• closed: normal operation
• open: block request (after a failure threshold)
• half: test a few requests

// Using opossum circuit breaker with Next.js API route
import CircuitBreaker from 'opossum';

// pages/api/products.js
export default async function handler(req, res) {
  const breaker = new CircuitBreaker(fetchProducts, {
    timeout: 3000,// ms
    errorThresholdPercentage: 50,
    resetTimeout: 30000// ms
  });

  try {
    const data = await breaker.fire();
    res.status(200).json(data);
  } catch (error) {
// Circuit is open or operation failed
    res.status(503).json({ error: 'Service temporarily unavailable' });
  }
}