Asset Studio video in 16:9 and 9:16: two Sume requests

Sume's video requests take one aspect ratio each, so the same brief becomes two requests: one at 16:9 and one at 9:16. Google's August 2026 Demand Gen drop says Multimodal Video Creation in Asset Studio is generally available and lets you "go from storyboarding to creating horizontal and vertical assets in one workflow"; the Sume docs describe no matching single call.

Google's text is from its blog post of 2026-08-27, read 2026-09-30. Sume limits are from Video Router and Timeline 1.0.

What are the per-model limits?

Limits are per model, and the docs tell you to read capabilities from GET /v1/video-router/models instead of assuming one envelope.

How do I produce both orientations?

Send the same prompt twice to POST /v1/video-router/generate, changing only aspect_ratio. Use a different Idempotency-Key for each so neither replays the other.

const prompt = "A ceramic mug on a wooden desk, steam rising, soft window light";
const ids = [];
for (const aspect_ratio of ["16:9", "9:16"]) {
  const res = await fetch("https://api.sume.com/v1/video-router/generate", {
    method: "POST",
    headers: {
      Authorization: "Bearer " + process.env.SUME_API_KEY,
      "Content-Type": "application/json",
      "Idempotency-Key": "mug-" + aspect_ratio,
    },
    body: JSON.stringify({
      model: "seedance-2.5",
      prompt,
      resolution: "720p",
      duration: 8,
      aspect_ratio,
    }),
  });
  ids.push(await res.json());
}
console.log(ids);

Will the two clips match each other?

Not frame for frame. They are two generations, so composition and motion can differ. If you need the same shot in both shapes, generate once and reframe: Timeline's video[].fit is cover (default), contain, stretch or blur, and the default output is 1080x1920 (see Timeline fit modes). Timeline also joins ordered slots into one MP4 when you want a longer storyboard; see assemble long-form video. For the specs Demand Gen asks for, see Demand Gen video ad specs.