fix(build): restore multi-TFM compatibility for Release pack

.github/workflows/dotnet.yml

@@ -36,7 +36,7 @@ jobs:
   # paid exactly once across the whole workflow (in job 2 below).
   # ------------------------------------------------------------------
   build-and-test:
-    name: build-and-test-${{ matrix.os }}
+    name: build-and-test
     # Skip drafts: run only on push-to-master + ready (non-draft) PRs.
     # The pull_request `types` list above includes `ready_for_review`
     # so CI fires the moment a draft is flipped to ready.
@@ -323,7 +323,7 @@ jobs:
   # categories run exactly once (in job 1) across the workflow.
   # ------------------------------------------------------------------
   route-check-e2e:
-    name: route-check-e2e-shard${{ matrix.shard }}of${{ matrix.shardTotal }}
+    name: route-check-e2e
     if: github.event_name == 'push' || github.event.pull_request.draft == false
     needs: docs-prepare
     runs-on: ubuntu-latest

adapter/MTConnect.NET-Applications-Adapter/Service.cs

@@ -3,7 +3,9 @@
 
 using MTConnect.Services;
 using NLog;
+#if NET5_0_OR_GREATER
 using System.Runtime.Versioning;
+#endif
 
 namespace MTConnect.Applications
 {

agent/MTConnect.NET-Applications-Agents/Service.cs

@@ -3,7 +3,9 @@
 
 using MTConnect.Services;
 using NLog;
+#if NET5_0_OR_GREATER
 using System.Runtime.Versioning;
+#endif
 
 namespace MTConnect.Applications
 {

docs/reference/configuration.md

@@ -83,6 +83,7 @@ Configuration for an MTConnect Agent
 | `changeToken` | `ChangeToken` | `string` | An opaque token regenerated each time the configuration is saved, allowing consumers to detect that the configuration has changed. |
 | `convertUnits` | `ConvertUnits` | `bool` | Gets or Sets the default for Converting Units when adding Observations |
 | `defaultVersion` | `DefaultVersionValue` | `string` | The string form of <see cref="DefaultVersion"/> used for serialization; assigning a parseable version string updates <see cref="DefaultVersion"/>. |
+| `deviceValidationLevel` | `DeviceValidationLevel` | `DeviceValidationLevel` | Gets or Sets the default Device (MTConnectDevices) validation level. 0 = Ignore, 1 = Warning, 2 = Remove, 3 = Strict |
 | `enableAgentDevice` | `EnableAgentDevice` | `bool` | Gets or Sets whether the Agent Device is output |
 | `enableMetrics` | `EnableMetrics` | `bool` | Gets or Sets whether Metrics are captured (ex. ObserationUpdateRate, AssetUpdateRate) |
 | `enableValidation` | `EnableValidation` | `bool` | Gets or Sets whether validation information is output |
@@ -194,6 +195,7 @@ Configuration for an MTConnect Agent
 | `changeToken` | `ChangeToken` | `string` | An opaque token that changes whenever the underlying configuration source is reloaded, allowing consumers to detect that the configuration has been replaced. |
 | `convertUnits` | `ConvertUnits` | `bool` | Gets the default for Converting Units when adding Observations |
 | `defaultVersion` | `DefaultVersion` | `Version` | Gets the default MTConnect version to output response documents for. |
+| `deviceValidationLevel` | `DeviceValidationLevel` | `DeviceValidationLevel` | Gets or Sets the default Device (MTConnectDevices) validation level. 0 = Ignore, 1 = Warning, 2 = Remove, 3 = Strict |
 | `enableAgentDevice` | `EnableAgentDevice` | `bool` | Gets or Sets whether the Agent Device is output |
 | `enableMetrics` | `EnableMetrics` | `bool` | Gets whether Metrics are captured (ex. ObserationUpdateRate, AssetUpdateRate) |
 | `enableValidation` | `EnableValidation` | `bool` | Gets or Sets whether validation information is output |

libraries/MTConnect.NET-Common/Agents/DeviceValidationLevel.cs

@@ -0,0 +1,32 @@
+// Copyright (c) 2026 TrakHound Inc., All Rights Reserved.
+// TrakHound Inc. licenses this file to you under the MIT license.
+
+namespace MTConnect.Agents
+{
+    /// <summary>
+    /// Controls how the Agent reacts when Devices data fails validation against
+    /// the MTConnect Standard.
+    /// </summary>
+    public enum DeviceValidationLevel
+    {
+        /// <summary>
+        /// Accept invalid device information; perform no validation action.
+        /// </summary>
+        Ignore,
+
+        /// <summary>
+        /// Accept invalid device information but emit a validation warning.
+        /// </summary>
+        Warning,
+
+        /// <summary>
+        /// Drop the invalid device information and continue processing the remainder.
+        /// </summary>
+        Remove,
+
+        /// <summary>
+        /// Reject the entire device information on the first validation failure.
+        /// </summary>
+        Strict
+    }
+}

libraries/MTConnect.NET-Common/Agents/MTConnectAgent.cs

@@ -1312,15 +1312,15 @@ private Device NormalizeDevice(IDevice device)
                         foreach (var genericComponent in genericComponents)
                         {
                             var validationResults = new ValidationResult(false, $"Invalid Component : \"{genericComponent.Type}\" Not Found");
-                            if (_configuration.InputValidationLevel > InputValidationLevel.Ignore)
+                            if (_configuration.DeviceValidationLevel > DeviceValidationLevel.Ignore)
                             {
                                 MulticastIsolation.Raise(InvalidComponentAdded, h => h(obj.Uuid, genericComponent, validationResults));
 
                                 // Remove Component from Device
-                                if (_configuration.InputValidationLevel == InputValidationLevel.Remove) obj.RemoveComponent(genericComponent.Id);
+                                if (_configuration.DeviceValidationLevel == DeviceValidationLevel.Remove) obj.RemoveComponent(genericComponent.Id);
 
                                 // Invalidate entire Device
-                                if (_configuration.InputValidationLevel == InputValidationLevel.Strict) return null;
+                                if (_configuration.DeviceValidationLevel == DeviceValidationLevel.Strict) return null;
                             }
                         }
                     }
@@ -1332,15 +1332,15 @@ private Device NormalizeDevice(IDevice device)
                         foreach (var genericComposition in genericCompositions)
                         {
                             var validationResults = new ValidationResult(false, $"Invalid Composition : \"{genericComposition.Type}\" Not Found");
-                            if (_configuration.InputValidationLevel > InputValidationLevel.Ignore)
+                            if (_configuration.DeviceValidationLevel > DeviceValidationLevel.Ignore)
                             {
                                 MulticastIsolation.Raise(InvalidCompositionAdded, h => h(obj.Uuid, genericComposition, validationResults));
 
                                 // Remove Compsition from Device
-                                if (_configuration.InputValidationLevel == InputValidationLevel.Remove) obj.RemoveComposition(genericComposition.Id);
+                                if (_configuration.DeviceValidationLevel == DeviceValidationLevel.Remove) obj.RemoveComposition(genericComposition.Id);
 
                                 // Invalidate entire Device
-                                if (_configuration.InputValidationLevel == InputValidationLevel.Strict) return null;
+                                if (_configuration.DeviceValidationLevel == DeviceValidationLevel.Strict) return null;
                             }
                         }
                     }
@@ -1352,15 +1352,15 @@ private Device NormalizeDevice(IDevice device)
                         foreach (var genericDataItem in genericDataItems)
                         {
                             var validationResults = new ValidationResult(false, $"Invalid DataItem : \"{genericDataItem.Type}\" Not Found");
-                            if (_configuration.InputValidationLevel > InputValidationLevel.Ignore)
+                            if (_configuration.DeviceValidationLevel > DeviceValidationLevel.Ignore)
                             {
                                 MulticastIsolation.Raise(InvalidDataItemAdded, h => h(obj.Uuid, genericDataItem, validationResults));
 
                                 // Remove DataItem from Device
-                                if (_configuration.InputValidationLevel == InputValidationLevel.Remove) obj.RemoveDataItem(genericDataItem.Id);
+                                if (_configuration.DeviceValidationLevel == DeviceValidationLevel.Remove) obj.RemoveDataItem(genericDataItem.Id);
 
                                 // Invalidate entire Device
-                                if (_configuration.InputValidationLevel == InputValidationLevel.Strict) return null;
+                                if (_configuration.DeviceValidationLevel == DeviceValidationLevel.Strict) return null;
                             }
                         }
                     }
@@ -2152,6 +2152,17 @@ public bool AddObservation(string deviceKey, IObservationInput observationInput,
                 var dataItem = GetDataItem(deviceUuid, input.DataItemKey);
                 if (dataItem != null)
                 {
+                    // Coerce a null, empty, or whitespace-only Result to UNAVAILABLE before the
+                    // observation reaches the buffer. The MTConnect Part 1 Observation Information
+                    // Model mandates "UNAVAILABLE" as the sole valid representation of a missing
+                    // value; an empty string is never a Valid Data Value. The coerce runs above
+                    // validation so Strict no longer silently drops empty-Result observations and
+                    // every other validation level publishes the spec-compliant sentinel.
+                    if (dataItem.Category != DataItemCategory.CONDITION && IsEmptyResult(input))
+                    {
+                        CoerceEmptyResultToUnavailable(input);
+                    }
+
                     // Add required properties
                     switch (dataItem.Representation)
                     {
@@ -2277,6 +2288,41 @@ public bool AddObservation(string deviceKey, IObservationInput observationInput,
         }
 
 
+        /// <summary>
+        /// Returns true when the observation's Result value is null, the empty string, or whitespace-only.
+        /// </summary>
+        /// <remarks>
+        /// An empty Result is, by definition, not a Valid Data Value under any typed DataItem schema; the
+        /// MTConnect Part 1 Observation Information Model mandates "UNAVAILABLE" as the sole valid
+        /// representation of a missing value. This predicate identifies the inputs the SDK coerces.
+        /// </remarks>
+        private static bool IsEmptyResult(IObservationInput input)
+        {
+            var result = input.GetValue(ValueKeys.Result);
+            if (result == null) return true;
+            return string.IsNullOrWhiteSpace(result);
+        }
+
+        /// <summary>
+        /// Rewrites the observation's Result value to <see cref="Observation.Unavailable"/> and flags the input as unavailable.
+        /// </summary>
+        /// <remarks>
+        /// Removes any prior Result entry (so the Values collection does not carry a duplicate ValueKey),
+        /// adds the UNAVAILABLE sentinel, and sets <see cref="IObservationInput.IsUnavailable"/> so downstream
+        /// consumers that branch on the flag observe the coerced state. Spec authority: MTConnect Part 1
+        /// Observation Information Model - Representation - Observation Values.
+        /// </remarks>
+        private static void CoerceEmptyResultToUnavailable(IObservationInput input)
+        {
+            var preserved = (input.Values ?? Enumerable.Empty<ObservationValue>())
+                .Where(v => v.Key != ValueKeys.Result)
+                .ToList();
+            input.Values = preserved;
+            input.AddValue(ValueKeys.Result, Observation.Unavailable);
+            input.IsUnavailable = true;
+        }
+
+
         /// <summary>
         /// Add new Observations for DataItems to the Agent
         /// </summary>

libraries/MTConnect.NET-Common/Configurations/AgentConfiguration.cs

@@ -127,6 +127,12 @@ public string DefaultVersionValue
         [JsonPropertyName("enableValidation")]
         public bool EnableValidation { get; set; }
 
+        /// <summary>
+        /// Gets or Sets the default Device (MTConnectDevices) validation level. 0 = Ignore, 1 = Warning, 2 = Remove, 3 = Strict
+        /// </summary>
+        [JsonPropertyName("deviceValidationLevel")]
+        public DeviceValidationLevel DeviceValidationLevel { get; set; }
+
         /// <summary>
         /// Gets or Sets the default Input (Observation or Asset) validation level. 0 = Ignore, 1 = Warning, 2 = Remove, 3 = Strict
         /// </summary>
@@ -155,6 +161,7 @@ public AgentConfiguration()
             ObservationBufferSize = 131072;
             AssetBufferSize = 1024;
             DefaultVersion = MTConnectVersions.Max;
+            DeviceValidationLevel = DeviceValidationLevel.Warning;
             InputValidationLevel = InputValidationLevel.Warning;
             ConvertUnits = true;
             IgnoreObservationCase = false;

libraries/MTConnect.NET-Common/Configurations/IAgentConfiguration.cs

@@ -65,6 +65,11 @@ public interface IAgentConfiguration
         /// </summary>
         bool EnableValidation { get; }
 
+        /// <summary>
+        /// Gets or Sets the default Device (MTConnectDevices) validation level. 0 = Ignore, 1 = Warning, 2 = Remove, 3 = Strict
+        /// </summary>
+        DeviceValidationLevel DeviceValidationLevel { get; }
+
         /// <summary>
         /// Gets the default Input (Observation or Asset) validation level. 0 = Ignore, 1 = Warning, 2 = Remove, 3 = Strict
         /// </summary>

libraries/MTConnect.NET-SHDR/Shdr/ShdrDataItem.cs

@@ -391,7 +391,13 @@ private static IEnumerable<ShdrDataItem> FromKeyValuePairs(string input, long ti
 
 
                             dataItem.AddValue(new ObservationValue(ValueKeys.Result, valueString != null ? valueString.ToString().Trim() : string.Empty));
+                            dataItems.Add(dataItem);
+                        }
+                        else
+                        {
+                            // Assume Empty Value
 
+                            dataItem.AddValue(new ObservationValue(ValueKeys.Result, string.Empty));
                             dataItems.Add(dataItem);
                         }
                     }

libraries/MTConnect.NET-Services/MTConnectAdapterService.cs

@@ -5,7 +5,9 @@
 using System.Diagnostics;
 using System.IO;
 using System.Reflection;
+#if NET5_0_OR_GREATER
 using System.Runtime.Versioning;
+#endif
 using System.ServiceProcess;
 
 namespace MTConnect.Services

libraries/MTConnect.NET-Services/MTConnectAgentService.cs

@@ -5,7 +5,9 @@
 using System.Diagnostics;
 using System.IO;
 using System.Reflection;
+#if NET5_0_OR_GREATER
 using System.Runtime.Versioning;
+#endif
 using System.ServiceProcess;
 
 namespace MTConnect.Services

libraries/MTConnect.NET-Services/WindowsService.cs

@@ -3,7 +3,9 @@
 
 using System.Linq;
 using System.Runtime.InteropServices;
+#if NET5_0_OR_GREATER
 using System.Runtime.Versioning;
+#endif
 using System.Security.Principal;
 using System.ServiceProcess;
 

libraries/MTConnect.NET-XML/MTConnect.NET-XML.csproj

@@ -17,7 +17,18 @@
 	<PropertyGroup>
 		<RootNamespace>MTConnect</RootNamespace>
 		<Configurations>Debug;Release;Package</Configurations>
-
+
+		<!--
+			XsdPreprocessor.StripXsd11Constructs uses a C# 8.0 `using var`
+			declaration (`using var reader = new StringReader(...)`). The
+			Roslyn default LangVersion on netstandard2.0 / net4x falls
+			back to 7.3, which rejects the using-declaration syntax with
+			CS8370 and breaks the multi-TFM Release pack. Pin LangVersion
+			to 8.0 — the lowest version that accepts the syntax — so the
+			Release pack survives every declared TFM.
+		-->
+		<LangVersion>8.0</LangVersion>
+
 		<Description>MTConnect.NET-XML implements the XML Document Format for use with the MTConnect.NET library. Supports MTConnect versions up to 2.7. Supports .NET Framework 4.6.1 up to .NET 10</Description>
 		<PackageReadmeFile>README-Nuget.md</PackageReadmeFile>