/**
 * Validate metadata size constraints to prevent abuse.
 * Returns an error message if validation fails, null if valid.
 */
export interface MetadataLimits {
    maxBytes: number;
    maxDepth: number;
}
export declare const DEFAULT_METADATA_LIMITS: MetadataLimits;
export declare function validateMetadataSize(metadata: Record<string, unknown>, limits?: MetadataLimits): string | null;
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