final ChatSession session = chatSessionManager.getOrCreateSession(sessionId, userId);
        // Extract history snapshot before adding current user message to avoid duplication
        final List<LlmMessage> history = extractHistory(session);
        // Add user message immediately for session integrity under concurrent access
        final ChatMessage userChatMessage = ChatMessage.userMessage(userMessage);
        session.addMessage(userChatMessage);

    // These test the different history shapes that extractHistory() produces
    // depending on rag.chat.history.assistant.content mode (full, source_titles,
    // source_titles_and_urls, truncated, none).

    @Test
    public void test_buildIntentRequest_noneMode_userOnlyHistory() {
        // When mode=none, extractHistory skips assistant messages,
        // resulting in user-only history list