# description
The synchronous rejection body returned when the responding NP has exceeded a request rate limit (AUT_RATE_LIMITED) or a policy-governed engagement capacity limit (POL_NP_CAPACITY_EXCEEDED). The caller MUST apply back-off before retrying. Implementations SHOULD include a Retry-After header on 429 responses.

NackTooManyRequests appears as the response body for 429 responses on all endpoints.

Relationship: Extends the Ack schema with status constrained to NACK and an error code constrained to the two retryable capacity/rate-limit codes.