Does cartesia/sonic-3-latest still route to Sonic 3.5, or Sonic 3?

Agents
,
1

Hey team,

Back around April 30, cartesia/sonic-3-latest was added to LiveKit Inference after this thread: Support for Cartesia sonic-3-latest model

At the time, my understanding was that Cartesia’s sonic-3-latest pointed to the new Sonic 3.5 preview, so using cartesia/sonic-3-latest through LiveKit Inference should have routed to Sonic 3.5.

Cartesia now documents explicit Sonic 3.5 model IDs:

  • sonic-3.5
  • sonic-3.5-2026-05-04
  • sonic-latest

But in LiveKit Inference today, I’m seeing:

  • cartesia/sonic-3-latest works
  • cartesia/sonic-3 works
  • cartesia/sonic-3.5 returns model not found
  • cartesia/sonic-3.5-2026-05-04 returns model not found
  • cartesia/sonic-latest returns model not found

Can you confirm what cartesia/sonic-3-latest currently routes to?

Specifically:

  1. Is cartesia/sonic-3-latest still Sonic 3.5, or is it now Sonic 3?
  2. If it is Sonic 3, is there a supported LiveKit Inference model ID for Cartesia Sonic 3.5?
  3. Should we expect cartesia/sonic-3.5 or cartesia/sonic-latest support soon?

Thanks.

2

@Abdulaziz, your empirical testing is the right method. Verified on main (livekit-agents/livekit/agents/inference/tts.py): inference.TTS doesn’t validate model names client-side; the string passes straight through to the gateway, so “model not found” is a gateway-level rejection against LK’s internal allowlist.

The mapping from cartesia/sonic-3-latest to its upstream Cartesia model ID lives in LK Cloud’s Inference config, not in OSS code. Only @CWilson or @darryncampbell can authoritatively answer:

  • Current routing: what cartesia/sonic-3-latest resolves to today (Sonic 3 vs Sonic 3.5)

  • Pointer behavior: whether it auto-follows Cartesia’s sonic-latest upstream, or is pinned to a specific version

  • 3.5 ID timeline: ETA on adding cartesia/sonic-3.5, cartesia/sonic-3.5-2026-05-04, and cartesia/sonic-latest to the Inference allowlist

The “Support for Cartesia sonic-3-latest” thread you linked is the right precedent channel for these adds. Pinging the team here to surface the 3.5 question.

3

I see a change was pushed last night to the Inference product meaning these should now resolve.

  1. Is cartesia/sonic-3-latest still Sonic 3.5, or is it now Sonic 3? → This is pointing at Sonic-3

  2. If it is Sonic 3, is there a supported LiveKit Inference model ID for Cartesia Sonic 3.5? → Yes, the 3 models you listed that were previously ‘not found’ should now point to 3.5

  3. Should we expect cartesia/sonic-3.5 or cartesia/sonic-latest support soon? → Sorry I missed this message when it was originally posted