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Payment flow

This is the canonical flow we use across all platforms. It’s the same x402 flow but wrapped by Gx402 middleware patterns so every client behaves the same.

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1) Create (client → backend)

  • Client requests POST /create-payment with { itemId, amount, userAddress, metadata }.
  • Server creates a paymentSession and builds a deterministic payload (paymentId, amount, timestamp, chainId, optional nonce).
  • Server may optionally call x402’s create endpoint to register the session — not required if you only need a client-sign flow.
Server response 
{ "paymentId": "pay_123", "payload": "string-to-sign", "expiresAt": 1670000000000 }