A2A v0.3.0 JSON-RPC: message/send answers with one final Message

A2A v0.3.0 JSON-RPC 2.0 over HTTP POST (Content-Type application/json, at most 16 KiB). message/send takes one DataPart {skill, ...inputs} or one short TextPart ("country IR", "incidents IR" or "start") and answers with one final Message: a JSON data part, plus a text part for country.status, incidents.search, agent.start, watch.add and watch.read. Other plain text of up to 200 characters gets a text-only help reply; empty text, longer text or an invalid JSON skill object is refused with -32602. Synchronous only: no task is stored, nothing streams, and there are no push notifications. Skills: country.status, incidents.search, agent.start, watch.add, watch.read, directory.search, catalog.search and capability.lookup; the agent card lists each skill's inputs. Public skills need no key; watch.add and watch.read read only the X-Agent-Key HTTP header. country.status and incidents.search return the same dated records as /v1/answers and /data/incidents, not live reachability checks. Claim verification, per-domain checks, messaging, checkout, signing and payment are not offered. 30 calls a minute per network plus each forwarded route's own limits and switches; the safety desk refuse list is checked on every call. GET answers 405.