customerio-sdk-patterns

# Customer.io SDK Patterns

## Overview
Production-ready patterns for Customer.io SDK usage including error handling, batching, and type safety.

## Prerequisites
- Customer.io SDK installed
- TypeScript project (recommended)
- Understanding of async/await patterns

## Instructions

### Pattern 1: Type-Safe Client
```typescript
// types/customerio.ts
export interface UserAttributes {
  email: string;
  first_name?: string;
  last_name?: string;
  created_at?: number;
  plan?: 'free' | 'pro' | 'enterprise';
  [key: string]: string | number | boolean | undefined;
}

export interface EventData {
  [key: string]: string | number | boolean | object;
}

export type EventName =
  | 'signed_up'
  | 'subscription_started'
  | 'subscription_cancelled'
  | 'feature_used'
  | 'email_verified';

// lib/customerio-client.ts
import { TrackClient, RegionUS } from '@customerio/track';
import type { UserAttributes, EventData, EventName } from '../types/customerio';

export class TypedCustomerIO {
  private client: TrackClient;

  constructor() {
    this.client = new TrackClient(
      process.env.CUSTOMERIO_SITE_ID!,
      process.env.CUSTOMERIO_API_KEY!,
      { region: RegionUS }
    );
  }

  async identify(userId: string, attributes: UserAttributes): Promise<void> {
    await this.client.identify(userId, {
      ...attributes,
      _updated_at: Math.floor(Date.now() / 1000)
    });
  }

  async track(userId: string, event: EventName, data?: EventData): Promise<void> {
    await this.client.track(userId, { name: event, data });
  }
}
```

### Pattern 2: Retry with Exponential Backoff
```typescript
// lib/customerio-resilient.ts
import { TrackClient } from '@customerio/track';

interface RetryConfig {
  maxRetries: number;
  baseDelay: number;
  maxDelay: number;
}

const defaultRetryConfig: RetryConfig = {
  maxRetries: 3,
  baseDelay: 1000,
  maxDelay: 10000
};

async function withRetry<T>(
  operation: () => Promise<T>,
  config: RetryConfig = defaultRetryConfig
): Promise<T>