/**
 * detach/drivers/sendBeacon.ts — Browser-only driver that ships work
 *                                via `navigator.sendBeacon` so it
 *                                survives page-unload.
 *
 * Pattern:  Strategy / Adapter — translates the consumer's child
 *           flowchart into a sendBeacon POST. The "child" is expected
 *           to produce a JSON-serializable payload via its
 *           `inputMapper`; the URL endpoint is set at driver creation.
 * Role:     The narrow but high-value driver for analytics / error
 *           reporting / page-leave telemetry — the one case where
 *           "fire-and-forget" must really mean "ships even if the
 *           user closes the tab right after."
 *
 * `navigator.sendBeacon` semantics:
 *   - Browser queues the POST in the OS network stack BEFORE returning
 *     control. Survives page-unload, navigation, refresh.
 *   - Limited to ~64 KB per call (per HTML5 spec).
 *   - Fire-and-forget — no response observable.
 *
 * Caveats:
 *   - Browser-only (`browserSafe: true, survivesUnload: true`).
 *     `validate()` throws helpfully if `navigator.sendBeacon` isn't a
 *     function (e.g., when imported in Node).
 *   - The driver does NOT run the child flowchart through a
 *     `FlowChartExecutor` — it serializes the input and POSTs. This
 *     is an intentional simplification: sendBeacon's semantics
 *     wouldn't survive an executor's async stages anyway.
 */
import type { DetachDriver } from '../types.js';
export interface SendBeaconDriverOptions {
    /** Endpoint URL — required. e.g., `'https://telemetry.example.com/ingest'`. */
    readonly url: string;
    /** Custom serializer. Defaults to `JSON.stringify(input)` with
     *  `application/json` content type. */
    readonly serialize?: (input: unknown) => Blob | string | FormData;
}
export declare function createSendBeaconDriver(opts: SendBeaconDriverOptions): DetachDriver;