How to Set Up Blockchain Monitoring — Tenderly, Forta, and On-Chain Alerts

// Tenderly webhook alert configuration
const tenderlyAlert = {
    name: "Large Withdrawal Alert",
    conditions: [
        {
            contract_address: "0x...",   // Your protocol contract
            method: "withdraw",
            // Alert when withdrawal > $100,000 equivalent
            parameters: { amount: { gt: "100000000000" } } // USDC 6 decimals
        }
    ],
    targets: [
        { type: "webhook", url: "https://yourapp.com/webhooks/tenderly" }
    ],
    deliveryChannels: ["email", "slack", "pagerduty"]
};

// Webhook handler for Tenderly alerts
app.post('/webhooks/tenderly', async (req, res) => {
    const alert = req.body;
    
    console.log(`Alert: ${alert.name}`);
    console.log(`Transaction: ${alert.transaction.hash}`);
    console.log(`Block: ${alert.transaction.block_number}`);
    
    // High-value withdrawal: notify on-call team immediately
    if (alert.name === "Large Withdrawal Alert") {
        await pagerduty.trigger({
            title: `Large withdrawal detected: ${alert.transaction.hash}`,
            severity: 'warning'
        });
    }
    
    res.status(200).send('OK');
});

// GraphQL query for suspicious activity monitoring
const SUSPICIOUS_ACTIVITY_QUERY = `
  query CheckAnomalies($threshold: BigInt!, $timeWindow: Int!) {
    largeWithdrawals: withdrawals(
      where: { 
        amount_gt: $threshold,
        timestamp_gt: $timeWindow
      }
      orderBy: amount
      orderDirection: desc
    ) {
      id
      user
      amount
      timestamp
      transaction
    }
    
    rapidRepayments: repayments(
      where: { timestamp_gt: $timeWindow }
      orderBy: timestamp
    ) {
      id
      user
      amount
    }
  }
`;

// Run hourly anomaly detection
async function detectAnomalies() {
    const oneHourAgo = Math.floor(Date.now() / 1000) - 3600;
    const HIGH_VALUE_THRESHOLD = "1000000000000"; // $1M in USDC
    
    const { data } = await apolloClient.query({
        query: SUSPICIOUS_ACTIVITY_QUERY,
        variables: { threshold: HIGH_VALUE_THRESHOLD, timeWindow: oneHourAgo }
    });
    
    if (data.largeWithdrawals.length > 0) {
        await alertSecurityTeam(data.largeWithdrawals);
    }
}

// On-chain circuit breaker that pauses the protocol
contract CircuitBreaker is Ownable {
    uint256 public maxWithdrawalPerHour;
    uint256 public withdrawalThisHour;
    uint256 public hourStart;
    
    event CircuitBreakerTripped(uint256 amount, uint256 limit);
    
    function checkWithdrawalLimit(uint256 amount) internal {
        if (block.timestamp >= hourStart + 1 hours) {
            hourStart = block.timestamp;
            withdrawalThisHour = 0;
        }
        
        withdrawalThisHour += amount;
        
        if (withdrawalThisHour > maxWithdrawalPerHour) {
            emit CircuitBreakerTripped(withdrawalThisHour, maxWithdrawalPerHour);
            // Trigger automatic pause
            _pause(); // Assumes Pausable mixin
        }
    }
}