/basset-vault-contracts

Primary LanguageRust

Contracts

  1. bAsset vault
  2. bAsset vault strategy
  3. psi distributor
  4. nAsset token
  5. nAsset token config holder
  6. nAsset token rewards

Halborn audit report

link

bAsset vault

v1

basset_vault is a main contract. The instantiation of this contract implies the instantiation of all child contracts in right order and setting up their interaction:

  1. Instantiate nasset_token_config_holder.
  2. Instantiate nasset_token.
  3. Instantiate nasset_token_rewards.
  4. Instantiate psi_destributor.

P.S. Anyone can set nasset_token_rewards in nasset_token_config_holder but only once.

basset_vault is able to hadle a list of messages:

  • HonestWork {}:

    • claim ANC from anchor contract;
    • swap ANC to stablecoins on TerraSwap;
    • few options are possible here:
      • If stablecoins value < stablecoins value before selling ANC : do nothing;
      • buy psi tokens and destribute rewards
      • deposite to anchor to be able to repay loans later

  • Rebalance {}: Here basset_vault_strategy comes up on the stage. Strategy decides what to do to achieve the main basset_vault aims.

    Strategy which borrows UST and lend it to Anchor Earn for 20% yeild. Anchor pays to borrowers, so contract also sell ANC tokens in favor of bAsset depositors and $PSI token stakers.

    Contract ask basset_vault_strategy on Rebalance how much to borrow or repay.

    Query:

    BorrowerAction {
    borrowed_amount: Uint256,
    locked_basset_amount: Uint256,
}

    Response:

    pub enum BorrowerActionResponse {
    Nothing,
    Borrow {
        amount: Uint256,
        advised_buffer_size: Uint256,
    },
    Repay {
        amount: Uint256,
        advised_buffer_size: Uint256,
    },
}

  • ClaimRemainder {}: The chance that it will happen is slim to none. basset_vault locks 101% of loans.
    Query borrowed info from anchor smart contract and check loan_amount. If it's zero (all users have withdrown all bAsset deposits):

    • if aUST is not zero basset_vault redeems UST;
    • basset_vault uses extra 1% of UST to byu psi_tokens and sent them to governance stakers (there are no any nasset holders at thit moment). There is claim_rewards_delay parrameter to avoid blockchain spam.

Rebalance strategy

Repayment logic

If contract needs to repay part of loan (in case of bAsset withdraw or bAsset price drops) it should sell some of aUST(withdraw from Anchor Earn). But it is possible that this action will fail - there are too many borrowers and Anchor prevent withdrawing UST that is borrowed. So, contract will not be able to repay loan in that case... and will be liquidated.

To avoid that we do not deposit all borrowed UST to Anchor (convering to aUST). Instead portion of UST just stays on the balance and is used when redeeming aUST returns error. In case of error we repaying loan from UST on balance, and then redeem aUST for exactly the same amount. Repeat that cycle until balance achieved.

Take a look at repay logic.

And on (submsg id: RedeemStableOnRepayLoan & RepayLoan & Borrowing & RedeemStableOnRemainder) reply handler.

Borrow logic

Nothing bad will happen if we fail to borrow more, so no error handling here. Worth to mention that in case of borrowing error on deposit - we return error to user. Do not want to add logic for claiming rewards for holding bAsset(staking rewards).

v2

Borrow UST from Anchor and use it in a sophisticated Mirror strategies. Will be available in the future.

bAsset vault strategy

v1

The simplest strategy is to maintain bounds:

  • borrow to aim_ltv if ltv < minimum_ltv (75%)
  • repay to aim_ltv if ltv > minimum_ltv (85%)
  • do nothing otherwise

aim_ltv: 80%

Halving LTV if price in bAsset oracle is obsolete.

v2

Frontrun oracle price and maintain LTV at maximum(basset_max_ltv - 0.1%).

PSi distributor

This contract receive PSi bought by basset_vault and distribute it between:

  1. nAsset token holders
  2. governance stakers
  3. community pool

nAsset token

CW20 compatible contract where that CW20_base contracts methods are synhcronized with nAsset_token_rewards to reward nAsset token holders (no need to stake). nAsset token represent share of bAsset tokens locked in basset_vault and used as collateral on Anchor Earn.

nAsset token config holder

Helper contract. CW20 contract have no ability to reward token holders, so some workaround needed. (same as in bLuna)

nAsset token rewards

Helper contract. CW20 contract have no ability to reward token holders, so some workaround needed. (same as in bLuna)