Integrating with gtUSDa

gtUSDa is the ERC20 for our flagship stablecoin vault on Base which can be integrated into other DeFi applications. Here is a basic integration guide to incorporate gtUSDa into your protocol or app.

gtUSDa is a transferable ERC20 on Base

All user interactions with the vault happen on Base. We also have a dedicated frontend for supplying into this vault at app.gauntlet.xyz/vaults/gtusda.

Supplying via Contract Calls

Supplying into gtUSDa is a combination of 2 function calls: an approve call to spend the USDC, and a requestDeposit call.

  1. call approve on the USDC contract to allow the USDC amount to be spent by the provisioner contract

    1. Note that this is not the vault contract itself, as the request runs through the provisioner to issue vault units asynchronously via a solving mechanism (see Entry/Exit with Provisioner for more details)

  2. requestDeposit . requestDeposit is an asynchronous operation, the user will submit the USDC to the provisioner and after the request is solved gtUSDa units will be sent back to the users wallet directly. This will generally happen within 6 hours though can take up to as long as 3 days (or otherwise based on deadline). See Entry/Exit with Provisioner for more details

    1. token: 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 (USDC contract on base)

    2. tokensIn: USDC amount in (decimal adjusted value)

    3. minUnitsOut: This parameter needs to be based on the current price of gtUSDa. To calculate it refer to the PriceAndFeeCalculator contract, specifically theconvertTokensToUnit function call.

      1. convertTokensToUnit(0x000000000001CdB57E58Fa75Fe420a0f4D6640D5, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, tokensIn) -> Returns the decimal adjusted gtUSDa units

      2. Multiply the above value by 0.97 (some buffer in case there are price changes)

    4. solverTip: 0

    5. deadline: block.timestamp + 259200 (3 days in seconds)

    6. maxPriceAge: 3600 (1 hour in seconds)

    7. isFixedPrice: False

minUnitsOut is technically not required for automatically priced orders if the vault price is trusted but is highly recommended for safety. Please do not include a solverTip as the solver will not solve these requests. Please do not include a large deadline as unfillable orders cannot be refunded ahead of the deadline.

Example Request to deposit 1000 USDC

Call approve on the Base USDC contract to allow the provisioner to spend

approve(
    0x18CF8d963E1a727F9bbF3AEffa0Bd04FB4dBdA07, // Provisioner Contract Address 
    1000000000 // USDC amount decimal adjusted
)

call requestDeposit on the provisioner, parameterizing this call is important

requestDeposit(
    0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, // USDC Contract on base
    1000000000, // USDC amount decimal adjusted
    0.97 * convertTokensToUnit(0x000000000001CdB57E58Fa75Fe420a0f4D6640D5, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, 1000000000), // minUnitsOut see above for more details
    0, // solverTip
    block.timestamp + 259200, // deadline: Set to at least 3 days, this is 3 days in seconds
    3600, // maxPriceAge: Set to 1 hour, 1 hour in seconds
    False // isFixedPrice
)

Withdrawing via contract calls

To withdraw you similarly need to do an approve call followed by requestRedeem on the Provisioner Contract with the correct parameters.

  1. call approve on the gtUSDa contract to allow the gtUSDa amount to be spent by the provisioner contract

  2. requestRedeem This is similarly an asynchronous call where the user provides vaultUnits back to the Provisioner contract and after the request is solved the user will receive USDC in their wallet

    1. token: 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 (USDC contract on base)

    2. unitsIn: The amount of vault units you wish to redeem, correctly decimal adjusted. If you want to calculate the unitsIn based on the USDC value for the user you can again use the convertTokenToUnits function on the PriceAndFeeCalculator contract as per the deposit call.

    3. minTokensOut: This parameter needs to be based on the current price of gtUSDa. To calculate it refer to the PriceAndFeeCalculator contract, specifically the convertUnitsToToken function.

      1. convertUnitsToToken(0x000000000001CdB57E58Fa75Fe420a0f4D6640D5, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, unitsIn) -> Returns the Decimal adjusted USDC value of the VaultUnits

      2. Multiply the above value by 0.97 (some buffer in case there are price changes)

    4. solverTip: 0

    5. deadline: block.timestamp + 259200 (3 days in seconds)

    6. maxPriceAge: 3600 (1 hour in seconds)

    7. isFixedPrice: False

minTokensOut is technically not required for automatically priced orders if the vault price is trusted but is highly recommended for safety. Please do not include a solverTip as the solver will not solve these requests. Please do not include a large deadline as unfillable orders cannot be refunded ahead of the deadline.

Example Request to withdraw 1000 USDC

call approve on the gtUSDa contract to allow the provisioner to spend

approve(
    0x18CF8d963E1a727F9bbF3AEffa0Bd04FB4dBdA07, // Provisioner Contract Address 
    convertTokensToUnit(0x000000000001CdB57E58Fa75Fe420a0f4D6640D5, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, 1000000000) // gtusda amount decimal adjusted
)

call requestRedeem on the provisioner, parameterizing this call is important

requestRedeem(
    0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, // token: USDC Contract on base
    convertTokensToUnit(0x000000000001CdB57E58Fa75Fe420a0f4D6640D5, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, 1000000000), // unitsIn: 1000 USDC via the PriceAndFee calculator
    0.97* convertUnitsToToken(0x000000000001CdB57E58Fa75Fe420a0f4D6640D5, 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913, unitsIn), // minTokensOut: unitsIn is the previous line response
    0, // solverTip
    block.timestamp + 259200, // deadline: Set to at least 3 days, this is 3 days in seconds
    3600, // maxPriceAge: Set to 1 hour days, this is 1 hour in seconds
    False // isFixedPrice
)

[ADVANCED] Monitoring and refunding orders

Tracking orders

When an asynchronous order is placed, the user will have an active but unfilled order. To provide additional transparency to users, these orders can be monitored by tracking the following DepositRequested or RedeemRequested events:

/// @notice Emitted when a user creates a deposit request
/// @param user The address requesting the deposit
/// @param token The token being deposited
/// @param tokensIn The amount of tokens to deposit
/// @param minUnitsOut The minimum amount of units expected
/// @param solverTip The tip offered to the solver in deposit token terms
/// @param deadline Timestamp until which the request is valid
/// @param maxPriceAge Maximum age of price data that solver can use
/// @param isFixedPrice Whether the request is a fixed price request
/// @param depositRequestHash The hash of the deposit request
event DepositRequested(
    address indexed user,
    IERC20 indexed token,
    uint256 tokensIn,
    uint256 minUnitsOut,
    uint256 solverTip,
    uint256 deadline,
    uint256 maxPriceAge,
    bool isFixedPrice,
    bytes32 depositRequestHash
);

/// @notice Emitted when a user creates a redeem request
/// @param user The address requesting the redemption
/// @param token The token requested in return for units
/// @param minTokensOut The minimum amount of tokens the user expects to receive
/// @param unitsIn The amount of units being redeemed
/// @param solverTip The tip offered to the solver in redeem token terms
/// @param deadline The timestamp until which this request is valid
/// @param maxPriceAge Maximum age of price data that solver can use
/// @param isFixedPrice Whether the request is a fixed price request
/// @param redeemRequestHash The hash of the redeem request
event RedeemRequested(
    address indexed user,
    IERC20 indexed token,
    uint256 minTokensOut,
    uint256 unitsIn,
    uint256 solverTip,
    uint256 deadline,
    uint256 maxPriceAge,
    bool isFixedPrice,
    bytes32 redeemRequestHash
);

Checking when orders are filled

When a deposit or redeem is filled, one of the following events will be emitted in the Provisioner:

/// @notice Emitted when a deposit request is solved successfully
/// @param depositHash The unique identifier of the deposit request that was solved
event DepositSolved(bytes32 indexed depositHash);

/// @notice Emitted when a redeem request is solved successfully
/// @param redeemHash The unique identifier of the redeem request that was solved
event RedeemSolved(bytes32 indexed redeemHash);

Refunding expired orders

If the deadline passes but an order isn't solved (rare), the user has to claim back their USDC or gtUSDa tokens using the refundRequest function.

/// @notice Request parameters for deposits and redemptions
/// @dev
/// - For deposits:
///   - units: minimum units the user wants to receive (minUnitsOut)
///   - tokens: amount of tokens the user is providing (tokensIn)
/// - For redemptions:
///   - units: amount of units the user is redeeming (unitsIn)
///   - tokens: minimum tokens the user wants to receive (minTokensOut)
struct Request {
    /// @notice Request type(deposit/redeem + auto/fixed price)
    RequestType requestType;
    /// @notice User address making the request
    address user;
    /// @notice Amount of vault units
    uint256 units;
    /// @notice Amount of underlying tokens
    uint256 tokens;
    /// @notice Tip paid to solver, always in tokens
    uint256 solverTip;
    /// @notice Timestamp after which request expires
    uint256 deadline;
    /// @notice Maximum age of price data allowed
    uint256 maxPriceAge;
}

/// @notice Refund an expired deposit or redeem request
/// @param token The token involved in the request
/// @param request The request to refund
/// @dev Can only be called after request deadline has passed
function refundRequest(IERC20 token, Request calldata request) external;

Getting the User's balance of gtUSDa

Simply call the balanceOf function on gtUSDa with the user's address.

Pricing gtUSDa units in USDC (and vice versa)

We provide simple price conversion utilities between gtUSDa and USDC via the PriceAndFeeCalculator contract.

Specifically there are two functions of relevance

  • convertTokensToUnits -> Takes in USDC value and returns amount of vaultUnits at current price

    • vault: 0x000000000001CdB57E58Fa75Fe420a0f4D6640D5 (gtUSDa vault contract)

    • token: 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 (USDC contract on base)

    • tokenAmount: Decimal adjusted USDC value (USDC has 6 decimals)

  • convertUnitsToTokens -> Takes in vaultUnits and returns USDC value at current price

    • vault: 0x000000000001CdB57E58Fa75Fe420a0f4D6640D5 (gtUSDa vault contract)

    • token: 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 (USDC contract on base)

    • unitsAmount: Decimal adjusted gtUSDa value (gtUSDa has 18 decimals)

Fetching the APY of the vault

This one is a little trickier as of right now, but we aim to make this simpler in the future via an API. As of right now the best way to get the APY of the vault is to index the price of the vault units in USDC over a given time period and extrapolate this to a yearly APY number.

Calculating the TVL of the vault

To get the total TVL of the vault use the convertUnitsToTokens function and use the totalSupply of gtUSDa as an input.

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