Raft.fi code analysis

[dapp-whisperer]

Liquity fork stablecoin, using LSDs as collateral. The code is out!
https://raft.fi/
https://github.com/raft-fi/contracts

Key features to examine:

• Their simplified price feed contract that still has the two oracle setup
• One-step leverage
• Flash loans
• How rewards / interest is processed

[rayeaster]

Following are some quick takeaways for Raft codebase:

• PriceFeed in Raft use stETH/USD in ChainLink primarily and remove the Status (also the state machine) design to use simple booleans(isBrokenOrFrozen & priceChangeAboveMax) to denote the possible scenarios for primary(ChainLink) and secondary(Tellor) feeds. Basically, the fetchPrice() logic in Raft PriceFeed covers the case 1 in eBTC with a straight-forward idea to use the least changed one if prices from both feeds don't match closely
• OneStepLeverage looks a bit like (though lacks clearly-defined operation structs) the combination of BorrowerOperations and LeverageMacroBase#doOperation() in ebtc with an external entry function manageLeveragedPosition() but borrows(flashloan) ONLY debt token(its R stablecoin) for various position operations like adding collateral or repaying debt. In the meantime, Raft take some efforts to write specific codes for many popular DEX/aggregator integrations to facilitate the swap between collateral and debt though only one AMM could be set for each deployed OneStepLeverage: Balancer/1inch/Paraswap
• RToken inherits directly from OpenZeppelin's ERC20FlashMint with a customized maxFlashLoan() using a hardcoded upper limit of totalSupply() / 10 and its helper contract FlashMintLiquidator utilize the flashmint feature directly for liquidation. Another out-of-the-box tool FlashLoanLiquidator utilize Aave3 to flashloan collateral (added to position to mint R token for repayment during callback) for liquidation
• PositionManager defines a borrow rate with hard upper limit 5%. The borrowing fee is calculated(not compound interest) and sent to fee recipient directly upon debt creation. Since Raft use wstETH as collateral and its PositionManager doesn't support rebasing token like stETH yet, there is no LSD staking-reward split feature at this moment in Raft.