Lyria 3.5 is single-turn: budget retakes, not edits, on Sume

You cannot edit a Lyria 3.5 song, you regenerate it. Google's guide describes generation as single-turn with no iterative editing, says results vary between calls, and says all prompts are safety-screened. So a music workflow needs a retake budget: how many attempts you will pay for to get one approved track. At Google's $0.08 per song, five attempts cost $0.40; on Sume at a fixed $0.125, $0.625.

What the Google guide says

From the Lyria music generation guide, read 2026-10-04: single-turn generation, results vary between calls, all prompts are screened, and the model cannot generate specific artist voices or copyrighted lyrics. It recommends timestamps like [0:00 - 0:10] to control when instruments enter, and naming language, instruments, mood and BPM. Prices are on the pricing page.

Retake budget table

No edit means the unit of work is a take. Sume's Music Router has no seed, temperature or duration parameter, so a second request with the same prompt can return a different track. Idempotency keys protect you from a duplicate charge on a network retry, not from a deliberate second take: use a new key per intentional take.

Make each take count

Since you pay per take, spend effort on the brief rather than on volume. The Music 1.0 page recommends a seven-axis brief: emotion, genre lineage, tempo as a number, key and mode, two to four textured instruments, an arc with one named moment, and era or production style. Close with "Instrumental, no vocals." when you want a bed, and put exclusions in the positive prompt, since a non-empty negative_prompt is rejected.

• Change one axis per retake so you learn what moved the result.
• Store the winning prompt in the job metadata.
• Pin the engine id for the retakes so comparisons are fair.
• Stop at a ceiling you set before you start.

When a retake is not the answer

If you like a track except for its length, do not regenerate: trim or loop it with Timeline 1.0 or split it with timeline audio. If you like it except for one section, Sume has no section-level edit, so that is a new take or a different tool. Be explicit about that with clients up front.