구독 및 수집

step 1. Subscriber delegates EOA to SubscriptionManager (EIP-7702)
        tx: 0x7702...aaaa

step 2. Subscriber registers subscription (10 USDT0 / 30 days)
        subscriptionId: 0xabc...
        nextChargeAt:   2026-05-23T12:00:00Z

step 3. Provider calls collect() on day 30
        collected:    10 USDT0
        gas cost:     ~0.000050 USDT0
        nextChargeAt: 2026-06-22T12:00:00Z

step 4. Provider calls collect() on day 60
        collected:    10 USDT0
        gas cost:     ~0.000050 USDT0
        nextChargeAt: 2026-07-22T12:00:00Z

step 5. Subscriber cancels
        subscription: inactive

─── Subscriber ───────────────────────────────────────
// One-time setup: delegate EOA to the subscription contract
signAuthorization(delegateContract)
sendTransaction({ type: 4, authorizationList: [signedAuth] })

// Subscribe: set billing terms on own EOA
sendTransaction({ to: self, data: subscribe(subscriptionId, provider, amount, interval) })

// Cancel: revoke billing access at any time
sendTransaction({ to: self, data: cancelSubscription(subscriptionId) })

─── Service Provider ────────────────────────────────
// Each billing cycle: collect payment from subscriber's EOA
// The delegate contract verifies caller, billing schedule, and amount
sendTransaction({ to: subscriberEOA, data: collect(subscriptionId) })

// Automate with a cron job matching the billing interval
// The contract reverts if called before the interval has elapsed

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
 
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 
/// @title SubscriptionManager (example)
/// @notice Delegate contract for EIP-7702 subscription billing.
///         Runs on the subscriber's EOA via delegation.
contract SubscriptionManager {
    struct Subscription {
        address provider;
        uint256 amount;
        uint256 interval;
        uint256 nextChargeAt;
        bool active;
    }
 
    // Keyed by subscriptionId.
    // Storage is already per subscriber EOA under delegation.
    mapping(bytes32 => Subscription) public subscriptions;
 
    IERC20 public immutable usdt0;
 
    event SubscriptionCreated(
        bytes32 indexed subscriptionId,
        address indexed provider,
        uint256 amount,
        uint256 interval,
        uint256 nextChargeAt
    );
 
    event SubscriptionCollected(
        bytes32 indexed subscriptionId,
        address indexed provider,
        uint256 amount,
        uint256 collectedAt
    );
 
    event SubscriptionCancelled(bytes32 indexed subscriptionId);
 
    constructor(address _usdt0) {
        usdt0 = IERC20(_usdt0);
    }
 
    /// @notice Register a subscription. Called by the subscriber on their own EOA.
    function subscribe(
        bytes32 subscriptionId,
        address provider,
        uint256 amount,
        uint256 interval
    ) external {
        require(msg.sender == address(this), "subscriber only");
        require(provider != address(0), "invalid provider");
        require(amount > 0, "invalid amount");
        require(interval > 0, "invalid interval");
        require(!subscriptions[subscriptionId].active, "already exists");
 
        uint256 nextChargeAt = block.timestamp + interval;
 
        subscriptions[subscriptionId] = Subscription({
            provider: provider,
            amount: amount,
            interval: interval,
            nextChargeAt: nextChargeAt,
            active: true
        });
 
        emit SubscriptionCreated(subscriptionId, provider, amount, interval, nextChargeAt);
    }
 
    /// @notice Collect a payment for a specific subscription. Called by the service provider.
    function collect(bytes32 subscriptionId) external {
        Subscription storage sub = subscriptions[subscriptionId];
 
        require(sub.active, "not active");
        require(msg.sender == sub.provider, "not provider");
        require(block.timestamp >= sub.nextChargeAt, "too early");
 
        sub.nextChargeAt += sub.interval;
 
        require(usdt0.transfer(sub.provider, sub.amount), "transfer failed");
 
        emit SubscriptionCollected(subscriptionId, sub.provider, sub.amount, block.timestamp);
    }
 
    /// @notice Cancel a specific subscription. Called by the subscriber.
    function cancelSubscription(bytes32 subscriptionId) external {
        require(msg.sender == address(this), "subscriber only");
        require(subscriptions[subscriptionId].active, "not active");
 
        delete subscriptions[subscriptionId];
 
        emit SubscriptionCancelled(subscriptionId);
    }
}

// config.ts
import { ethers } from "ethers";
 
export const STABLE_TESTNET_RPC = "https://rpc.testnet.stable.xyz";
export const CHAIN_ID = 2201;
export const USDT0_ADDRESS = "0x78Cf24370174180738C5B8E352B6D14c83a6c9A9";
export const SUBSCRIPTION_MANAGER = "0xYourDeployedSubscriptionManager";
 
export const provider = new ethers.JsonRpcProvider(STABLE_TESTNET_RPC);
export const subscriberWallet = new ethers.Wallet(process.env.SUBSCRIBER_KEY!, provider);

// delegate.ts
import { subscriberWallet, provider, CHAIN_ID, SUBSCRIPTION_MANAGER } from "./config";
 
// The subscriber sends this transaction itself, so the authorization must use
// the next nonce: the account nonce increments before authorizations are checked.
const txNonce = await provider.getTransactionCount(subscriberWallet.address);
 
const signedAuth = await subscriberWallet.authorize({
  chainId: CHAIN_ID,
  address: SUBSCRIPTION_MANAGER,
  nonce: txNonce + 1,
});
 
const tx = await subscriberWallet.sendTransaction({
  type: 4,
  to: subscriberWallet.address,
  authorizationList: [signedAuth],
  maxPriorityFeePerGas: 0n,
});
 
const receipt = await tx.wait(1);
console.log("Delegation tx:", receipt.hash);

npx tsx delegate.ts

Delegation tx: 0x7702...aaaa

// subscribe.ts
import { ethers } from "ethers";
import { subscriberWallet } from "./config";
 
const subscriptionManager = new ethers.Interface([
  "function subscribe(bytes32 subscriptionId, address provider, uint256 amount, uint256 interval)",
]);
 
const serviceProvider = "0xServiceProviderAddress";
const monthlyAmount = ethers.parseUnits("10", 6); // 10 USDT0
const interval = 30 * 24 * 60 * 60;              // 30 days in seconds
 
// Derive a unique subscriptionId from provider + plan name + local nonce
const subscriptionId = ethers.solidityPackedKeccak256(
  ["address", "string", "uint256"],
  [serviceProvider, "pro-monthly", 1]
);
 
const tx = await subscriberWallet.sendTransaction({
  to: subscriberWallet.address, // call self (delegate code executes)
  data: subscriptionManager.encodeFunctionData("subscribe", [
    subscriptionId,
    serviceProvider,
    monthlyAmount,
    interval,
  ]),
  maxPriorityFeePerGas: 0n,
});
 
const receipt = await tx.wait(1);
console.log("Subscription registered, tx:", receipt.hash);
console.log("Subscription ID:", subscriptionId);

npx tsx subscribe.ts

Subscription registered, tx: 0xabcd...1234
Subscription ID: 0xfedc...9876

// collect.ts
import { ethers } from "ethers";
 
const provider = new ethers.JsonRpcProvider("https://rpc.testnet.stable.xyz");
const providerWallet = new ethers.Wallet(process.env.PROVIDER_KEY!, provider);
 
const subscriptionManager = new ethers.Interface([
  "function collect(bytes32 subscriptionId)",
]);
 
const subscriberEOA = "0xSubscriberEOAAddress";
const subscriptionId = "0xYourSubscriptionId";
 
const tx = await providerWallet.sendTransaction({
  to: subscriberEOA, // subscriber's EOA (runs delegate code)
  data: subscriptionManager.encodeFunctionData("collect", [subscriptionId]),
  maxPriorityFeePerGas: 0n,
});
 
const receipt = await tx.wait(1);
console.log("Payment collected, tx:", receipt.hash);
console.log("Gas used:", receipt.gasUsed.toString());
 
// In production, run this on a cron schedule matching the billing interval.
// The delegate contract will revert if called before the interval has elapsed.

npx tsx collect.ts

Payment collected, tx: 0x8f3a...2d41
Gas used: 52000

// cancel.ts
import { ethers } from "ethers";
import { subscriberWallet } from "./config";
 
const subscriptionManager = new ethers.Interface([
  "function cancelSubscription(bytes32 subscriptionId)",
]);
 
const subscriptionId = "0xYourSubscriptionId";
 
const tx = await subscriberWallet.sendTransaction({
  to: subscriberWallet.address,
  data: subscriptionManager.encodeFunctionData("cancelSubscription", [subscriptionId]),
  maxPriorityFeePerGas: 0n,
});
 
const receipt = await tx.wait(1);
console.log("Subscription cancelled, tx:", receipt.hash);

npx tsx cancel.ts

Subscription cancelled, tx: 0xdef0...5678