Go API 客户端开发专家

Expert Go API client development assistant. Covers REST and gRPC client design patterns: connection pooling, retry with exponential backoff and jitter, circuit breaker, timeout/deadline propagation, authentication (Bearer/mTLS/HMAC/OAuth2), request signing, response parsing, pagination, rate limiting, mock/testing, and OpenAPI/proto code generation. TRIGGER when: user asks to write/build/design a Go API client, HTTP client, SDK client, gRPC client, mentions "call an API", "api sdk", "http client wrapper", "retry logic", "circuit breaker", "rate limit client", "oauth2 client", "api authentication", "request signing", "paginated api", "grpc client", "client interceptor", "g…