Gallery documents in the library

The library now has gallery documents: a hero image, a filmstrip, a cover, drag-to-reorder, and a prompt up to 20,000 characters.

The library can now hold gallery documents alongside articles and X posts.

A gallery is for a set of images, not an article stuffed with pictures:

One layout: read and edit both use a hero image plus a filmstrip.
Cover: star an image; the tree and lists use that cover.
Order: drag the filmstrip while editing.
Prompt: paste a generation prompt while editing, up to 20,000 characters. Hidden in read mode.
Limit: 20 images per gallery.

Galleries do not ship through the browser extension and have no social preview. To publish, keep using articles (extension) or X posts (official API).

Guide: Gallery docs.