/**
 * A headless scheduler with a deterministic idle signal.
 *
 * Like `createHeadlessScheduler`, `asap` and `paint` resolve on the
 * microtask queue (no `requestAnimationFrame`). Unlike it, this scheduler
 * tracks outstanding work — queued microtasks and in-flight `delay` timers
 * — and exposes `idle()`, a promise that resolves the moment the scheduler
 * has nothing left to run. `renderToImage` uses this to settle as fast as a
 * tree's synchronous + timer-driven behaviors quiesce, instead of waiting a
 * fixed wall-clock window.
 *
 * Note `idle()` cannot observe bare `Promise`s (e.g. `fromPromise` /
 * `switchMap(async …)`) — those resolve on the JS microtask queue without
 * touching the scheduler. Their downstream emits *do* re-enter via `asap`,
 * so already-pending resolutions are absorbed, but a value that arrives over
 * the network (a real macrotask later) is invisible here. Resolve such data
 * at the boundary before rendering, or pass `settleMs` to add a quiet guard.
 */
import type { I$Scheduler } from '../ui/index.js';
export interface ISettleScheduler extends I$Scheduler {
    /** Resolves once no microtask batch is queued and no `delay` timer is pending. */
    idle(): Promise<void>;
}
export declare function createSettleScheduler(): ISettleScheduler;