fix: 400 Bad Request when restoring conversation from persistence (#152)

Author: xinyi-gong

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServerConnection.java

@@ -286,23 +286,23 @@ public CompletableFuture<ChatCreateResult> createConversation(String workDoneTok
       param.setChatMode(chatModeName);
       param.setCustomChatModeId(customChatModeId);
 
+      // Set historical turns if provided, inserting them before the current user message.
+      if (turns != null && turns.size() > 0) {
+        param.getTurns().addAll(0, turns);
+      }
+
       if (StringUtils.isBlank(agentSlug)) {
         param.setWorkspaceFolder(PlatformUtils.getWorkspaceRootUri());
         param.setWorkspaceFolders(LSPEclipseUtils.getWorkspaceFolders());
         param.setTodoList(todos);
       } else {
-        // Set agentSlug if provided - this will modify the first turn's agentSlug
+        // Set agentSlug on the last turn (current user message) after history insertion
         if (param.getTurns() != null && !param.getTurns().isEmpty()) {
-          param.getTurns().get(0).setAgentSlug(agentSlug);
+          param.getTurns().get(param.getTurns().size() - 1).setAgentSlug(agentSlug);
         }
         param.setWorkspaceFolder(agentJobWorkspaceFolder);
       }
 
-      // Set historical turns if provided.
-      if (turns != null && turns.size() > 0) {
-        param.getTurns().addAll(turns);
-      }
-
       // TODO: remove needToolCallConfirmation when CLS fully supports it across all IDEs.
       param.setNeedToolCallConfirmation(true);
       if (currentFile != null) {

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/persistence/ConversationDataFactory.java

@@ -26,7 +26,7 @@
 import com.microsoft.copilot.eclipse.core.persistence.CopilotTurnData.ReplyData;
 import com.microsoft.copilot.eclipse.core.persistence.CopilotTurnData.ToolCallData;
 import com.microsoft.copilot.eclipse.core.persistence.UserTurnData.MessageData;
-import com.microsoft.copilot.eclipse.core.utils.ChatMessageUtils;
+
 
 /**
  * Factory for creating and transforming conversation data objects. Responsible only for pure data transformation with
@@ -218,12 +218,10 @@ public List<Turn> convertToTurns(List<AbstractTurnData> turnDataList) {
             .forLeft(requestText == null ? "" : requestText);
         result.add(new Turn(request, null, null));
       } else if (turnData instanceof CopilotTurnData copilotTurnData) {
-        // TODO: We don't persist images for now, so hard code the modelSupportVersion to false. In the future, handle
-        // images in responses and pass the model support version here if needed.
+        // Assistant turns only contribute the response text; the request field is intentionally empty.
         String responseText = extractResponseFromCopilotTurnData(copilotTurnData);
-        Either<String, List<ChatCompletionContentPart>> response = ChatMessageUtils
-            .createMessageWithImages(responseText, new ArrayList<>(), false);
-        result.add(new Turn(response, responseText, null));
+        Either<String, List<ChatCompletionContentPart>> request = Either.forLeft("");
+        result.add(new Turn(request, responseText, null));
       }
     }
     return result;