/** Whether a CRAN signature database is installed, i.e. more than the `base` shard every checkout ships. */
export declare function cranDatabaseAvailable(): boolean;
/** The warning shown when a page that documents the signature database is generated without one. */
export declare function missingSigDbWarning(target: string): string;
/**
 * Warns that `target` documents the signature database while none is installed, so whatever it would write
 * shows base R alone. Returns whether the database is missing, so a caller can skip the page instead.
 */
export declare function warnMissingSigDb(target: string): boolean;