/** A selection-mode state machine for a multi-select list: enter, toggle, select-or-clear all, exit. Items
 *  are string ids; the list renders its overlay from `selected` (e.g. `<FileThumbnailGrid selectedIds>`).
 *  Logic only; the action bar and confirm are the consumer's. */
export interface SelectionMode {
    active: boolean;
    selected: ReadonlySet<string>;
    enter: () => void;
    /** Also clears the selection. */
    exit: () => void;
    toggle: (id: string) => void;
    /** Selects all unless all are selected, else clears, staying in mode. */
    toggleAll: (ids: readonly string[]) => void;
}
export declare function useSelectionMode(): SelectionMode;