Svelte 5: $ prefix is reserved for script with context=module

[mquandalle]

Describe the bug

The following code used in a Svelte 4 app throws an error on Svelte 5:

<script context="module">
	import { writable, derived } from "svelte/store";

	const a = writable(1)
	const b = derived([a], ([$a]) => $a * 2)
</script>
<div>hello world</div>

If I remove the context=module, the code works. I think this file shouldn't run in runes mode since it's not using runes.

Reproduction

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAAE0WOQQqDMBBFrzIMLrQI0i6tCj2HcRF1hICakIy2Rbx7Ryrt8s-f93kbDmakgHm94awnwhwfzmGK_HZHCCuNTJKDXXx3XIrQeeMYOjszvbhUONl-GUlhpWbFZnLWM2zw9IZ1O1IKPXmzUg87DN5OoM7RLLD1gt0FE1D2AoOG8kfG1-RftFKcQ3GtmxTiOtJNAmUFkYYL3OS3yL5ulfiKlBkM9ZizX2hv9g_Pi9Ht6gAAAA==

Logs

No response

System Info

Svelte 5

Severity

annoyance

[trueadm]

AFAIK you can't use reactivity in context module in Svelte 4. However, the error here is wrong too.

[Conduitry]

Reactivity with stores works fine in context=module in Svelte 4.

<script context='module'>
	import { writable, derived } from 'svelte/store';
	const x = writable(0);
	const y = derived(x, $x => $x * 2);
</script>

<input type='number' bind:value={$x}> * 2 = {$y}

This will be reactive and synchronized between all component instances.

[brunnerh]

It just uses store reactivity, there is no "regular" reactivity in the module script.
You also cannot use $store/$: syntax, hence derived.

[trueadm]

Put up a PR for this, let me know if that helps.