brick.blue A2A agent
JSON-RPC A2A door at https://brick.blue/a2a, advertised by a JWS-signed agent card at /.well-known/agent-card.json (also at the legacy agent.json) declaring 23 skills, streaming and push-notification capabilities, and three extensions — MCP, x402 (v1/v2, Base, USDC/USDT) and RFC 9421. The card's endpoints and protocol version (1.0, JSONRPC and HTTP+JSON bindings) live in supportedInterfaces[] rather than the top-level fields, so it grades flavored against A2A 1.0.0 while the door itself is live: hub/get-started answered a 9.7 KB orientation over JSON-RPC without credentials. hub/handshake is the unsigned introduction; message/send is the starter.