Luma Ray 3.2 video.loop: rejected with 10s, hdr or end_frame

In Luma's Agents API, video.loop: true asks for a seamlessly looping video, but it is rejected when combined with duration: "10s", hdr: true or end_frame. Sume has no loop flag. On a model that reports first and last frame inputs, you can send the same image as both ends.

Luma's rules are from its generation guide; Sume's are from the video generation docs, read 2026-10-01.

What are Luma's loop conflicts?

The page says loop is create-only: valid for type: "video" and rejected on type: "video_edit". It also lists three conflicts, and says HDR is itself unsupported with a 10s duration or with loop.

How do I get a loop on Sume?

Sume's video request takes frame_images, each with a frame_type of first_frame or last_frame, for image-to-video. Models list what they accept in supported_frame_images; the docs example shows ["first_frame", "last_frame"]. Check the field for your model, then send the same image for both. That is a technique, not a Sume loop feature, and the docs do not promise a seamless seam.

A worked version is in seamless loop with first and last frame.

Is there another way to loop?

Timeline 1.0 can pad or loop short sources and reports short-source pad/loop warnings. That repeats a finished clip rather than generating a seamless one; see increase video length by looping.

What should I check before relying on a loop?

Play the result end to end. Compare the last frame with the first, and watch the seam at normal speed. If it jumps, shorten the clip or regenerate with a prompt that keeps motion small near the ends.