[composite] Fire Space key activation on `keydown` not `keyup`

[nattui]

Bug report

Current behavior

I’ve noticed an inconsistency in keyboard behavior between the Space and Enter/Return keys when interacting with focusable components (e.g., ToggleGroup or Toolbar).

When a component is focused:

• Pressing Enter (Return) to activate an item, then pressing the Right Arrow key to move to the next item, behaves as expected, the activated state is preserved.
• However, when pressing Space to activate the same item and then pressing the Right Arrow key, the activation does not appear to be applied. The behavior is as if the Space key activation was ignored.

Expected behavior

Both Space and Enter should activate the focused item consistently, and the activated state should persist when navigating with arrow keys.

Reproducible example

Any one of these components, if you focus and then press space and then arrow keys, the space does not get applied

https://base-ui.com/react/components/accordion
https://base-ui.com/react/components/toggle-group
https://base-ui.com/react/components/toolbar
https://base-ui.com/react/components/navigation-menu
https://base-ui.com/react/components/menubar
https://base-ui.com/react/components/menu

Base UI version

"@base-ui/react": "1.1.0"

Which browser are you using?

Helium https://helium.computer
Chrome
Safari

Which OS are you using?

Mac OS

[linear]

BAS-380

[mj12albert]

Possibly a browser issue?

Helium is proudly based on ungoogled-chromium

I quickly tested that space activation works on ungoogled chromium, normal Chrome, FF & Safari, have you tried other browsers? @nattui

[nattui]

Possibly a browser issue?

Helium is proudly based on ungoogled-chromium

I quickly tested that space activation works on ungoogled chromium, normal Chrome, FF & Safari, have you tried other browsers? @nattui

Yes, I just tested on Chrome and Safari on MacOS, same issue! I'll update the description to include those browsers as well @mj12albert

[mj12albert]

Screen.Recording.2026-02-12.at.11.29.28.AM.mov

This is normal Chrome, is it different for you? @nattui

[nattui]

Thank you for your quick reply @mj12albert

What software the used to show keys while recording? I could record as well and post here. I am also on the base ui discord channel and I could show it there as well

In your video, you're not doing pressing the arrow keys sequentially after space fast enough

Basically, if you press space and then the arrow keys very quickly after, the space does not get applied. But if you press enter and then the arrow keys very quickly after, it does get applied

[atomiks]

Basically, if you press space and then the arrow keys very quickly after, the space does not get applied

Space activation is applied on keyup (same as with native buttons), while Enter is keydown, that may be your issue?

[nattui]

Basically, if you press space and then the arrow keys very quickly after, the space does not get applied

Space activation is applied on keyup (same as with native buttons), while Enter is keydown, that may be your issue?

That sounds correct, though I do find it odd that space does not get applied after with arrow keys. Even with native buttons, when I press space and then arrow keys, it still gets applied

[mj12albert]

What software the used to show keys while recording?

You can use keycastr: https://github.com/keycastr/keycastr

[atomiks]

I confirmed with a simple demo in CodePen that the issue "reproduces".

The issue is probably that you're (we're) pressing ArrowRight before keyup:

<button id=a>Click me</button>
<button id=b>Will navigate to me</button>

a.onclick = () => {
  console.log('click a')
}
a.onkeyup = () => {
  console.log('keyup a')
}
a.onkeydown = (e) => {
  if (e.key.startsWith('Arrow')) {
    b.focus();
  }
}
b.onclick = () => {
  console.log('click b')
}
b.onkeyup = () => {
  console.log('keyup b')
}
b.onkeydown = (e) => {
  if (e.key.startsWith('Arrow')) {
    a.focus();
  }
};

click a nor keyup a is logged when pressing ArrowRight quickly from a when focus is on the button, as focus relocates to a new button and the click/keyup activation never runs.

[nattui]

Here are additional screen recordings to better illustrate the issue with using keycastr software

Example of working on Radix UI

Screen.Recording.2026-02-11.at.7.56.57.PM.mov

Example not working on Base UI

Screen.Recording.2026-02-11.at.7.58.45.PM.mov