WordPress 7.1 client-side media processing and Sume images

WordPress 7.1 moves resizing, format conversion and thumbnail generation into the browser. For Sume images, that means you pick the output_format you want, and WordPress handles the rest of the sizing; Sume does not serve output_compression, so you cannot tune JPEG or WebP quality on the Sume side.

WordPress figures are from the 7.1 developer note dated 2026-07-22; Sume figures from the Images docs, read 2026-09-30.

What does WordPress 7.1 do in the browser?

What can I request from Sume?

The Images docs list output_format as png, jpeg, webp or svg, while the model-level enum in the docs example shows png, jpeg and webp, so read supported_parameters for the model you call. output_compression (0-100) is in the schema but not served in v1; sending it returns 400 unsupported_parameter.

Does the missing compression knob matter?

Less than it would on a server-side pipeline. WordPress re-encodes the sub-sizes it generates, using its own quality setting. Request jpeg or webp from Sume for photographic images so the file you sideload is already in a web format.

How do I get the file into the media library?

Sume results are durable media.sume.com HTTPS URLs that do not expire and are public to anyone holding the URL, so WordPress can download and sideload them. Size guidance for stores is in WooCommerce product image size.