/**
 * Generic threshold-crossing detection over ordered numeric boundaries.
 *
 * Deliberately relationship-agnostic and stateless: the same helper reports
 * reputation-tier transitions, meter milestones, temperature bands, ecosystem
 * pressure, difficulty ramps, or any value moving across labelled cut points.
 * Callers pass `before`/`after` and receive the crossings between them, so the
 * logic never lives inside a ledger or owns hidden state.
 */
export type ThresholdDirection = "up" | "down";
/** A labelled cut point on the value axis. `Id` is caller-owned (string, enum, or a policy object). */
export interface ThresholdBoundary<Id = string> {
    /** Stable identifier reported when this boundary is crossed. */
    readonly id: Id;
    /** Numeric position of the boundary on the value axis. */
    readonly at: number;
}
/** A single boundary transition between a `before` and `after` value. */
export interface ThresholdCrossing<Id = string> {
    readonly id: Id;
    readonly at: number;
    readonly direction: ThresholdDirection;
}
/** Exact-boundary and dead-band policy for {@link crossThresholds}. */
export interface CrossThresholdsOptions {
    /**
     * When true (default) a boundary is *occupied* at `value >= at`; when false it
     * is occupied only at `value > at`. Controls exact-boundary semantics: with the
     * default, landing exactly on `at` counts as an upward crossing and keeps you
     * above on the way down.
     */
    readonly inclusive?: boolean;
    /**
     * Symmetric dead-band (clamped to `>= 0`). An upward crossing of `at` requires
     * reaching `at + hysteresis`; a downward crossing requires falling below
     * `at - hysteresis`. Suppresses flapping when a value oscillates around a
     * boundary. Defaults to `0` (no dead-band).
     */
    readonly hysteresis?: number;
}
/**
 * Report every boundary crossed moving from `before` to `after`.
 *
 * Upward moves yield `up` crossings in ascending `at` order; downward moves yield
 * `down` crossings in descending order. Large jumps report every boundary passed;
 * a zero-width move reports nothing. Boundaries need not be pre-sorted.
 *
 * @capability detect fire-once threshold/milestone/tier crossings when a value moves
 */
export declare function crossThresholds<Id>(boundaries: readonly ThresholdBoundary<Id>[], before: number, after: number, options?: CrossThresholdsOptions): ThresholdCrossing<Id>[];
/**
 * The highest boundary at-or-below `value` — the band the value currently sits in.
 * Returns `null` when `value` is below every boundary. Boundaries need not be sorted.
 *
 * Tier labels stay caller policy: pass an `Id` object carrying whatever label,
 * relation, or colour the game needs.
 *
 * @capability resolve the current tier/band label for a keyed or scalar value
 */
export declare function tierAt<Id>(boundaries: readonly ThresholdBoundary<Id>[], value: number, options?: {
    readonly inclusive?: boolean;
}): ThresholdBoundary<Id> | null;