/**
 * Google Cloud Storage Provider
 *
 * Alternative production storage using GCP Cloud Storage.
 * Uses service account credentials for authentication.
 *
 * Security:
 * - Uses service account key file
 * - Bucket should not be publicly accessible
 * - Signed URLs provide temporary access
 */
import type { StorageProvider, StorageObject, UploadResult, HealthCheckResult } from "./provider.js";
export interface GCPStorageConfig {
    /** GCP project ID */
    projectId: string;
    /** GCS bucket name */
    bucket: string;
    /** Path to service account key file (optional if using default credentials) */
    keyFile?: string;
}
export declare class GCPStorageProvider implements StorageProvider {
    readonly name = "gcp";
    private storage;
    private bucket;
    private bucketName;
    constructor(config: GCPStorageConfig);
    upload(localPath: string, remotePath: string): Promise<UploadResult>;
    download(remotePath: string, localPath: string): Promise<void>;
    list(prefix: string): Promise<StorageObject[]>;
    getSignedUrl(remotePath: string, expiresInSeconds?: number): Promise<string>;
    healthCheck(): Promise<HealthCheckResult>;
    delete(remotePath: string): Promise<void>;
    exists(remotePath: string): Promise<boolean>;
    /**
     * Guess content type from file extension
     */
    private guessContentType;
}