{"service":"A2A Handshake Endpoint","version":"0.1.0","loaded_agents":["youhuiying-audit-agent","ta-neo"],"endpoints":{"GET  /":"服务说明","GET  /health":"健康检查","GET  /a2a/agents":"列出已注册 agent","GET  /a2a/agents/{id}/card":"拉取某个 agent 的公开卡","POST /a2a/handshake":"握手入口","POST /a2a/agents/register":"开放注册 (第二口令; 卡被强制只读中性化)","DELETE /a2a/agents/{id}":"注销注册卡 (第二口令, 仅限 registered/)","GET  /a2a/sessions/{handshake_id}":"查握手会话状态","GET  /a2a/notifications?limit=N":"查最近的握手报告 (COMPLETE/REJECT)"},"protocol":{"transport":"HTTP + JSON","phases":["INIT","NEGOTIATE","COMPLETE","REJECT"],"envelope_required_fields":["handshake_id","phase","from_agent","to_agent"],"gate":"内容端点需口令 (X-Gate-Token / query token / payload.gate_token)","exchange":"NEGOTIATE 需携带发起方 from_card 或 from_card_url (双向交换)"}}