/**
 * Symbol used to attach gateway metadata to a Fastify route object.
 *
 * Stamped as a non-enumerable property by `withGatewayMetadata()`, by
 * `buildApiRoute(..., { gatewayMetadata })`, or by the shared
 * `attachGatewayMetadata` helper. Read back by `readGatewayMetadata()` and by
 * `DIContext.buildGatewayManifest()`. Using `Symbol.for` ensures every module
 * resolving the same key gets the same symbol, even across realms or duplicate
 * package copies.
 */
export declare const GATEWAY_METADATA_SYMBOL: unique symbol;