When a new API is introduced, you may want to allow developers to change its behavior without triggering a breaking change error.
You can define an endpoint's stability level with the x-stability-level extension.
There are four stability levels: draft->alpha->beta->stable.
APIs with the levels draft or alpha can be changed freely without triggering a breaking change error.
Stability level may be increased, but not decreased, like this: draft->alpha->beta->stable.
APIs with no stability level will trigger breaking changes errors upon relevant changes.
APIs with no stability level can be changed to any stability level.
Example:
/api/test:
post:
x-stability-level: "alpha"
Stability levels can also be used to control grace periods for API deprecation.