/**
 * Temperature units + pure conversion/formatting helpers.
 *
 * Framework-agnostic and product-agnostic — nothing here knows about any
 * particular story, Reuters, or Svelte. This is the foundation the rest of the
 * toolkit (detection, storage, the reactive state and the components) builds on.
 */
/** A temperature display unit. */
export type TemperatureUnit = 'celsius' | 'fahrenheit';
/** The known units, in a stable order (Celsius first). */
export declare const TEMPERATURE_UNITS: readonly ["celsius", "fahrenheit"];
/** Narrowing type guard for untrusted input (events, storage, attributes). */
export declare function isTemperatureUnit(value: unknown): value is TemperatureUnit;
/** The "other" unit — handy for toggles. */
export declare function otherUnit(unit: TemperatureUnit): TemperatureUnit;
/**
 * Convert an absolute temperature in Celsius to the target unit.
 *
 * @param celsius - Temperature in degrees Celsius.
 * @param unit - Target display unit.
 */
export declare function convertTemperature(celsius: number, unit: TemperatureUnit): number;
/**
 * Convert a temperature *delta* (a difference/anomaly) in Celsius to the target
 * unit. Deltas scale by 9/5 only — no +32 offset.
 */
export declare function convertDelta(celsius: number, unit: TemperatureUnit): number;
/** Options for the string formatters. */
export interface FormatOptions {
    /** Decimal places (default 0). */
    digits?: number;
    /** Append the degree suffix (default true). */
    suffix?: boolean;
    /** Include the degree ring in the suffix (default true → `°F`, else `F`). */
    degree?: boolean;
}
/** The degree suffix for a unit, e.g. `°F` (or `F` with `degree: false`). */
export declare function unitSuffix(unit: TemperatureUnit, { degree }?: Pick<FormatOptions, 'degree'>): string;
/** Format an absolute temperature: convert, round, and (optionally) suffix. */
export declare function formatTemperature(celsius: number, unit: TemperatureUnit, { digits, suffix, degree }?: FormatOptions): string;
/**
 * Format a temperature delta with an explicit sign (e.g. `+3°F`, `−2°C`). Uses a
 * true minus sign (U+2212) for typographic parity with the plus.
 */
export declare function formatDelta(celsius: number, unit: TemperatureUnit, { digits, suffix, degree }?: FormatOptions): string;