Using spread props with range input breaks reactivity

[mrsproutt]

Describe the bug

Using spread props breaks the reactivity of the step attribute. This may be a part of a larger issue, although I could not find a duplicate issue that matches. You can fix it by wrapping the input in {#key step}.

Reproduction

https://svelte.dev/playground/hello-world?version=5.37.1#H4sIAAAAAAAACn2PwWrDMBBEf2VZerBBOE6Pwjbk1g_oLepBjTdFoKyFd500CP17EW16Kr0-3swwGdlfCC2-UIwL3JY1ztDQHJTmFg2eQyRBe8yo91S9CtA8UoeUOrlS1MrevdBf_LSwEqugxUFOa0g6OY6kIEoJRngS9UqNQ893h61jIX0NF1o2bZoWxukh7nsD-77v_1F-Sgw8f3vD7nfR8RA4bQr1yehw9fxBDiHXaIHcdV0uBXYTGlT6VLS6blTeDKoP8RZ4Rnv2Uah8Acv4cSY1AQAA

Logs

System Info

Binaries:
  Node: 22.13.0 - C:\Program Files\nodejs\node.EXE
  pnpm: 10.13.1 - ~\AppData\Local\pnpm\pnpm.CMD
Browsers:
  Chrome: 138.0.7204.158
npmPackages:
  svelte: ^5.36.13 => 5.36.16

Severity

annoyance

[KTibow]

I'm not a Svelte dev, but I think I figured this one out.

__attributes is never updated when you set step to 10, because numerical values are properties instead of attributes. This makes Svelte think step is still "any", and skip setting it to "any".

No idea what the best fix is though ¯\_(ツ)_/¯

[MotionlessTrain]

What exactly should the reproduction be showing? Step is updated by the timeout (which can easily be seen by adding an $inspect), and as the value on the slider is not used, you cannot easily verify the currrent step size of the slider by just sliding it

reproduction that shows that step is correctly updated, you may be fast to see the stepsize=10 working, but it does

[KTibow]

@MotionlessTrain it should be set back to any after 2 seconds. it is not.

[MotionlessTrain]

Ah, it seems to specifically be ‘any’ that doesn’t work when it is set later