Best way for server/client to react to URL updates as source of truth and avoid excess network calls?

[TranscendentalRide]

To simplify what I'm looking to do, let's say there is a button that toggles showing or hiding data on the page. The data is always there, loaded from the server, all that changes is showing or hiding.

Now clicking hide/show sets a URL parameter ?show=true or ?show=false.

I want both the server and the client to detect this parameter and show or hide based on the parameter. Once on the client, I don't want to make another network call, only update the url and have the page reactively update. Page history is optionally pushed or replaced.

How can I do this in Sveltekit given it has its own router? Or do I need to create my own store and interact with the native browser history directly?

Thanks.