Function canon_handler_signature 

pub fn canon_handler_signature(
    h: &HandlerSignature,
    types: &HashMap<String, Arc<TypeDecl>>,
) -> String

P8.1 (#1512, [DECISION C]): the canonical form of a HandlerSignature. given renders sorted — its rendered CapRef names have no meaningful order to preserve (it’s a set, not a sequence). kind is rendered first (PR #1517’s own bot review, finding #1) — two handlers that differ only in HTTP method or route, or in on call vs. on message, must not canonicalise identically.