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

    @Test
    public void test_smartSummary_exactlyAtBudget() {
        // omitMarker = "\n...[omitted]...\n" (18 chars), suffix="" (no sources), bodyBudget = 500 - 0 - 18 = 482
        // Content of 482 chars is <= bodyBudget, so returned with suffix (empty) appended as-is