What's a "user prompt"?

[gsnedders]

c.f. https://w3c.github.io/webdriver/#user-prompts

Safari, for example, shows a dialog for downloading files, given there's various ways that websites can effectively trigger a download themselves:

Based on my reading of the spec, I think it's… not a user prompt? Our cross-reference for "user prompt" is https://html.spec.whatwg.org/multipage/timers-and-user-prompts.html#user-prompts, which is a section and not a definition.

Should the expectation be that SafariDriver automatically dismisses these dialogs as they appear (as which option?), or what is expected to be the behaviour with other UA-generated modals (noting e.g. window.print may do something different—despite being in the section of the HTML spec referenced for "user dialogs"!—per #1091, as in some UAs it is not provided by the UA, but rather by the OS)?