diff --git a/src/Libraries/Microsoft.Extensions.AI.Abstractions/ChatCompletion/ChatResponseUpdateExtensions.cs b/src/Libraries/Microsoft.Extensions.AI.Abstractions/ChatCompletion/ChatResponseUpdateExtensions.cs
index bfc2c3fd60f..25104461cd9 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Abstractions/ChatCompletion/ChatResponseUpdateExtensions.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Abstractions/ChatCompletion/ChatResponseUpdateExtensions.cs
@@ -89,10 +89,11 @@ static async Task<ChatResponse> ToChatResponseAsync(
     /// <param name="response">The <see cref="ChatResponse"/> object whose properties should be updated based on <paramref name="update"/>.</param>
     private static void ProcessUpdate(ChatResponseUpdate update, Dictionary<int, ChatMessage> messages, ChatResponse response)
     {
-        response.ResponseId ??= update.ResponseId;
+        response.ChatThreadId ??= update.ChatThreadId;
         response.CreatedAt ??= update.CreatedAt;
         response.FinishReason ??= update.FinishReason;
         response.ModelId ??= update.ModelId;
+        response.ResponseId ??= update.ResponseId;
 
 #if NET
         ChatMessage message = CollectionsMarshal.GetValueRefOrAddDefault(messages, update.ChoiceIndex, out _) ??=
diff --git a/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting.Azure/Storage/AzureStorageResultStore.cs b/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting.Azure/Storage/AzureStorageResultStore.cs
index 7636f8901a5..1ff06c07467 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting.Azure/Storage/AzureStorageResultStore.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Evaluation.Reporting.Azure/Storage/AzureStorageResultStore.cs
@@ -187,7 +187,7 @@ private static string GetLastSegmentFromPath(string name)
         => name.Substring(name.LastIndexOf('/') + 1);
 
     private static string StripExtension(string name)
-        => name.Substring(0, name.LastIndexOf(".", StringComparison.Ordinal));
+        => name.Substring(0, name.LastIndexOf('.'));
 
     private static (string path, bool isDir) GetResultPath(
         string? executionName = null,
diff --git a/src/Libraries/Microsoft.Extensions.AI.Ollama/OllamaChatClient.cs b/src/Libraries/Microsoft.Extensions.AI.Ollama/OllamaChatClient.cs
index 727d00f05c8..d3f45358d10 100644
--- a/src/Libraries/Microsoft.Extensions.AI.Ollama/OllamaChatClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.Ollama/OllamaChatClient.cs
@@ -426,7 +426,7 @@ private IEnumerable<OllamaChatRequestMessage> ToOllamaChatRequestMessages(ChatMe
                         currentTextMessage = new OllamaChatRequestMessage
                         {
                             Role = content.Role.Value,
-                            Content = textContent.Text ?? string.Empty,
+                            Content = textContent.Text,
                         };
                         break;
 
diff --git a/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIAssistantClient.cs b/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIAssistantClient.cs
index 96bd316d746..513ce3652c8 100644
--- a/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIAssistantClient.cs
+++ b/src/Libraries/Microsoft.Extensions.AI.OpenAI/OpenAIAssistantClient.cs
@@ -232,6 +232,11 @@ strictObj is bool strictValue ?
             // Store the tool mode.
             switch (options.ToolMode)
             {
+                case NoneChatToolMode:
+                    runOptions.ToolConstraint = ToolConstraint.None;
+                    break;
+
+                case null:
                 case AutoChatToolMode:
                     runOptions.ToolConstraint = ToolConstraint.Auto;
                     break;
diff --git a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/ChatCompletion/ChatResponseUpdateExtensionsTests.cs b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/ChatCompletion/ChatResponseUpdateExtensionsTests.cs
index c233ab85b29..fea25191aff 100644
--- a/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/ChatCompletion/ChatResponseUpdateExtensionsTests.cs
+++ b/test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/ChatCompletion/ChatResponseUpdateExtensionsTests.cs
@@ -42,7 +42,7 @@ public async Task ToChatResponse_SuccessfullyCreatesResponse(bool useAsync, bool
             new() { ChoiceIndex = 1, Text = "Hey", ResponseId = "12345", CreatedAt = new DateTimeOffset(1, 2, 3, 4, 5, 6, TimeSpan.Zero), ModelId = "model124" },
 
             new() { ChoiceIndex = 0, Text = ", ", AuthorName = "Someone", Role = ChatRole.User, AdditionalProperties = new() { ["a"] = "b" } },
-            new() { ChoiceIndex = 1, Text = ", ", AuthorName = "Else", Role = ChatRole.System, AdditionalProperties = new() { ["g"] = "h" } },
+            new() { ChoiceIndex = 1, Text = ", ", AuthorName = "Else", Role = ChatRole.System, ChatThreadId = "123", AdditionalProperties = new() { ["g"] = "h" } },
 
             new() { ChoiceIndex = 0, Text = "world!", CreatedAt = new DateTimeOffset(2, 2, 3, 4, 5, 6, TimeSpan.Zero), AdditionalProperties = new() { ["c"] = "d" } },
             new() { ChoiceIndex = 1, Text = "you!", Role = ChatRole.Tool, CreatedAt = new DateTimeOffset(3, 2, 3, 4, 5, 6, TimeSpan.Zero), AdditionalProperties = new() { ["e"] = "f", ["i"] = 42 } },
@@ -69,6 +69,8 @@ public async Task ToChatResponse_SuccessfullyCreatesResponse(bool useAsync, bool
         Assert.Equal(new DateTimeOffset(1, 2, 3, 4, 5, 6, TimeSpan.Zero), response.CreatedAt);
         Assert.Equal("model123", response.ModelId);
 
+        Assert.Equal("123", response.ChatThreadId);
+
         Assert.Equal(3, response.Choices.Count);
 
         ChatMessage message = response.Choices[0];