My page looks different once published

The page your assistant showed you looks different, or parts of it do not work, at its address. A link inside it opens a page that says:

The link may be mistyped or cut short, or the page may have moved.

Or a link you paste into a chat shows a plain card, and the setting that would show more warns:

Anything above generic is visible to anyone with the URL — no sign-in needed.

A published artifact runs on an address of its own, in a sandbox: scripts, styles, fonts and requests to other https addresses work, but cookies, local storage and requests that need a sign-in elsewhere do not, so a page that saved something in the browser in the preview starts empty every time. A link to a file that was not published with the page has nothing to open. A markdown file published as it is, with no page around it, reaches a browser as a file to download. And while an artifact is not public, the card a chat app draws for its link shows only what you have chosen to let anyone see.

Ask your assistant to publish a single page with everything it needs inside it, or to include every file the page links to. Ask for a page rather than a bare markdown file (Publishing markdown). To show more on pasted links, choose a level on the artifact's Link preview card (Control what a pasted link reveals).

Still stuck? Write to support with the artifact's address.