ChatMessages parameter in Agent.Call was not accumulating messages (#1212)

* Apply fix on #1208 to CallAgent

* Add default ToJson implementation for ExternalCollections, enabling proper ToJson behavior for ChatMessage collections.

* Remove identation.

---------

Co-authored-by: claudiamurialdo <c.murialdo@globant.com>

Author: claudiamurialdo

dotnet/src/dotnetcore/Providers/AI/Model/GXAgent.cs

@@ -42,8 +42,7 @@ protected string CallAgent(string assistant, GXProperties gxproperties, IList ch
 			{
 				GXLogging.Debug(log, "Calling Agent: ", assistant);
 
-				List<ChatMessage> chatMessagesList = chatMessages!=null ? chatMessages.Cast<ChatMessage>().ToList() :null;
-				ChatCompletionResult chatCompletion = AgentService.AgentHandlerInstance.CallAgent(assistant, chatMessagesList, gxproperties, context).GetAwaiter().GetResult();
+				ChatCompletionResult chatCompletion = AgentService.AgentHandlerInstance.CallAgent(assistant, chatMessages, gxproperties, context).GetAwaiter().GetResult();
 
 				if (chatCompletion != null && chatCompletion.Choices != null)
 				{
@@ -54,8 +53,8 @@ protected string CallAgent(string assistant, GXProperties gxproperties, IList ch
 							case ChatCompletionResult.FINISH_REASON_STOP:
 								return choice.Message.Content;
 							case ChatCompletionResult.FINISH_REASON_TOOL_CALLS:
-								chatMessagesList.Add(choice.Message);
-								return ProcessChatResponse(choice, stream, assistant, gxproperties, chatMessagesList, result);	
+								chatMessages.Add(choice.Message);
+								return ProcessChatResponse(choice, stream, assistant, gxproperties, chatMessages, result);	
 						}
 					}
 				}

dotnet/src/dotnetcore/Providers/AI/Services/AgentService.cs

@@ -51,7 +51,7 @@ static string AddChatToUrl(string url)
 			uriBuilder.Path += "chat";
 			return uriBuilder.Uri.ToString();
 		}
-		internal async Task<ChatCompletionResult> CallAgent(string assistant, List<Chat.ChatMessage> messages, GXProperties properties, IGxContext context)
+		internal async Task<ChatCompletionResult> CallAgent(string assistant, IList messages, GXProperties properties, IGxContext context)
 		{
 			try
 			{

dotnet/src/dotnetframework/GxClasses/Domain/GxCollections.cs

@@ -2708,7 +2708,15 @@ public void AddObjectProperty(string name, object prop)
 		}
 		public string ToJSonString()
 		{
+#if NETCORE
+			string json =  JSONHelper.DefaultSerialize(ExternalInstance);
+			if (json!=null)
+				return json;
+			else
+				return new JArray().ToString();
+#else
 			return string.Empty;
+#endif
 		}
 		public string ToJSonString(bool includeState)
 		{

dotnet/src/dotnetframework/GxClasses/Helpers/JSONHelper.cs

@@ -128,6 +128,15 @@ internal override string WriteNullableJSON(Dictionary<string, object> kbObject)
 			});
 		}
 
+		internal override string DefaultSerialize<T>(T value)
+		{
+			if (value != null)
+			{
+				return JsonSerializer.Serialize(value);
+			}
+			return null;
+		}
+
 		internal override bool IsJsonString(string jobject)
 		{
 			try
@@ -229,6 +238,9 @@ internal static GXJsonSerializer Instance
 		internal abstract string WriteJSON<T>(T kbObject) where T : class;
 
 		internal abstract string WriteNullableJSON(Dictionary<string, object> kbObject);
+#if NETCORE
+		internal abstract string DefaultSerialize<T>(T value) where T : class;
+#endif
 	}
 
 	public class JSONHelper
@@ -328,7 +340,20 @@ public static string Serialize<T>(T kbObject) where T : class
 		{
 			return Serialize<T>(kbObject, Encoding.UTF8);
 		}
-
+#if NETCORE
+		public static string DefaultSerialize<T>(T value) where T : class
+		{
+			try
+			{
+				return GXJsonSerializer.Instance.DefaultSerialize<T>(value);
+			}
+			catch (Exception ex)
+			{
+				GXLogging.Error(log, "DefaultSerialize error ", ex);
+				return null;
+			}
+		}
+#endif
 		public static string Serialize<T>(T kbObject, Encoding encoding) where T : class
 		{
 			return Serialize<T>(kbObject, encoding, null);