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Architecture

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Overview

Unbound consists of two main smart contracts that work together to provide leveraged vault functionality:

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Contract Details

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UnboundVault

Purpose: User-facing contract for deposits and withdrawals. Implements ERC-4626 tokenized vault standard. Key Responsibilities:
  • Accept user deposits
  • Mint/burn vault shares
  • Track user positions
  • Coordinate with Executor for leverage operations
  • Collect performance fees
Storage: 
struct Storage {
    underlying_asset: ContractAddress,  // wBTC
    debt_asset: ContractAddress,        // USDC
    vesu_pool: ContractAddress,
    executor: ContractAddress,
    paused: bool,
    performance_fee_bps: u256,
    treasury: ContractAddress,
}

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FlashLoanExecutor

Purpose: Handles the flash loan callback and executes the leverage/deleverage operations. Key Responsibilities:
  • Receive flash loans from Vesu
  • Execute swaps via AVNU
  • Manage Vesu position (deposit collateral, borrow debt)
  • Ensure atomicity of operations
Security: Only the Vesu Pool can call on_flash_loan. 
fn on_flash_loan(
    sender: ContractAddress,  // Must be Vault
    asset: ContractAddress,   // USDC
    amount: u256,
    data: Span<felt252>       // Operation details
)

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External Integrations

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Vesu V2

Vesu is Starknet’s lending protocol used for:
FunctionUsage
flash_loanGet USDC without collateral
modify_positionAdd collateral / borrow debt
positionQuery current position state
priceGet asset oracle prices
Pool Parameters (wBTC/USDC pair):
  • Max LTV: 86%
  • Liquidation Factor: 90%
  • Borrow APR: Variable (~1.8%)
  • BTCFi Rewards: ~1.4% (reduces net cost)

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AVNU

AVNU is a DEX aggregator for optimal swap execution:
FunctionUsage
multi_route_swapExecute USDC ↔ wBTC swaps
Why AVNU?
  • Best execution across multiple DEXs
  • Single transaction for complex routes
  • Built-in slippage protection

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Data Flow

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Position Creation

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Position Closure

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Trust Model

EntityTrust LevelWhy
Vault OwnerHighCan pause, set fees
ExecutorMediumOnly vault can trigger operations
VesuCriticalHolds all collateral and debt
AVNUMediumSwap execution only
UserNone neededPermission-less interaction

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Upgrade Path

Current contracts are not upgradeable. To upgrade:
  1. Deploy new vault with updated logic
  2. Users withdraw from old vault
  3. Users deposit to new vault
This ensures users always have full control over their assets.