CSR not working with remote functions when preloading is enabled

[connorjan]

Describe the bug

In the <script> tag of a +page.svelte file, if you import a remote function and then call it in the script tag, the page will not client-side render (i.e. navigating to a different page, then return back via the client somehow). This only seems to be an issue with data-sveltekit-preload-data="hover". Downgrading to svelte@5.43.12 seems to resolve the issue. I do not see any errors or warnings.

Reproduction

Navigating to a page from the client containing the following does not work:

<script lang="ts">
  import { test } from "$lib/api/test.remote";

  const myTest = test()
</script>

{await myTest}

Removing data-sveltekit-preload-data="hover" seems to cause everything to start working again.

Additionally, this only seems to occur when calling the remote function within the <script> tag. Doing something like the following does not seem to cause any issue:

<script lang="ts">
  import { test } from "$lib/api/test.remote";
</script>

{await test()}

The contents of test.remote.ts are as follows:

import { query } from "$app/server"

export const test = query(() => {
  return Math.random()
})

Logs

System Info

System:
    OS: Linux 5.15 Ubuntu 22.04.5 LTS 22.04.5 LTS (Jammy Jellyfish)
    CPU: (4) x64 Intel(R) Core(TM) i5-3340 CPU @ 3.10GHz
    Memory: 5.35 GB / 11.55 GB
    Container: Yes
    Shell: 5.8.1 - /usr/bin/zsh
  Binaries:
    Node: 22.20.0 - /home/connor/.local/share/pnpm/node
    npm: 10.9.3 - /home/connor/.local/share/pnpm/npm
    pnpm: 10.20.0 - /home/connor/.local/share/pnpm/pnpm
    bun: 1.3.2 - /home/connor/.bun/bin/bun
  Browsers:
    Firefox: 145.0.1
    Firefox Developer Edition: 145.0.1
  npmPackages:
    svelte: ^5.43.14 => 5.43.14

Severity

annoyance

[connorjan]

Here's the full repro in case it helps: https://codesandbox.io/p/devbox/vjtryr