Inconsistent compilation of value when using context

[cycsd]

Given the following code:
Context
When I getContext in the Child Component

<script>
	import {getContext} from "svelte"

	let getData = getContext('data');

	let data = getData();
	
	const handleInput = (e)=>{
		data = e.target.value;
	}
	
</script>

<input oninput={handleInput}/>
<p>should not change, because pass by value?  {data}</p>

I expect the data can't update the view when it is updated, but it will.

The JS output is

let data = $.mutable_source(getData())

And if I add some code

	import {getContext} from "svelte"

	let getData = getContext('data');

	let data = getData();
+       let foo = $derived('');
	const handleInput = (e)=>{
		data = e.target.value;
	}

The warning data is updated, but is not declared with $state(...). Changing its value will not correctly trigger updates show up,

and the data won't update the view when it is updated.

The JS output is

let data = getData();

Is this a bug, or am I missing something?

[Ocean-OS]

This isn't about context, this is because Svelte compiled your code in legacy mode in the first example. Currently, Svelte will default to compiling your code in legacy mode if it doesn't see any Svelte 5 features being used (eg runes). In legacy mode, all top level variables that are reassigned are implicitly reactive, which is why data was reactive in the first example.

[cycsd]

Thank you very much!

I don't notice the rune mode toggle off ...