unknown_scope
POST /v1/api-keys naming a scope outside the catalog (03-domain-model.md §Authorization). Refused rather than stored: a key minted with an unknown scope appears to grant something, grants nothing, and surfaces much later as a confusing 403. errors[] names the field.
Problem shape
Every non-2xx response is an RFC 9457 application/problem+json body. The type URI below is stable and machine-matchable, so branch on the final path segment (the code) and treat the status as redundant confirmation. See the error-handling guide.
{
"type": "https://docs.vocapable.com/errors/unknown_scope",
"title": "…",
"status": 422,
"detail": "…",
"instance": "/v1/…"
}