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Lender Contract

The Lender contract implements the core lending functionality for an instance: collateral management, debt accounting, interest accrual, liquidations, redemptions, and PSM conversions. Contract implementation

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User-Facing Functions

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adjust

function adjust(address account, int collateralDelta, int debtDelta, bool chooseRedeemable) external
Adjusts a user’s position by modifying collateral and/or debt. This is the primary function for depositing, withdrawing, borrowing, repaying and changing redemption status. Parameters:
  • account: Address of the position to adjust
  • collateralDelta: Amount to add (positive) or remove (negative) collateral (in wei)
  • debtDelta: Amount to borrow (positive) or repay (negative) debt (in wei)
  • chooseRedeemable: True to turn on redeemable (free debt) mode. False to turn off.
Requirements:
  • If collateralDelta > 0: msg.sender must provide collateral in (approval required)
  • If debtDelta > 0: Position must remain solvent after the change
  • If debtDelta < 0: Caller must provide Coin to repay (approval required)
  • If decreasing collateral or increasing debt: caller must be account or a delegated address
  • If debtDelta != 0: resulting debt must be 0 or ≥ minDebt
Behavior:
  • Automatically accrues interest before adjustment
  • Updates collateral and debt of the borrower
  • Maintains minimum debt requirements
  • Emits position update events

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liquidate

function liquidate(address borrower, uint repayAmount, uint minCollateralOut) external returns (uint collateralOut)
Liquidates an undercollateralized position to maintain protocol solvency. Oracle‑gated; disabled when price is stale/invalid. Parameters:
  • borrower: Address of the position to liquidate
  • repayAmount: Amount of debt to repay (in wei)
  • minCollateralOut: Minimum collateral amount to receive (caller protection)
Returns:
  • collateralOut: Amount of collateral received by liquidator
Requirements:
  • Borrower loan must be unhealthy at the oracle price and liquidations allowed
  • Up to 25% of total debt can be liquidated per call (minimum 10,000 Coin chunk, or full debt if smaller)
  • Liquidator must provide Coin to repay and set an acceptable minCollateralOut
Liquidation Process:
  1. Accrue interest on borrower’s position
  2. Verify liquidation conditions
  3. Transfer Coin from liquidator to repay debt
  4. Calculate collateral reward with incentive
  5. Transfer collateral to liquidator
  6. Update borrower’s position
Incentive Calculation:
  • Incentive scales from 0% (at collateralFactor) up to 10% (5 percentage points above collateralFactor), linearly in between

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redeem

function redeem(uint amountIn, uint minAmountOut) external returns (uint amountOut)
Redeems Coin for collateral from the redeemable pool at the oracle price minus a redemption fee. Parameters:
  • amountIn: Amount of Coin to redeem (in wei)
  • minAmountOut: Minimum collateral amount to receive (slippage protection)
Returns:
  • amountOut: Amount of collateral received
Requirements:
  • Redemptions must be allowed (fresh oracle)
  • Redeemable borrowers must have sufficient collateral to redeem and debt to repay
  • amountOut must be ≥ minAmountOut
Redemption Amount:
  • amountOut = amountIn * 1e18 * (10000 - redeemFeeBps) / price / 10000

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sell

function sell(uint coinIn, uint minAssetOut) external returns (uint assetOut)
Sells Coin for PSM asset at a 1:1 nominal rate (decimals‑adjusted). No fee. Parameters:
  • coinIn: Amount of Coin to sell (in wei)
  • minAssetOut: Minimum PSM asset amount to receive
Returns:
  • assetOut: Amount of PSM asset received
Requirements:
  • PSM must be configured with a psmAsset
  • Sufficient PSM reserves available
  • assetOut must be ≥ minAssetOut
Pricing:
  • Decimals conversion between 18‑dec Coin and psmAsset decimals. No fee.

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buy

function buy(uint assetIn, uint minCoinOut) external returns (uint coinOut)
Buys Coin using PSM asset (only before immutability deadline). A time‑based buy fee may apply. Parameters:
  • assetIn: Amount of PSM asset to spend (in wei)
  • minCoinOut: Minimum Coin amount to receive
Returns:
  • coinOut: Amount of Coin received
Requirements:
  • PSM must be configured
  • Must be before immutability deadline
  • coinOut must be ≥ minCoinOut
Pricing:
  • Decimals conversion; buy fee ramps from 0→100 bps during the second half of the immutability window

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delegate

function delegate(address delegatee, bool isDelegatee) external
Delegates or revokes delegation rights for position management. Parameters:
  • delegatee: Address to grant/revoke delegation
  • isDelegatee: True to grant, false to revoke
Effects:
  • Allows delegatee to borrow and withdraw collateral via adjust() and call setRedemptionStatus() on behalf of delegator
  • A delegator may assign multiple concurrent delegatees.
  • Delegation can be changed at any time by delegator

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setRedemptionStatus

function setRedemptionStatus(address account, bool chooseRedeemable) external
Sets whether an account’s position participates in redemptions (free debt) or accrues interest (paid debt). Parameters:
  • account: Address to set redemption status for (can be any address)
  • chooseRedeemable: True to allow redemption, false to prevent
Requirements:
  • Caller must be account or a delegated address
Effects:
  • Toggles redeemable status. If true, borrower pays 0 interest. If false, borrowers pays variable rate.
  • Default is non‑redeemable.

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accrueInterest

function accrueInterest() public
Accrues interest on paid debt. Called automatically by state‑changing functions and may be called directly. Effects:
  • Uses the shared InterestModel to compute current rate and interest
  • Splits interest into fees (local/global reserves) and staking yield (minted to the Vault)

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writeOff

function writeOff(address borrower, address to) external returns (bool writtenOff)
Writes off unrecoverable debt and socializes losses across all borrowers. Parameters:
  • borrower: Address with bad debt position
  • to: Address to receive written-off collateral
Returns:
  • writtenOff: True if debt was written off
Requirements:
  • Oracle must allow liquidations
  • Position must be extremely undercollateralized (debt > 100× collateral value)
  • Callable by anyone (also attempted from liquidate() via try/catch)
Effects:
  • Deletes borrower debt
  • Redistributes it across free/paid pools proportionally
  • Sends remaining collateral to to

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View Functions

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getDebtOf

function getDebtOf(address account) public view returns (uint debt)
Returns the current debt amount for an account, including accrued interest. Parameters:
  • account: Address to query debt for
Returns:
  • debt: Current debt amount in wei

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getCollateralPrice

function getCollateralPrice() public view returns (uint price, bool reduceOnly, bool allowLiquidations)
Returns the normalized collateral price and safety flags. Returns:
  • price: Normalized to 36 - collateralDecimals digits (never zero inside consumers)
  • reduceOnly: True if only reductions allowed
  • allowLiquidations: True if liquidations/redemptions/write‑offs permitted

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getFreeDebtRatio

function getFreeDebtRatio() public view returns (uint ratio)
Returns the current ratio of free debt to total debt (includes PSM assets in the free buffer). Returns:
  • ratio: Free debt ratio in basis points (0–10000)

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getRedeemAmountOut

function getRedeemAmountOut(uint amountIn) public view returns (uint amountOut)
Calculates the amount of collateral received for redeeming Coin. Parameters:
  • amountIn: Amount of Coin to redeem
Returns:
  • amountOut: Amount of collateral received

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getSellAmountOut

function getSellAmountOut(uint coinIn) public view returns (uint assetOut)
Calculates the amount of PSM asset received for selling Coin (pure decimals conversion). Parameters:
  • coinIn: Amount of Coin to sell
Returns:
  • assetOut: Amount of PSM asset received

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getBuyAmountOut

function getBuyAmountOut(uint assetIn) public view returns (uint coinOut, uint coinFee)
Calculates the amount of Coin and buy fee for buying with PSM asset (pre‑deadline). Parameters:
  • assetIn: Amount of PSM asset to spend
Returns:
  • coinOut: Amount of Coin received
  • coinFee: Fee amount deducted

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getFeedPrice

function getFeedPrice() external view returns (uint price, uint updatedAt)
Returns raw price feed data without protocol modifications. Returns:
  • price: Raw price from Chainlink feed
  • updatedAt: Timestamp when price was last updated

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Protocol Management Functions

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setPendingOperator

function setPendingOperator(address _pendingOperator) external
Sets a new pending operator address (two‑step handoff). Parameters:
  • _pendingOperator: New operator address
Requirements:
  • Caller must be current operator

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acceptOperator

function acceptOperator() external
Accepts operator role for pending operator. Requirements:
  • Caller must be pending operator

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setManager

function setManager(address _manager) external
Sets or updates the manager address (shared with operator for certain pre‑deadline actions). Parameters:
  • _manager: New manager address
Requirements:
  • Caller must be operator or manager

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enableImmutabilityNow

function enableImmutabilityNow() external
Immediately enables immutability (locks certain configuration permanently). Requirements:
  • Caller must be operator
  • Must be before immutability deadline

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pullLocalReserves

function pullLocalReserves() external
Mints accumulated local reserves to the caller (operator only). Requirements:
  • Caller must be operator

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pullGlobalReserves

function pullGlobalReserves(address _to) external
Mints accumulated global reserves to _to. Parameters:
  • _to: Address to receive reserves
Requirements:
  • Caller must be Factory

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reapprovePsmVault

function reapprovePsmVault() external
Reapproves the PSM vault for unlimited spending (before immutability deadline). Requirements:
  • Must be before immutability deadline

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Configuration Functions

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setHalfLife

function setHalfLife(uint64 halfLife) external
Sets the interest rate half-life for exponential decay and growth. Parameters:
  • halfLife: New half-life in seconds
Requirements:
  • Caller must be operator or manager
  • Must be before immutability deadline

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setTargetFreeDebtRatio

function setTargetFreeDebtRatio(uint16 startBps, uint16 endBps) external
Sets the target free debt ratio range in basis points. Parameters:
  • startBps: Minimum free debt ratio (basis points)
  • endBps: Maximum free debt ratio (basis points)
Requirements:
  • Caller must be operator or manager
  • Must be before immutability deadline

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setRedeemFeeBps

function setRedeemFeeBps(uint16 _redeemFeeBps) external
Sets the redemption fee in basis points. Parameters:
  • _redeemFeeBps: New redemption fee (basis points)
Requirements:
  • Caller must be operator or manager
  • Must be before immutability deadline

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setLocalReserveFeeBps

function setLocalReserveFeeBps(uint _feeBps) external
Sets the local reserve fee rate. Parameters:
  • _feeBps: New fee rate (basis points)
Requirements:
  • Caller must be operator

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Key State Variables

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totalPaidDebt

Cached total amount of interest-bearing debt in the protocol. May be missing accrued interest.

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totalFreeDebt

Total amount of non-interest-bearing debt in the protocol.

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collateralFactor

Maximum borrower collateralization ratio in basis points (e.g., 8000 = 80%).

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minDebt

Minimum debt amount required for positions.

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immutabilityDeadline

Timestamp after which protocol becomes immutable.

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feeBps

Protocol fee rate in basis points.

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Events

  • PositionAdjusted(address account, int collateralDelta, int debtDelta)
  • HalfLifeUpdated(uint64 halfLife)
  • TargetFreeDebtRatioUpdated(uint16 startBps, uint16 endBps)
  • RedeemFeeBpsUpdated(uint16 redeemFeeBps)
  • DelegationUpdated(address delegator, address delegatee, bool isDelegatee)
  • PendingOperatorUpdated(address pendingOperator)
  • OperatorAccepted(address operator)
  • ManagerUpdated(address manager)
  • LocalReserveFeeUpdated(uint256 feeBps)
  • RedemptionStatusUpdated(address account, bool isRedeemable)
  • Liquidated(address borrower, address liquidator, uint repayAmount, uint collateralOut)
  • WrittenOff(address borrower, address to, uint debt, uint collateral)
  • NewEpoch(uint epoch)
  • Redeemed(address account, uint amountIn, uint amountOut)
  • Sold(address account, uint coinIn, uint assetOut)
  • Bought(address account, uint assetIn, uint coinOut)