Function canon_unit_signature 

pub fn canon_unit_signature(sig: &UnitSignature) -> String

P8.1 (#1512, [DECISION C]): UnitSignature::canonical’s own implementation — the single rendering R3.14’s own stability proof compares. Every category is rendered sorted (by the caller’s own BTreeMap/BTreeSet keys, or an explicit sort for Vec-shaped fields like a handler’s own given), so construction order never perturbs the form — the same “compare the canonical string, not map/vec iteration order” discipline service_normal_form’s record-field sort already established for ADR 0200.