final Map<String, Object> doc = new HashMap<>();
        doc.put("title", "Doc Title");
        doc.put("url", "http://example.com");
        assistantMsg.addSource(new ChatSource(1, doc));
        session.addMessage(assistantMsg);

        final List<LlmMessage> history = chatClient.testExtractHistory(session);
        assertEquals(2, history.size());
        assertEquals("user", history.get(0).getRole());