Function prospective_partition_bound_accepts_document 

pub fn prospective_partition_bound_accepts_document(
    context: &PartitionContext<'_>,
    parent: &str,
    bound: &PartitionBound,
    document: &ResultRow,
) -> Result<bool, SQLError>

Test one stored row against a prospective direct-child bound before the hierarchy edge is installed. DEFAULT means no existing non-default sibling accepts the row, matching the routing decision the new edge will expose.