Text-to-speech

Turn text into audio. The body is the audio; the request id, provider, model and charge come back as headers.

#Request

curl https://yelno.ai/v1/audio/speech \
  -H "Authorization: Bearer $YELNO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "MODEL",
    "input": "Your order has shipped and arrives on Thursday.",
    "response_format": "mp3"
  }' \
  --output speech.mp3 --dump-header headers.txt

#Response

200 with the audio bytes, Content-Type as the provider returned it (some models only produce pcm; the model's own 400 says so). Because the body is audio, the evidence travels in headers: X-Request-Id, Yelno-Provider, Yelno-Model, Yelno-Cost-State (pending until the provider reports the cost) and Yelno-Charge-Nanos once it is known.

HTTP/1.1 200 OK
Content-Type: audio/mpeg            # as the provider returned it
X-Request-Id: req_…
Yelno-Provider: …
Yelno-Model: …
Yelno-Cost-State: pending          # until the provider reports this response's cost
Yelno-Charge-Nanos: …              # once the cost is known

<audio bytes>

#Notes

No streaming yet, and no Idempotency-Key replay on this route — the audio bytes are not stored. Voice cloning is not offered: any field this route does not list is refused with 400 code: "unsupported_parameter". Speech returns bare audio, so the charge settles when the provider publishes that response's cost.

Sending a model to a route it is not served on answers 422 capability_unsupported with code: "operation_unsupported" and a message naming the route that serves it. Every model in the catalog shows its type and route.