Generate API Collection

Core principle: Every API surface (Rails app or engine) has a single API collection file that stays in sync with its endpoints.

Rules at a Glance

Aspect	Rule
When	Create or update collection when creating or modifying any REST API endpoint (route + controller action)
Format	Postman Collection JSON v2.1 (`schema` or `info.schema` references v2.1)
Location	One file per app or engine — `docs/api-collections/<app-or-engine-name>.json` or `spec/fixtures/api-collections/`; if a collection folder already exists, update the existing file
Language	All request names, descriptions, and variable names must be in English
Variables	Use `{{base_url}}` for the base URL so the collection works across environments
Per request	method, URL, headers, body, description, and test scripts (e.g. `pm.response.to.have.status(200)`)
Folders	Group related endpoints into folders using nested `item` arrays
Exception	GraphQL endpoints — use implement-graphql instead