hmm. the section that describes how service worker clients are created, specifically for the window client case, it links toSet up a window environment settings object.

https://w3c.github.io/ServiceWorker/#control-and-use-window-client

Which is here: https://html.spec.whatwg.org/multipage/nav-history-apis.html#set-up-a-window-environment-settings-object

A service worker client has an algorithm defined as the origin that returns the service worker client's origin if the service worker client is an environment settings object, and the service worker client's creation URL’s origin otherwise.

Er... when would a service worker client not be an environment settings object? All the cases described in section 2.5 are a service worker client created from either Set up a window environment settings object or Set up a worker environment settings object.