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 {

        session.addMessage(message);

        assertNotNull(session.getMessages());
        assertEquals(1, session.getMessages().size());
    }

    @Test
    public void test_addUserMessage() {
        final ChatSession session = new ChatSession();
        session.addUserMessage("User message content");

        assertEquals(1, session.getMessages().size());

        assertEquals(originalException.getMessage(), deserializedException.getMessage());
        assertNotNull(deserializedException.getCause());
        assertEquals(originalException.getCause().getMessage(), deserializedException.getCause().getMessage());
    }

    @Test
    public void test_getMessage() {
        // Test getMessage() method
        String message = "Custom SSO error message";

        assertEquals("SSO process failed", topLevel.getMessage());
        assertEquals(level1, topLevel.getCause());
        assertEquals("Level 1: Authentication service error", topLevel.getCause().getMessage());
        assertEquals(level2, topLevel.getCause().getCause());
        assertEquals("Level 2: User lookup failed", topLevel.getCause().getCause().getMessage());

            // If exception thrown, validation is working
            assertTrue(e.getMessage().contains("Invalid negotiate context data length") || e.getMessage().contains("Buffer too small")
                    || e.getMessage().contains("negotiate context"), "Validation detected issue: " + e.getMessage());
        }
    }

    /**
     * Test negotiate context buffer overflow protection.
     */

        assertNotSame(exception2, exception3);
        assertNotSame(exception1, exception3);

        assertEquals("First instance", exception1.getMessage());
        assertEquals("Second instance", exception2.getMessage());
        assertEquals("Third instance", exception3.getMessage());
    }

    @Test
    public void test_specialCharactersInMessage() {
        // Test with special characters in message

        assertEquals(rootCause, finalException.getCause().getCause());
        assertEquals("Final error", finalException.getMessage());
        assertEquals("Intermediate", intermediateCause.getMessage());
        assertEquals("Root error", rootCause.getMessage());
    }

    @Test
    @DisplayName("Should preserve stack trace")
    void testStackTracePreservation() {
        // When

        assertTrue(exception instanceof FessSystemException);
    }

    @Test
    public void test_constructorWithNullMessage() {
        // Test constructor with null message
        SearchQueryException exception = new SearchQueryException((String) null);

        assertNull(exception.getMessage());
        assertNull(exception.getCause());

        assertEquals("Type1", exception1.getType());
        assertEquals("Message1", exception1.getMessage());
        assertEquals("Type2", exception2.getType());
        assertEquals("Message2", exception2.getMessage());

        assertNotSame(exception1, exception2);
    }

    @Test
    public void test_serialVersionUID() {

        assertEquals("service1 is not available.", exception1.getMessage());

        ContainerNotAvailableException exception2 = new ContainerNotAvailableException("service2", new RuntimeException());
        assertEquals("service2 is not available.", exception2.getMessage());

        ContainerNotAvailableException exception3 = new ContainerNotAvailableException(new RuntimeException());