/**
 * StrictDB Input Sanitization — Backend-specific
 *
 * MongoDB: Already handled internally by core/db/mongo.ts (whitelist-based)
 * SQL: Column name validation against schema + parameterized values
 * Elasticsearch: Field name validation + script injection prevention
 */
import type { Backend, SanitizeRule } from './types.js';
/**
 * Register known fields for a collection. Used by the filter translator
 * to validate field names in filters and prevent identifier injection.
 */
export declare function registerFields(collection: string, fields: string[]): void;
export declare function getRegisteredFields(collection: string): Set<string> | undefined;
export declare function clearFieldRegistry(): void;
/**
 * Validate that all field names in a filter exist in the registered schema.
 * Only validates if schema is registered for the collection.
 * If no schema registered, allows all field names through (runtime introspection fallback).
 */
export declare function validateFilterFields(collection: string, filter: Record<string, unknown>, backend: Backend): void;
/**
 * Validate field names for Elasticsearch queries.
 * Blocks access to internal ES fields and validates against schema.
 */
export declare function validateElasticFields(collection: string, filter: Record<string, unknown>): void;
/**
 * Validate an Elasticsearch index name to prevent cross-index access.
 */
export declare function validateIndexName(name: string): void;
/**
 * Validate regex patterns for catastrophic backtracking.
 * Rejects patterns with nested quantifiers that could cause exponential matching.
 */
export declare function validateRegexComplexity(pattern: string): void;
/**
 * Run backend-specific sanitization on a filter.
 * MongoDB: No-op (handled internally by core/db/mongo.ts)
 * SQL: Validates field names against registered schema
 * Elasticsearch: Validates field names + blocks internal fields
 */
export declare function sanitizeFilter(collection: string, filter: Record<string, unknown>, backend: Backend): void;
/**
 * Apply user-defined sanitize rules to a data object.
 * Returns a new object (never mutates input). Short-circuits if rules is empty.
 */
export declare function applySanitizeRules(data: Record<string, unknown>, collection: string, rules: SanitizeRule[]): Record<string, unknown>;
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