export type RuntimeEnv = "browser" | "terminal" | "unknown";
export type TimerApi = Readonly<{
    setTimeout: typeof setTimeout;
    clearTimeout: typeof clearTimeout;
    setInterval: typeof setInterval;
    clearInterval: typeof clearInterval;
}>;
export type RafApi = Readonly<{
    request: (cb: FrameRequestCallback) => number;
    cancel: (id: number) => void;
}>;
export type ClipboardApi = Readonly<{
    supported: boolean;
    canRead?: boolean;
    canWrite?: boolean;
    readText: () => Promise<string>;
    writeText: (text: string) => Promise<void>;
}>;
export type RuntimeOptions = Readonly<{
    clipboard?: ClipboardApi;
}>;
export type Runtime = Readonly<{
    env: Readonly<{
        kind: RuntimeEnv;
        isBrowser: boolean;
        isTerminal: boolean;
    }>;
    now: () => number;
    timer: TimerApi;
    raf: RafApi;
    clipboard: ClipboardApi;
    getWindow: () => Window | null;
    getDocument: () => Document | null;
    measureText: (text: string, opts?: Readonly<{
        font?: string;
    }>) => number | null;
}>;
export declare function createRuntime(kind?: RuntimeEnv, options?: RuntimeOptions): Runtime;