SchemaDirection

Which way a schema's values flow: an INPUT is what old clients send, such as a command or a route's request, so it may only accept more; an OUTPUT is what old clients read, such as a route's response, so it may only produce less: a type widened, an enum value added, a field made optional or an alternative added breaks it, and a required field added or an optional one removed does not. A STORED schema is what the service's own records were written with, an event's or a state's, which it reads back: an input for the structure, but no stored record is checked against a constraint (a bound, a pattern, a multipleOf), so a constraint changed either way is additive there; whether it breaks is its readers' to say, an OUTPUT's.