/**
 * SpeculativeEvaluator -- threshold proximity prefetching.
 *
 * When a boundary signal is near a threshold, pre-compute the next state.
 * Uses hysteresis dead zone as the prefetch window and linear extrapolation
 * from velocity (last 3-4 signal values) to predict crossings.
 *
 * Wrong prediction cost: ~80ns to recompute (negligible).
 *
 * @module
 */
import { Boundary } from './boundary.js';
import type { StateUnion } from './type-utils.js';
import { type Clock } from './clock.js';
interface SpeculativeResult<B extends Boundary.Shape> {
    readonly current: StateUnion<B>;
    readonly prefetched?: StateUnion<B>;
    readonly confidence: number;
}
interface SpeculativeEvaluatorShape<B extends Boundary.Shape> {
    evaluate(value: number, velocity?: number): SpeculativeResult<B>;
}
/**
 * Creates a speculative evaluator for a boundary that prefetches the next state
 * when the signal value is near a threshold and moving toward it.
 *
 * @example
 * ```ts
 * const boundary = Boundary.make({
 *   thresholds: [768, 1024],
 *   states: ['mobile', 'tablet', 'desktop'] as const,
 *   hysteresis: 20,
 * });
 * const spec = SpeculativeEvaluator.make(boundary);
 * const result = spec.evaluate(760, 2.0); // approaching 768 threshold
 * result.current;     // 'mobile'
 * result.prefetched;  // 'tablet' (pre-computed)
 * result.confidence;  // 0.0-1.0 likelihood of crossing
 * ```
 */
declare function _make<B extends Boundary.Shape>(boundary: B, clock?: Clock): SpeculativeEvaluatorShape<B>;
/**
 * SpeculativeEvaluator -- threshold proximity prefetching for boundaries.
 * Pre-computes the next discrete state when a signal is near a threshold,
 * using velocity estimation and hysteresis-based prefetch windows.
 *
 * @example
 * ```ts
 * const boundary = Boundary.make({
 *   thresholds: [600],
 *   states: ['small', 'large'] as const,
 * });
 * const spec = SpeculativeEvaluator.make(boundary);
 * const { current, prefetched, confidence } = spec.evaluate(595, 1.5);
 * // current='small', prefetched='large', confidence ~0.85
 * ```
 */
export declare const SpeculativeEvaluator: {
    make: typeof _make;
};
export declare namespace SpeculativeEvaluator {
    /** Structural shape of an evaluator bound to a specific {@link Boundary}. */
    type Shape<B extends Boundary.Shape> = SpeculativeEvaluatorShape<B>;
    /** Prediction result from `evaluate()` — current state, optional prefetched next state, and confidence. */
    type Result<B extends Boundary.Shape> = SpeculativeResult<B>;
}
export {};
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