error-recovery-patterns

Error Recovery Patterns Skill

What to do when things break.

Recovery Hierarchy

Prevent → Detect → Contain → Recover → Learn

Retry Rules

Retry	Don't Retry
Network timeouts	Validation errors (400)
Rate limits (429)	Auth failures (401, 403)
Server errors (5xx)	Not found (404)
Connection refused	Business logic errors

Retry with Backoff

const delay = baseDelay * Math.pow(2, attempt - 1);
const jitter = Math.random() * 0.3 * delay;
await sleep(delay + jitter);

Circuit Breaker States

CLOSED → (failures > threshold) → OPEN → (timeout) → HALF-OPEN → (success) → CLOSED

Fallback Patterns

Pattern	Use Case
Default value	Config loading
Cached value	Data fetch failure
Degraded service	Non-critical features

const result = await primary().catch(() => fallback());

Rollback Patterns

Pattern	Use Case
DB transaction	Atomic operations
Saga (compensate)	Distributed transactions
Feature flag	Instant rollback

Saga Pattern Implementation

// Compensating transactions for distributed operations
interface SagaStep<T> {
  execute: () => Promise<T>;
  compensate: () => Promise<void>;
}

async function executeSaga<T>(steps: SagaStep<T>[]): Promise<T[]> {
  const completed: SagaStep<T>[] = [];
  const results: T[] = [];
  
  try {
    for (const step of steps) {
      results.push(await step.execute());
      completed.push(step);
    }
    return results;
  } catch (error) {
    // Compensate in reverse order
    for (const step of completed.reverse()) {
      try {
        await step.compensate();
      } catch (compensateError) {
        console.error('Compensation failed:', compensateError);
        // Log but continue compensating other steps
      }
    }
    throw error;
  }
}

// Usage: Order processing saga
const orderSaga: SagaStep<void>[] = [
  {
    execute: () => reserveInventory(orderId),
    compensate: () => releaseInventory(orderId)
  },
  {
    execute: () => chargePayment(orderId),
    compensate: () => refundPayment(orderId)
  },
  {
    execute: () => scheduleShipment(orderId),
    compensate: () => cancelShipment(orderId)
  }
];