/**
 * Google Drive adapter — service-account auth (W0207).
 *
 * Resolves credentials from three env vars in precedence order:
 * 1. `AILF_GOOGLE_DRIVE_SERVICE_ACCOUNT_JSON` — raw JSON string
 * 2. `AILF_GOOGLE_DRIVE_SERVICE_ACCOUNT_PATH` — path to a credentials file
 * 3. `GOOGLE_APPLICATION_CREDENTIALS` — Google's standard ADC env var
 *
 * No OAuth user flow — v1 is service-account only.
 */
import { GoogleAuth } from "google-auth-library";
/** The subset of environment variables this loader reads. */
export interface AuthLoaderEnv {
    AILF_GOOGLE_DRIVE_SERVICE_ACCOUNT_JSON?: string;
    AILF_GOOGLE_DRIVE_SERVICE_ACCOUNT_PATH?: string;
    GOOGLE_APPLICATION_CREDENTIALS?: string;
}
/** Scope granted to the constructed credential. */
export declare const DRIVE_READONLY_SCOPE = "https://www.googleapis.com/auth/drive.readonly";
/**
 * Construct a `GoogleAuth` instance for the Drive `readonly` scope from
 * service-account credentials.
 *
 * Throws a clear error citing all three accepted env vars when nothing is
 * configured. Invalid JSON in `AILF_GOOGLE_DRIVE_SERVICE_ACCOUNT_JSON`
 * surfaces as a parse error at construction time.
 */
export declare function loadGoogleAuth(env?: AuthLoaderEnv): GoogleAuth;
