export declare function validateExistingRoot(input: string, label: string): string;
export declare function ensureSafeDirectory(root: string, segments: readonly string[]): string;
/**
 * Segment-wise check for existing directories only (no create).
 * Rejects symlinks at every present segment under root.
 */
export declare function assertExistingSafeDirectory(root: string, segments: readonly string[]): void;
export declare function validateSafeFile(root: string, segments: readonly string[], required: boolean): string;
export declare function validateFutureFile(root: string, segments: readonly string[]): string;