Isolated lending

One loan asset and one collateral asset

Each Serevin market has one loan asset, one different collateral asset, an oracle, a treasury and explicit initial parameters. Suppliers deposit the loan asset. Borrowers pledge collateral to borrow from that market’s available cash.

A market does not automatically share funds with another Serevin market. A loss recognized in one market reduces that market’s asset accounting. This separation does not remove shared dependencies such as administrators, token issuers, an oracle or an execution venue.

What a supplier owns

Depositing the loan asset mints ERC-4626 supplier shares. These represent a proportional claim on market assets. During normal operation, accounting assets include cash held by the contract, outstanding borrowed assets and pending interest.

Shares are not a fixed cash balance. Available cash limits maxWithdraw and maxRedeem. When most capital has been borrowed, a supplier may be unable to withdraw their full accounting claim immediately. This implementation has no withdrawal queue.

The share conversions use one virtual asset and 1,000,000 virtual shares. A depositWithMinShares entry point lets the depositor reject a transaction if too few shares would be minted. Exact inbound balance checks reject taxed transfers. Rebasing and fee-on-transfer assets are not supported by this design.

Accounting assets = cash + outstanding borrowed assets + pending interest

Debt shares and interest

Borrowing creates debt shares, rounded upward so a new loan does not understate its debt. Debt valuation also rounds upward. Repayment accepts a maximum payment, removes the affordable debt shares and can be made by someone other than the borrower.

Pending interest is computed from total borrowed assets, the configured annual rate and elapsed seconds, using a 365-day year. Integer division rounds down. Accrual adds the interest to debt and resets the last-accrual time.

The model accrues at interaction boundaries. It is not a utilization-responsive rate curve or a promise of a particular supplier APY. Supplier outcomes depend on borrowing, protocol dilution, liquidity and recognized losses.

Pending interest = floor(borrowed assets × APR bps × elapsed seconds / (10,000 × 365 days))

How the protocol receives interest fees

The configured protocol share of interest is represented by new supplier shares minted to the treasury. It is not an immediate cash payment from the borrower to the treasury.

Previews account for pending treasury dilution. Treasury shares still need available liquidity to be redeemed into cash. A cumulative interest counter must not be treated as spendable money for a buyback.

Fee assets = floor(pending interest × protocol interest bps / 10,000)
Fee shares = floor(fee assets × (share supply + 1,000,000) / (assets after interest − fee assets + 1))

Borrowing against collateral

Collateral is recorded against a borrower’s address. The oracle supplies both asset prices in common 18-decimal units. The market values collateral in loan-asset units using the price ratio and each token’s precision.

New borrowing and debt-bearing collateral removal require debt at or below the maximum loan-to-value ratio. Maximum LTV is lower than the liquidation threshold. That buffer gives a position room to move; it does not prevent price gaps or guarantee liquidation execution.

Initialization enforces distinct deployed assets with at most 18 decimals, an APR and protocol share each no greater than 10,000 basis points, and 0 < maximum LTV < liquidation threshold < 10,000. It also constrains the liquidation incentive so the threshold and incentive do not imply repayment beyond collateral value. These are code bounds, not approved launch settings.

Illustrative position

Suppose collateral is valued at 1,000 loan-asset units and a hypothetical market allows 60% maximum LTV. Before other constraints, the maximum debt would be 600 units. Those are explanatory numbers, not Serevin production parameters.

If collateral value falls or debt grows through interest, the position’s LTV rises. The maximum borrowing limit and the liquidation threshold are different checks. See Liquidations & oracles for the exact default path.