Follow-up to #2666, which fixed the non-virtual path only. A virtualized Listbox still pulled the whole page to itself on mount (same root cause as nuxt/ui#6513).

Root cause

In ListboxRoot, highlightSelected(event, scroll) dropped the scroll flag whenever isVirtual was true — it just called virtualFocusHook.trigger(event). So on mount a virtualized list with no checked item (e.g. multiple + empty v-model) fell into the hook's else → highlightFirstItem() → synthetic PageUp → changeHighlight(firstItem) with default focus + scrollIntoView, yanking a below-the-fold listbox into view on load.

Fix

Thread the mount intent through the virtualFocusHook payload ({ event, scroll }) so the virtualizer sets its roving-tabindex target without focusing/scrolling on mount, mirroring the non-virtual path. The checked-item branch keeps scrollToIndex — that only scrolls the internal listbox container, never the page.

Notes for reviewers

• Behavior change (intended): aligns virtualized mount behavior with the non-virtual fix from fix(Listbox): prevent page scroll on mount caused by changeHighlight #2666. User-driven paths (keyboard, typeahead, select, entry-focus) are unchanged.
• Internal type change: virtualFocusHook's payload shape changed. It lives on the context exposed by injectListboxRootContext, but it's an internal coordination hook not realistically triggered/consumed externally — no public API or runtime behavior for normal usage changes. Not a breaking change.
• Tests cover both mount cases (no selection → first item; pre-selected → checked item), each asserting no page scroll + no focus theft; plus a regression guard that user entry-focus does focus/scroll.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Virtual listboxes now properly manage focus and scrolling during initial mount and item highlighting.
  • Eliminated unwanted focus stealing and document-level scrolling on component initialization.
  • Pre-selected items now correctly highlight without triggering unintended focus changes or scrolling.

• Tests

  • Added comprehensive test coverage for virtualized listbox focus and scroll behavior in various user interaction scenarios.