Every Transaction
      │
      ▼
┌─────────────────┐
│  10% Fee        │──────► Insurance Pool
└─────────────────┘
      │
      ▼
┌─────────────────┐
│  90% to Vault   │──────► Staker Yield
└─────────────────┘

// Borrower defaults on $100 loan
const defaultedAmount = 100;

const insuranceCoverage = defaultedAmount * 0.80; // $80
const stakerLoss = defaultedAmount * 0.20;        // $20

// Insurance Pool pays $80 to cover the default
// Stakers collectively absorb $20 loss

// InsurancePool.sol (simplified)
contract InsurancePool {
    uint256 public poolBalance;
    uint256 public targetReserveRatio = 15; // 15%

    function coverDefault(address borrower, uint256 amount) external onlyVault {
        uint256 coverage = (amount * 80) / 100;
        require(poolBalance >= coverage, "Insufficient pool balance");

        poolBalance -= coverage;
        emit DefaultCovered(borrower, amount, coverage);
    }
}