Custom Account Clients

Use the low-level client when your account library already constructs and signs EntryPoint v0.7 UserOperations. Most applications should use the Viem adapter shown in Pay Gas with Stablecoins.

import { createInkPublicPaymasterClient } from "@hellomoon/ink-paymaster";
 
const paymaster = createInkPublicPaymasterClient();
const prepared = await paymaster.prepareUserOperation({
  userOperation: operationWithCorrectlySizedStubSignature,
  token: "USDC",
  maxTokenCost: 100_000n,
  idempotencyKey: "checkout-order-123",
});
 
// Sign after the quote and estimated gas fields have been applied.
const signed = await account.signUserOperation(prepared.userOperation);
const hash = await paymaster.sendUserOperation(signed);
const receipt = await paymaster.waitForUserOperationReceipt({ hash });
if (!receipt.success) throw new Error("prepaid operation reverted");

Required ordering

1. Construct a complete v0.7 UserOperation with the correct sender, nonce, account callData, fees, and a stub signature with the same size as the final signature.
2. Call prepareUserOperation to obtain and attach the signed quote and final gas estimates.
3. Sign the resulting operation.
4. Submit that exact signed operation with sendUserOperation.
5. Wait for its receipt and check receipt.success.

Do not change quote-bound fields after preparation. A changed sender, nonce, factory, account call, token, reimbursement ceiling, or validity window invalidates the quote signature.

UserOperation format

The default INK_PUBLIC_PAYMASTER deployment accepts EntryPoint v0.7 fields such as factory and factoryData. It rejects the v0.6 initCode shape and EIP-7702 operations. Use INK_PUBLIC_PAYMASTER_V08 and the v0.8 eip7702Auth shape for a custom EIP-7702 client. Represent numeric JSON-RPC fields as hexadecimal quantities.

The stub signature supplied before estimation must have the same byte length as the final signature. A differently sized signature changes preVerificationGas and can invalidate the final estimate.

Idempotency

Reuse one key for transport retries of the same logical operation. Generate a new key after changing the sender, nonce, factory, account call, token, or reimbursement ceiling. Keys must contain 8–128 letters, numbers, dots, underscores, colons, or hyphens.