ManagedLeveragedVault::getAvailableDebt() used in ManagedLeveragedVault::increaseLeverage() is incorrect

Summary

ManagedLeveragedVault::increaseLeverage() allows borrowing until the maxSystemDebt limit, but the check doesn't account for the borrowing fee triggered.

Vulnerability Detail

This is the ManagedLeveragedVault::getAvailableDebt() function:

function getAvailableDebt() internal view returns (uint256) {
    BoycoVaultStorage storage b$ = _getBoycoVaultStorage();

    IDenManager denManager = IDenManager(b$.denManager);

    uint256 borrowCap = denManager.maxSystemDebt();
    uint256 totalActiveDebt = denManager.getTotalActiveDebt();
    uint256 defaultedDebt = denManager.defaultedDebt();

    return borrowCap - totalActiveDebt - defaultedDebt;
}

It doesn't account for the borrowing fee triggered, which means the max debt will be overestimated.

Impact

This function would be used most likely offchain to calculate the max debt to leverage up, which would revert.

Code Snippet

https://github.com/sherlock-audit/2025-04-beraborrow-vault-update/pull/1/files#diff-2d972f52027e0ba1065b2de2b424416244bfef9e2a79d2604e1687867f72c91eR428

Tool Used

Manual Review

Recommendation

This function should return the debt multiplied by (1 - borrowingFee).