Fraxlend Autopilot

Fraxlend Autopilot ('Autopilot') is a yield aggregator for Fraxlend built using Yearn V2. Users can deposit FRAX to the vault, and Autopilot automatically distributes assets to maximize yield. Unlike existing products, this distribution is done permissionlessly on-chain: any user can call adjustPosition to automatically allocate assets in the vault among Fraxlend markets. adjustPosition works by moving assets from lowest return to highest, taking into account the change in yield after depositing.

The vault has an admin role who can whitelist Fraxlend markets and set a cap for each market. For example, Autopilot could be used to manage the Fraxlend AMO according to the per-market caps set out by governance.

Next steps

We want to take Autopilot further, by creating a competitive market for proposing new asset allocations via ZK proofs. While the current adjustPosition function is useful, it is not 100% optimal. We want to change this, by enabling any user to propose a new distribution of assets among Fraxlend markets. If this distribution results in a higher overall yield (as confirmed by a ZK proof), the vault will shuffle assets accordingly. Additionally, we want to upgrade Autopilot to Yearn V3 to improve composability.

After these improvements, we plan to get at least two audits for Autopilot.

Dev Environment

• Configure environment file (.env)

ALCHEMY_KEY="xxx"

• Install

yarn install

• Compile

yarn compile

• Run the hardhat node on localhost.

FORK=main yarn hardhat node

• For test, run the following task

yarn test

Specification

User Action

Deposit

Deposit assets (FRAX) into the vault.

• @param assets The amount of assets to deposit.
• @param receiver The address to receive the shares.

  function deposit(uint256 assets, address receiver) external;
  

Mint

Mint shares (FRAX) for the receiver.

• @param shares The amount of shares to mint.
• @param receiver The address to receive the shares.

  function mint(uint256 shares, address receiver) external;
  

Withdraw

Withdraw an amount of asset (FRAX) to receiver burning owners shares.

• @param assets The amount of asset to withdraw.
• @param receiver The address to receive the assets.
• @param owner The address who's shares are being burnt.

  function withdraw(
    uint256 assets,
    address receiver,
    address owner
  ) external;
  

Redeem

Redeems an amount of shares (FRAX) of owners shares sending funds to receiver.

• @param shares The amount of shares to burn.
• @param receiver The address to receive the assets.
• @param owner The address who's shares are being burnt.

  function redeem(
    uint256 shares,
    address receiver,
    address owner
  ) external;
  

AdjustPosition

Adjust the position based on the lender's APR value. This will deposit most of assets to highest APR lender.

function adjustPosition() external

EstimateAdjustPosition

Estimates highest and lowest apr lenders. Public for debugging purposes but not much use to general public.

• @return the lowest lender index.

• @return the lowest APR value.

• @return the highest lender index.

• @return the potential APR after deposit to highest lender.

• @return the amount of adjusting position.

  function estimateAdjustPosition()
    public
    view
    returns (
      uint256 _lowest,
      uint256 _lowestApr,
      uint256 _highest,
      uint256 _potential,
      uint256 _adjustPositionAmount
    )
  

Admin Action

Init

Init the lp token name, symbol, decimals.

• @param _name The lp token name.
• @param _symbol The lp token symbol.
• @param decimals The lp token decimals.

  function init(
    string memory _name,
    string memory _symbol,
    uint8 decimals
  ) external;
  

SetAdmin

Set the admin address.

• @param _admin The address of admin.

  function setAdmin(address _admin) external;
  

SetActive

Set the vault status. If status is false, withdraw all from lenders.

• @param _active The vault status.

  function setActive(bool _active) external;
  

AddLender

Register the new lender with supply limit value.

• @param _lender The new lender address.
• @param _supplyCap The deposit limit valut of lender.

  function addLender(address _lender, uint256 _supplyCap) external;
  

RemoveLender

Unregister the lender.

• @param _lender The unregistering lender address.

  function removeLender(address _lender) external;
  

SetSupplyCap

Set the supply limit value of registered lender.

• @param _lender The lender address.
• @param _supplyCap The deposit limit valut of lender.

  function setSupplyCap(address _lender, uint256 _supplyCap) external;
  

MigrationLender

Replace the existing lender with new lender. This will withdraw all from old lender and deposit new lender keeping same supply limit value.

• @param _oldLender The existing lender address.
• @param _newLender The new lender address.

  function migrationLender(address _oldLender, address _newLender) external;
  

ManualWithdraw

Manually withdraw all from lender.

• @param _lender The lender address.

  function manualWithdraw(address _lender) external;