/**
 * @module @arcis/node/sanitizers/nosql
 * NoSQL injection prevention (MongoDB operators)
 */
/**
 * Checks if a key is a dangerous MongoDB operator.
 *
 * @param key - The key to check
 * @returns True if the key is a MongoDB operator
 *
 * @example
 * isDangerousNoSqlKey('$gt') // true
 * isDangerousNoSqlKey('name') // false
 */
export declare function isDangerousNoSqlKey(key: string): boolean;
/**
 * Recursively checks if an object contains dangerous MongoDB operators.
 *
 * @param obj - The object to check
 * @param maxDepth - Maximum recursion depth (default: 10)
 * @returns True if dangerous operators found
 */
export declare function detectNoSqlInjection(obj: unknown, maxDepth?: number): boolean;
/**
 * Detects a MongoDB operator appearing in a STRING value.
 *
 * detectNoSqlInjection only inspects object keys. But operators also
 * arrive as strings: `?user[$ne]=1` reaches the handler as the literal
 * `$ne` before any object is built, and mongo-shell payloads like
 * `$where: '1==1'` are plain strings. This is the string-level check
 * used by block-mode scanThreats, matching Python's `_NOSQL_DETECT`.
 *
 * @param input - The string to check
 * @returns True if a NoSQL operator token is present
 *
 * @example
 * detectNoSqlString("$where: 'this.a==1'") // true
 * detectNoSqlString("$invoice total")      // false ($in not a token here)
 */
export declare function detectNoSqlString(input: string): boolean;
/**
 * Get list of all MongoDB operators considered dangerous.
 * Useful for documentation or custom validation.
 *
 * @returns Array of dangerous operator strings
 */
export declare function getDangerousOperators(): string[];
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