declare enum Environment {
    Development = "development",
    Test = "test",
    Production = "production"
}
declare class EnvironmentVariables {
    NODE_ENV: Environment;
    PORT: number;
    API_PREFIX: string;
    FRONTEND_ORIGINS: string;
    DATABASE_URL: string;
    CARD_IMAGES_DIR: string;
    PUBLIC_SESSION_COOKIE_NAME: string;
    PUBLIC_SESSION_TTL_HOURS: number;
    PUBLIC_SESSION_COOKIE_SECURE: string;
    PUBLIC_SESSION_COOKIE_SAME_SITE: string;
    GEMINI_API_KEY?: string;
    GEMINI_MODEL: string;
    GEMINI_DAILY_HARD_LIMIT: number;
    GEMINI_DAILY_OPERATIONAL_LIMIT: number;
    GEMINI_TIMEOUT_MS: number;
    GEMINI_MAX_RETRIES: number;
}
export declare function validateEnvironment(input: Record<string, unknown>): EnvironmentVariables;
export {};