A2A 1.0 vs 0.3 Bindings

A2A 1.0 supports JSON‑RPC, REST/HTTP and native gRPC bindings, whereas version 0.3 only offers JSON‑RPC. The protocol uses an x‑a2a OpenAPI extension to describe version, binding, endpoint and contracts, and tasks can be cancelled by sending a CancelTask request; a local stop only ends the UI stream, not the remote work. This ensures precise control over agent interactions across different transport layers.