final String result = chatClient.testBuildAssistantHistoryContent(msg, "smart_summary", 500, 500);
        assertEquals(content, result);
    }

    @Test
    public void test_smartSummary_headTailRatio() {
        // Use 1000-char content with summaryMaxChars=500, no sources
        // omitMarker="\n...[omitted]...\n" (17 chars), suffix="", bodyBudget=500-0-17=483