assertEquals(1, session.getMessages().size());
        assertEquals("Hello", session.getMessages().get(0).getContent());
        assertTrue(session.getLastAccessedAt().isAfter(beforeAdd) || session.getLastAccessedAt().isEqual(beforeAdd));
    }

    @Test
    public void test_addMessageWithNullMessages() {
        final ChatSession session = new ChatSession();
        session.setMessages(null);

                .setLevel(Level.ERROR)
                .setMessage(new SimpleMessage("test message 1"))
                .build();

        LogEvent event2 = Log4jLogEvent.newBuilder()
                .setLoggerName("another.logger.sub")
                .setLevel(Level.ERROR)
                .setMessage(new SimpleMessage("test message 2"))
                .build();

        return Log4jLogEvent.newBuilder() //
                .setLoggerName(loggerName) //
                .setLevel(level) //
                .setMessage(new SimpleMessage(message)) //
                .setTimeMillis(System.currentTimeMillis()) //
                .build();
    }

    @Test
    public void test_createAppender() {

            return null;
        }
        session.touch();
        if (logger.isDebugEnabled()) {
            logger.debug("Session retrieved. sessionId={}, messageCount={}", sessionId, session.getMessages().size());
        }
        return session;
    }

    /**
     * Gets or creates a session.
     *
     * @param sessionId the session ID (can be null to create a new session)

        final String llmType = getLlmType();
        if (logger.isDebugEnabled()) {
            logger.debug("[LLM] Starting LLM chat request. llmType={}, messageCount={}", llmType, request.getMessages().size());
            for (final LlmMessage msg : request.getMessages()) {
                logger.debug("[LLM] message: role={}, content={}", msg.getRole(), msg.getContent());
            }
        }
        try {

            final List<LlmMessage> history = new ArrayList<>();
            for (final ChatMessage msg : session.getMessages()) {
                if (msg.isUser()) {
                    history.add(LlmMessage.user(msg.getContent()));
                } else if (msg.isAssistant()) {
                    final String content =