.Net Agents - Add Streaming support for OpenAIAssistantAgent and `A…

…gentChat` (#8175)

### Motivation and Context
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Add streaming support to direct invocation of `OpenAIAssistantAgent` and
also `AgentChat`:

Fixes: #4833
Fixes: #5643

Integrates with existing streaming support for `ChatCompletionAgent`.

### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

Streaming returns the expected streaming content types as well as
providing whole messages in the provided history.

Support both agent invocation (no-chat) and via `AgentChat`.

Introduced:
- `StreamingAnnotationContent`
- `StreamingFileReferenceContent`

Added samples and tests.

### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

---------

Co-authored-by: SergeyMenshykh <[email protected]>
Co-authored-by: Roger Barreto <[email protected]>
Co-authored-by: SergeyMenshykh <[email protected]>
Co-authored-by: Roger Barreto <[email protected]>
Co-authored-by: Dmytro Struk <[email protected]>

dotnet/samples/Concepts/Agents/ChatCompletion_Streaming.cs

@@ -1,6 +1,5 @@
 // Copyright (c) Microsoft. All rights reserved.
 using System.ComponentModel;
-using System.Text;
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents;
 using Microsoft.SemanticKernel.ChatCompletion;
@@ -9,8 +8,7 @@
 namespace Agents;
 
 /// <summary>
-/// Demonstrate creation of <see cref="ChatCompletionAgent"/> and
-/// eliciting its response to three explicit user messages.
+/// Demonstrate consuming "streaming" message for <see cref="ChatCompletionAgent"/>.
 /// </summary>
 public class ChatCompletion_Streaming(ITestOutputHelper output) : BaseAgentsTest(output)
 {
@@ -35,6 +33,9 @@ public async Task UseStreamingChatCompletionAgentAsync()
         await InvokeAgentAsync(agent, chat, "Fortune favors the bold.");
         await InvokeAgentAsync(agent, chat, "I came, I saw, I conquered.");
         await InvokeAgentAsync(agent, chat, "Practice makes perfect.");
+
+        // Output the entire chat history
+        DisplayChatHistory(chat);
     }
 
     [Fact]
@@ -61,6 +62,9 @@ public async Task UseStreamingChatCompletionAgentWithPluginAsync()
         // Respond to user input
         await InvokeAgentAsync(agent, chat, "What is the special soup?");
         await InvokeAgentAsync(agent, chat, "What is the special drink?");
+
+        // Output the entire chat history
+        DisplayChatHistory(chat);
     }
 
     // Local function to invoke agent and display the conversation messages.
@@ -70,29 +74,44 @@ private async Task InvokeAgentAsync(ChatCompletionAgent agent, ChatHistory chat,
         chat.Add(message);
         this.WriteAgentChatMessage(message);
 
-        StringBuilder builder = new();
+        int historyCount = chat.Count;
+
+        bool isFirst = false;
         await foreach (StreamingChatMessageContent response in agent.InvokeStreamingAsync(chat))
         {
             if (string.IsNullOrEmpty(response.Content))
             {
                 continue;
             }
 
-            if (builder.Length == 0)
+            if (!isFirst)
             {
-                Console.WriteLine($"# {response.Role} - {response.AuthorName ?? "*"}:");
+                Console.WriteLine($"\n# {response.Role} - {response.AuthorName ?? "*"}:");
+                isFirst = true;
             }
 
             Console.WriteLine($"\t > streamed: '{response.Content}'");
-            builder.Append(response.Content);
         }
 
-        if (builder.Length > 0)
+        if (historyCount <= chat.Count)
+        {
+            for (int index = historyCount; index < chat.Count; index++)
+            {
+                this.WriteAgentChatMessage(chat[index]);
+            }
+        }
+    }
+
+    private void DisplayChatHistory(ChatHistory history)
+    {
+        // Display the chat history.
+        Console.WriteLine("================================");
+        Console.WriteLine("CHAT HISTORY");
+        Console.WriteLine("================================");
+
+        foreach (ChatMessageContent message in history)
         {
-            // Display full response and capture in chat history
-            ChatMessageContent response = new(AuthorRole.Assistant, builder.ToString()) { AuthorName = agent.Name };
-            chat.Add(response);
-            this.WriteAgentChatMessage(response);
+            this.WriteAgentChatMessage(message);
         }
     }
 

dotnet/samples/Concepts/Agents/MixedChat_Streaming.cs

@@ -0,0 +1,122 @@
+// Copyright (c) Microsoft. All rights reserved.
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.Agents;
+using Microsoft.SemanticKernel.Agents.Chat;
+using Microsoft.SemanticKernel.Agents.OpenAI;
+using Microsoft.SemanticKernel.ChatCompletion;
+
+namespace Agents;
+
+/// <summary>
+/// Demonstrate consuming "streaming" message for <see cref="ChatCompletionAgent"/> and
+/// <see cref="OpenAIAssistantAgent"/> both participating in an <see cref="AgentChat"/>.
+/// </summary>
+public class MixedChat_Streaming(ITestOutputHelper output) : BaseAgentsTest(output)
+{
+    private const string ReviewerName = "ArtDirector";
+    private const string ReviewerInstructions =
+        """
+        You are an art director who has opinions about copywriting born of a love for David Ogilvy.
+        The goal is to determine is the given copy is acceptable to print.
+        If so, state that it is approved.
+        If not, provide insight on how to refine suggested copy without example.
+        """;
+
+    private const string CopyWriterName = "CopyWriter";
+    private const string CopyWriterInstructions =
+        """
+        You are a copywriter with ten years of experience and are known for brevity and a dry humor.
+        The goal is to refine and decide on the single best copy as an expert in the field.
+        Only provide a single proposal per response.
+        You're laser focused on the goal at hand.
+        Don't waste time with chit chat.
+        Consider suggestions when refining an idea.
+        """;
+
+    [Fact]
+    public async Task UseStreamingAgentChatAsync()
+    {
+        // Define the agents: one of each type
+        ChatCompletionAgent agentReviewer =
+            new()
+            {
+                Instructions = ReviewerInstructions,
+                Name = ReviewerName,
+                Kernel = this.CreateKernelWithChatCompletion(),
+            };
+
+        OpenAIAssistantAgent agentWriter =
+            await OpenAIAssistantAgent.CreateAsync(
+                kernel: new(),
+                clientProvider: this.GetClientProvider(),
+                definition: new(this.Model)
+                {
+                    Instructions = CopyWriterInstructions,
+                    Name = CopyWriterName,
+                    Metadata = AssistantSampleMetadata,
+                });
+
+        // Create a chat for agent interaction.
+        AgentGroupChat chat =
+            new(agentWriter, agentReviewer)
+            {
+                ExecutionSettings =
+                    new()
+                    {
+                        // Here a TerminationStrategy subclass is used that will terminate when
+                        // an assistant message contains the term "approve".
+                        TerminationStrategy =
+                            new ApprovalTerminationStrategy()
+                            {
+                                // Only the art-director may approve.
+                                Agents = [agentReviewer],
+                                // Limit total number of turns
+                                MaximumIterations = 10,
+                            }
+                    }
+            };
+
+        // Invoke chat and display messages.
+        ChatMessageContent input = new(AuthorRole.User, "concept: maps made out of egg cartons.");
+        chat.AddChatMessage(input);
+        this.WriteAgentChatMessage(input);
+
+        string lastAgent = string.Empty;
+        await foreach (StreamingChatMessageContent response in chat.InvokeStreamingAsync())
+        {
+            if (string.IsNullOrEmpty(response.Content))
+            {
+                continue;
+            }
+
+            if (!lastAgent.Equals(response.AuthorName, StringComparison.Ordinal))
+            {
+                Console.WriteLine($"\n# {response.Role} - {response.AuthorName ?? "*"}:");
+                lastAgent = response.AuthorName ?? string.Empty;
+            }
+
+            Console.WriteLine($"\t > streamed: '{response.Content}'");
+        }
+
+        // Display the chat history.
+        Console.WriteLine("================================");
+        Console.WriteLine("CHAT HISTORY");
+        Console.WriteLine("================================");
+
+        ChatMessageContent[] history = await chat.GetChatMessagesAsync().Reverse().ToArrayAsync();
+
+        for (int index = 0; index < history.Length; index++)
+        {
+            this.WriteAgentChatMessage(history[index]);
+        }
+
+        Console.WriteLine($"\n[IS COMPLETED: {chat.IsComplete}]");
+    }
+
+    private sealed class ApprovalTerminationStrategy : TerminationStrategy
+    {
+        // Terminate when the final message contains the term "approve"
+        protected override Task<bool> ShouldAgentTerminateAsync(Agent agent, IReadOnlyList<ChatMessageContent> history, CancellationToken cancellationToken)
+            => Task.FromResult(history[history.Count - 1].Content?.Contains("approve", StringComparison.OrdinalIgnoreCase) ?? false);
+    }
+}

dotnet/samples/Concepts/Agents/OpenAIAssistant_Streaming.cs

@@ -0,0 +1,142 @@
+// Copyright (c) Microsoft. All rights reserved.
+using System.ComponentModel;
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.Agents.OpenAI;
+using Microsoft.SemanticKernel.ChatCompletion;
+
+namespace Agents;
+
+/// <summary>
+/// Demonstrate consuming "streaming" message for <see cref="OpenAIAssistantAgent"/>.
+/// </summary>
+public class OpenAIAssistant_Streaming(ITestOutputHelper output) : BaseAgentsTest(output)
+{
+    private const string ParrotName = "Parrot";
+    private const string ParrotInstructions = "Repeat the user message in the voice of a pirate and then end with a parrot sound.";
+
+    [Fact]
+    public async Task UseStreamingChatCompletionAgentAsync()
+    {
+        // Define the agent
+        OpenAIAssistantAgent agent =
+            await OpenAIAssistantAgent.CreateAsync(
+                kernel: new(),
+                clientProvider: this.GetClientProvider(),
+                new(this.Model)
+                {
+                    Instructions = ParrotInstructions,
+                    Name = ParrotName,
+                    Metadata = AssistantSampleMetadata,
+                });
+
+        // Create a thread for the agent conversation.
+        string threadId = await agent.CreateThreadAsync(new OpenAIThreadCreationOptions { Metadata = AssistantSampleMetadata });
+
+        // Respond to user input
+        await InvokeAgentAsync(agent, threadId, "Fortune favors the bold.");
+        await InvokeAgentAsync(agent, threadId, "I came, I saw, I conquered.");
+        await InvokeAgentAsync(agent, threadId, "Practice makes perfect.");
+
+        // Output the entire chat history
+        await DisplayChatHistoryAsync(agent, threadId);
+    }
+
+    [Fact]
+    public async Task UseStreamingChatCompletionAgentWithPluginAsync()
+    {
+        const string MenuInstructions = "Answer questions about the menu.";
+
+        // Define the agent
+        OpenAIAssistantAgent agent =
+            await OpenAIAssistantAgent.CreateAsync(
+                kernel: new(),
+                clientProvider: this.GetClientProvider(),
+                new(this.Model)
+                {
+                    Instructions = MenuInstructions,
+                    Name = "Host",
+                    Metadata = AssistantSampleMetadata,
+                });
+
+        // Initialize plugin and add to the agent's Kernel (same as direct Kernel usage).
+        KernelPlugin plugin = KernelPluginFactory.CreateFromType<MenuPlugin>();
+        agent.Kernel.Plugins.Add(plugin);
+
+        // Create a thread for the agent conversation.
+        string threadId = await agent.CreateThreadAsync(new OpenAIThreadCreationOptions { Metadata = AssistantSampleMetadata });
+
+        // Respond to user input
+        await InvokeAgentAsync(agent, threadId, "What is the special soup?");
+        await InvokeAgentAsync(agent, threadId, "What is the special drink?");
+
+        // Output the entire chat history
+        await DisplayChatHistoryAsync(agent, threadId);
+    }
+
+    // Local function to invoke agent and display the conversation messages.
+    private async Task InvokeAgentAsync(OpenAIAssistantAgent agent, string threadId, string input)
+    {
+        ChatMessageContent message = new(AuthorRole.User, input);
+        await agent.AddChatMessageAsync(threadId, message);
+        this.WriteAgentChatMessage(message);
+
+        ChatHistory history = [];
+
+        bool isFirst = false;
+        await foreach (StreamingChatMessageContent response in agent.InvokeStreamingAsync(threadId, history))
+        {
+            if (string.IsNullOrEmpty(response.Content))
+            {
+                continue;
+            }
+
+            if (!isFirst)
+            {
+                Console.WriteLine($"\n# {response.Role} - {response.AuthorName ?? "*"}:");
+                isFirst = true;
+            }
+
+            Console.WriteLine($"\t > streamed: '{response.Content}'");
+        }
+
+        foreach (ChatMessageContent content in history)
+        {
+            this.WriteAgentChatMessage(content);
+        }
+    }
+
+    private async Task DisplayChatHistoryAsync(OpenAIAssistantAgent agent, string threadId)
+    {
+        Console.WriteLine("================================");
+        Console.WriteLine("CHAT HISTORY");
+        Console.WriteLine("================================");
+
+        ChatMessageContent[] messages = await agent.GetThreadMessagesAsync(threadId).ToArrayAsync();
+        for (int index = messages.Length - 1; index >= 0; --index)
+        {
+            this.WriteAgentChatMessage(messages[index]);
+        }
+    }
+
+    public sealed class MenuPlugin
+    {
+        [KernelFunction, Description("Provides a list of specials from the menu.")]
+        [System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1024:Use properties where appropriate", Justification = "Too smart")]
+        public string GetSpecials()
+        {
+            return @"
+Special Soup: Clam Chowder
+Special Salad: Cobb Salad
+Special Drink: Chai Tea
+";
+        }
+
+        [KernelFunction, Description("Provides the price of the requested menu item.")]
+        public string GetItemPrice(
+            [Description("The name of the menu item.")]
+        string menuItem)
+        {
+            return "$9.99";
+        }
+    }
+}

dotnet/samples/GettingStartedWithAgents/Step06_DependencyInjection.cs

@@ -69,7 +69,7 @@ public async Task UseDependencyInjectionToCreateAgentAsync()
         AgentClient agentClient = serviceProvider.GetRequiredService<AgentClient>();
 
         // Execute the agent-client
-        await WriteAgentResponse("The sunset is very colorful.");
+        await WriteAgentResponse("The sunset is nice.");
         await WriteAgentResponse("The sunset is setting over the mountains.");
         await WriteAgentResponse("The sunset is setting over the mountains and filled the sky with a deep red flame, setting the clouds ablaze.");
 

dotnet/samples/GettingStartedWithAgents/Step11_AssistantTool_FileSearch.cs

@@ -62,7 +62,7 @@ await agent.CreateThreadAsync(
         finally
         {
             await agent.DeleteThreadAsync(threadId);
-            await agent.DeleteAsync(CancellationToken.None);
+            await agent.DeleteAsync();
             await vectorStoreClient.DeleteVectorStoreAsync(vectorStore);
             await fileClient.DeleteFileAsync(fileInfo.Id);
         }