Extend retry loop to handle HTTP 429 Too Many Requests: when the server includes a
Retry-After header, that duration is used as the retry delay; otherwise falls back to
the configured BackOffDelay. Add DoJSONRequest[Req, Resp] free function that serialises
the request body as JSON, sets Content-Type, and delegates response decoding to DoJSON.
Bump logz and xerrors from v0.9.0 to v1.0.0. API committed as stable.
Resilient HTTP client with circuit breaking, exponential-backoff retry, X-Request-ID propagation, and a generic typed JSON helper.
What's included:
- Client interface with Do(req) method; New(logger, cfg) and NewWithDefaults(logger) constructors
- Config struct with env-tag support for timeout, dial timeout, retry, and circuit breaker parameters
- Retry via avast/retry-go/v4 with BackOffDelay; triggers only on network errors and HTTP 5xx
- Circuit breaker via sony/gobreaker wrapping the full retry loop; open circuit → xerrors.ErrUnavailable
- X-Request-ID header propagated automatically from context via logz.GetRequestID on every attempt
- DoJSON[T](ctx, client, req) generic helper for typed JSON request/response with xerrors error mapping
- MapStatusToError(code, msg) exported function mapping HTTP status codes to xerrors types
Tested-via: todo-api POC integration
Reviewed-against: docs/adr/
