Spamming mutations can cause issues with withOverride

Describe the bug

I'm running into a strange issue with the withOverride function.
After submitting the form, it looks like the old object state is still being used instead of the updated one.
The behavior is inconsistent — sometimes the list updates as expected, and sometimes it seems to reuse the previous state.
It only happens on my computer, not on SvelteLab.

https://github.com/user-attachments/assets/e5f8d935-0a40-411f-8727-55d43bc37e8b

Reproduction

Here’s the repo:
https://github.com/timootten/SvelteKit-Remotefunctions/blob/main/src/routes/todos/todos.svelte

It’s strange because the exact same repo doesn’t reproduce the bug on SvelteLab:
https://www.sveltelab.dev/?provider=github&owner=timootten&repo=SvelteKit-Remotefunctions

<script lang="ts">
	import { createTodo, deleteTodo, getTodos } from './todos.remote';

	const todos = $derived(await getTodos());
</script>

<form
	{...createTodo.enhance(async ({ form, data, submit }) => {
		try {
			form.reset();
			await submit().updates(
				getTodos().withOverride((todos) => [
					...todos,
					{
						id: Math.random().toString(36).substring(2, 9),
						title: data.title,
						checked: false
					}
				])
			);

			console.log('Todo created');
		} catch (error) {
			console.error('Failed to create todo', error);
		}
	})}
>
	<input {...createTodo.fields.title.as('text')} placeholder="Todo" required />
	<button type="submit">Add Todo</button>
</form>

<ul>
	{#each todos as todo}
		<li>
			{todo.title}
			<form {...deleteTodo.for(todo.id)}>
				<button type="submit">Delete</button>
			</form>
		</li>
	{/each}
</ul>

Logs

System Info

System:
    OS: Windows 11 10.0.26100
    CPU: (16) x64 AMD Ryzen 7 5700X 8-Core Processor
    Memory: 16.68 GB / 31.91 GB
  Binaries:
    Node: 22.2.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
    pnpm: 9.3.0 - C:\Users\timoo\.bun\bin\pnpm.EXE
    bun: 1.2.23 - C:\Users\timoo\AppData\Local\pnpm\bun.CMD
    Deno: 2.3.3 - C:\Users\timoo\.deno\bin\deno.EXE
  Browsers:
    Chrome: 141.0.7390.56
    Edge: Chromium (140.0.3485.54)
    Firefox: 143.0.4 - C:\Program Files\Mozilla Firefox\firefox.exe
    Internet Explorer: 11.0.26100.1882
  npmPackages:
    @sveltejs/adapter-node: ^5.3.3 => 5.3.3
    @sveltejs/kit: ^2.46.4 => 2.46.4
    @sveltejs/vite-plugin-svelte: ^6.2.1 => 6.2.1
    svelte: ^5.39.11 => 5.39.11
    vite: ^7.1.9 => 7.1.9

Severity

blocking an upgrade

Additional Information

No response

Start by reproducing the issue with the linked SvelteKit repository, especially src/routes/todos/todos.svelte and the createTodo.enhance flow. Inspect how getTodos().withOverride is applied after repeated submissions and compare local behavior with SvelteLab; done means rapid mutations consistently render the current todo list rather than an older state.