feat(popup-menu): exempt an external element from outside press

[kianbazza]

Summary

usePopupMenuRoot accepts getDismissExemptElements: elements outside the menu that don't dismiss it when pressed or when focus moves to them. The suggestion menu passes its host input, so clicking the field doesn't close its menu.

Two mechanisms dismiss a menu, and both respect the exemption:

our document pointerdown listener   -> a press inside an exempt element counts as inside
Base UI's dismissal (handleOpenChange)
  outside-press                     -> ignored when event.target is exempt
  focus-out                         -> ignored when relatedTarget (the element gaining focus) is exempt

Evidence

New use-popup-menu-root.outside-press.test.tsx:

• Pressing the exempt input keeps the menu open. Removing either of the two checks makes this fail, so both mechanisms fire.
• Pressing anything else still closes it, as does pressing the input when it isn't exempt.
• Focus moving to the input keeps the menu open. Focus leaving the input for another element closes it.

Merge Danger

Door: two-way

Blast Radius: none

No member passes exempt elements yet.

Closes UI-555

[vercel]

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Project	Deployment	Actions	Updated
ui-canary	Ready	Preview	Sep 29, 2026 2:31pm UTC

[linear-code]

UI-555