[dialog] Fix confirmation return focus

[atomiks]

The new Drawer close confirmation demo exposed a focus restore bug: after canceling an outside-press close and opening a confirmation dialog, choosing “Go back” could send focus back to the original trigger instead of the field inside the still-open dialog/drawer.

Steps

https://deploy-preview-5024--base-ui.netlify.app/react/components/drawer#close-confirmation

1. Click 'Tweet' trigger.
2. Click textarea and type 'x'.
3. Click outside the Drawer (on its backdrop) with a pointer.
4. Press 'Go Back' using keyboard Enter.
5. Focus returns to 'Tweet' despite drawer being open and modal. Focus is lost.

Root cause

When the outside press blurred the focused field to the document body, the detached confirmation dialog had no useful pre-open focus target to restore.

Changes

• Records the focused element when focus is lost from inside a floating element to no concrete destination.
• Adds a Chromium regression test for the canceled-close confirmation flow.

[pkg-pr-new]

• base-ui-tanstack-start

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@5024
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@5024
  

commit: e2d2ffe

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	🔺+33B(+0.01%)	🔺+18B(+0.01%)

Details of bundle changes

Performance

Total duration: 1,217.74 ms -26.36 ms^(-2.1%) | Renders: 50 ⁽⁺⁰⁾ | Paint: 1,824.89 ms -53.62 ms^(-2.9%)

Test	Duration	Renders
Checkbox mount (500 instances)	70.19 ms ▼-29.64 ms(-29.7%)	1 (+0)

11 tests within noise — details

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[Copilot]

Pull request overview

Fixes a focus restoration edge case in Base UI’s floating focus management where an outside-press (backdrop) can temporarily blur focus to document.body, causing a subsequently opened “close confirmation” dialog to restore focus to the original trigger instead of back into the still-open modal.

Changes:

• Record the last focused element inside the floating element when focus is lost with no concrete relatedTarget (e.g. blur-to-body on backdrop press).
• Add a browser-only regression test covering the “outside press → canceled close → confirmation dialog → Go back → focus returns into dialog” flow.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/react/src/floating-ui-react/components/FloatingFocusManager.tsx	Records the focused element when focus is lost to no relatedTarget, enabling correct focus restoration after a transient blur-to-body.
packages/react/src/dialog/root/DialogRoot.test.tsx	Adds a non-JSDOM regression test validating focus returns into the dialog after closing an outside-press confirmation.

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