Describe the bug

I don't think this is a bug, but would like to open the discussion through this issue.

We now have the possibility to use the page object from $app/state instead of the store from $app/stores, which is awesome !

Something that could be confusing however is that the page object exposes runes only in client mode, and not in server mode.
Which means that if a user writes the following code:

import {page} from '$app/state';

export const routing = new (class Routing {
    #nameUpper = $derived(page.params.name?.toUpperCase());
    get nameUpper() {
        return this.#nameUpper;
    }
})();

This will work perfectly fine client-side, but will not work for pre-rendered routes !
You can check the reproduction link to see it.

Obviously, a simple fix is updating the above code to the following:

import {page} from '$app/state';

export const routing = new (class Routing {
    get nameUpper() {
        return page.params.name?.toUpperCase();
    }
})();

So there is no bug, just a slight confusion... Should users avoid using $derived with the page info ? Should they check if running in the browser to use $derived or simple getters ?

Reproduction

https://github.com/quentinderoubaix/showcase-app-state-behavior

Logs

No response

System Info

System:
  OS: Linux 5.15 Ubuntu 24.04.1 LTS 24.04.1 LTS (Noble Numbat)
  CPU: (20) x64 12th Gen Intel(R) Core(TM) i7-1280P
  Memory: 8.45 GB / 15.47 GB
  Container: Yes
  Shell: 5.2.21 - /bin/bash
Binaries:
  Node: 22.11.0 - /usr/local/bin/node
  Yarn: 1.22.19 - /usr/local/bin/yarn
  npm: 10.9.2 - /usr/local/bin/npm
  pnpm: 9.15.3 - /usr/local/bin/pnpm
  bun: 1.1.0 - ~/.bun/bin/bun
  Watchman: 4.9.0 - /usr/bin/watchman
npmPackages:
  @sveltejs/adapter-static: ^3.0.6 => 3.0.8 
  @sveltejs/kit: ^2.0.0 => 2.15.2 
  @sveltejs/vite-plugin-svelte: ^4.0.0 => 4.0.4 
  svelte: ^5.0.0 => 5.16.5 
  vite: ^5.4.11 => 5.4.11

Severity

annoyance

Additional Information

No response