Function phase_resolve_uses 

pub fn phase_resolve_uses(
    groups: &BTreeMap<String, Vec<usize>>,
    kinds: &BTreeMap<String, UnitKind>,
    parsed: &[ParsedFile],
    unit_tables: &HashMap<String, UnitTable>,
    errors: &mut ErrorSink,
) -> HashMap<String, Vec<String>>

Phase 5: resolve each unit’s uses clauses, checking the target exists, is a commons, and is not self-referential. Returns unit → deduplicated list of used commons; diagnostics go into errors.