/**
 * Walks a value tree and replaces anything with an async body (`Request`,
 * `Response`, `Blob`, `File`) with a sync-buffered snapshot, so the result can
 * be handed to a synchronous encoder.
 *
 * Recurses through plain objects, arrays, `Map`s, and `Set`s. Leaves
 * primitives, typed arrays, and sync class instances (`Headers`, `URL`, etc.)
 * alone — those either have no async surface or msgpackr handles them natively
 * via registered extensions at pack time.
 *
 * Dedupes by reference within a single call so that a tree sharing the same
 * `Request`/`Response`/`Blob`/`File` in multiple places doesn't trigger "body
 * already used".
 *
 * Does not detect cycles. Automation outputs are expected to be tree-shaped.
 *
 * @param value - Value tree to prepare for synchronous encoding.
 */
export declare function bufferAsyncValues(value: unknown): Promise<unknown>;