Versioning

The API is versioned in its path: /v1. A breaking change gets a new prefix (/v2) for the resources it affects; /v1 keeps working.

Not breaking (can ship any time)	Breaking (needs a new version)
New optional request fields, new response fields, new values in response-only enums, new endpoints, new error codes	Removing or renaming fields, tightening validation, changing defaults or types, new required fields

Write clients that ignore unknown response fields and unknown enum values.

Deprecation

Every response from a deprecated endpoint or model carries:

Deprecation: @1798761600
Sunset: Sat, 01 Jan 2027 00:00:00 GMT
Link: <https://docs.antarah.dev/models>; rel="deprecation"

What	Notice before `Sunset`
Endpoints	At least 90 days
Models	At least 30 days

After its sunset a model answers 410 model_retired. GET /v1/models shows deprecated and sunset_at for each model.