import { type Config, type OptimizeResult } from "./core.js";
/**
 * Lazy worker offload. The core (`index.ts`) `import()`s this module only when
 * `optimize(svg, { worker: true })` runs, so the main bundle never carries the
 * worker machinery (or pays for loading `worker.js`) until a caller opts in.
 * The environment entries install a factory (`setWorkerFactory`); browsers get
 * a module `Worker` by default. All state is local to this module.
 *
 * This file runs on the MAIN thread, managing the shared worker. The script it
 * spawns (`worker.js` / `worker.node.js`) imports only the loader-free core.
 */
/** Minimal shape of a `Worker`, kept bundler/type-safe and runtime-agnostic. */
export interface WasmWorker {
    postMessage(message: unknown, transfer?: readonly Transferable[]): void;
    addEventListener(type: "message" | "error", listener: (event: {
        data: unknown;
    }) => void): void;
    removeEventListener(type: "message" | "error", listener: (event: {
        data: unknown;
    }) => void): void;
    terminate(): void | Promise<unknown>;
}
/**
 * Produces the shared worker. Browsers get a module `Worker` by default
 * (`dist/worker.js`); the Node entry installs a `node:worker_threads` wrapper
 * via `setWorkerFactory`. Advanced callers can swap the factory entirely.
 */
export type WasmWorkerFactory = () => Promise<WasmWorker> | WasmWorker;
/** Install a custom worker factory (see {@link WasmWorkerFactory}). */
export declare function setWorkerFactory(factory: WasmWorkerFactory | null): void;
/**
 * Permanently shut down the shared worker and release its thread. Only needed
 * when callers want to free the worker; ordinary `reset()` keeps reusing it,
 * so concurrent worker use never trips the terminate/recreate reclamation race.
 */
export declare function shutdownWorkers(): Promise<void>;
/**
 * Run `optimize` on the shared worker, or `null` when no worker could be
 * brought up (the caller then falls back to the main thread). Rejections from
 * the worker itself (parse/config errors, `SvgoError`) are not swallowed.
 */
export declare function tryOptimizeInWorker(svg: string, config?: Config | null): Promise<OptimizeResult | null>;
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