/**
 * Input validation utilities to prevent injection and traversal attacks
 * on external service inputs (Slack, S3, Google Sheets).
 */
/**
 * Result of a validation check
 */
export interface ValidationResult {
    valid: boolean;
    error?: string;
}
/**
 * Validates a Slack channel name format.
 *
 * Valid channel names:
 * - May optionally start with '#'
 * - Must start with a lowercase letter or number (after optional '#')
 * - May contain lowercase letters, numbers, hyphens, and underscores
 * - Must be between 1 and 80 characters (excluding optional '#' prefix)
 *
 * @param channel - The channel name to validate
 * @returns ValidationResult indicating whether the channel name is valid
 */
export declare function validateSlackChannel(channel: string): ValidationResult;
/**
 * Validates an S3 key to prevent directory traversal and other attacks.
 *
 * Invalid keys:
 * - Contain '..' (directory traversal)
 * - Start with '/' (absolute paths)
 * - Contain null bytes
 * - Are empty
 * - Exceed 1024 characters (S3 key limit)
 *
 * @param key - The S3 key to validate
 * @returns ValidationResult indicating whether the key is valid
 */
export declare function validateS3Key(key: string): ValidationResult;
/**
 * Validates a Google Sheets A1 notation range.
 *
 * Valid formats:
 * - Simple cell: 'A1', 'B2', 'AA100'
 * - Cell range: 'A1:B10', 'A1:Z999'
 * - With sheet name: 'Sheet1!A1', 'Sheet1!A1:B10'
 * - With quoted sheet name: "'My Sheet'!A1:B10"
 *
 * @param range - The A1 notation string to validate
 * @returns ValidationResult indicating whether the range is valid
 */
export declare function validateGoogleSheetsRange(range: string): ValidationResult;