EIP-7702를 사용한 세션 키

npm install @alchemy/wallet-apis viem

added 2 packages

// config.ts
import { alchemyWalletTransport, createSmartWalletClient } from "@alchemy/wallet-apis";
import { createPublicClient, http, type Hex } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { stableTestnet } from "viem/chains";
 
export const chain = stableTestnet;
export const transport = alchemyWalletTransport({ apiKey: process.env.ALCHEMY_API_KEY! });
export const paymaster = process.env.ALCHEMY_GAS_POLICY_ID
  ? { policyId: process.env.ALCHEMY_GAS_POLICY_ID }
  : undefined;
 
export const USDT0_ADDRESS = "0x78Cf24370174180738C5B8E352B6D14c83a6c9A9";
 
export const owner = privateKeyToAccount(process.env.OWNER_PRIVATE_KEY as Hex);
export const account = owner.address;
 
export const ownerClient = createSmartWalletClient({ transport, chain, signer: owner, paymaster });
export const publicClient = createPublicClient({ chain, transport: http() });

// delegate.ts
import { account, ownerClient, publicClient } from "./config";
 
// 위임된 EOA는 코드 0xef0100 || 위임 주소를 가집니다.
const code = await publicClient.getCode({ address: account });
 
if (code?.startsWith("0xef0100")) {
  console.log("already delegated to", `0x${code.slice(8)}`);
} else {
  const { id } = await ownerClient.sendCalls({ calls: [] });
  const status = await ownerClient.waitForCallsStatus({ id });
  if (status.status !== "success") throw new Error("delegation failed");
  console.log("delegated in tx", status.receipts?.[0]?.transactionHash);
}

delegated in tx 0x...

// grant.ts
import { generatePrivateKey, privateKeyToAccount } from "viem/accounts";
import { parseUnits } from "viem";
import { account, ownerClient, USDT0_ADDRESS } from "./config";
 
// 이 키는 이를 사용하는 앱 또는 에이전트가 실행되는 곳에 저장합니다.
export const sessionKey = privateKeyToAccount(generatePrivateKey());
const expirySec = Math.floor(Date.now() / 1000) + 60 * 60;
 
export const permissions = await ownerClient.grantPermissions({
  account,
  expirySec,
  key: { publicKey: sessionKey.address, type: "secp256k1" },
  permissions: [
    {
      type: "erc20-token-transfer",
      data: { address: USDT0_ADDRESS, allowance: parseUnits("10", 6) },
    },
  ],
});
 
console.log("session key", sessionKey.address);
console.log("expires    ", new Date(expirySec * 1000).toISOString());

session key 0x...
expires     2026-10-12T13:00:00.000Z

// send.ts
import { createSmartWalletClient } from "@alchemy/wallet-apis";
import { encodeFunctionData, erc20Abi, parseUnits } from "viem";
import { account, chain, paymaster, transport, USDT0_ADDRESS } from "./config";
import { permissions, sessionKey } from "./grant";
 
const sessionClient = createSmartWalletClient({ transport, chain, signer: sessionKey, account, paymaster });
 
const { id } = await sessionClient.sendCalls({
  calls: [
    {
      to: USDT0_ADDRESS,
      data: encodeFunctionData({
        abi: erc20Abi,
        functionName: "transfer",
        args: ["0xRecipient...", parseUnits("1", 6)],
      }),
    },
  ],
  capabilities: { permissions },
});
 
const status = await sessionClient.waitForCallsStatus({ id });
if (status.status !== "success") throw new Error("session-key call failed");
console.log("sent in tx", status.receipts?.[0]?.transactionHash);

sent in tx 0x...

// undelegate.ts
import { createWalletClient, http, zeroAddress } from "viem";
import { chain, owner } from "./config";
 
const walletClient = createWalletClient({ account: owner, chain, transport: http() });
 
const authorization = await walletClient.signAuthorization({
  contractAddress: zeroAddress,
  executor: "self", // the EOA sends the transaction, so the authorization nonce is its nonce + 1
});
 
const hash = await walletClient.sendTransaction({
  to: owner.address,
  authorizationList: [authorization],
  maxPriorityFeePerGas: 0n,
});
console.log("delegation cleared in tx", hash);

delegation cleared in tx 0x...