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Overview

PaymentIndexRecorder records a sequential index for each payment action, enabling multiple refund requests per payment. Each time record() is called, the index increments by 1.

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When to Use

  • You need on-chain payment lookups without a subgraph
  • You need to support multiple refund requests per payment (each keyed by nonce)
  • Other contracts need to read the payment index on-chain
Skip when: You’re using a subgraph for payment queries — the subgraph can derive indexes from events without the on-chain gas cost.

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State

mapping(bytes32 paymentInfoHash => uint256 count) public paymentIndex;

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Methods

function record(
    AuthCaptureEscrow.PaymentInfo calldata paymentInfo,
    uint256 amount,
    address caller
) external {
    bytes32 hash = escrow.getHash(paymentInfo);
    paymentIndex[hash]++;
}

function getPaymentIndex(
    AuthCaptureEscrow.PaymentInfo calldata paymentInfo
) external view returns (uint256) {
    return paymentIndex[escrow.getHash(paymentInfo)];
}

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Integration with RefundRequest

The nonce parameter in RefundRequest.requestRefund() corresponds to the payment index. This allows one refund request per charge/action: 
// After two charges on the same payment:
// paymentIndex = 2

// Refund request for first charge
await refundRequest.requestRefund(paymentInfo, amount1, 0); // nonce 0

// Refund request for second charge
await refundRequest.requestRefund(paymentInfo, amount2, 1); // nonce 1

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Gas

Cost: ~20k gas per record() call (one SSTORE for the counter increment).

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Next Steps

RecorderCombinator

Combine with other recorders in a single slot.

Recorders Overview

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