$page.state not reactive anymore since 2.12.0

[oversanne]

Describe the bug

Hello,

Since release 2.12.0, the following code is not reactive anymore with Svelte 4.2, when pressing the button.

Before this release, the number was increasing each time the button is pressed.
After this release, the number increases once to 1, and then is not changing.

In my apps, I have many conditions that are based on the reactiveness of the $page.state (like displaying modals, or panels), and these are not working anymore, and apps can't be used anymore.

Reproduction

<script lang="ts">
	import { pushState } from '$app/navigation';
	import { page } from '$app/stores';

	$: number = $page.state.number ?? 0;
</script>

<div>{number}</div>
<div>{$page.state.number}</div>

<button on:click={() => pushState('', { number: number + 1 })}> Increment </button>

Logs

No response

System Info

System:
    OS: Linux 6.10 Alpine Linux
    CPU: (12) arm64 unknown
    Memory: 5.32 GB / 7.65 GB
    Container: Yes
    Shell: Unknown - /bin/sh
  Binaries:
    Node: 22.12.0 - /usr/local/bin/node
    Yarn: 1.22.22 - /usr/local/bin/yarn
    npm: 10.9.0 - /usr/local/bin/npm
  npmPackages:
    @sveltejs/adapter-vercel: 5.5.2 => 5.5.2 
    @sveltejs/kit: ^2.12.0 => 2.12.0 
    @sveltejs/vite-plugin-svelte: ^3.1.2 => 3.1.2 
    svelte: ^4.2.19 => 4.2.19 
    vite: ^5.4.11 => 5.4.11

Severity

blocking all usage of SvelteKit

Additional Information

No response

[paoloricciuti]

I suspect this was already fixed by #13205 (it needs to be released tho)

[eltigerchino]

This is fixed by #13205 and will be included in the next release #13277

[oversanne]

I confirm, 2.15.2 indeed solved the issue.
Thank you!