.NET: Use extension methods from A2A package for converting between MEAI & A2A model classes (microsoft#1600)

* use extension methods from A2A package for converting between MEAI and A2A model classes.

* Update dotnet/tests/Microsoft.Agents.AI.A2A.UnitTests/A2AAgentTests.cs

Co-authored-by: Stephen Toub <[email protected]>

* remove unused using

---------

Co-authored-by: Stephen Toub <[email protected]>

Author: SergeyMenshykh

dotnet/Directory.Packages.props

@@ -72,8 +72,8 @@
     <!-- Agent SDKs -->
     <PackageVersion Include="Microsoft.Agents.CopilotStudio.Client" Version="1.2.41" />
     <!-- A2A -->
-    <PackageVersion Include="A2A" Version="0.3.1-preview" />
-    <PackageVersion Include="A2A.AspNetCore" Version="0.3.1-preview" />
+    <PackageVersion Include="A2A" Version="0.3.3-preview" />
+    <PackageVersion Include="A2A.AspNetCore" Version="0.3.3-preview" />
     <!-- MCP -->
     <PackageVersion Include="ModelContextProtocol" Version="0.4.0-preview.2" />
     <!-- Inference SDKs -->

dotnet/samples/AgentWebChat/AgentWebChat.Web/A2AAgentClient.cs

@@ -58,7 +58,7 @@ public async override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync
             if (a2aResponse is AgentMessage message)
             {
                 var responseMessage = message.ToChatMessage();
-                if (responseMessage is not null)
+                if (responseMessage is { Contents.Count: > 0 })
                 {
                     results.Add(new AgentRunResponseUpdate(responseMessage.Role, responseMessage.Contents)
                     {
@@ -78,11 +78,7 @@ public async override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync
 
                         foreach (var part in artifact.Parts)
                         {
-                            var aiContent = ConvertPartToAIContent(part);
-                            if (aiContent != null)
-                            {
-                                (aiContents ??= []).Add(aiContent);
-                            }
+                            (aiContents ??= []).Add(part.ToAIContent());
                         }
 
                         if (aiContents is not null)
@@ -155,20 +151,6 @@ public async override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync
             return (a2aClient, a2aCardResolver);
         });
 
-    private static AIContent? ConvertPartToAIContent(Part part) =>
-        part switch
-        {
-            TextPart textPart => new TextContent(textPart.Text)
-            {
-                RawRepresentation = textPart
-            },
-            FilePart filePart when filePart.File is FileWithUri fileWithUrl => new HostedFileContent(fileWithUrl.Uri)
-            {
-                RawRepresentation = filePart
-            },
-            _ => null
-        };
-
     private static AdditionalPropertiesDictionary? ConvertMetadataToAdditionalProperties(Dictionary<string, JsonElement>? metadata)
     {
         if (metadata is not { Count: > 0 })
@@ -184,22 +166,3 @@ public async override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync
         return additionalProperties;
     }
 }
-
-// Extension method to convert multiple chat messages to A2A messages
-internal static class ChatMessageExtensions
-{
-    public static List<AgentMessage> ToA2AMessages(this IList<ChatMessage> chatMessages)
-    {
-        if (chatMessages is null || chatMessages.Count == 0)
-        {
-            return [];
-        }
-
-        var result = new List<AgentMessage>();
-        foreach (var chatMessage in chatMessages)
-        {
-            result.Add(chatMessage.ToA2AMessage());
-        }
-        return result;
-    }
-}

dotnet/src/Microsoft.Agents.AI.A2A/A2AHostAgent.cs

@@ -4,6 +4,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using A2A;
+using Microsoft.Extensions.AI;
 using Microsoft.Shared.Diagnostics;
 
 namespace Microsoft.Agents.AI.A2A;

dotnet/src/Microsoft.Agents.AI.A2A/Extensions/A2AAIContentExtensions.cs

@@ -15,13 +15,13 @@ internal static class A2AAIContentExtensions
     /// </summary>
     /// <param name="contents">The collection of AI contents to convert.</param>"
     /// <returns>The list of A2A <see cref="Part"/> objects.</returns>
-    internal static List<Part>? ToA2AParts(this IEnumerable<AIContent> contents)
+    internal static List<Part>? ToParts(this IEnumerable<AIContent> contents)
     {
         List<Part>? parts = null;
 
         foreach (var content in contents)
         {
-            var part = content.ToA2APart();
+            var part = content.ToPart();
             if (part is not null)
             {
                 (parts ??= []).Add(part);
@@ -30,18 +30,4 @@ internal static class A2AAIContentExtensions
 
         return parts;
     }
-
-    /// <summary>
-    ///  Converts a <see cref="AIContent"/> to a <see cref="Part"/> object."/>
-    /// </summary>
-    /// <param name="content">AI content to convert.</param>
-    /// <returns>The corresponding A2A <see cref="Part"/> object, or null if the content type is not supported.</returns>
-    internal static Part? ToA2APart(this AIContent content) =>
-        content switch
-        {
-            TextContent textContent => new TextPart { Text = textContent.Text },
-            HostedFileContent hostedFileContent => new FilePart { File = new FileWithUri { Uri = hostedFileContent.FileId } },
-            // Ignore unknown content types (FunctionCallContent, FunctionResultContent, etc.)
-            _ => null,
-        };
 }

dotnet/src/Microsoft.Agents.AI.A2A/Extensions/A2AMessageExtensions.cs

@@ -17,7 +17,7 @@ internal static AgentMessage ToA2AMessage(this IEnumerable<ChatMessage> messages
 
         foreach (var message in messages)
         {
-            if (message.Contents.ToA2AParts() is { Count: > 0 } ps)
+            if (message.Contents.ToParts() is { Count: > 0 } ps)
             {
                 allParts.AddRange(ps);
             }