/**
 * Saving a blob to the user's disk, shared by every MolVis surface.
 *
 * `sketch` and `stage` had one mechanism each and neither could reach the
 * other's: stage opened a File System Access picker and *threw* where the
 * API was missing (Firefox, Safari, most embedded webviews); sketch always
 * used an anchor download and so never offered a picker even in browsers
 * that support one. This module does the picker when available and falls
 * back to the anchor, so both surfaces behave the same everywhere.
 */
declare global {
    interface Window {
        showSaveFilePicker?: (options?: {
            suggestedName?: string;
            types?: {
                description?: string;
                accept: Record<string, string[]>;
            }[];
        }) => Promise<{
            createWritable(): Promise<{
                write(data: Blob): Promise<void>;
                close(): Promise<void>;
            }>;
        }>;
    }
}
export interface SaveFileType {
    description?: string;
    /** MIME type → extensions, e.g. `{ "chemical/x-pdb": [".pdb"] }`. */
    accept: Record<string, string[]>;
}
export interface SaveBlobOptions {
    /**
     * File-type filters for the save picker. Ignored by the anchor
     * fallback, which can only honour the suggested filename.
     */
    types?: SaveFileType[];
}
/**
 * Write `blob` to a user-chosen location.
 *
 * Resolves once the bytes are handed off. The anchor fallback resolves as
 * soon as the download is triggered — the browser owns it from there, so
 * neither path can report where the file actually landed.
 */
export declare function saveBlob(blob: Blob, suggestedName: string, options?: SaveBlobOptions): Promise<void>;
/**
 * Anchor-based download — the fallback for hosts without the File System
 * Access API. Exported because a caller may want to force it (a headless
 * or automated context where a picker would block).
 */
export declare function downloadBlob(blob: Blob, filename: string): void;