apollo-sdk-patterns

# Apollo SDK Patterns

## Overview
Production-ready patterns for Apollo.io API integration. Apollo has no official SDK — these patterns wrap the REST API (`https://api.apollo.io/api/v1/`) with type safety, retry logic, pagination, and bulk operations. All requests use the `x-api-key` header.

## Prerequisites
- Completed `apollo-install-auth` setup
- TypeScript 5+ with strict mode

## Instructions

### Step 1: Type-Safe Client with Zod Validation
```typescript
// src/apollo/client.ts
import axios, { AxiosInstance } from 'axios';
import { z } from 'zod';

const ConfigSchema = z.object({
  apiKey: z.string().min(10, 'API key too short'),
  baseURL: z.string().url().default('https://api.apollo.io/api/v1'),
  timeout: z.number().default(30_000),
});

let instance: AxiosInstance | null = null;

export function getApolloClient(config?: Partial<z.input<typeof ConfigSchema>>): AxiosInstance {
  if (instance) return instance;

  const parsed = ConfigSchema.parse({
    apiKey: config?.apiKey ?? process.env.APOLLO_API_KEY,
    ...config,
  });

  instance = axios.create({
    baseURL: parsed.baseURL,
    timeout: parsed.timeout,
    headers: {
      'Content-Type': 'application/json',
      'x-api-key': parsed.apiKey,
    },
  });

  return instance;
}

// Reset for testing
export function resetClient() { instance = null; }
```

### Step 2: Custom Error Classes
```typescript
// src/apollo/errors.ts
import { AxiosError } from 'axios';

export class ApolloApiError extends Error {
  constructor(
    message: string,
    public statusCode: number,
    public endpoint: string,
    public retryable: boolean,
    public requestId?: string,
  ) {
    super(message);
    this.name = 'ApolloApiError';
  }

  static fromAxios(err: AxiosError): ApolloApiError {
    const status = err.response?.status ?? 0;
    const body = err.response?.data as any;
    return new ApolloApiError(
      body?.message ?? err.message,
      status,
      err.config?.url ?? 'unknown',
      [429, 500, 502, 503, 504].includes(status),
      err.response?.headers?.['x-request-id'],
    );
  }
}

export class ApolloRateLimitError extends ApolloApiError {
  constructor(
    public retryAfterMs: number,
    endpoint: string,
  ) {
    super(`Rate limited on ${endpoint}`, 429, endpoint, true);
    this.name = 'ApolloRateLimitError';
  }
}
```

### Step 3: Retry with Exponential Backoff
```typescript
// src/apollo/retry.ts
import { ApolloApiError } from './errors';

export async function withRetry<T>(
  fn: () => Promise<T>,
  opts: { maxRetries?: number; baseMs?: number; maxMs?: number } = {},
): Promise<T> {
  const { maxRetries = 3, baseMs = 1000, maxMs = 30_000 } = opts;

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      return await fn();
    } catch (err) {
      const isRetryable = err instanceof ApolloApiError && err.retryable;
      if (!isRetryable || attempt === maxRetries) throw err;

      const jitter = Math.random() * 500;
      const delay = Math.min(baseMs * 2 ** attempt + jitter, maxMs);
      await new Promise((r) => setTimeout(r, delay));
    }
  }
  throw new Error('Unreachable');
}
```

### Step 4: Async Pagination Iterator
Apollo endpoints return `pagination.total_entries` and accept `page`/`per_page`. The People Search API limits to 500 pages (50,000 records).

```typescript
// src/apollo/paginator.ts
import { getApolloClient } from './client';
import { withRetry } from './retry';

export async function* paginate<T>(
  endpoint: string,
  body: Record<string, unknown>,
  itemKey: string = 'people',
  perPage: number = 100,
  maxPages: number = 500,
): AsyncGenerator<T[], void, undefined> {
  const client = getApolloClient();
  let page = 1;
  let totalPages = Infinity;

  while (page <= Math.min(totalPages, maxPages)) {
    const { data } = await withRetry(() =>
      client.post(endpoint, { ...body, page, per_page: perPage }),
    );

    const items: T[] = data[itemKey] ?? [];
    totalPages = data.pagination?.total_pages ?? 1;
    if (items.length === 0) break;

    yield items;
    page++;
  }
}

// Usage:
// for await (const batch of paginate('/mixed_people/api_search', {
//   q_organization_domains_list: ['stripe.com'],
// })) {
//   await processBatch(batch);
// }
```

### Step 5: Bulk Enrichment with Rate Awareness
Apollo's Bulk People Enrichment endpoint handles up to 10 records per call.

```typescript
// src/apollo/bulk-enrich.ts
import { getApolloClient } from './client';
import { withRetry } from './retry';

interface EnrichmentDetail {
  email?: string;
  linkedin_url?: string;
  first_name?: string;
  last_name?: string;
  organization_domain?: string;
}

export async function bulkEnrichPeople(
  details: EnrichmentDetail[],
  opts: { revealPersonalEmails?: boolean; revealPhoneNumber?: boolean } = {},
): Promise<any[]> {
  const client = getApolloClient();
  const results: any[] = [];

  // Apollo bulk endpoint accepts max 10 at a time
  for (let i = 0; i < details.length; i += 10) {
    const batch = details.slice(i, i + 10);

    const { data } = await withRetry(() =>
      client.post('/people/bulk_match', {
        details: batch,
        reveal_personal_emails: opts.revealPersonalEmails ?? false,
        reveal_phone_number: opts.revealPhoneNumber ?? false,
      }),
    );

    results.push(...(data.matches ?? []));

    // Brief pause between batches to respect rate limits
    if (i + 10 < details.length) {
      await new Promise((r) => setTimeout(r, 500));
    }
  }

  return results;
}
```

## Output
- `src/apollo/client.ts` — Zod-validated singleton with `x-api-key` header
- `src/apollo/errors.ts` — `ApolloApiError` + `ApolloRateLimitError` with retryable flag
- `src/apollo/retry.ts` — Exponential backoff with jitter
- `src/apollo/paginator.ts` — Async generator for paginated endpoints (500-page limit)
- `src/apollo/bulk-enrich.ts` — Batch enrichment via `/people/bulk_match` (10 per call)

## Error Handling
| Pattern | When to Use |
|---------|-------------|
| Singleton client | Always — one client instance per process |
| Retry | 429 rate limits, 5xx server errors |
| Pagination | Search results > 100 records |
| Bulk enrichment | Multiple contacts need email/phone data |
| Custom errors | Typed catch blocks distinguishing auth vs rate limit vs server |

## Examples

### Full Pipeline: Search, Paginate, Enrich
```typescript
import { paginate } from './apollo/paginator';
import { bulkEnrichPeople } from './apollo/bulk-enrich';

async function enrichLeadsAtCompany(domain: string) {
  const allPeople: any[] = [];
  for await (const batch of paginate('/mixed_people/api_search', {
    q_organization_domains_list: [domain],
    person_seniorities: ['vp', 'director', 'c_suite'],
  })) {
    allPeople.push(...batch);
  }
  console.log(`Found ${allPeople.length} decision-makers at ${domain}`);

  // Bulk enrich only those without email
  const toEnrich = allPeople
    .filter((p) => !p.email && p.linkedin_url)
    .map((p) => ({ linkedin_url: p.linkedin_url }));

  const enriched = await bulkEnrichPeople(toEnrich);
  console.log(`Enriched ${enriched.length} contacts`);
}
```

## Resources
- [Apollo API Overview](https://docs.apollo.io/docs/api-overview)
- [Bulk People Enrichment](https://docs.apollo.io/reference/bulk-people-enrichment)
- [Zod Schema Validation](https://zod.dev/)

## Next Steps
Proceed to `apollo-core-workflow-a` for lead search implementation.