueSession(first);
+        _sessionFactory.EnqueueSession(second);
+        await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(new NodeId("tag", 2), ct: TestContext.Current.CancellationToken);
+        var firstSubscription = first.CreatedSubscriptions.Single();
+        var queued = firstSubscription.CaptureDataCallback(firstSubscription.ActiveHandles.Single());
+        var received = new List<DataValue>();
+        _service.DataChanged += (_, e) => received.Add(e.Value);
+        first.SimulateKeepAlive(false);
+        await _service.LastFailover!.WaitAsync(TestContext.Current.CancellationToken);
+        queued("ns=2;s=tag", new DataValue(Variant.From(1)));
+        received.ShouldBeEmpty();
+        var current = second.CreatedSubscriptions.Single();
+        current.SimulateDataChange(current.ActiveHandles.Single(), new DataValue(Variant.From(2)));
+        received.ShouldHaveSingleItem().WrappedValue.ShouldBe(Variant.From(2));
+    }
+
     // --- Dispose tests ---
 
     /// <summary>
@@ -1598,7 +1720,7 @@ public class OpcUaClientServiceTests : IDisposable
         await Should.ThrowAsync<ObjectDisposedException>(() =>
             _service.ConnectAsync(ValidSettings()));
         await Should.ThrowAsync<ObjectDisposedException>(() =>
-            _service.ReadValueAsync(new NodeId("ns=2;s=X")));
+            _service.ReadValueAsync(NodeId.Parse("ns=2;s=X")));
     }
 
     // --- Factory tests ---
@@ -1643,7 +1765,7 @@ public class OpcUaClientServiceTests : IDisposable
         await _service.ConnectAsync(ValidSettings(), TestContext.Current.CancellationToken);
 
         // Subscribe data (uses dataFakeSub from session.NextSubscription).
-        await _service.SubscribeAsync(new NodeId("ns=2;s=Node1"), ct: TestContext.Current.CancellationToken);
+        await _service.SubscribeAsync(NodeId.Parse("ns=2;s=Node1"), ct: TestContext.Current.CancellationToken);
 
         // Now set NextSubscription on the session so SubscribeAlarmsAsync gets the alarm fake.
         session.NextSubscription = alarmFakeSub;

tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/Fakes/FakeOpcUaClientService.cs

@@ -191,7 +191,7 @@ public sealed class FakeOpcUaClientService : IOpcUaClientService
         LastBrowseParentNodeId = parentNodeId;
         if (BrowseException != null) throw BrowseException;
 
-        if (parentNodeId != null && BrowseResultsByParent.TryGetValue(parentNodeId.ToString(), out var perParent))
+        if (parentNodeId != null && BrowseResultsByParent.TryGetValue(parentNodeId.Value.ToString(), out var perParent))
             return Task.FromResult(perParent);
 
         return Task.FromResult(BrowseResults);

tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/ReadWriteViewModelTests.cs

@@ -23,6 +23,26 @@ public class ReadWriteViewModelTests
         _vm = new ReadWriteViewModel(_service, dispatcher);
     }
 
+    [Fact]
+    public async Task ReadCommand_FormatsSdkArraysByteStringsAndEmptyText()
+    {
+        _vm.IsConnected = true;
+        _vm.SelectedNodeId = "ns=2;s=SomeNode";
+        foreach (var (value, expected) in new (Variant Value, string Expected)[]
+        {
+            (Variant.From(new int[] { 1, 2 }.ToArrayOf()), "[1,2]"),
+            (Variant.From(ArrayOf<int>.Empty), "[]"),
+            (Variant.From(ByteString.From(new byte[] { 3, 4 })), "[3,4]"),
+            (Variant.From(LocalizedText.Null), ""),
+            (Variant.Null, "(null)")
+        })
+        {
+            _service.ReadResult = new DataValue(value, StatusCodes.Good);
+            await _vm.ReadCommand.ExecuteAsync(null);
+            _vm.CurrentValue.ShouldBe(expected);
+        }
+    }
+
     /// <summary>Verifies that the read command cannot execute when disconnected.</summary>
     [Fact]
     public void ReadCommand_CannotExecute_WhenDisconnected()