{"service": "SignCheck", "version": "0.2", "what": "HTTP 消息签名（RFC 9421）与 402 支付凭据的确定性体检", "endpoints": {"POST /v1/register": "免费登记 Ed25519 公钥", "POST /v1/verify": "按次计费，0.002 USD/call", "POST /v1/verify-batch": "批量体检（≤20 份），0.02 USD/call", "POST /v1/mcpaudit": "MCP 授权栈体检（被动、无凭据），0.05 USD/call", "POST /mcp": "MCP streamable HTTP（JSON-RPC）：tools/list、tools/call", "POST /v1/receipt/redeem": "兑现收据：需兑现方钥匙签名；金额 ≥ 0.01 要一次 step-up 绑定码"}, "pricing": {"amount": "0.002", "currency": "USD", "payTo": "signcheck_demo", "resource": "/v1/verify", "network": "demo-ledger", "unit": "per_call", "what": "一次签名/支付凭据体检"}, "pricing_batch": {"amount": "0.02", "currency": "USD", "payTo": "signcheck_demo", "resource": "/v1/verify-batch", "network": "demo-ledger", "unit": "per_call", "what": "一次批量体检（最多 20 份）"}, "pricing_mcpaudit": {"amount": "0.05", "currency": "USD", "payTo": "signcheck_demo", "resource": "/v1/mcpaudit", "network": "demo-ledger", "unit": "per_call", "what": "一次 MCP 授权栈体检（被动、无凭据、单端点）"}, "step_up_at": "0.01", "seller_key": "GET /seller-key.jwk"}