Contracts

Two small contracts: a vault that holds USDG and a registry that records each Roll.

Overview

Rentday runs on two Solidity contracts, both built on OpenZeppelin Contracts 5 and compiled with Solidity 0.8.28. The source is in contracts/src, the exported ABIs in contracts/abi and the tests in contracts/test. contracts/README.md documents the package: building, testing, deploying and the operator scripts. Neither contract is upgradeable. Both addresses read Launch soon on Chain and addresses until deployment.

RentdayVault

An OpenZeppelin ERC-4626 vault over USDG. The share token is named Rentday Vault Share, with the symbol vRENT and 18 decimals.

Feature	Behaviour
Constructor	`constructor(usdg, initialOwner, initialCap)`. Reads the asset's `decimals()` and reverts with `RentdayVaultInvalidAssetDecimals` unless it is 6. Emits `CapUpdated(0, initialCap)`.
`totalAssets()`	The vault's USDG balance, the OpenZeppelin default. Nobody pushes a valuation in.
Decimals offset	`_decimalsOffset()` returns 12, so shares have 6 + 12 = 18 decimals and 10^12 virtual shares stand against one virtual unit of USDG. Yield arrives as plain transfers, so donations to the vault are possible by design. The offset makes a first-depositor or donation inflation attack cost the attacker far more than it can extract.
Deposit cap	`cap()` returns the cap in USDG base units, compared with `totalAssets()`. `setCap(uint256)` is owner-only and emits `CapUpdated(previousCap, newCap)`.
Pause	`pause()` and `unpause()` are owner-only. While paused, `maxDeposit` and `maxMint` return 0, so `deposit` and `mint` revert with `ERC4626ExceededMaxDeposit` and `ERC4626ExceededMaxMint`. `redeem`, `withdraw`, share transfers and `addCapital` keep working.
`addCapital(uint256 amount)`	Callable by anyone. Pulls `amount` USDG from the caller, which needs a USDG approval first, and emits `CapitalAdded(from, amount)`. Reverts with `RentdayVaultZeroAmount` for 0, and with `RentdayVaultNoShares` while no vRENT exists, because USDG added to an empty vault would be captured by the virtual shares. A plain USDG transfer has the same effect on the price without the event.
Withdrawal paths	None for the owner. USDG leaves only through `redeem` or `withdraw`, called by a holder or by someone the holder approved.
Ownership	Ownable2Step: the owner calls `transferOwnership(address)` and the new owner calls `acceptOwnership()`. `renounceOwnership()` always reverts with `RentdayVaultRenounceDisabled`.
`maxMint(address)`	Returns the uint256 maximum instead of reverting if the cap is set so high that the conversion would overflow, as ERC-4626 requires of its max functions.

RollRegistry

An append-only record of Rolls, numbered from 1. Each entry is stored as:

struct Roll {
    bytes32 docHash;      // SHA-256 of the exact CSV bytes
    uint256 navPerShare;  // USDG per vRENT, 12 decimals
    string  uri;          // where the file is published
    uint64  at;           // block timestamp of publication
}

Function or event	Behaviour
`rolls(uint16 n)` returns `(bytes32 docHash, uint256 navPerShare, string uri, uint64 at)`	Returns Roll `n` in that order. An unpublished number returns zeros, with `at` equal to 0.
`latest()` returns `(uint16)`	The number of the most recent Roll, or 0 before the first.
`publish(uint16 n, bytes32 docHash, uint256 navPerShare, string uri)`	Owner only. `n` must equal `latest()` + 1, or the call reverts with `RollRegistryUnexpectedRollNumber(expected, provided)`. A zero `docHash` reverts with `RollRegistryZeroDocHash`. Stores the Roll with the block timestamp and emits `RollPublished`.
`event RollPublished(uint16 indexed n, bytes32 docHash, uint256 navPerShare, string uri, uint64 at)`	Emitted once per Roll.

The registry has no function to change or delete a Roll. Ownership is Ownable2Step, and renounceOwnership() reverts with RollRegistryRenounceDisabled, since a registry without an owner could never publish again. Roll numbers are uint16, which allows up to 65,535 Rolls.

Functions the site calls

The site encodes its calls itself, without a library, in site/js/abi.js. Its SIG table holds these signatures. Each selector is the first four bytes of the keccak-256 hash of the signature, as listed in contracts/abi/selectors.json.

Signature	Selector	Contract	Used for
`balanceOf(address)`	`0x70a08231`	USDG, RentdayVault	Your USDG and vRENT balances
`allowance(address,address)`	`0xdd62ed3e`	USDG	Your current approval to the vault
`approve(address,uint256)`	`0x095ea7b3`	USDG	Exact-amount approval before a deposit
`decimals()`	`0x313ce567`	RentdayVault	Identity check (must be 18)
`symbol()`	`0x95d89b41`	RentdayVault	Identity check
`asset()`	`0x38d52e0f`	RentdayVault	Identity check (must be USDG)
`totalAssets()`	`0x01e1d114`	RentdayVault	USDG held
`totalSupply()`	`0x18160ddd`	RentdayVault	vRENT outstanding
`convertToAssets(uint256)`	`0x07a2d13a`	RentdayVault	Share price, called with 1e18
`previewDeposit(uint256)`	`0xef8b30f7`	RentdayVault	Deposit quote
`previewRedeem(uint256)`	`0x4cdad506`	RentdayVault	Cash-out quote
`maxDeposit(address)`	`0x402d267d`	RentdayVault	Room under the cap, 0 while paused
`deposit(uint256,address)`	`0x6e553f65`	RentdayVault	Deposit
`redeem(uint256,address,address)`	`0xba087652`	RentdayVault	Cash out
`cap()`	`0x355274ea`	RentdayVault	Deposit cap
`paused()`	`0x5c975abb`	RentdayVault	Pause flag
`addCapital(uint256)`	`0xbea10f96`	RentdayVault	Settling rent and token fees
`rolls(uint16)`	`0x514f5ab2`	RollRegistry	Roll verification
`latest()`	`0x52bfe789`	RollRegistry	Latest Roll number

The operator scripts also call publish(uint16,bytes32,uint256,string), selector 0x41c50a25. A test in the contracts package checks that every selector in selectors.json is present in the compiled bytecode.

Source and tests

cd contracts
npm install
npm test

Security describes what the tests cover. contracts/README.md is the reference for the package's scripts, and Operator guide shows them in use.