Floating UI

Use @floating-ui/dom for every interactive element positioned relative to a trigger. Do not calculate coordinates manually or rely on CSS absolute offsets for dropdowns, popovers, menus, combobox lists, or tooltips.

Required structure

• Render overlays through createPortal(..., document.body) so layout and stacking contexts do not clip them.
• Position with computePosition inside autoUpdate; clean up the function returned by autoUpdate when the overlay closes or unmounts.
• Start from the closest existing control in apps/desktop/src/components/ui. Match its placement, offset, flip, shift, and size middleware unless the interaction requires a deliberate difference.
• Store computed left, top, width, and available height in React state. Apply the state to the portal root; do not mutate element styles directly.
• Use size when reference width or viewport height constrains the overlay. Lists that can grow must use components/virtual/VirtualList.tsx; keep fixed headers and footers outside the virtual viewport.

Interaction invariants

• Keep the trigger's open/focus border visible while focus is inside a portaled overlay.
• Close on outside pointer interaction and Escape, then return focus to the trigger.
• Outside-click checks must include both trigger and overlay. A nested portaled overlay must stop its pointer event from reaching the parent's outside-click listener, so interacting with a child menu never closes its parent.
• Expose trigger state with aria-expanded, aria-controls, and the appropriate aria-haspopup; give the overlay the matching menu, listbox, dialog, or tooltip semantics.
• Verify placement near all viewport edges, nested-overlay clicks, keyboard dismissal, virtual scrolling, and fixed footer behavior.