Function split_conflicts 

fn split_conflicts(
    units: &[Unit],
    extents: &[Extent],
    index: &ExtentIndex<'_>,
    work_budget: usize,
) -> Option<Vec<Vec<usize>>>

Positions of the split units each unit conflicts with, sorted. Files of different units never conflict, so only split files have any.

Returns None once the index traversal has visited more than work_budget nodes, so a dense window cannot materialize an unbounded adjacency.