address automated code review and formatting issues

dotnet/src/Microsoft.Agents.AI.A2A/A2AContinuationToken.cs

@@ -52,7 +52,7 @@ internal class A2AContinuationToken : ResponseContinuationToken
             {
                 case "taskId":
                     reader.Read();
-                    taskId = reader.GetString()!;
+                    taskId = reader.GetString() ?? throw new JsonException("The 'taskId' property must contain a non-null string value.");
                     break;
                 default:
                     throw new JsonException($"Unrecognized property '{propertyName}'.");

dotnet/src/Microsoft.Agents.AI.Hosting.A2A/A2AAgentHandler.cs

@@ -138,7 +138,7 @@ internal sealed class A2AAgentHandler : IAgentHandler
         catch (Exception)
         {
             var failUpdater = new TaskUpdater(eventQueue, context.TaskId, contextId);
-            await failUpdater.FailAsync(message: null, cancellationToken).ConfigureAwait(false);
+            await failUpdater.FailAsync(message: null, CancellationToken.None).ConfigureAwait(false);
             throw;
         }
 

dotnet/tests/Microsoft.Agents.AI.A2A.UnitTests/A2AContinuationTokenTests.cs

@@ -106,6 +106,18 @@ public sealed class A2AContinuationTokenTests
         Assert.Throws<ArgumentException>(() => A2AContinuationToken.FromToken(emptyToken));
     }
 
+    [Fact]
+    public void FromToken_WithNullTaskIdValue_ThrowsJsonException()
+    {
+        // Arrange
+        var jsonWithNullTaskId = System.Text.Encoding.UTF8.GetBytes("{ \"taskId\": null }").AsMemory();
+        var mockToken = new MockResponseContinuationToken(jsonWithNullTaskId);
+
+        // Act & Assert
+        var ex = Assert.Throws<JsonException>(() => A2AContinuationToken.FromToken(mockToken));
+        Assert.Contains("taskId", ex.Message);
+    }
+
     [Fact]
     public void FromToken_WithMissingTaskIdProperty_ThrowsException()
     {

dotnet/tests/Microsoft.Agents.AI.A2A.UnitTests/Extensions/A2AAgentCardExtensionsTests.cs

@@ -3,7 +3,6 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Linq;
 using System.Net;
 using System.Net.Http;
 using System.Text;

dotnet/tests/Microsoft.Agents.AI.Hosting.A2A.UnitTests/A2AAgentHandlerTests.cs

@@ -368,6 +368,47 @@ public sealed class A2AAgentHandlerTests
         Assert.True(events.StatusUpdates.Count > 0);
     }
 
+    /// <summary>
+    /// Verifies that when the agent throws during a continuation and the cancellation token
+    /// is already cancelled, the handler still emits a Failed status and re-throws the
+    /// original exception (not an OperationCanceledException from FailAsync).
+    /// </summary>
+    [Fact]
+    public async Task ExecuteAsync_OnContinuation_WhenAgentThrowsWithCancelledToken_StillEmitsFailedStatusAsync()
+    {
+        // Arrange
+        int callCount = 0;
+        Mock<AIAgent> agentMock = CreateAgentMockWithCallCount(ref callCount, _ =>
+            throw new InvalidOperationException("Agent failed"));
+        A2AAgentHandler handler = CreateHandler(agentMock);
+
+        using var cts = new CancellationTokenSource();
+        cts.Cancel(); // Pre-cancel the token
+
+        // Act & Assert - the original InvalidOperationException should be thrown, not OperationCanceledException
+        var events = new EventCollector();
+        var eventQueue = new AgentEventQueue();
+        var readerTask = ReadEventsAsync(eventQueue, events);
+        await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            handler.ExecuteAsync(
+                new RequestContext
+                {
+                    StreamingResponse = false,
+                    Message = new Message { MessageId = "empty", Role = Role.User, Parts = [] },
+                    TaskId = "task-1",
+                    ContextId = "ctx-1",
+
+                    Task = new AgentTask { Id = "task-1", ContextId = "ctx-1", History = [new Message { Role = Role.User, Parts = [new Part { Text = "Hello" }] }] }
+                },
+                eventQueue,
+                cts.Token));
+        eventQueue.Complete(null);
+        await readerTask;
+
+        // Assert - should have emitted Failed status even with a cancelled token
+        Assert.True(events.StatusUpdates.Count > 0);
+    }
+
     /// <summary>
     /// Verifies that when the agent throws OperationCanceledException during a continuation,
     /// no Failed status is emitted.

dotnet/tests/Microsoft.Agents.AI.Hosting.A2A.UnitTests/A2AEndpointRouteBuilderExtensionsTests.cs

@@ -5,6 +5,7 @@ using Microsoft.Agents.AI.Hosting.A2A.UnitTests.Internal;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.AI;
 using Microsoft.Extensions.DependencyInjection;
+using Moq;
 
 namespace Microsoft.Agents.AI.Hosting.A2A.UnitTests;
 
@@ -392,6 +393,124 @@ public sealed class A2AEndpointRouteBuilderExtensionsTests
         Assert.Equal("agentBuilder", exception.ParamName);
     }
 
+    /// <summary>
+    /// Verifies that MapA2AHttpJson throws ArgumentNullException for null AIAgent.
+    /// </summary>
+    [Fact]
+    public void MapA2AHttpJson_WithAIAgent_NullAgent_ThrowsArgumentNullException()
+    {
+        // Arrange
+        WebApplicationBuilder builder = WebApplication.CreateBuilder();
+        builder.Services.AddLogging();
+        using WebApplication app = builder.Build();
+        AIAgent agent = null!;
+
+        // Act & Assert
+        ArgumentNullException exception = Assert.Throws<ArgumentNullException>(() =>
+            app.MapA2AHttpJson(agent, "/a2a"));
+
+        Assert.Equal("agent", exception.ParamName);
+    }
+
+    /// <summary>
+    /// Verifies that MapA2AHttpJson throws ArgumentNullException for AIAgent with null Name.
+    /// </summary>
+    [Fact]
+    public void MapA2AHttpJson_WithAIAgent_NullName_ThrowsArgumentException()
+    {
+        // Arrange
+        WebApplicationBuilder builder = WebApplication.CreateBuilder();
+        builder.Services.AddLogging();
+        using WebApplication app = builder.Build();
+        var agentMock = new Mock<AIAgent>();
+        agentMock.Setup(a => a.Name).Returns((string?)null);
+
+        // Act & Assert
+        ArgumentNullException exception = Assert.Throws<ArgumentNullException>(() =>
+            app.MapA2AHttpJson(agentMock.Object, "/a2a"));
+
+        Assert.Equal("agent.Name", exception.ParamName);
+    }
+
+    /// <summary>
+    /// Verifies that MapA2AHttpJson throws ArgumentException for AIAgent with whitespace Name.
+    /// </summary>
+    [Fact]
+    public void MapA2AHttpJson_WithAIAgent_WhitespaceName_ThrowsArgumentException()
+    {
+        // Arrange
+        WebApplicationBuilder builder = WebApplication.CreateBuilder();
+        builder.Services.AddLogging();
+        using WebApplication app = builder.Build();
+        var agentMock = new Mock<AIAgent>();
+        agentMock.Setup(a => a.Name).Returns("   ");
+
+        // Act & Assert
+        ArgumentException exception = Assert.Throws<ArgumentException>(() =>
+            app.MapA2AHttpJson(agentMock.Object, "/a2a"));
+
+        Assert.Equal("agent.Name", exception.ParamName);
+    }
+
+    /// <summary>
+    /// Verifies that MapA2AJsonRpc throws ArgumentNullException for null AIAgent.
+    /// </summary>
+    [Fact]
+    public void MapA2AJsonRpc_WithAIAgent_NullAgent_ThrowsArgumentNullException()
+    {
+        // Arrange
+        WebApplicationBuilder builder = WebApplication.CreateBuilder();
+        builder.Services.AddLogging();
+        using WebApplication app = builder.Build();
+        AIAgent agent = null!;
+
+        // Act & Assert
+        ArgumentNullException exception = Assert.Throws<ArgumentNullException>(() =>
+            app.MapA2AJsonRpc(agent, "/a2a"));
+
+        Assert.Equal("agent", exception.ParamName);
+    }
+
+    /// <summary>
+    /// Verifies that MapA2AJsonRpc throws ArgumentNullException for AIAgent with null Name.
+    /// </summary>
+    [Fact]
+    public void MapA2AJsonRpc_WithAIAgent_NullName_ThrowsArgumentException()
+    {
+        // Arrange
+        WebApplicationBuilder builder = WebApplication.CreateBuilder();
+        builder.Services.AddLogging();
+        using WebApplication app = builder.Build();
+        var agentMock = new Mock<AIAgent>();
+        agentMock.Setup(a => a.Name).Returns((string?)null);
+
+        // Act & Assert
+        ArgumentNullException exception = Assert.Throws<ArgumentNullException>(() =>
+            app.MapA2AJsonRpc(agentMock.Object, "/a2a"));
+
+        Assert.Equal("agent.Name", exception.ParamName);
+    }
+
+    /// <summary>
+    /// Verifies that MapA2AJsonRpc throws ArgumentException for AIAgent with whitespace Name.
+    /// </summary>
+    [Fact]
+    public void MapA2AJsonRpc_WithAIAgent_WhitespaceName_ThrowsArgumentException()
+    {
+        // Arrange
+        WebApplicationBuilder builder = WebApplication.CreateBuilder();
+        builder.Services.AddLogging();
+        using WebApplication app = builder.Build();
+        var agentMock = new Mock<AIAgent>();
+        agentMock.Setup(a => a.Name).Returns("   ");
+
+        // Act & Assert
+        ArgumentException exception = Assert.Throws<ArgumentException>(() =>
+            app.MapA2AJsonRpc(agentMock.Object, "/a2a"));
+
+        Assert.Equal("agent.Name", exception.ParamName);
+    }
+
     /// <summary>
     /// Verifies that MapA2AHttpJson throws InvalidOperationException when no A2AServer has been
     /// registered for the specified agent via AddA2AServer.

dotnet/tests/Microsoft.Agents.AI.Hosting.A2A.UnitTests/A2AServerServiceCollectionExtensionsTests.cs

@@ -251,6 +251,42 @@ public sealed class A2AServerServiceCollectionExtensionsTests
         Assert.Throws<ArgumentNullException>(() => services.AddA2AServer(agent: null!));
     }
 
+    /// <summary>
+    /// Verifies that AddA2AServer with an agent instance throws when the agent's Name is null.
+    /// </summary>
+    [Fact]
+    public void AddA2AServer_WithAgent_NullName_ThrowsArgumentNullException()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+        var agentMock = new Mock<AIAgent>();
+        agentMock.Setup(a => a.Name).Returns((string?)null);
+
+        // Act & Assert
+        ArgumentNullException exception = Assert.Throws<ArgumentNullException>(() =>
+            services.AddA2AServer(agentMock.Object));
+
+        Assert.Equal("agent.Name", exception.ParamName);
+    }
+
+    /// <summary>
+    /// Verifies that AddA2AServer with an agent instance throws when the agent's Name is whitespace.
+    /// </summary>
+    [Fact]
+    public void AddA2AServer_WithAgent_WhitespaceName_ThrowsArgumentException()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+        var agentMock = new Mock<AIAgent>();
+        agentMock.Setup(a => a.Name).Returns("   ");
+
+        // Act & Assert
+        ArgumentException exception = Assert.Throws<ArgumentException>(() =>
+            services.AddA2AServer(agentMock.Object));
+
+        Assert.Equal("agent.Name", exception.ParamName);
+    }
+
     private static Mock<AIAgent> CreateAgentMock(string name)
     {
         Mock<AIAgent> agentMock = new() { CallBase = true };

dotnet/tests/Microsoft.Agents.AI.Hosting.A2A.UnitTests/Converters/MessageConverterTests.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System.Collections.Generic;
 using System.Linq;
 using A2A;
 using Microsoft.Agents.AI.Hosting.A2A.Converters;
@@ -82,4 +83,68 @@ public class MessageConverterTests
         var textContent = Assert.IsType<TextContent>(chatMessage.Contents.First());
         Assert.Equal("Hello, world!", textContent.Text);
     }
+
+    [Fact]
+    public void ToParts_NullList_ReturnsEmptyList()
+    {
+        // Arrange
+        IList<ChatMessage>? messages = null;
+
+        // Act
+        var result = messages!.ToParts();
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public void ToParts_EmptyList_ReturnsEmptyList()
+    {
+        // Arrange
+        IList<ChatMessage> messages = [];
+
+        // Act
+        var result = messages.ToParts();
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public void ToParts_WithTextContent_ReturnsTextPart()
+    {
+        // Arrange
+        IList<ChatMessage> messages =
+        [
+            new ChatMessage(ChatRole.Assistant, "Hello from the agent!")
+        ];
+
+        // Act
+        var result = messages.ToParts();
+
+        // Assert
+        Assert.Single(result);
+        Assert.Equal("Hello from the agent!", result[0].Text);
+    }
+
+    [Fact]
+    public void ToParts_WithMultipleMessages_ReturnsAllParts()
+    {
+        // Arrange
+        IList<ChatMessage> messages =
+        [
+            new ChatMessage(ChatRole.User, "First message"),
+            new ChatMessage(ChatRole.Assistant, "Second message")
+        ];
+
+        // Act
+        var result = messages.ToParts();
+
+        // Assert
+        Assert.Equal(2, result.Count);
+        Assert.Equal("First message", result[0].Text);
+        Assert.Equal("Second message", result[1].Text);
+    }
 }