If anyone wants to test their implementation, I built a free validator:
ucptools.dev
Checks version format, service bindings, capabilities, namespace rules,
signing keys (for Order capability), etc. Shows exactly which fields
are missing or malformed.
Google Universal Commerce Protocol (UCP) Guide · HackerTrans
Checks version format, service bindings, capabilities, namespace rules, signing keys (for Order capability), etc. Shows exactly which fields are missing or malformed.