/** Spring-driven easing, compiled to CSS `linear()` so the DOM wrapper and the
 *  SVG blob can share one GPU-composited transition — the core of zero-lag
 *  mirrored sync. Falls back to cubic-bezier where `linear()` is unsupported. */
export interface SpringConfig {
    stiffness?: number;
    damping?: number;
    mass?: number;
}
export type TransitionPreset = 'snappy' | 'smooth' | 'bouncy';
export type Transition = TransitionPreset | SpringConfig | {
    duration: number;
    ease?: string;
};
export interface ResolvedTransition {
    /** ms */
    duration: number;
    /** CSS timing function */
    easing: string;
}
export declare const presets: Record<TransitionPreset, Required<SpringConfig>>;
/** Advance one value along a preset's spring by a WALL-CLOCK `dt` (seconds),
 *  carrying its velocity. Returns `[position, velocity]`.
 *
 *  Tuffex-only addition, not in liquid-gooey. `resolveTransition` compiles a
 *  preset into a fixed CSS curve, and a fixed curve always starts from rest:
 *  retarget it mid-flight and the motion restarts at zero velocity, a visible
 *  stall. Geometry drawn frame by frame from JS (TxFusionSurface's buds, the
 *  send split built on its geometry) has to keep its momentum through a
 *  retarget, so it integrates the same `presets` here instead of compiling
 *  them — one set of curves for the whole library, two ways to run it.
 *
 *  This resolves the preset and steps on utils' `stepSpring`: semi-implicit
 *  Euler, the same scheme as `observer.ts`'s private `springSteps` and
 *  `simulate()` below, with a substep cap equal to `DT` rather than
 *  observer's 1/60 s. The stepping lives in utils so hosts of the indicator
 *  engine outside the components can reach it without this module. */
export declare function springSteps(position: number, velocity: number, target: number, config: TransitionPreset | SpringConfig, dt: number): [number, number];
export declare function resolveTransition(t: Transition | undefined, reducedMotion?: boolean): ResolvedTransition;