STUSD Wrapper

The STUSD wrapper turns sUSDC (soul-bound) into STUSD, a portable ERC20. It preserves the hedge while giving treasuries liquidity for trading, lending, or settlements.

Contract Architecture

Wrapper Contract

contract STUSDWrapper {
    /// Wrap sUSDC into STUSD (1:1)
    function wrap(uint256 amount) external;

    /// Lock state
    function getLockInfo(address account) external view returns (uint256 locked, uint256 unlockAt);
}

Key behaviors:

• 1:1 minting between sUSDC and STUSD
• Wrapper is the only entity allowed to mint STUSD
• Optional lock schedules enforced at the wrapper level (no unwrap flow)
• Governed controls around minting and reserves

STUSD Token

contract STUSD is ERC20Permit, AccessControl {
    IWrapper public immutable wrapper;

    function _update(address from, address to, uint256 amount) internal override {
        (uint256 locked,) = wrapper.getLockInfo(from);
        require(balanceOf(from) - amount >= locked, "STUSD: amount locked");
        super._update(from, to, amount);
    }

    function issueFromWrapper(address to, uint256 amount) external onlyRole(WRAPPER_ROLE) { ... }
}

The token contract checks wrapper lock data before every transfer, guaranteeing that vesting or compliance constraints are upheld even after wrapping.

Why the Wrapper Matters

• Capital efficiency – desks can deploy STUSD across DeFi venues without dismantling the hedge.
• Proof of collateral – every STUSD maps back to a verifiable sUSDC position.
• Programmable liquidity – locks, thaw windows, and governance switches offer fine-grained control.

Primary Workflows

1. Liquidity Deployment

1. Deposit USDC → mint sUSDC.
2. wrap(amount) to receive STUSD.
3. Use STUSD in DEX pools, lending markets, or automation strategies.
4. Return to sUSDC by sweeping reserves (no public unwrap function).

2. Vesting & Locks

• wrapLocked() issues STUSD with an enforced unlock timestamp.
• Wrapper + token guard transfers until the schedule matures.
• Ideal for team distributions, partner deals, or compliance programs.

3. Emergency Controls

• Global pausing of wrap/unwrap flows if venues report anomalies.
• Admin multi-sig can sweep stuck tokens back to treasury wallets.
• Daily mint ceilings prevent runaway issuance.

Security Features

• One contract surface: only the wrapper mints/burns STUSD.
• Lock auditing: getLockInfo() exposes every time-lock on-chain.
• Reentrancy guards + safe transfers baked into state mutations.
• Transparent telemetry: dashboard surfaces show minted STUSD, pending unwraps, and unlock readiness.

Integration Tips

// Wrap 10k sUSDC into STUSD
SUSDC.approve(address(wrapper), 10_000e18);
wrapper.wrap(10_000e18);

// Query lock data before transferring
(uint256 locked, uint256 unlockAt) = wrapper.getLockInfo(msg.sender);

// No public unwrap: liquidity return is managed via wrapper reserves

• Always check lock info if you expose STUSD transfers in your app.
• Display wrapper telemetry (minted supply, pending unwraps) for end-user trust.
• Treat STUSD like any ERC20 when integrating with AMMs or money markets.

Summary

The STUSD wrapper bridges StoneYield’s locked core to the rest of DeFi. Every liquid STUSD stays fully collateralized by sUSDC, while treasuries get programmable, auditable liquidity on demand.