import type { Run } from "../runtime/asyncContext.js";
import { AgencyFunction } from "../runtime/agencyFunction.js";
/**
 * Register a scoped callback for the dynamic extent of the caller's function
 * or node. Implementation backing for `callback(name, fn)` in std::index.
 *
 * Frame targeting:
 *   - At top level (inside `__initializeGlobals`, before any node frame is
 *     pushed) — route to `ctx.topLevelCallbacks`, which lives on the
 *     execution context for the whole run.
 *   - Otherwise — push onto the caller's stack frame, which auto-cleans up
 *     when the caller's frame pops.
 *
 * NOTE on the AgencyFunction wrapping: this function needs the run, to
 * walk the state stack and find the caller's frame. It is wrapped as an
 * AgencyFunction because `invoke()` passes every body the run as its first
 * argument.
 */
export declare function _callbackImpl(run: Run, name: string, fn: unknown): void;
export declare const _callback: AgencyFunction;