4.2AI-Powered Contract Generation

The Prompt

Analyze this API client code and generate Pact consumer tests for every
external API call it makes.

```typescript
// services/product-client.ts
export class ProductClient {
  constructor(private baseUrl: string, private token: string) {}

  async getProduct(id: string): Promise<Product> {
    const res = await fetch(`${this.baseUrl}/api/v2/products/${id}`, {
      headers: { Authorization: `Bearer ${this.token}` }
    });
    if (!res.ok) throw new ApiError(res.status, await res.text());
    return res.json();
  }

  async searchProducts(query: string, limit = 20): Promise<ProductList> {
    const res = await fetch(
      `${this.baseUrl}/api/v2/products?q=${encodeURIComponent(query)}&limit=${limit}`,
      { headers: { Authorization: `Bearer ${this.token}` } }
    );
    if (!res.ok) throw new ApiError(res.status, await res.text());
    return res.json();
  }
}

Generate Pact consumer tests using @pact-foundation/pact that:

1. Define the expected request (method, path, headers, query params)
2. Define the expected response shape (using Pact matchers for flexibility)
3. Cover both success and error scenarios
4. Use Pact matchers (like, eachLike, term) instead of exact values

### What AI Detects from Client Code

| Client Code Pattern | AI-Generated Contract |
|--------------------|-----------------------|
| `fetch(\`/api/v2/products/${id}\`)` | GET /api/v2/products/{id} interaction |
| `headers: { Authorization: \`Bearer ${token}\` }` | Auth header expectation |
| `if (!res.ok) throw new ApiError(...)` | Error scenario interactions |
| `res.json()` | JSON response body expectation |
| `query: string, limit = 20` | Query parameter expectations |
| `Promise<Product>` | Response body shape from Product type |