assertTrue(result.length() > 0);
    }

    // ========== additional source_titles tests ==========

    @Test
    public void test_sourceTitles_truncatesLongContent() {
        final ChatMessage msg = createAssistantWithSources("A".repeat(1000), "My Doc");
        final String result = chatClient.testBuildAssistantHistoryContent(msg, "source_titles", 500, 500);
        assertTrue(result.contains("... [truncated]"));