let mut old = baseline.program.with_overlapped_reductions(2).unwrap();
    old.refresh_estimates().unwrap();
    let old_low = crate::low::expand::expand_tiles(&old, false).unwrap();
    assert_eq!(expanded, old_low, "scoped grouping preserves the old executable graph");
    let capture = std::path::Path::new("/srv/home/gc-sdk/ipu-stack/artifacts/structure-refactor-20260915/scoped-grouping");
    std::fs::write(capture.join("before-low.txt"), format!("{old_low:#?}")).unwrap();
    std::fs::write(capture.join("after-low.txt"), format!("{expanded:#?}")).unwrap();