export interface StoredTokens {
    client_id: string;
    access_token: string;
    refresh_token?: string;
    expiry_date: number;
    scope: string;
    token_type: string;
    obtained_at: string;
}
export declare function readTokens(email: string): StoredTokens | null;
/**
 * Force-refresh the access token using the stored refresh_token. Persists
 * the new access_token + expiry_date back to tokens.json (keeps the
 * existing refresh_token since Google doesn't rotate it on every refresh).
 */
export declare function refreshAccessToken(email: string): Promise<StoredTokens>;
/**
 * Return a valid access token for the account — auto-refreshing if the
 * stored one is expired or within EXPIRY_BUFFER_MS of expiry. Throws
 * AxiError if the account isn't authenticated or refresh fails.
 */
export declare function getValidAccessToken(email: string): Promise<StoredTokens>;