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Implement MagicSpend on SOCKET

"MagicSpend: Spend Now, Debit Later" allows users to spend assets immediately while deferring the debit process. SOCKET's chain-abstraction architecture is well-suited to facilitate this by combining offchain agents and onchain contracts.

Implementation Steps​

Step 1: Immediate Spending Logic​

  • The MagicSpendAppGateway listens for user spend requests to execute the immediate transaction.
  • Returns a confirmation to the user.
Click to expand code snippet
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract MagicSpendAppGateway {
    (...)
    mapping(address => uint256) public balances;

    event Spend(address indexed user, uint256 amount);

    function spendNow(address user, uint256 amount) external {
        require(balances[user] >= amount, "Insufficient balance");
        balances[user] -= amount;
        emit Spend(user, amount);
    }
}

Step 2: Deferred Debit Mechanism​

  • The AppGateway schedules the debit in the EVMx.
  • The Watcher monitors the scheduled time.
  • When the time arrives, the Watcher triggers a proof for the Switchboard.
  • The Smart Contract executes the debit from the user’s account.
Click to expand code snippet
contract MagicSpendAppGateway {
    (...)
    struct DebitSchedule {
        uint256 amount;
        uint256 executeAt;
        bool executed;
    }

    mapping(address => DebitSchedule) public schedules;

    event DebitScheduled(address indexed user, uint256 amount, uint256 executeAt);
    event DebitExecuted(address indexed user, uint256 amount);

    function scheduleDebit(address user, uint256 amount, uint256 delay) external {
        schedules[user] = DebitSchedule(amount, block.timestamp + delay, false);
        emit DebitScheduled(user, amount, block.timestamp + delay);
    }

    function executeDebit(address user) external {
        require(block.timestamp >= schedules[user].executeAt, "Too early");
        require(!schedules[user].executed, "Already executed");

        schedules[user].executed = true;
        emit DebitExecuted(user, schedules[user].amount);
    }
}

Key Considerations​

Security Measures​

  • Onchain State Validation: Before allowing a spend, check balances using read() functions.
  • Fraud Prevention: Implement signature verifications in Switchboard.
  • Failover Handling: Define fail-safe conditions if a scheduled debit fails (e.g., fallback mechanisms, notifications).

Handling Async Operations​

  • Use the async modifier in MagicSpendAppGateway to manage multiple chained operations efficiently.
  • Implement callback-based promises to synchronize transactions with user accounts.

What's next!​

By leveraging SOCKET’s architecture, MagicSpend can be implemented securely and efficiently, ensuring users can spend assets immediately while managing debits asynchronously.

Key Use Cases

Read more about other usecases SOCKET enables

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