HappyHorse 1.1 API watermark defaults to on: how to turn it off

On Alibaba's HappyHorse image-to-video reference, the optional watermark parameter adds a "Happy Horse" text mark to the bottom-right corner when enabled, and the default is true (Alibaba Model Studio, read 2026-10-09). A request that leaves it out returns a marked clip. Set watermark to false in the request body, and look at the last frame before you ship.

What else should you know about the output?

What does this look like on Sume?

Sume lists no HappyHorse id (catalog read 2026-10-09), so there is no watermark switch to flip. Sume's video docs describe no visible mark added to generated clips. Google states that every Omni clip carries SynthID, an invisible watermark that can be detected programmatically (Google Omni docs, read 2026-10-09). That is invisible, so it does not mark the frame.

What is the delivery check?

If you run Omni on Sume, Sume's video docs show finished clips returned as Sume-hosted artifact URLs (on media.sume.com).

• Pull the final frame and the first frame with Sume's video frames or your own tool, and look at the bottom-right corner.
• On HappyHorse's own API the video URL is deleted after 24 hours, so save the file the day you render it; for a Sume artifact URL, keep your own copy too.
• Keep the request body in your job log so you can prove watermark: false was sent.