From a76f2e215f8b0cff2349697abe232370142de3da Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 10 Feb 2026 10:56:04 +0000
Subject: [PATCH] Fix streaming path to include chat history in messages sent
 to chat client

RunCoreStreamingAsync was passing inputMessagesForProviders (which lacks
chat history) to GetStreamingResponseAsync instead of
inputMessagesForChatClient (which includes chat history). This caused
streaming runs to lose conversation context on subsequent calls.

The non-streaming path (RunCoreAsync) already correctly used
inputMessagesForChatClient. This aligns the streaming path to match.

Also adds a unit test that validates chat history is included in
messages sent to the chat client during streaming on subsequent calls.

Co-authored-by: lokitoth <6936551+lokitoth@users.noreply.github.com>
---
 .../ChatClient/ChatClientAgent.cs             |  2 +-
 .../ChatClient/ChatClientAgentTests.cs        | 39 +++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs b/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs
index 5878d877b2..37e673f710 100644
--- a/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs
+++ b/dotnet/src/Microsoft.Agents.AI/ChatClient/ChatClientAgent.cs
@@ -226,7 +226,7 @@ protected override async IAsyncEnumerable<AgentResponseUpdate> RunCoreStreamingA
         try
         {
             // Using the enumerator to ensure we consider the case where no updates are returned for notification.
-            responseUpdatesEnumerator = chatClient.GetStreamingResponseAsync(inputMessagesForProviders, chatOptions, cancellationToken).GetAsyncEnumerator(cancellationToken);
+            responseUpdatesEnumerator = chatClient.GetStreamingResponseAsync(inputMessagesForChatClient, chatOptions, cancellationToken).GetAsyncEnumerator(cancellationToken);
         }
         catch (Exception ex)
         {
diff --git a/dotnet/tests/Microsoft.Agents.AI.UnitTests/ChatClient/ChatClientAgentTests.cs b/dotnet/tests/Microsoft.Agents.AI.UnitTests/ChatClient/ChatClientAgentTests.cs
index 41fb29bfed..c23e8cffaf 100644
--- a/dotnet/tests/Microsoft.Agents.AI.UnitTests/ChatClient/ChatClientAgentTests.cs
+++ b/dotnet/tests/Microsoft.Agents.AI.UnitTests/ChatClient/ChatClientAgentTests.cs
@@ -1320,6 +1320,45 @@ public async Task RunStreamingAsyncUsesChatHistoryProviderWhenNoConversationIdRe
         mockFactory.Verify(f => f(It.IsAny<ChatClientAgentOptions.ChatHistoryProviderFactoryContext>(), It.IsAny<CancellationToken>()), Times.Once);
     }
 
+    /// <summary>
+    /// Verify that RunStreamingAsync includes chat history in messages sent to the chat client on subsequent calls.
+    /// </summary>
+    [Fact]
+    public async Task RunStreamingAsyncIncludesChatHistoryInMessagesToChatClientAsync()
+    {
+        // Arrange
+        List<IEnumerable<ChatMessage>> capturedMessages = [];
+        Mock<IChatClient> mockService = new();
+        ChatResponseUpdate[] returnUpdates =
+            [
+                new ChatResponseUpdate(role: ChatRole.Assistant, content: "response"),
+            ];
+        mockService.Setup(
+            s => s.GetStreamingResponseAsync(
+                It.IsAny<IEnumerable<ChatMessage>>(),
+                It.IsAny<ChatOptions>(),
+                It.IsAny<CancellationToken>()))
+            .Returns(ToAsyncEnumerableAsync(returnUpdates))
+            .Callback<IEnumerable<ChatMessage>, ChatOptions?, CancellationToken>((msgs, _, _) => capturedMessages.Add(msgs.ToList()));
+        ChatClientAgent agent = new(mockService.Object, options: new()
+        {
+            ChatOptions = new() { Instructions = "test instructions" },
+        });
+
+        // Act
+        ChatClientAgentSession? session = await agent.CreateSessionAsync() as ChatClientAgentSession;
+        await agent.RunStreamingAsync([new(ChatRole.User, "first")], session).ToListAsync();
+        await agent.RunStreamingAsync([new(ChatRole.User, "second")], session).ToListAsync();
+
+        // Assert - the second call should include chat history (first user message + first response) plus the new message
+        Assert.Equal(2, capturedMessages.Count);
+        var secondCallMessages = capturedMessages[1].ToList();
+        Assert.Equal(3, secondCallMessages.Count);
+        Assert.Equal("first", secondCallMessages[0].Text);
+        Assert.Equal("response", secondCallMessages[1].Text);
+        Assert.Equal("second", secondCallMessages[2].Text);
+    }
+
     /// <summary>
     /// Verify that RunStreamingAsync throws when a <see cref="ChatHistoryProvider"/> factory is provided and the chat client returns a conversation id.
     /// </summary>