| as_legacy_envelope | Convert an envelope to the old four-field shape |
| body_or_null | The parsed body, or NULL |
| breaker_open | Is a host's breaker open |
| breaker_record | Record a call outcome against a host |
| breaker_reset | Clear all breaker state |
| cache | The cache store |
| cached | Serve from cache, or fetch and cache a success |
| cache_key | Build a cache key |
| cache_reset | Empty the cache |
| classify_condition | Classify a transport condition onto the status enum |
| classify_http | Classify an HTTP status code onto the status enum |
| envelope | Build a result envelope |
| get_json | GET a JSON endpoint |
| get_json_many | GET many JSON endpoints as one batch |
| get_text | GET a text endpoint |
| graphql_error | Catch a GraphQL query error inside a 200 |
| http_error_message | A user-facing sentence for a failed call |
| is_blank | Is a value blank |
| is_transient | Is a response worth retrying |
| perform | Perform a request and normalize the result |
| perform_many | Perform many requests as one batch |
| perform_text | Perform a request and return the body as text |
| pluck_at | Pull a value out of a nested list |
| post_json | POST a JSON body |
| post_json_many | POST many JSON bodies as one batch |
| redact_secrets | Remove secret values from a string |
| req_defaults | Apply the shared request options |
| status_constructors | Envelope constructors, one per status |
| status_error | Envelope constructors, one per status |
| STATUS_LEVELS | The seven envelope statuses |
| status_message | The user-facing sentence for an outcome |
| status_no_data | Envelope constructors, one per status |
| status_ok | Envelope constructors, one per status |
| status_rate_limited | Envelope constructors, one per status |
| status_skipped | Envelope constructors, one per status |
| status_stale | Envelope constructors, one per status |
| status_timeout | Envelope constructors, one per status |
| user_agent | Build an attributable User-Agent string |