/**
 * Locale-aware default unit detection.
 *
 * Picks a sensible first-visit unit for a reader who has not made an explicit
 * choice: Fahrenheit for the handful of countries that use it, Celsius for the
 * rest of the world. Pure and dependency-free so it can be unit-tested and
 * reused; {@link browserDefaultUnit} is the thin wrapper that reads the live
 * browser globals.
 */
import type { TemperatureUnit } from './units';
/** Countries (ISO 3166-1 alpha-2) whose readers default to Fahrenheit. */
export declare const FAHRENHEIT_REGIONS: ReadonlySet<string>;
/** Signals used to infer a default unit (mirrors the browser globals). */
export interface DefaultUnitInput {
    /** BCP-47 locale tags, most-preferred first (e.g. `navigator.languages`). */
    languages?: readonly string[];
    /** IANA time zone (e.g. `Intl.DateTimeFormat().resolvedOptions().timeZone`). */
    timeZone?: string;
    /**
     * Regions (ISO 3166-1 alpha-2) that default to Fahrenheit. Defaults to the
     * toolkit's {@link FAHRENHEIT_REGIONS}; override to customize the list.
     */
    fahrenheitRegions?: ReadonlySet<string>;
}
/**
 * Choose the first-load unit for a reader with no stored preference.
 *
 * Uses the first locale that carries a region: Fahrenheit if that country is in
 * {@link FAHRENHEIT_REGIONS}, otherwise Celsius. When no locale carries a region
 * (e.g. a bare `en`), falls back to the time zone (US zones → Fahrenheit), then
 * defaults to Celsius.
 */
export declare function resolveDefaultUnit(input?: DefaultUnitInput): TemperatureUnit;
/** Read the locale/time-zone signals from the browser (SSR-safe). */
export declare function browserDefaultUnit(): TemperatureUnit;