Prepare Payment

Authorize and generate the blockchain transaction data (calldata) required to execute the payment.

POST /payment/prepare

EIP-712 Authorization

This endpoint requires an EIP-712 signature with the purpose prepare_payment. This signature acts as the final confirmation from the user to execute the transaction.

Request Parameters

Field	Type	Required	Description
message	Object	✅	The EIP-712 message object signed by the user.
message.purpose	String	✅	Must be prepare_payment.
message.sessionId	String	✅	The Session ID.
message.merchantId	String	✅	The Merchant ID.
message.payer	Address	✅	The payer address.
message.payerEmail	String	✅	The payer email.
message.paymentChainId	String	✅	The chain ID.
message.paymentToken	Address	✅	The token address.
message.authorizationNonce	Bytes32	✅	Unique nonce.
message.authorizationExpiresAt	Timestamp	✅	Expiration time.
signature	Bytes	✅	The EIP-712 signature.

Request Example

{
  "message": {
    "purpose": "prepare_payment",
    "sessionId": "sess_example_payment_03",
    "merchantId": "f7d65b193454db46fb2d6277e2f5e593bffcf6adde5064a2bb5dee6fd9b0fb7a",
    "paymentChainId": "137",
    "paymentToken": "0x3c499c542cef5e3811e1192ce70d8cc03d5c3359",
    "payer": "0x1234567890123456789012345678901234567890",
    "payerEmail": "test@example.com",
    "authorizationNonce": "0x3132...",
    "authorizationExpiresAt": "1769488108"
  },
  "signature": "0x48a654a..."
}

Response Structure

The response contains the calldata for the blockchain transaction and the paymentExecutionGuide in the aiView.

Response Example

{
  "calldata": "0xa9059cbb000000000000000000000000f7d65b193454db46fb2d6277e2f5e593bffcf6ad00000000000000000000000000000000000000000000000000000000002de6b0",
  "aiView": {
    "pricingModel": { "type": "fixed" },
    "paymentExecutionGuide": {
      "authorizationRequired": false,
      "executionRequest": {
        "purpose": "execute_payment_guide",
        "sessionId": "sess_example_payment_03",
        "txRequest": {
          "chainId": "137",
          "to": "0x3c499c542cef5e3811e1192ce70d8cc03d5c3359",
          "data": "0xa9059cbb...",
          "value": "0"
        },
        "userReview": {
          "description": "This transaction will execute the prepared payment on-chain.",
          "irreversible": true
        }
      }
    },
    "workflow": {
      "stage": "payment_prepared",
      "nextAction": {
        "action": "execute_payment_client_side",
        "description": "Client must execute the on-chain transaction."
      }
    }
  }
}

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Error Handling

This endpoint follows the Unified Error Handling standard. Business errors return HTTP 200 with a non-zero code.