Flash composition

Basket flash loans borrow the basket's configured constituent vector for a BasketToken-equivalent share amount. They are typed and atomic: the receiver gets a callback, does its work, and must restore principal plus a fee before the transaction ends.

#Quoting

quoteFlashLoan returns the principal vector and a quoted fee for every constituent.

principal_i   = floor(bundle_i * flashShares / 1e18)
quotedFee_i   = ceil(principal_i * flashFeeBps / 10000)
requested_i   = principal_i + quotedFee_i

#The typed callback

The receiver must implement IStaticsFlashBorrower and return keccak256("IStaticsFlashBorrower.onStaticsFlashLoan") from its callback. The Diamond uses OpenZeppelin ReentrancyGuardTransient: short persistent guard phases protect disbursement and repayment accounting, while the receiver callback runs outside the common persistent guard.

function onStaticsFlashLoan(
    uint256 basketId,
    uint256 shares,
    address feeReceiver,
    bytes calldata data
) external returns (bytes4) {
    // ... searcher logic ...
    return IStaticsFlashBorrower.onStaticsFlashLoan.selector;
}

Because the callback runs outside the persistent guard, a callback may call the ordinary public mint and redeem entrypoints. Those calls receive no privilege and pay all normal basket and hook fees. The transient guard still rejects nested flashLoan calls.

#Exact principal, measured fee

Outbound disbursement debits the Diamond and credits the receiver by exactly the quoted principal. Outbound-tax and sender-extra-tax assets are incompatible and revert atomically.

After the callback returns the required hash, the Diamond requests principal plus quoted fee and measures its actual receipt:

success requires: measuredReceipt_i >= principal_i
actualFee_i = measuredReceipt_i - principal_i

The basket vault is restored by exactly the principal. Actual excess — which may differ from the quote for an inbound-tax token — enters the global non-swap fee ledger. A callback revert, invalid return hash, nested flash attempt, or insufficient measured principal reverts the entire transaction.

#Optional arbitrage receiver

Statics ships a narrow optional StaticsFlashArbitrageReceiver for the overpriced mint-and-sell direction. A caller supplies a complete allocation across canonical pools, per-asset net profit floors, and a deadline. The receiver pulls only static-mint top-ups, uses ordinary fee-paying entrypoints, approves exact repayment, returns every net profit asset to the caller, and retains no route balances.