0.148.0
Defaults for omitted Query, Header, Cookie, and Form parameters and model fields are no longer treated as user input. Defaults are not validated unless validate_default=True is enabled. If you rely on validators running for omitted values, enable default validation with Field(validate_default=True) for model fields or, for example, Query(validate_default=True) for individual parameters. Body(validate_default=True) is now honored too.
For parameter models, applying a default no longer marks a field as explicitly set, so model_dump(exclude_unset=True) excludes it. Default factories run once, and validation errors no longer include injected defaults in input.
Omitted boolean form fields still become False and count as explicitly set.