import { type Locale } from '../../core/i18n.js';
/** Operator display preferences. Extensible — language today, room for date/number formats etc. */
export interface Preferences {
    lang?: Locale;
}
export declare function loadPreferences(): Preferences;
/** Resolve the persisted UI language, defaulting to 'en'. */
export declare function loadLang(): Locale;
/** Persist the UI language, preserving any other preference keys already on disk. */
export declare function setLang(loc: Locale): void;
/** Test-only: redirect the preferences file to an isolated temp location. */
export declare function _testSetPreferencesFile(p: string): void;