Resilience Patterns

Production-grade patterns for surviving failures without cascading.

Circuit Breaker

// States: CLOSED (normal) → OPEN (blocking) → HALF_OPEN (testing)
type CircuitState = 'CLOSED' | 'OPEN' | 'HALF_OPEN'

class CircuitBreaker {
  private state: CircuitState = 'CLOSED'
  private failureCount = 0
  private lastFailureTime = 0
  private successCount = 0