Cartesia sonic-3.6-2026-08-27 snapshot: which id Sume accepts
Cartesia's dated snapshot ids never change, but Sume's TTS Router lists only sonic-3.6, 3.5, 3, latest and preview. Here is what that means for repeat takes.
Sume's TTS Router does not take Cartesia's dated snapshot ids such as sonic-3.6-2026-08-27. Its model field is an enum of five ids: sonic-3.6, sonic-3.5, sonic-3, sonic-latest and sonic-preview, and an id outside the catalog fails with 400 model_not_found plus the catalog URL. If you need a take to stay exactly as it is, keep the audio file the job returned instead of trying to regenerate it on a frozen model.
What does Cartesia mean by a dated snapshot?
On its Sonic 3.6 page (read 2026-10-02), Cartesia lists three ways to name the model. A dated id such as sonic-3.6-2026-08-27 is snapshotted and will never change, and Cartesia recommends it for customers who want to run internal evals before any update. The undated sonic-3.6 is updated to point at the most recent stable snapshot. sonic-preview is the beta channel.
The same page lists one snapshot for 3.6, released August 27, 2026, with status Stable. Cartesia's older models page (read 2026-10-02) lists sonic-3.5-2026-05-04 and sonic-3-2026-01-12 as Stable, and sonic-3-2025-10-27 as sunsetting on October 20, 2026.
| Cartesia id form | What Cartesia says it does | Accepted by Sume's router? |
|---|---|---|
sonic-3.6-2026-08-27 | Snapshot, never changes | No, not in the catalog enum |
sonic-3.6 | Follows the latest stable snapshot | Yes |
sonic-3.5 | Older model, snapshots listed as stable | Yes |
sonic-preview | Beta, can change without notice | Yes |
What happens if I send a dated id anyway?
The request schema sets model to the five-value enum and does not allow extra shapes, and the endpoint description says unknown ids fail with 400 model_not_found and the catalog URL. The request is refused before a job starts, so there is nothing to bill. Ask the catalog first with GET /v1/tts-router/models/{model_id}; it returns 404 when the id is not in the catalog.
How do I keep a take stable on Sume?
Treat the generated file as the fixed thing. A completed TTS job returns a durable audio URL, and also records model_id, the voice, language, output_format, generation_config and speed, as described in Jobs and results. Store the audio, and store that record next to it.
When you must regenerate one line, pin the model id you used, for example sonic-3.5, rather than sonic-latest. Sume documents sonic-latest as an alias for sonic-3.6, so what it means can move when that alias moves.
curl https://api.sume.com/v1/tts-router/models/sonic-3.6 \
-H "Authorization: Bearer $SUME_API_KEY"Sources
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