Function probe_with_kept 

fn probe_with_kept(
    all_defs: &Map<String, Value>,
    universe: &BTreeSet<String>,
    keep_real: &BTreeSet<String>,
) -> ProbeOutcome

Builds a candidate schema where every definition in universe but not in keep_real is opaqued to true; definitions outside universe are left exactly as they are in all_defs. Probes it with typify.