[.Net] fix #2695 and #2884 (#3069)

* add round robin orchestrator

* add constructor for orchestrators

* add tests

* revert change

* return single orchestrator

* address comment

dotnet/Directory.Build.props

@@ -31,6 +31,7 @@
     <PackageReference Include="xunit" Version="$(XUnitVersion)" />
     <PackageReference Include="xunit.runner.console" Version="$(XUnitVersion)" />
     <PackageReference Include="xunit.runner.visualstudio" Version="$(XUnitVersion)" />
+    <PackageReference Include="Moq" Version="4.20.70" />
   </ItemGroup>
 
   <ItemGroup  Condition="'$(IsTestProject)' == 'true'">

dotnet/src/AutoGen.Anthropic/Agent/AnthropicClientAgent.cs

@@ -67,7 +67,8 @@ private ChatCompletionRequest CreateParameters(IEnumerable<IMessage> messages, G
             Stream = shouldStream,
             Temperature = (decimal?)options?.Temperature ?? _temperature,
             Tools = _tools?.ToList(),
-            ToolChoice = _toolChoice ?? ToolChoice.Auto
+            ToolChoice = _toolChoice ?? (_tools is { Length: > 0 } ? ToolChoice.Auto : null),
+            StopSequences = options?.StopSequence?.ToArray(),
         };
 
         chatCompletionRequest.Messages = BuildMessages(messages);
@@ -95,6 +96,22 @@ private List<ChatMessage> BuildMessages(IEnumerable<IMessage> messages)
             }
         }
 
-        return chatMessages;
+        // merge messages with the same role
+        // fixing #2884
+        var mergedMessages = chatMessages.Aggregate(new List<ChatMessage>(), (acc, message) =>
+        {
+            if (acc.Count > 0 && acc.Last().Role == message.Role)
+            {
+                acc.Last().Content.AddRange(message.Content);
+            }
+            else
+            {
+                acc.Add(message);
+            }
+
+            return acc;
+        });
+
+        return mergedMessages;
     }
 }

dotnet/src/AutoGen.Anthropic/AnthropicClient.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // AnthropicClient.cs
 
 using System;
@@ -90,13 +90,7 @@ public async IAsyncEnumerable<ChatCompletionResponse> StreamingChatCompletionsAs
                 {
                     var res = await JsonSerializer.DeserializeAsync<ChatCompletionResponse>(
                         new MemoryStream(Encoding.UTF8.GetBytes(currentEvent.Data)),
-                        cancellationToken: cancellationToken);
-
-                    if (res == null)
-                    {
-                        throw new Exception("Failed to deserialize response");
-                    }
-
+                        cancellationToken: cancellationToken) ?? throw new Exception("Failed to deserialize response");
                     if (res.Delta?.Type == "input_json_delta" && !string.IsNullOrEmpty(res.Delta.PartialJson) &&
                         currentEvent.ContentBlock != null)
                     {

dotnet/src/AutoGen.Core/Agent/IAgent.cs

@@ -7,10 +7,14 @@
 using System.Threading.Tasks;
 
 namespace AutoGen.Core;
-public interface IAgent
+
+public interface IAgentMetaInformation
 {
     public string Name { get; }
+}
 
+public interface IAgent : IAgentMetaInformation
+{
     /// <summary>
     /// Generate reply
     /// </summary>

dotnet/src/AutoGen.Core/Extension/GroupChatExtension.cs

@@ -100,8 +100,7 @@ internal static IEnumerable<IMessage> ProcessConversationsForRolePlay(
             var msg = @$"From {x.From}:
 {x.GetContent()}
 <eof_msg>
-round # 
-                {i}";
+round # {i}";
 
             return new TextMessage(Role.User, content: msg);
         });

dotnet/src/AutoGen.Core/GroupChat/GroupChat.cs

@@ -15,6 +15,7 @@ public class GroupChat : IGroupChat
     private List<IAgent> agents = new List<IAgent>();
     private IEnumerable<IMessage> initializeMessages = new List<IMessage>();
     private Graph? workflow = null;
+    private readonly IOrchestrator orchestrator;
 
     public IEnumerable<IMessage>? Messages { get; private set; }
 
@@ -36,6 +37,37 @@ public GroupChat(
         this.initializeMessages = initializeMessages ?? new List<IMessage>();
         this.workflow = workflow;
 
+        if (admin is not null)
+        {
+            this.orchestrator = new RolePlayOrchestrator(admin, workflow);
+        }
+        else if (workflow is not null)
+        {
+            this.orchestrator = new WorkflowOrchestrator(workflow);
+        }
+        else
+        {
+            this.orchestrator = new RoundRobinOrchestrator();
+        }
+
+        this.Validation();
+    }
+
+    /// <summary>
+    /// Create a group chat which uses the <paramref name="orchestrator"/> to decide the next speaker(s).
+    /// </summary>
+    /// <param name="members"></param>
+    /// <param name="orchestrator"></param>
+    /// <param name="initializeMessages"></param>
+    public GroupChat(
+        IEnumerable<IAgent> members,
+        IOrchestrator orchestrator,
+        IEnumerable<IMessage>? initializeMessages = null)
+    {
+        this.agents = members.ToList();
+        this.initializeMessages = initializeMessages ?? new List<IMessage>();
+        this.orchestrator = orchestrator;
+
         this.Validation();
     }
 
@@ -64,12 +96,6 @@ private void Validation()
                 throw new Exception("All agents in the workflow must be in the group chat.");
             }
         }
-
-        // must provide one of admin or workflow
-        if (this.admin == null && this.workflow == null)
-        {
-            throw new Exception("Must provide one of admin or workflow.");
-        }
     }
 
     /// <summary>
@@ -81,6 +107,7 @@ private void Validation()
     /// <param name="currentSpeaker">current speaker</param>
     /// <param name="conversationHistory">conversation history</param>
     /// <returns>next speaker.</returns>
+    [Obsolete("Please use RolePlayOrchestrator or WorkflowOrchestrator")]
     public async Task<IAgent> SelectNextSpeakerAsync(IAgent currentSpeaker, IEnumerable<IMessage> conversationHistory)
     {
         var agentNames = this.agents.Select(x => x.Name).ToList();
@@ -140,37 +167,40 @@ public void AddInitializeMessage(IMessage message)
     }
 
     public async Task<IEnumerable<IMessage>> CallAsync(
-        IEnumerable<IMessage>? conversationWithName = null,
+        IEnumerable<IMessage>? chatHistory = null,
         int maxRound = 10,
         CancellationToken ct = default)
     {
         var conversationHistory = new List<IMessage>();
-        if (conversationWithName != null)
+        conversationHistory.AddRange(this.initializeMessages);
+        if (chatHistory != null)
         {
-            conversationHistory.AddRange(conversationWithName);
+            conversationHistory.AddRange(chatHistory);
         }
+        var roundLeft = maxRound;
 
-        var lastSpeaker = conversationHistory.LastOrDefault()?.From switch
+        while (roundLeft > 0)
         {
-            null => this.agents.First(),
-            _ => this.agents.FirstOrDefault(x => x.Name == conversationHistory.Last().From) ?? throw new Exception("The agent is not in the group chat"),
-        };
-        var round = 0;
-        while (round < maxRound)
-        {
-            var currentSpeaker = await this.SelectNextSpeakerAsync(lastSpeaker, conversationHistory);
-            var processedConversation = this.ProcessConversationForAgent(this.initializeMessages, conversationHistory);
-            var result = await currentSpeaker.GenerateReplyAsync(processedConversation) ?? throw new Exception("No result is returned.");
+            var orchestratorContext = new OrchestrationContext
+            {
+                Candidates = this.agents,
+                ChatHistory = conversationHistory,
+            };
+            var nextSpeaker = await this.orchestrator.GetNextSpeakerAsync(orchestratorContext, ct);
+            if (nextSpeaker == null)
+            {
+                break;
+            }
+
+            var result = await nextSpeaker.GenerateReplyAsync(conversationHistory, cancellationToken: ct);
             conversationHistory.Add(result);
 
-            // if message is terminate message, then terminate the conversation
-            if (result?.IsGroupChatTerminateMessage() ?? false)
+            if (result.IsGroupChatTerminateMessage())
             {
-                break;
+                return conversationHistory;
             }
 
-            lastSpeaker = currentSpeaker;
-            round++;
+            roundLeft--;
         }
 
         return conversationHistory;

dotnet/src/AutoGen.Core/GroupChat/RoundRobinGroupChat.cs

@@ -3,9 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 
 namespace AutoGen.Core;
 
@@ -25,76 +22,12 @@ public SequentialGroupChat(IEnumerable<IAgent> agents, List<IMessage>? initializ
 /// <summary>
 /// A group chat that allows agents to talk in a round-robin manner.
 /// </summary>
-public class RoundRobinGroupChat : IGroupChat
+public class RoundRobinGroupChat : GroupChat
 {
-    private readonly List<IAgent> agents = new List<IAgent>();
-    private readonly List<IMessage> initializeMessages = new List<IMessage>();
-
     public RoundRobinGroupChat(
         IEnumerable<IAgent> agents,
         List<IMessage>? initializeMessages = null)
+        : base(agents, initializeMessages: initializeMessages)
     {
-        this.agents.AddRange(agents);
-        this.initializeMessages = initializeMessages ?? new List<IMessage>();
-    }
-
-    /// <inheritdoc />
-    public void AddInitializeMessage(IMessage message)
-    {
-        this.SendIntroduction(message);
-    }
-
-    public async Task<IEnumerable<IMessage>> CallAsync(
-        IEnumerable<IMessage>? conversationWithName = null,
-        int maxRound = 10,
-        CancellationToken ct = default)
-    {
-        var conversationHistory = new List<IMessage>();
-        if (conversationWithName != null)
-        {
-            conversationHistory.AddRange(conversationWithName);
-        }
-
-        var lastSpeaker = conversationHistory.LastOrDefault()?.From switch
-        {
-            null => this.agents.First(),
-            _ => this.agents.FirstOrDefault(x => x.Name == conversationHistory.Last().From) ?? throw new Exception("The agent is not in the group chat"),
-        };
-        var round = 0;
-        while (round < maxRound)
-        {
-            var currentSpeaker = this.SelectNextSpeaker(lastSpeaker);
-            var processedConversation = this.ProcessConversationForAgent(this.initializeMessages, conversationHistory);
-            var result = await currentSpeaker.GenerateReplyAsync(processedConversation) ?? throw new Exception("No result is returned.");
-            conversationHistory.Add(result);
-
-            // if message is terminate message, then terminate the conversation
-            if (result?.IsGroupChatTerminateMessage() ?? false)
-            {
-                break;
-            }
-
-            lastSpeaker = currentSpeaker;
-            round++;
-        }
-
-        return conversationHistory;
-    }
-
-    public void SendIntroduction(IMessage message)
-    {
-        this.initializeMessages.Add(message);
-    }
-
-    private IAgent SelectNextSpeaker(IAgent currentSpeaker)
-    {
-        var index = this.agents.IndexOf(currentSpeaker);
-        if (index == -1)
-        {
-            throw new ArgumentException("The agent is not in the group chat", nameof(currentSpeaker));
-        }
-
-        var nextIndex = (index + 1) % this.agents.Count;
-        return this.agents[nextIndex];
     }
 }

dotnet/src/AutoGen.Core/Orchestrator/IOrchestrator.cs

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// IOrchestrator.cs
+
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace AutoGen.Core;
+
+public class OrchestrationContext
+{
+    public IEnumerable<IAgent> Candidates { get; set; } = Array.Empty<IAgent>();
+
+    public IEnumerable<IMessage> ChatHistory { get; set; } = Array.Empty<IMessage>();
+}
+
+public interface IOrchestrator
+{
+    /// <summary>
+    /// Return the next agent as the next speaker. return null if no agent is selected.
+    /// </summary>
+    /// <param name="context">orchestration context, such as candidate agents and chat history.</param>
+    /// <param name="cancellationToken">cancellation token</param>
+    public Task<IAgent?> GetNextSpeakerAsync(
+        OrchestrationContext context,
+        CancellationToken cancellationToken = default);
+}