change Agent interface to return a list of messages

Author: dantelmomsft

app/copilot/copilot-backend/src/main/java/com/microsoft/openai/samples/assistant/controller/ChatController.java

@@ -53,9 +53,9 @@ public ResponseEntity<ChatResponse> openAIAsk(@RequestBody ChatAppRequest chatRe
 
         LOGGER.debug("Processing chat conversation..", chatHistory.get(chatHistory.size()-1));
 
-        supervisorAgent.invoke(chatHistory);
+        List<ChatMessage> agentsResponse = supervisorAgent.invoke(chatHistory);
 
-        AiMessage generatedResponse = (AiMessage) chatHistory.get(chatHistory.size()-1);
+        AiMessage generatedResponse = (AiMessage) agentsResponse.get(agentsResponse.size()-1);
         return ResponseEntity.ok(
                 ChatResponse.buildChatResponse(generatedResponse));
     }

app/copilot/langchain4j-agents/src/main/java/com/microsoft/langchain4j/agent/AbstractReActAgent.java

@@ -16,6 +16,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public abstract class AbstractReActAgent implements Agent {
 
@@ -31,7 +32,7 @@ protected AbstractReActAgent(ChatLanguageModel chatModel) {
     }
 
     @Override
-    public void invoke(List<ChatMessage> chatHistory) throws AgentExecutionException {
+    public List<ChatMessage> invoke(List<ChatMessage> chatHistory) throws AgentExecutionException {
         LOGGER.info("------------- {} -------------", this.getName());
 
         try {
@@ -67,20 +68,17 @@ public void invoke(List<ChatMessage> chatHistory) throws AgentExecutionException
 
             // add last ai message to agent internal memory
             internalChatMemory.add(aiMessage);
-            updateChatHistory(chatHistory, internalChatMemory);
+            return buildResponse(chatHistory, internalChatMemory);
         } catch (Exception e) {
             throw new AgentExecutionException("Error during agent [%s] invocation".formatted(this.getName()), e);
         }
     }
 
-    protected void updateChatHistory(List<ChatMessage> chatHistory, ChatMemory internalChatMemory) {
-        //delete extenal messages to avoid duplication
-        chatHistory.clear();
-        //add previous history + agent internal messages
-        internalChatMemory.messages()
-            .stream()
-            .filter(m -> !(m instanceof SystemMessage))
-            .forEach(chatHistory::add);
+    protected List<ChatMessage> buildResponse(List<ChatMessage> chatHistory, ChatMemory internalChatMemory) {
+        return internalChatMemory.messages()
+                .stream()
+                .filter(m -> !(m instanceof SystemMessage))
+                .collect(Collectors.toList());
     }
 
     protected List<ToolExecutionResultMessage> executeToolRequests(List<ToolExecutionRequest> toolExecutionRequests) {

app/copilot/langchain4j-agents/src/main/java/com/microsoft/langchain4j/agent/Agent.java

@@ -8,5 +8,5 @@ public interface Agent {
 
     String getName();
     AgentMetadata getMetadata();
-    void invoke(List<ChatMessage> chatHistory) throws AgentExecutionException;
+    List<ChatMessage> invoke(List<ChatMessage> chatHistory) throws AgentExecutionException;
 }

app/copilot/langchain4j-agents/src/main/java/com/microsoft/openai/samples/assistant/langchain4j/agent/SupervisorAgent.java

@@ -16,6 +16,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -55,7 +56,7 @@ public SupervisorAgent(ChatLanguageModel chatLanguageModel, List<Agent> agents)
     }
 
 
-    public void invoke(List<ChatMessage> chatHistory) {
+    public List<ChatMessage> invoke(List<ChatMessage> chatHistory) {
         LOGGER.info("------------- SupervisorAgent -------------");
 
         var internalChatMemory = buildInternalChat(chatHistory);
@@ -69,27 +70,29 @@ public void invoke(List<ChatMessage> chatHistory) {
         LOGGER.info("Supervisor Agent handoff to [{}]", nextAgent);
 
      if (routing) {
-            singleTurnRouting(nextAgent, chatHistory);
+           return singleTurnRouting(nextAgent, chatHistory);
         }
+
+     return new ArrayList<>();
     }
 
 
-    protected void singleTurnRouting(String nextAgent, List<ChatMessage> chatHistory) {
+    protected List<ChatMessage> singleTurnRouting(String nextAgent, List<ChatMessage> chatHistory) {
         if("none".equalsIgnoreCase(nextAgent)){
             LOGGER.info("Gracefully handle clarification.. ");
             AiMessage clarificationMessage = AiMessage.builder().
                     text(" I'm not sure about your request. Can you please clarify?")
                     .build();
             chatHistory.add(clarificationMessage);
-            return;
+            return chatHistory;
         }
 
         Agent agent = agents.stream()
                 .filter(a -> a.getName().equals(nextAgent))
                 .findFirst()
                 .orElseThrow(() -> new AgentExecutionException("Agent not found: " + nextAgent));
 
-        agent.invoke(chatHistory);
+        return agent.invoke(chatHistory);
     }