/**
 * @license
 * Copyright 2026 Steven Roussey <sroussey@gmail.com>
 * SPDX-License-Identifier: Apache-2.0
 */
/**
 * Widths of the two rails, in pixels. The shell is a three-column grid and
 * both outer columns are draggable, so the numbers live here — clamping and
 * persistence are the parts worth testing, and neither needs a DOM.
 */
export type RailSide = "left" | "right";
export declare const RAIL_DEFAULTS: Readonly<Record<RailSide, number>>;
export interface RailWidths {
    readonly left: number;
    readonly right: number;
}
/**
 * The width a drag actually lands on: never below the side's minimum, never
 * past `RAIL_MAX`, and never so wide that the centre column drops under
 * `MIN_MAIN`. The minimum wins over the viewport budget on a narrow window —
 * a rail that collapses to nothing is worse than one that overflows, and the
 * layout drops to stacked panes down there anyway.
 */
export declare function clampRailWidth(side: RailSide, width: number, viewport: number, otherWidth: number): number;
interface WidthStore {
    getItem(key: string): string | null;
    setItem(key: string, value: string): void;
}
/**
 * Last session's widths, or the defaults. Anything unparseable is the default:
 * a corrupt entry must not leave the page with no rails.
 */
export declare function loadRailWidths(store?: WidthStore | undefined): RailWidths;
export declare function saveRailWidths(widths: RailWidths, store?: WidthStore | undefined): void;
export {};