/**
 * @fractary/core - GCS Storage Implementation
 *
 * Google Cloud Storage backend for file operations.
 * Uses @google-cloud/storage with lazy loading.
 */
import { Storage, GCSStorageConfig } from './types';
/**
 * Google Cloud Storage implementation
 */
export declare class GCSStorage implements Storage {
    private config;
    private storageClient;
    private bucket;
    constructor(config: GCSStorageConfig);
    /**
     * Get or create the GCS client (lazy loaded)
     */
    private getClient;
    /**
     * Get the full GCS path with optional prefix
     */
    private getPath;
    /**
     * Check if an error is a "not found" error
     * Google Cloud SDK uses error.code (number) or error.errors[].reason
     */
    private isNotFoundError;
    /**
     * Write content to GCS
     */
    write(id: string, content: string | Buffer): Promise<string>;
    /**
     * Read content from GCS
     */
    read(id: string): Promise<string | null>;
    /**
     * Check if object exists in GCS
     */
    exists(id: string): Promise<boolean>;
    /**
     * List objects in GCS with optional prefix
     */
    list(prefix?: string): Promise<string[]>;
    /**
     * Delete object from GCS
     */
    delete(id: string): Promise<void>;
    /**
     * Get a signed URL for the object
     */
    getUrl(id: string, expiresIn?: number): Promise<string | null>;
    /**
     * Get the bucket name
     */
    getBucket(): string;
    /**
     * Get the project ID
     */
    getProjectId(): string;
    /**
     * Get the configured prefix
     */
    getPrefix(): string | undefined;
}
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