LendingVault.sol

UUPS upgradeable lending vault. Reads BatchToken collateral directly on Mantle. Integrates Chainlink price feeds with staleness guard and timelocked admin override.

Key Design Decisions

Decision	Rationale
UUPS upgradeable	Allows bug fixes without data migration. Upgrade requires DEFAULT_ADMIN_ROLE + 48-hour timelock.
Chainlink 24-hr staleness guard	Reverts on stale price rather than using outdated price. Prevents mispriced loans.
48-hr timelock on price override	Prevents hasty admin decisions. Emergency-only mechanism.
BatchToken same chain	Direct BatchToken.balanceOf() call — no bridge message needed.

Chainlink Integration

pragma solidity ^0.8.20;

import {AggregatorV3Interface} from
    "@chainlink/contracts/src/v0.8/shared/interfaces/AggregatorV3Interface.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/access/AccessControlUpgradeable.sol";

contract LendingVault is UUPSUpgradeable, AccessControlUpgradeable {

    AggregatorV3Interface internal coffeeUsdFeed;
    AggregatorV3Interface internal weatherFeed;

    uint256 public constant STALENESS_THRESHOLD = 86400;   // 24 hours
    uint256 public constant OVERRIDE_TIMELOCK   = 172800;  // 48 hours

    function getCoffeePrice() public view returns (uint256) {
        (,int256 price,,uint256 updatedAt,) = coffeeUsdFeed.latestRoundData();
        if (block.timestamp - updatedAt > STALENESS_THRESHOLD) {
            require(
                manualPriceOverride > 0 &&
                block.timestamp >= manualPriceTimestamp + OVERRIDE_TIMELOCK,
                "LendingVault: price stale, no valid override"
            );
            return manualPriceOverride;
        }
        require(price > 0, "LendingVault: invalid price");
        return uint256(price);
    }

    function droughtRiskElevated() public view returns (bool) {
        (,int256 riskScore,,,) = weatherFeed.latestRoundData();
        return riskScore > 7000; // >70% drought probability freezes new loans
    }
}