export interface OpfsSyncAccessHandle {
    read(buffer: Uint8Array, options?: {
        at?: number;
    }): number;
    write(buffer: Uint8Array, options?: {
        at?: number;
    }): number;
    truncate(size: number): void;
    flush(): void;
    close(): void;
    getSize(): number;
}
/**
 * Streams large assets into OPFS and exposes both sync access handles for the
 * model load path and File objects for incidental reads (projector, metadata
 * detection). The model load path mounts shards via the
 * SyncAccessHandleFS provider in `wasm/sync-access-handle-fs.ts`.
 */
export declare class FileSystemStorage {
    private root;
    private readonly rootPath;
    constructor(storageRoot?: string);
    /**
     * Check if OPFS is supported in the current environment.
     */
    static isSupported(): boolean;
    static isSyncAccessSupported(): Promise<boolean>;
    private ensureRoot;
    private getDirectory;
    private getFileHandleAt;
    private isNotFoundError;
    private toWritableFileSink;
    private createSyncWritableFileSink;
    /**
     * Get a File handle for an existing file in storage.
     */
    getFile(fileName: string): Promise<File | null>;
    listFileNames(): Promise<string[]>;
    listFileNamesAt(path: readonly string[]): Promise<string[]>;
    createSyncAccessHandle(fileName: string, options?: {
        create?: boolean;
    }): Promise<OpfsSyncAccessHandle>;
    readText(fileName: string): Promise<string | null>;
    readTextAt(path: readonly string[]): Promise<string | null>;
    writeText(fileName: string, contents: string): Promise<void>;
    writeTextAt(path: readonly string[], contents: string): Promise<void>;
    /**
     * Stream a web response body directly to OPFS.
     */
    streamToDisk(fileName: string, stream: ReadableStream<Uint8Array>, onProgress?: (bytes: number) => void, signal?: AbortSignal): Promise<File>;
    /**
     * Delete a file from storage.
     */
    deleteFile(fileName: string): Promise<void>;
    deleteFileAt(path: readonly string[]): Promise<void>;
}