.NET: Fix some more static analysis diagnostics (#1025)

* S1006

* S2219

* S3236

* S3260

* S1125

* IDE0063

* IDE0062

* IDE0028

dotnet/samples/GettingStarted/Agents/Agent_Step07_3rdPartyThreadStorage/Program.cs

@@ -96,7 +96,7 @@ namespace SampleApp
 
         public string? ThreadDbKey { get; private set; }
 
-        public override async Task AddMessagesAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken)
+        public override async Task AddMessagesAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken = default)
         {
             this.ThreadDbKey ??= Guid.NewGuid().ToString("N");
 
@@ -113,7 +113,7 @@ namespace SampleApp
             }), cancellationToken);
         }
 
-        public override async Task<IEnumerable<ChatMessage>> GetMessagesAsync(CancellationToken cancellationToken)
+        public override async Task<IEnumerable<ChatMessage>> GetMessagesAsync(CancellationToken cancellationToken = default)
         {
             var collection = this._vectorStore.GetCollection<string, ChatHistoryItem>("ChatHistory");
             await collection.EnsureCollectionExistsAsync(cancellationToken);

dotnet/samples/GettingStarted/Workflows/Concurrent/MapReduce/Program.cs

@@ -219,7 +219,7 @@ internal sealed class Shuffler(string[] reducerIds, string[] mapperIds, string i
 {
     private readonly string[] _reducerIds = reducerIds;
     private readonly string[] _mapperIds = mapperIds;
-    private readonly List<MapComplete> _mapResults = new();
+    private readonly List<MapComplete> _mapResults = [];
 
     /// <summary>
     /// Aggregate mapper outputs and write one partition file per reducer.

dotnet/src/Microsoft.Agents.AI.Abstractions/InMemoryChatMessageStore.cs

@@ -97,7 +97,7 @@ public sealed class InMemoryChatMessageStore : ChatMessageStore, IList<ChatMessa
     }
 
     /// <inheritdoc />
-    public override async Task AddMessagesAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken)
+    public override async Task AddMessagesAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken = default)
     {
         _ = Throw.IfNull(messages);
 
@@ -110,7 +110,7 @@ public sealed class InMemoryChatMessageStore : ChatMessageStore, IList<ChatMessa
     }
 
     /// <inheritdoc />
-    public override async Task<IEnumerable<ChatMessage>> GetMessagesAsync(CancellationToken cancellationToken)
+    public override async Task<IEnumerable<ChatMessage>> GetMessagesAsync(CancellationToken cancellationToken = default)
     {
         if (this.ReducerTriggerEvent is ChatReducerTriggerEvent.BeforeMessagesRetrieval && this.ChatReducer is not null)
         {

dotnet/src/Microsoft.Agents.AI.Hosting.A2A/AIAgentExtensions.cs

@@ -26,8 +26,8 @@ public static class AIAgentExtensions
         TaskManager? taskManager = null,
         ILoggerFactory? loggerFactory = null)
     {
-        ArgumentNullException.ThrowIfNull(agent, nameof(agent));
-        ArgumentNullException.ThrowIfNull(agent.Name, nameof(agent.Name));
+        ArgumentNullException.ThrowIfNull(agent);
+        ArgumentNullException.ThrowIfNull(agent.Name);
 
         taskManager ??= new();
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/DeclarativeWorkflowOptions.cs

@@ -15,7 +15,7 @@ public sealed class DeclarativeWorkflowOptions(WorkflowAgentProvider agentProvid
     /// <summary>
     /// Defines the agent provider.
     /// </summary>
-    public WorkflowAgentProvider AgentProvider { get; } = Throw.IfNull(agentProvider, nameof(agentProvider));
+    public WorkflowAgentProvider AgentProvider { get; } = Throw.IfNull(agentProvider);
 
     /// <summary>
     /// Defines the configuration settings for the workflow.

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/AddConversationMessageExecutor.cs

@@ -15,7 +15,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class AddConversationMessageExecutor(AddConversationMessage model, WorkflowAgentProvider agentProvider, WorkflowFormulaState state) :
     DeclarativeActionExecutor<AddConversationMessage>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(this.Model.ConversationId, $"{nameof(this.Model)}.{nameof(this.Model.ConversationId)}");
         string conversationId = this.Evaluator.GetValue(this.Model.ConversationId).Value;

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/ClearAllVariablesExecutor.cs

@@ -13,7 +13,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class ClearAllVariablesExecutor(ClearAllVariables model, WorkflowFormulaState state)
     : DeclarativeActionExecutor<ClearAllVariables>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         EvaluationResult<VariablesToClearWrapper> variablesResult = this.Evaluator.GetValue(this.Model.Variables);
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/ConditionGroupExecutor.cs

@@ -48,7 +48,7 @@ internal sealed class ConditionGroupExecutor : DeclarativeActionExecutor<Conditi
         return string.Equals(Steps.Else(this.Model), executorMessage.Result as string, StringComparison.Ordinal);
     }
 
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         for (int index = 0; index < this.Model.Conditions.Length; ++index)
         {

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/CopyConversationMessagesExecutor.cs

@@ -16,7 +16,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class CopyConversationMessagesExecutor(CopyConversationMessages model, WorkflowAgentProvider agentProvider, WorkflowFormulaState state) :
     DeclarativeActionExecutor<CopyConversationMessages>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(this.Model.ConversationId, $"{nameof(this.Model)}.{nameof(this.Model.ConversationId)}");
         string conversationId = this.Evaluator.GetValue(this.Model.ConversationId).Value;

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/CreateConversationExecutor.cs

@@ -12,7 +12,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class CreateConversationExecutor(CreateConversation model, WorkflowAgentProvider agentProvider, WorkflowFormulaState state) :
     DeclarativeActionExecutor<CreateConversation>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         string conversationId = await agentProvider.CreateConversationAsync(cancellationToken).ConfigureAwait(false);
         await this.AssignAsync(this.Model.ConversationId?.Path, FormulaValue.New(conversationId), context).ConfigureAwait(false);

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/DefaultActionExecutor.cs

@@ -11,7 +11,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class DefaultActionExecutor(DialogAction model, WorkflowFormulaState state) :
     DeclarativeActionExecutor(model, state)
 {
-    protected override ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         // No action needed - the edge will be followed automatically
         return default;

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/EditTableExecutor.cs

@@ -16,7 +16,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 
 internal sealed class EditTableExecutor(EditTable model, WorkflowFormulaState state) : DeclarativeActionExecutor<EditTable>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         PropertyPath variablePath = Throw.IfNull(this.Model.ItemsVariable?.Path, $"{nameof(this.Model)}.{nameof(this.Model.ItemsVariable)}");
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/EditTableV2Executor.cs

@@ -16,7 +16,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 
 internal sealed class EditTableV2Executor(EditTableV2 model, WorkflowFormulaState state) : DeclarativeActionExecutor<EditTableV2>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         PropertyPath variablePath = Throw.IfNull(this.Model.ItemsVariable?.Path, $"{nameof(this.Model)}.{nameof(this.Model.ItemsVariable)}");
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/ForeachExecutor.cs

@@ -35,7 +35,7 @@ internal sealed class ForeachExecutor : DeclarativeActionExecutor<Foreach>
 
     protected override bool IsDiscreteAction => false;
 
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         this._index = 0;
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/InvokeAzureAgentExecutor.cs

@@ -20,7 +20,7 @@ internal sealed class InvokeAzureAgentExecutor(InvokeAzureAgent model, WorkflowA
     private AzureAgentInput? AgentInput => this.Model.Input;
     private AzureAgentOutput? AgentOutput => this.Model.Output;
 
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         string? conversationId = this.GetConversationId();
         string agentName = this.GetAgentName();

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/ParseValueExecutor.cs

@@ -17,7 +17,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class ParseValueExecutor(ParseValue model, WorkflowFormulaState state) :
     DeclarativeActionExecutor<ParseValue>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         PropertyPath variablePath = Throw.IfNull(this.Model.Variable?.Path, $"{nameof(this.Model)}.{nameof(model.Variable)}");
         ValueExpression valueExpression = Throw.IfNull(this.Model.Value, $"{nameof(this.Model)}.{nameof(this.Model.Value)}");

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/QuestionExecutor.cs

@@ -37,7 +37,7 @@ internal sealed class QuestionExecutor(Question model, WorkflowFormulaState stat
         return executorMessage.Result is null;
     }
 
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         await this._promptCount.WriteAsync(context, 0).ConfigureAwait(false);
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/ResetVariableExecutor.cs

@@ -14,7 +14,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class ResetVariableExecutor(ResetVariable model, WorkflowFormulaState state) :
     DeclarativeActionExecutor<ResetVariable>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(this.Model.Variable, $"{nameof(this.Model)}.{nameof(model.Variable)}");
         await context.QueueStateResetAsync(this.Model.Variable).ConfigureAwait(false);

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/RetrieveConversationMessageExecutor.cs

@@ -14,7 +14,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class RetrieveConversationMessageExecutor(RetrieveConversationMessage model, WorkflowAgentProvider agentProvider, WorkflowFormulaState state) :
     DeclarativeActionExecutor<RetrieveConversationMessage>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(this.Model.ConversationId, $"{nameof(this.Model)}.{nameof(this.Model.ConversationId)}");
         string conversationId = this.Evaluator.GetValue(this.Model.ConversationId).Value;

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/RetrieveConversationMessagesExecutor.cs

@@ -16,7 +16,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class RetrieveConversationMessagesExecutor(RetrieveConversationMessages model, WorkflowAgentProvider agentProvider, WorkflowFormulaState state) :
     DeclarativeActionExecutor<RetrieveConversationMessages>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         Throw.IfNull(this.Model.ConversationId, $"{nameof(this.Model)}.{nameof(this.Model.ConversationId)}");
         string conversationId = this.Evaluator.GetValue(this.Model.ConversationId).Value;

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/SendActivityExecutor.cs

@@ -12,7 +12,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class SendActivityExecutor(SendActivity model, WorkflowFormulaState state) :
     DeclarativeActionExecutor<SendActivity>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         if (this.Model.Activity is MessageActivityTemplate messageActivity)
         {

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/SetMultipleVariablesExecutor.cs

@@ -14,7 +14,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class SetMultipleVariablesExecutor(SetMultipleVariables model, WorkflowFormulaState state)
     : DeclarativeActionExecutor<SetMultipleVariables>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         foreach (VariableAssignment assignment in this.Model.Assignments)
         {

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/SetTextVariableExecutor.cs

@@ -13,7 +13,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class SetTextVariableExecutor(SetTextVariable model, WorkflowFormulaState state)
     : DeclarativeActionExecutor<SetTextVariable>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         if (this.Model.Value is null)
         {

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/SetVariableExecutor.cs

@@ -15,7 +15,7 @@ namespace Microsoft.Agents.AI.Workflows.Declarative.ObjectModel;
 internal sealed class SetVariableExecutor(SetVariable model, WorkflowFormulaState state)
     : DeclarativeActionExecutor<SetVariable>(model, state)
 {
-    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken)
+    protected override async ValueTask<object?> ExecuteAsync(IWorkflowContext context, CancellationToken cancellationToken = default)
     {
         PropertyPath variablePath = Throw.IfNull(this.Model.Variable?.Path, $"{nameof(this.Model)}.{nameof(model.Variable)}");
 

dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/PowerFx/WorkflowExpressionEngine.cs

@@ -43,7 +43,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<bool> Evaluate(BoolExpression expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -67,7 +67,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<string> Evaluate(StringExpression expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -96,7 +96,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<long> Evaluate(IntExpression expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -120,7 +120,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<double> Evaluate(NumberExpression expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -149,7 +149,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<DataValue> Evaluate(ValueExpression expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -163,7 +163,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<TValue> Evaluate<TValue>(EnumExpression<TValue> expression) where TValue : EnumWrapper
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -184,7 +184,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<TValue?> Evaluate<TValue>(ObjectExpression<TValue> expression) where TValue : BotElement
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.LiteralValue is not null)
         {
@@ -215,7 +215,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<ImmutableArray<TValue>> Evaluate<TValue>(ArrayExpression<TValue> expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         if (expression.IsLiteral)
         {
@@ -229,7 +229,7 @@ internal sealed class WorkflowExpressionEngine
 
     private EvaluationResult<ImmutableArray<TValue>> Evaluate<TValue>(ArrayExpressionOnly<TValue> expression)
     {
-        Throw.IfNull(expression, nameof(expression));
+        Throw.IfNull(expression);
 
         EvaluationResult<FormulaValue> expressionResult = this.EvaluateScope(expression);
 

dotnet/src/Microsoft.Agents.AI.Workflows/AgentWorkflowBuilder.cs

@@ -583,7 +583,7 @@ public static partial class AgentWorkflowBuilder
             public ValueTask ResetAsync() => default;
         }
 
-        private record class HandoffState(
+        private sealed record class HandoffState(
             TurnToken TurnToken,
             string? InvokedHandoff,
             List<ChatMessage> Messages);

dotnet/src/Microsoft.Agents.AI.Workflows/Execution/EdgeMap.cs

@@ -11,7 +11,7 @@ namespace Microsoft.Agents.AI.Workflows.Execution;
 internal sealed class EdgeMap
 {
     private readonly Dictionary<EdgeId, EdgeRunner> _edgeRunners = [];
-    private readonly Dictionary<EdgeId, IStatefulEdgeRunner> _statefulRunners = new();
+    private readonly Dictionary<EdgeId, IStatefulEdgeRunner> _statefulRunners = [];
     private readonly Dictionary<string, InputEdgeRunner> _portEdgeRunners;
 
     private readonly InputEdgeRunner _inputRunner;

dotnet/src/Microsoft.Agents.AI.Workflows/Execution/MessageEnvelope.cs

@@ -21,7 +21,7 @@ internal sealed class MessageEnvelope(object message, ExecutorIdentity source, T
     internal MessageEnvelope(object message, ExecutorIdentity source, Type declaredType, string? targetId = null)
         : this(message, source, new TypeId(declaredType), targetId)
     {
-        if (!declaredType.IsAssignableFrom(message.GetType()))
+        if (!declaredType.IsInstanceOfType(message))
         {
             throw new ArgumentException($"The declared type {declaredType} is not compatible with the message instance of type {message.GetType()}");
         }

dotnet/src/Microsoft.Agents.AI.Workflows/ExternalRequest.cs

@@ -39,7 +39,7 @@ public record ExternalRequest(InputPortInfo PortInfo, string RequestId, Portable
     /// <exception cref="InvalidOperationException">Thrown when the input data object does not match the expected request type.</exception>
     public static ExternalRequest Create(InputPort port, [NotNull] object data, string? requestId = null)
     {
-        if (!port.Request.IsAssignableFrom(Throw.IfNull(data).GetType()))
+        if (!port.Request.IsInstanceOfType(Throw.IfNull(data)))
         {
             throw new InvalidOperationException(
                 $"Message type {data.GetType().Name} is not assignable to the request type {port.Request.Name} of input port {port.Id}.");

dotnet/src/Microsoft.Agents.AI.Workflows/PortableValue.cs

@@ -158,7 +158,7 @@ public sealed class PortableValue
             this._deserializedValueCache ??= delayedDeserialization.Deserialize(targetType);
         }
 
-        if (this.Value is not null && targetType.IsAssignableFrom(this.Value.GetType()))
+        if (this.Value is not null && targetType.IsInstanceOfType(this.Value))
         {
             value = this.Value;
             return true;

dotnet/src/Microsoft.Agents.AI.Workflows/Reflection/RouteBuilderExtensions.cs

@@ -86,7 +86,7 @@ internal static class RouteBuilderExtensions
         Throw.IfNull(builder);
 
         Type executorType = typeof(TExecutor);
-        Debug.Assert(executorType.IsAssignableFrom(executor.GetType()),
+        Debug.Assert(executorType.IsInstanceOfType(executor),
             "executorType must be the same type or a base type of the executor instance.");
 
         foreach (MessageHandlerInfo handlerInfo in executorType.GetHandlerInfos())

dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/RequestInfoExecutor.cs

@@ -11,7 +11,7 @@ namespace Microsoft.Agents.AI.Workflows.Specialized;
 
 internal sealed class RequestInfoExecutor : Executor
 {
-    private readonly Dictionary<string, ExternalRequest> _wrappedRequests = new();
+    private readonly Dictionary<string, ExternalRequest> _wrappedRequests = [];
     private InputPort Port { get; }
     private IExternalRequestSink? RequestSink { get; set; }
 
@@ -57,7 +57,7 @@ internal sealed class RequestInfoExecutor : Executor
         object? maybeRequest = message.AsType(this.Port.Request);
         if (maybeRequest != null)
         {
-            Debug.Assert(this.Port.Request.IsAssignableFrom(maybeRequest.GetType()));
+            Debug.Assert(this.Port.Request.IsInstanceOfType(maybeRequest));
 
             ExternalRequest request = ExternalRequest.Create(this.Port, maybeRequest!);
             await this.RequestSink!.PostAsync(request).ConfigureAwait(false);
@@ -93,7 +93,7 @@ internal sealed class RequestInfoExecutor : Executor
     public async ValueTask<ExternalRequest> HandleAsync(object message, IWorkflowContext context)
     {
         Throw.IfNull(message);
-        Debug.Assert(this.Port.Request.IsAssignableFrom(message.GetType()));
+        Debug.Assert(this.Port.Request.IsInstanceOfType(message));
 
         ExternalRequest request = ExternalRequest.Create(this.Port, message);
         await this.RequestSink!.PostAsync(request).ConfigureAwait(false);

dotnet/src/Microsoft.Agents.AI.Workflows/Visualization/WorkflowVisualizer.cs

@@ -21,7 +21,7 @@ public static class WorkflowVisualizer
     /// <returns>A string representation of the workflow in DOT format.</returns>
     public static string ToDotString(this Workflow workflow)
     {
-        Throw.IfNull(workflow, nameof(workflow));
+        Throw.IfNull(workflow);
 
         var lines = new List<string>
     {
@@ -249,10 +249,7 @@ public static class WorkflowVisualizer
     {
         var sortedSources = sources.OrderBy(x => x, StringComparer.Ordinal).ToList();
         var input = target + "|" + string.Join("|", sortedSources);
-        using (var sha256 = SHA256.Create())
-        {
-            return ComputeShortHash(input);
-        }
+        return ComputeShortHash(input);
     }
 
     private static string ComputeShortHash(string input)

dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowHostAgent.cs

@@ -24,7 +24,7 @@ internal sealed class WorkflowHostAgent : AIAgent
 
     public WorkflowHostAgent(Workflow<List<ChatMessage>> workflow, string? id = null, string? name = null)
     {
-        this._workflow = Throw.IfNull(workflow, nameof(workflow));
+        this._workflow = Throw.IfNull(workflow);
 
         this._id = id;
         this.Name = name;

dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowMessageStore.cs

@@ -45,14 +45,14 @@ internal sealed class WorkflowMessageStore : ChatMessageStore
 
     internal void AddMessages(params IEnumerable<ChatMessage> messages) => this._chatMessages.AddRange(messages);
 
-    public override Task AddMessagesAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken)
+    public override Task AddMessagesAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken = default)
     {
         this._chatMessages.AddRange(messages);
 
         return Task.CompletedTask;
     }
 
-    public override Task<IEnumerable<ChatMessage>> GetMessagesAsync(CancellationToken cancellationToken) => Task.FromResult<IEnumerable<ChatMessage>>(this._chatMessages.AsReadOnly());
+    public override Task<IEnumerable<ChatMessage>> GetMessagesAsync(CancellationToken cancellationToken = default) => Task.FromResult<IEnumerable<ChatMessage>>(this._chatMessages.AsReadOnly());
 
     public IEnumerable<ChatMessage> GetFromBookmark()
     {

dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowOutputEvent.cs

@@ -31,9 +31,7 @@ public sealed class WorkflowOutputEvent : WorkflowEvent
     /// </summary>
     /// <param name="type">The type to compare with the type of the underlying data.</param>
     /// <returns>true if the underlying data is assignable to type T; otherwise, false.</returns>
-    public bool IsType(Type type) => this.Data == null
-                                   ? false
-                                   : type.IsAssignableFrom(this.Data.GetType());
+    public bool IsType(Type type) => this.Data is { } data && type.IsInstanceOfType(data);
 
     /// <summary>
     /// Attempts to retrieve the underlying data as the specified type.

dotnet/src/Microsoft.Agents.AI.Workflows/WorkflowThread.cs

@@ -12,7 +12,7 @@ internal sealed class WorkflowThread : AgentThread
     public WorkflowThread(string workflowId, string? workflowName, string runId)
     {
         this.MessageStore = new();
-        this.RunId = Throw.IfNullOrEmpty(runId, nameof(runId));
+        this.RunId = Throw.IfNullOrEmpty(runId);
     }
 
     public WorkflowThread(JsonElement serializedThread, JsonSerializerOptions? jsonSerializerOptions = null)

dotnet/src/Microsoft.Agents.AI/OpenTelemetryAgent.cs

@@ -171,7 +171,7 @@ public sealed class OpenTelemetryAgent : DelegatingAIAgent, IDisposable
     private sealed class ForwardingChatClient(OpenTelemetryAgent parentAgent) : IChatClient
     {
         public async Task<ChatResponse> GetResponseAsync(
-            IEnumerable<ChatMessage> messages, ChatOptions? options, CancellationToken cancellationToken)
+            IEnumerable<ChatMessage> messages, ChatOptions? options = null, CancellationToken cancellationToken = default)
         {
             ForwardedOptions? fo = options as ForwardedOptions;
 
@@ -186,7 +186,7 @@ public sealed class OpenTelemetryAgent : DelegatingAIAgent, IDisposable
         }
 
         public async IAsyncEnumerable<ChatResponseUpdate> GetStreamingResponseAsync(
-            IEnumerable<ChatMessage> messages, ChatOptions? options, [EnumeratorCancellation] CancellationToken cancellationToken)
+            IEnumerable<ChatMessage> messages, ChatOptions? options = null, [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
             ForwardedOptions? fo = options as ForwardedOptions;
 

dotnet/tests/Microsoft.Agents.AI.UnitTests/ChatClient/ChatClientAgentRunOptionsTests.cs

@@ -320,7 +320,7 @@ public class ChatClientAgentRunOptionsTests
         // Arrange
         var originalClient = new Mock<IChatClient>();
 
-        IChatClient ClientFactory(IChatClient client) => null!;
+        static IChatClient ClientFactory(IChatClient client) => null!;
 
         var agent = new ChatClientAgent(originalClient.Object);
         var messages = new List<ChatMessage> { new(ChatRole.User, "Test message") };

dotnet/tests/Microsoft.Agents.AI.UnitTests/FunctionInvocationDelegatingAgentTests.cs

@@ -344,7 +344,7 @@ public sealed class FunctionInvocationDelegatingAgentTests
                 if (options?.Tools?.FirstOrDefault() is AIFunction function)
                 {
                     executionOrder.Add("Direct-Function-Invocation");
-                    await function.InvokeAsync(new AIFunctionArguments(), ct);
+                    await function.InvokeAsync([], ct);
                 }
                 return new ChatResponse([new ChatMessage(ChatRole.Assistant, "Response after direct invocation")]);
             });
@@ -476,7 +476,7 @@ public sealed class FunctionInvocationDelegatingAgentTests
         var messages = new List<ChatMessage> { new(ChatRole.User, "Test message") };
         const string ModifiedResult = "Modified by middleware";
 
-        async ValueTask<object?> MiddlewareCallbackAsync(AIAgent agent, FunctionInvocationContext context, Func<FunctionInvocationContext, CancellationToken, ValueTask<object?>> next, CancellationToken cancellationToken)
+        static async ValueTask<object?> MiddlewareCallbackAsync(AIAgent agent, FunctionInvocationContext context, Func<FunctionInvocationContext, CancellationToken, ValueTask<object?>> next, CancellationToken cancellationToken)
         {
             await next(context, cancellationToken);
             return ModifiedResult; // Return the modified result instead of setting context property
@@ -770,7 +770,7 @@ public sealed class FunctionInvocationDelegatingAgentTests
         var innerAgent = new ChatClientAgent(mockChatClient.Object);
         var messages = new List<ChatMessage> { new(ChatRole.User, "Test message") };
 
-        ValueTask<object?> MiddlewareCallbackAsync(AIAgent agent, FunctionInvocationContext context, Func<FunctionInvocationContext, CancellationToken, ValueTask<object?>> next, CancellationToken cancellationToken)
+        static ValueTask<object?> MiddlewareCallbackAsync(AIAgent agent, FunctionInvocationContext context, Func<FunctionInvocationContext, CancellationToken, ValueTask<object?>> next, CancellationToken cancellationToken)
         {
             // Don't call next() - this should prevent function execution
             // Return the blocked result directly

dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Framework/TestOutputAdapter.cs

@@ -21,13 +21,13 @@ public sealed class TestOutputAdapter(ITestOutputHelper output) : TextWriter, IL
 
     public bool IsEnabled(LogLevel logLevel) => true;
 
-    public override void WriteLine(object? value = null) => this.SafeWrite($"{value}");
+    public override void WriteLine(object? value) => this.SafeWrite($"{value}");
 
     public override void WriteLine(string? format, params object?[] arg) => this.SafeWrite(string.Format(format ?? string.Empty, arg));
 
     public override void WriteLine(string? value) => this.SafeWrite(value ?? string.Empty);
 
-    public override void Write(object? value = null) => this.SafeWrite($"{value}");
+    public override void Write(object? value) => this.SafeWrite($"{value}");
 
     public override void Write(char[]? buffer) => this.SafeWrite(new string(buffer));
 

dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/TestOutputAdapter.cs

@@ -21,13 +21,13 @@ public sealed class TestOutputAdapter(ITestOutputHelper output) : TextWriter, IL
 
     public bool IsEnabled(LogLevel logLevel) => true;
 
-    public override void WriteLine(object? value = null) => this.SafeWrite($"{value}");
+    public override void WriteLine(object? value) => this.SafeWrite($"{value}");
 
     public override void WriteLine(string? format, params object?[] arg) => this.SafeWrite(string.Format(format ?? string.Empty, arg));
 
     public override void WriteLine(string? value) => this.SafeWrite(value ?? string.Empty);
 
-    public override void Write(object? value = null) => this.SafeWrite($"{value}");
+    public override void Write(object? value) => this.SafeWrite($"{value}");
 
     public override void Write(char[]? buffer) => this.SafeWrite(new string(buffer));
 

dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/EdgeRunnerTests.cs

@@ -103,7 +103,7 @@ public class EdgeRunnerTests
                                     && (!targetMatch.HasValue || targetMatch.Value);
         bool expectForwardFrom3 = !assignerSelectsEmpty.HasValue && !targetMatch.HasValue; // if there is a target, it is never executor3
 
-        HashSet<string> expectedReceivers = new();
+        HashSet<string> expectedReceivers = [];
         if (expectForwardFrom2)
         {
             expectedReceivers.Add("executor2");

dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/Sample/05_Simple_Workflow_Checkpointing.cs

@@ -13,7 +13,7 @@ internal static class Step5EntryPoint
 {
     public static async ValueTask<string> RunAsync(TextWriter writer, Func<string, int> userGuessCallback, bool rehydrateToRestore = false, CheckpointManager? checkpointManager = null)
     {
-        Dictionary<CheckpointInfo, (NumberSignal signal, string? prompt)> checkpointedOutputs = new();
+        Dictionary<CheckpointInfo, (NumberSignal signal, string? prompt)> checkpointedOutputs = [];
 
         NumberSignal signal = NumberSignal.Init;
         string? prompt = Step4EntryPoint.UpdatePrompt(null, signal);

dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/WorkflowVisualizerTests.cs

@@ -84,7 +84,7 @@ public class WorkflowVisualizerTests
         var end = new MockExecutor("end");
 
         // Condition that is never used during viz, but presence should mark the edge
-        bool OnlyIfFoo(string? msg) => msg == "foo";
+        static bool OnlyIfFoo(string? msg) => msg == "foo";
 
         var workflow = new WorkflowBuilder("start")
             .AddEdge<string>(start, mid, OnlyIfFoo)
@@ -195,7 +195,7 @@ public class WorkflowVisualizerTests
         var c = new MockExecutor("c");
         var end = new ListStrTargetExecutor("end");
 
-        bool Condition(string? msg) => msg?.Contains("test") ?? false;
+        static bool Condition(string? msg) => msg?.Contains("test") ?? false;
 
         var workflow = new WorkflowBuilder("start")
             .AddEdge<string>(start, a, Condition) // Conditional edge
@@ -241,7 +241,7 @@ public class WorkflowVisualizerTests
         // Test visualization of self-loop edge
         var executor = new MockExecutor("loop");
 
-        bool LoopCondition(string? msg) => (msg?.Length ?? 0) < 10;
+        static bool LoopCondition(string? msg) => (msg?.Length ?? 0) < 10;
 
         var workflow = new WorkflowBuilder("loop")
             .AddEdge<string>(executor, executor, LoopCondition)
@@ -281,7 +281,7 @@ public class WorkflowVisualizerTests
         var mid = new MockExecutor("mid");
         var end = new MockExecutor("end");
 
-        bool OnlyIfFoo(string? msg) => msg == "foo";
+        static bool OnlyIfFoo(string? msg) => msg == "foo";
 
         var workflow = new WorkflowBuilder("start")
             .AddEdge<string>(start, mid, OnlyIfFoo)
@@ -374,7 +374,7 @@ public class WorkflowVisualizerTests
         var c = new MockExecutor("c");
         var end = new ListStrTargetExecutor("end");
 
-        bool Condition(string? msg) => msg?.Contains("test") ?? false;
+        static bool Condition(string? msg) => msg?.Contains("test") ?? false;
 
         var workflow = new WorkflowBuilder("start")
             .AddEdge<string>(start, a, Condition) // Conditional edge