Lyria 3.5 API: model id, request and how to call it

The Lyria 3.5 API is Google's music model, offered in the Gemini API under the model id lyria-3.5. It writes a full-length song from a text prompt, optionally with images. On Sume you reach it with one request to POST /v1/music-router/generate: leave model out (or send sume/music-auto, which resolves to Lyria 3.5 today) or pin lyria-3.5.

Google's side comes from its Lyria page and announcement; Sume's from the Music Router and Music 1.0 docs. All read 2026-09-29.

What does Google's Lyria 3.5 API page say?

How do I call Lyria 3.5 through Sume?

Send a prompt. The body has no seed, temperature or duration field; the docs say to steer length in the prompt and reject duration and duration_seconds.

curl -X POST https://api.sume.com/v1/music-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: lyria-35-api-001" \
  -d '{
    "model": "lyria-3.5",
    "prompt": "Warm lo-fi hip hop, 84 BPM, C minor. Dusty Rhodes chords, brushed boom-bap drums. A 30-second track. Instrumental, no vocals."
  }'

How do I get the audio back?

The call returns a job. Poll GET /v1/jobs/{id}/status, then read GET /v1/jobs/{id}/result. The audio is the entry in result.artifacts[] whose type is audio, typically audio/mpeg on media.sume.com. result.lyrics carries the model-reported lyrics or section map when present. job.request.routed_model names the engine that ran, so you can confirm it was lyria-3.5.

Which request fields exist?

• prompt: required, 1-5000 characters. Put exclusions in the positive prompt.
• image_url: optional public HTTPS image for visual conditioning.
• negative_prompt: not supported when non-empty (HTTP 400).
• mode, webhook_url, wait_timeout_seconds: how you learn the result.

Is Sume's price the same as Google's?

Google's own prices are on its Gemini API pricing page; Sume bills every Music Router model at its fixed music price per generation, listed on API pricing. The two are separate price lists, so check both before you plan volume.