/**
 * Reserved server-only meta keys.
 *
 * Defense-in-depth enforcement:
 * - Schema creation: Throws if extended meta defines these keys (design-time)
 * - Runtime normalization: Strips these keys from inbound messages (security boundary)
 *
 * CANONICAL LIST: @specs/rules.md#reserved-keys
 * IMPLEMENTATION: @specs/validation.md#normalization-rules
 * SCHEMA ENFORCEMENT: @specs/schema.md#Reserved-Server-Only-Meta-Keys
 */
export declare const RESERVED_META_KEYS: Set<string>;
export type ReservedMetaKey = "clientId" | "receivedAt";
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