customerio-rate-limits

# Customer.io Rate Limits

## Overview
Understand and implement proper rate limiting and backoff strategies for Customer.io API.

## Rate Limit Details

### Track API Limits
| Endpoint | Limit | Window |
|----------|-------|--------|
| Identify | 100 requests/second | Per workspace |
| Track events | 100 requests/second | Per workspace |
| Batch operations | 100 requests/second | Per workspace |
| Page/screen | 100 requests/second | Per workspace |

### App API Limits
| Endpoint | Limit | Window |
|----------|-------|--------|
| Transactional email | 100/second | Per workspace |
| Transactional push | 100/second | Per workspace |
| API queries | 10/second | Per workspace |

## Instructions

### Step 1: Implement Rate Limiter
```typescript
// lib/rate-limiter.ts
class RateLimiter {
  private tokens: number;
  private lastRefill: number;
  private readonly maxTokens: number;
  private readonly refillRate: number;

  constructor(maxRequestsPerSecond: number = 100) {
    this.maxTokens = maxRequestsPerSecond;
    this.tokens = maxRequestsPerSecond;
    this.refillRate = maxRequestsPerSecond;
    this.lastRefill = Date.now();
  }

  private refill(): void {
    const now = Date.now();
    const elapsed = (now - this.lastRefill) / 1000;
    this.tokens = Math.min(this.maxTokens, this.tokens + elapsed * this.refillRate);
    this.lastRefill = now;
  }

  async acquire(): Promise<void> {
    this.refill();

    if (this.tokens >= 1) {
      this.tokens -= 1;
      return;
    }

    // Wait for token to become available
    const waitTime = ((1 - this.tokens) / this.refillRate) * 1000;
    await new Promise(resolve => setTimeout(resolve, waitTime));
    this.tokens = 0;
    this.lastRefill = Date.now();
  }
}

export const trackApiLimiter = new RateLimiter(100);
```

### Step 2: Implement Exponential Backoff
```typescript
// lib/backoff.ts
interface BackoffConfig {
  maxRetries: number;
  baseDelay: number;
  maxDelay: number;
  jitterFactor: number;
}

const defaultConfig: