/**
 * Shared "required field" validity contract for form-associated custom
 * elements (Checkbox, Radio, Switch, Input, Select, …).
 *
 * Each control computes its own `missing` condition (what counts as empty
 * differs: unchecked, no value, no selection, …) and its own form value, then
 * calls `setRequiredValidity` instead of hand-rolling the `setValidity` call
 * and the default message string.
 *
 * @see AGENTS.md — "Required-field validity"
 */
export declare const DEFAULT_REQUIRED_MESSAGE = "This field is required.";
/** Sets or clears the `valueMissing` validity flag on a form-associated element. */
export declare function setRequiredValidity(internals: ElementInternals, missing: boolean, message: string): void;