[tooltip][popover][preview card] Fix broken scale transition with detached triggers

[michaldudak]

Fixed restoration of scale after it's forcibly set to 1 when measuring content dimensions in usePopupAutoresize.

Closes #3804

[pkg-pr-new]

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@3810
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@3810
  

commit: cf9c6bb

[mui-bot]

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui/react	0B(0.00%)	▼-3B(0.00%)

Details of bundle changes

---

Check out the code infra dashboard for more information about this PR.

[greptile-apps]

Greptile Summary

Fixed a critical bug where the inline scale style was not properly restored after measuring popup content dimensions in usePopupAutoResize. When switching between detached triggers, the scale was left at 1, which broke CSS scale transitions during exit animations. The fix changes restoreMeasurementOverrides() to restoreMeasurementOverridesIncludingScale() on line 167, ensuring the scale property is restored along with position and transform. Tests were added for all three affected components (Tooltip, Popover, PreviewCard) to verify the scale style is properly cleared after trigger switches.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The change is a simple one-line fix that correctly restores the scale property after measurement. The fix is well-targeted, addresses the root cause, and includes comprehensive test coverage across all affected components.
• No files require special attention

Important Files Changed

Filename	Overview
packages/react/src/utils/usePopupAutoResize.ts	Fixed critical bug where scale style was not restored after measuring content, breaking CSS transitions when switching between detached triggers
packages/react/src/popover/root/PopoverRoot.detached-triggers.test.tsx	Added test verifying scale style is properly cleared after switching triggers
packages/react/src/preview-card/root/PreviewCardRoot.detached-triggers.test.tsx	Added test verifying scale style is properly cleared after switching triggers
packages/react/src/tooltip/root/TooltipRoot.detached-triggers.test.tsx	Added test verifying scale style is properly cleared after switching triggers

[netlify]

✅ Deploy Preview for base-ui ready!

Name	Link
🔨 Latest commit	cf9c6bb
🔍 Latest deploy log	https://app.netlify.com/projects/base-ui/deploys/6970cad5d9355f00088b22e6
😎 Deploy Preview	https://deploy-preview-3810--base-ui.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[LukasTy]

LGTM. 👍 👌