Svelte 5: Sub-object losing reactivity

[enyo]

Describe the bug

I'm not sure if this is intended behavior, so I'm reporting to make sure.

When you destructure a $state object to a primitive value it loses reactivity. That's to be expected.

But I assumed, that I would be able to destructure a sub-object, and maintain proper reactivity when modifying this object.

Reproduction

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAAE5WRTW-DMAyG_4oXTWorVXBPAWnaadddxw4thDYdJAibrVPEf18-oGVrVWmHHOzYfh-_NqyStUDG3wxT20Ywzp7alq0ZfbcuwE9Rk7Ax6r4rXCbBopMtZbnKSTat7ggMFFqROBEMUHW6gUUUj5koDIiOuNjMOp4Psi7PtT4aK0OZe3YCutkoiKTaox2eTkK5SuILh0p2PZFWoFVRy-IjNcsVpNm5M8KD_npRr_udnfBwnR38Mr4VzI1vpxYUglqgjzNrS6NLWUlRMk5dL4b12cXf-18MPeLcTHHydoRVJxNTeETaklgahzXxcPChTUxcHJymS1rCYXWPxhP_96ojz72bzu40cc6utPlzJk_Bb1p8Df8-_ABVkSoAnAIAAA==

Logs

No response

System Info

Repl

Severity

annoyance

[brunnerh]

Note that you only have reactivity in App because it's not in runes mode.
REPL with mode set

I think this might be as intended. The proxy is only applied at the root.

Generally when destructuring from something stateful, one should use $derived.

const { settings } = $derived(context);

This then also works for primitives:

const { settings: { showInRgb } } = $derived(context);

REPL

[Rich-Harris]

This definitely looks like a bug. My hunch — can't check right now — is that it's caused by this effect_active() check:

svelte/packages/svelte/src/internal/client/proxy.js

Line 209 in 6b7f116

(effect_active() || updating_derived) &&

We should probably just always run this logic, even if we're getting the value in a non-reactive context (i.e. during component init)

[Rich-Harris]

#11102 is insufficient — we need to remove the check altogether, not replace it with current_effect !== null