.NET: Remove AGUI history special cases

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs

@@ -38,8 +38,6 @@ namespace Microsoft.Agents.AI;
 /// </remarks>
 public sealed partial class ChatClientAgent : AIAgent
 {
-    private const string AGUIProviderName = "ag-ui";
-
     private readonly ChatClientAgentOptions? _agentOptions;
     private readonly HashSet<string> _aiContextProviderStateKeys;
     private readonly AIAgentMetadata _agentMetadata;
@@ -818,7 +816,7 @@ public sealed partial class ChatClientAgent : AIAgent
 
         if (!string.IsNullOrWhiteSpace(responseConversationId))
         {
-            if (!IsAGUIProviderName(this._agentMetadata.ProviderName) && this._agentOptions?.ChatHistoryProvider is not null)
+            if (this._agentOptions?.ChatHistoryProvider is not null)
             {
                 // The agent has a ChatHistoryProvider configured, but the service returned a conversation id,
                 // meaning the service manages chat history server-side. Both cannot be used simultaneously.
@@ -932,9 +930,6 @@ public sealed partial class ChatClientAgent : AIAgent
         }
     }
 
-    private static bool IsAGUIProviderName(string? providerName) =>
-        string.Equals(providerName, AGUIProviderName, StringComparison.Ordinal);
-
     /// <summary>
     /// Ensures that <see cref="AIAgent.CurrentRunContext"/> contains the resolved session.
     /// </summary>
@@ -994,7 +989,6 @@ public sealed partial class ChatClientAgent : AIAgent
         // the provider the decorator depends on.
         bool serviceStoresHistory =
             !this.RequiresPerServiceCallChatHistoryPersistence
-            && !IsAGUIProviderName(this._agentMetadata.ProviderName)
             && (!string.IsNullOrWhiteSpace(chatOptions?.ConversationId)
                 || !string.IsNullOrWhiteSpace(session.ConversationId));
 

dotnet/tests/Microsoft.Agents.AI.Hosting.AGUI.AspNetCore.IntegrationTests/BasicStreamingTests.cs

@@ -131,12 +131,12 @@ public sealed class BasicStreamingTests : IAsyncDisposable
     }
 
     [Fact]
-    public async Task MultiTurnConversationPreservesAllMessagesInSessionAsync()
+    public async Task AGUIChatClientBackedAgentUsesLocalChatHistoryAcrossTurnsAsync()
     {
         // Arrange
         await this.SetupTestServerAsync();
         var chatClient = new AGUIChatClient(new(this._client!, ""));
-        AIAgent agent = chatClient.AsAIAgent(instructions: null, name: "assistant", description: "Sample assistant", tools: []);
+        ChatClientAgent agent = new(chatClient, instructions: null, name: "assistant", description: "Sample assistant", tools: []);
         ChatClientAgentSession chatClientSession = (ChatClientAgentSession)await agent.CreateSessionAsync();
         ChatMessage firstUserMessage = new(ChatRole.User, "First question");
 
@@ -149,6 +149,8 @@ public sealed class BasicStreamingTests : IAsyncDisposable
 
         // Assert first turn completed
         firstTurnUpdates.Should().Contain(u => !string.IsNullOrEmpty(u.Text));
+        firstTurnUpdates.Should().AllSatisfy(u => u.AsChatResponseUpdate().ConversationId.Should().BeNull());
+        chatClientSession.ConversationId.Should().BeNull();
 
         // Act - Second turn with another message
         ChatMessage secondUserMessage = new(ChatRole.User, "Second question");
@@ -160,14 +162,29 @@ public sealed class BasicStreamingTests : IAsyncDisposable
 
         // Assert second turn completed
         secondTurnUpdates.Should().Contain(u => !string.IsNullOrEmpty(u.Text));
+        secondTurnUpdates.Should().AllSatisfy(u => u.AsChatResponseUpdate().ConversationId.Should().BeNull());
+        chatClientSession.ConversationId.Should().BeNull();
 
-        // Verify first turn assistant response
+        // Verify the local provider retained both turns.
+        InMemoryChatHistoryProvider historyProvider = agent.ChatHistoryProvider.Should().BeOfType<InMemoryChatHistoryProvider>().Subject;
+        List<ChatMessage> history = historyProvider.GetMessages(chatClientSession);
+        history.Should().HaveCount(4);
+        history[0].Role.Should().Be(ChatRole.User);
+        history[0].Text.Should().Be("First question");
+        history[1].Role.Should().Be(ChatRole.Assistant);
+        history[1].Text.Should().Be("Hello from fake agent!");
+        history[2].Role.Should().Be(ChatRole.User);
+        history[2].Text.Should().Be("Second question");
+        history[3].Role.Should().Be(ChatRole.Assistant);
+        history[3].Text.Should().Be("Hello from fake agent!");
+
+        // Verify first turn assistant response.
         AgentResponse firstResponse = firstTurnUpdates.ToAgentResponse();
         firstResponse.Messages.Should().HaveCount(1);
         firstResponse.Messages[0].Role.Should().Be(ChatRole.Assistant);
         firstResponse.Messages[0].Text.Should().Be("Hello from fake agent!");
 
-        // Verify second turn assistant response
+        // Verify second turn assistant response.
         AgentResponse secondResponse = secondTurnUpdates.ToAgentResponse();
         secondResponse.Messages.Should().HaveCount(1);
         secondResponse.Messages[0].Role.Should().Be(ChatRole.Assistant);