Function handlePaymentRequired

src/services/x402/client.ts:341–391

(
  headerValue: string,
  sessionSpentUSD: number,
)

 * Returns the payment header value, or null if payment is not possible.
 */
export function handlePaymentRequired(
  headerValue: string,
  sessionSpentUSD: number,
): {
  paymentHeader: string
  record: X402PaymentRecord
} | null {
  const requirement = parsePaymentRequirement(headerValue)
  const validation = validatePaymentRequirement(requirement, sessionSpentUSD)

  if (!validation.valid) {
    logForDebugging(`[x402] Payment rejected: ${validation.reason}`)
    return null
  }

  const privateKey = getX402PrivateKey()
  if (!privateKey) {
    logForDebugging('[x402] No private key configured')
    return null
  }

  const config = getX402Config()
  const fromAddress = config.address
  if (!fromAddress) {
    logForDebugging('[x402] No wallet address configured')
    return null
  }

  const payment = createPayment(requirement, fromAddress, privateKey)
  const paymentHeader = encodePaymentHeader(payment)

  const record: X402PaymentRecord = {
    timestamp: Date.now(),
    resource: requirement.resource,
    amount: requirement.maxAmountRequired,
    amountUSD: tokenAmountToUSD(requirement.maxAmountRequired),
    token: requirement.extra?.name ?? 'USDC',
    network: requirement.network,
    payTo: requirement.payTo,
    signature: payment.payload.signature,
  }

  // Track the payment
  addX402Payment(record)

  logForDebugging(
    `[x402] Payment signed: $${record.amountUSD.toFixed(4)} to ${requirement.payTo} for ${requirement.resource}`,
  )

  return { paymentHeader, record }
}

/**
 * Get the facilitator URL for a given network.