Music Router: does pinning lyria-3-pro cost more than music-auto?

No. On Sume's Music Router, every routable model charges the same fixed Music price per audio generation, so pinning lyria-3-pro or lyria-3.5 costs the same as leaving model at sume/music-auto. The Music 1.0 page lists that price as $0.125 for each accepted generation, and says it does not change with prompt length or optional image conditioning. The router page states that the catalog lists the provider list price per model for reference only.

What pinning does change

The router has three routable ids: sume/music-auto (the default), lyria-3.5 and lyria-3-pro. If you omit model or send sume/music-auto, Sume selects the engine, which is Lyria 3.5 today. If you pin an id from GET /v1/music-router/models, the request passes through to that engine.

Two fields tell you what ran. job.model echoes the id you requested, so sume/music-auto stays sume/music-auto. job.request.routed_model names the catalog engine that ran, for example lyria-3.5. Log the second field if you ever compare tracks.

Pin or let Sume pick

Because the price is flat, an engine choice is a quality and consistency decision, not a budget decision. The only way to settle which is better for your brief is to render the same brief on each id and listen.

A request that pins an engine

The body is the same as Music 1.0, plus model. Control length in the prompt (for example A 30-second track). The API rejects duration and duration_seconds, and a non-empty negative_prompt.

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: music-router-pin-001" \
  -d '{
    "model": "lyria-3-pro",
    "prompt": "Warm lo-fi hip hop, 84 BPM, C minor. Dusty Rhodes chords, brushed drums. A 30-second track. Instrumental, no vocals."
  }'

Before you rely on it

Music 1.0 is retiring gradually. Its routes keep working and keep job.model = sume/music-1.0, but every request resolves through the router. New integrations should call POST /v1/music-router/generate.

Read the live rate with GET /v1/catalog before a large batch. The docs name the flat price, and the catalog is the source for the current number.