export type SpringValue = number | Record<string, number>;
export interface SpringDynamics {
    stiffness?: number;
    damping?: number;
    precision?: number;
}
export interface SpringOpts extends SpringDynamics {
    /**
     * Per-key dynamics overrides for object springs. Each key (e.g. `x`, `y`, `o`)
     * may carry its own stiffness/damping/precision, giving asymmetric, independent
     * motion per axis. Keys without an entry fall back to the base dynamics.
     */
    axes?: Record<string, SpringDynamics>;
}
export interface SpringSetOpts {
    hard?: boolean;
    soft?: boolean | number;
}
export declare class Spring<T extends SpringValue> {
    stiffness: number;
    damping: number;
    precision: number;
    axes: Record<string, SpringDynamics> | undefined;
    private value;
    private lastValue;
    private targetValue;
    private invMass;
    private invMassRecoveryRate;
    private cancelTask;
    private task;
    private lastTime;
    private settlePromise;
    private settleResolve;
    private readonly subscribers;
    constructor(value: T, opts?: SpringOpts);
    get current(): T;
    /** Whether the spring is at rest (no animation task is running). */
    get settled(): boolean;
    subscribe(fn: (value: T) => void): () => void;
    private notify;
    set(newValue: T, opts?: SpringSetOpts): Promise<void>;
    private resolveSettle;
    destroy(): void;
}
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