Gas Waiver

WrapperTx {
  from:     waiver_address,
  to:       0x000000000000000000000000000000000000f333,
  value:    0,                          // 0이어야 함
  data:     RLP(InnerTx),               // RLP 인코딩된 내부 트랜잭션
  gasPrice: 0,                          // 0이어야 함
  gasLimit: sufficient_for_inner,       // 내부 실행 + 오버헤드를 커버해야 함
  nonce:    waiver_nonce
}

InnerTx {
  from:     user_address,
  to:       target_contract,
  value:    value,
  data:     call_data,
  gasPrice: 0,                          // 0이어야 함
  gasLimit: execution_gas,
  nonce:    user_nonce
}

Authorization: Bearer <your-api-key>

{
  "transactions": ["0x<signedInnerTx1>", "0x<signedInnerTx2>"]
}

{"index":0,"id":"abc123","success":true,"txHash":"0x..."}
{"index":1,"id":"def456","success":false,"error":{"code":"VALIDATION_FAILED","message":"invalid signature"}}

const WAIVER_SERVER = "https://waiver.testnet.stable.xyz";

async function submitGaslessTransaction(signedInnerTxHex, apiKey) {
  const response = await fetch(`${WAIVER_SERVER}/v1/submit`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "Authorization": `Bearer ${apiKey}`,
    },
    body: JSON.stringify({
      transactions: [signedInnerTxHex],
    }),
  });

  const reader = response.body.getReader();
  const decoder = new TextDecoder();

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;

    const lines = decoder.decode(value).trim().split("\n");
    for (const line of lines) {
      const result = JSON.parse(line);
      console.log(result);
    }
  }
}

import { ethers } from "ethers";

async function createInnerTx(userWallet, contractAddress, callData, nonce) {
  const innerTx = {
    to: contractAddress,
    data: callData,
    value: value,
    gasPrice: 0,              // 면제를 위해 0이어야 함
    gasLimit: 100000,
    nonce: nonce,
    chainId: 2201,            // 메인넷: 988, 테스트넷: 2201
  };

  return await userWallet.signTransaction(innerTx);
}