Agent Skills: API Integration

API Integration

Build robust, type-safe API clients from specs and documentation.

Key Principles

• Type everything — Runtime-validated types for all requests and responses
• Fail explicitly — No silent failures; throw typed errors with context
• Auth is first-class — Handle auth in the client layer, not scattered in calls
• Retry intelligently — Only idempotent methods, only transient failures, with backoff
• Isolate the boundary — Transform API shapes at the integration layer, not in app code

When NOT to Use

• Designing your own APIs — Use api-design for building endpoints others will consume
• Writing API test suites — Use testing-strategy for test architecture, contract tests, mocking
• Building SDKs for your API — Use sdk-development for packaging your own API as a client library

Quick Start Checklist

1. Obtain API credentials and locate documentation (spec, docs, or examples)
2. Analyze inputs: extract base URL, auth scheme, endpoints, error formats
3. Choose architecture: typed wrapper (1-5 endpoints), service class (5-20), or generated client (20+)
4. Implement types, client, auth handling, and error classification
5. Add retry logic for transient failures and rate limit handling
6. Write tests with mocked responses and error scenarios

References

| Reference | Description | |-----------|-------------| | openapi-specs-types.md | Parsing OpenAPI specs, type generation strategies | | openapi-patterns-codegen.md | Common patterns, client generation, GraphQL, informal docs | | client-base-service-layer.md | Base client, interceptors, service layer pattern | | client-request-response-caching.md | Request config, response parsing, caching, logging | | error-classification.md | Error type hierarchy, classification, response conversion | | error-retry-circuit-breaker.md | Retry with backoff, rate limits, circuit breaker | | error-fallback-patterns.md | Fallback strategies, Result type, error boundaries, reporting | | auth-api-keys-bearer.md | API key and bearer token authentication | | auth-oauth2.md | OAuth 2.0 authorization code, PKCE, client credentials | | auth-jwt-hmac-storage.md | JWT handling, HMAC signatures, secure token storage | | testing-mocking-fixtures.md | HTTP mocking (MSW, Nock), test fixtures | | testing-unit-integration.md | Unit tests for transformers, integration tests for services | | testing-contract-e2e-config.md | Contract testing, E2E tests, Jest configuration |