Minor (Pri-4) follow-up of #387:

For the simple case of #388 (comment)

• Prefetch /page?param=1

  • Server responds with No-Vary-Search: "param"

• Navigate to /page?param=2

Desired result:

• Service worker for /page?param=1 observes the prefetch
• Prefetch bytes from /page?param=1 response are served
• Created Document's URL is /page?param=2
• Controlling service worker is /page?param=1 SW

For prefetch, ServiceWorker client creation URL is /page?param=2 because https://wicg.github.io/nav-speculation/prefetch.html#create-navigation-params-from-a-prefetch-record creates the ServiceWorker client based on the navigation URL.

For prerender, IIUC ServiceWorker client creation URL is /page?param=1, because https://wicg.github.io/nav-speculation/prerendering.html#prerendering-traversable-update-the-successor-for-activation Step 2 updates Document URL but doesn't update ServiceWorker client creation URL.

I don't expect this affect real use cases and thus Pri-4, no need to fix at least for mid term?
Anyway filing this issue to track (I'm sure I'll forget).