import { QuestionnaireState } from 'types/QuestionnaireState';
import { DescriptorState } from '../types';
/**
 * Field-update primitives composed by `useQuestionnaireStep` to keep the
 * form state internally consistent: applying side effects from
 * `getChangedFields`, resetting hidden fields, seeding defaults on newly
 * visible fields, and clearing stale option values when the available
 * choices have changed.
 *
 * They share an accumulator (`FieldUpdater`) so the hook can apply all
 * passes in one render and decide whether anything actually moved before
 * scheduling a setState.
 */
export type FieldUpdater = {
    current: QuestionnaireState;
    changed: boolean;
};
/** Merge getChangedFields side effects into fields for a given key. */
export declare const mergeChangedFields: (key: string, fields: QuestionnaireState, state: DescriptorState) => QuestionnaireState;
/**
 * Apply each hidden field's reset value. Default behavior (no `getResetValue`
 * declared) is to clear to undefined. Descriptors can override via
 * `getResetValue` to set a derived value, or return the current value to preserve.
 */
export declare const resetHiddenFields: (hiddenKeys: string[], state: DescriptorState, updater: FieldUpdater) => void;
/**
 * Seed each newly-visible field with its `getDefaultValue` when the field
 * has no value yet. "Newly visible" = currently visible AND not in the
 * previous render's visible set, so defaults fire on hidden→visible
 * transitions but not on every render. This prevents re-seeding fields
 * the user has explicitly cleared.
 */
export declare const applyVisibleDefaults: (visibleKeys: Set<string>, previouslyVisibleKeys: Set<string>, state: DescriptorState, updater: FieldUpdater) => void;
/** Reset radio/select values that don't match any available option. */
export declare const clearStaleOptionValues: (visibleKeys: Set<string>, state: DescriptorState, updater: FieldUpdater) => void;