export interface ChildManagerOptions {
    execPath: string;
    scriptPath: string;
    extraArgs: string[];
    cwd: string;
    killGraceMs?: number;
    /** How long a suspending child gets to release its resources (default: 15s). */
    suspendGraceMs?: number;
}
export interface ChildExitInfo {
    code: number | null;
    signal: NodeJS.Signals | null;
}
export interface ChildStreams {
    stdout: NodeJS.ReadableStream;
    stdin: NodeJS.WritableStream;
}
export declare class ChildManager {
    private readonly opts;
    private child;
    private onExitCallback;
    private readonly killGraceMs;
    private readonly suspendGraceMs;
    constructor(opts: ChildManagerOptions);
    /** Registered once; fires for every child this instance ever spawns. */
    onExit(callback: (info: ChildExitInfo) => void): void;
    spawn(): ChildStreams;
    isRunning(): boolean;
    /**
     * Ask the child to release everything it holds - Chrome, managed dev
     * servers, monitors - and exit, resolving once it has actually gone.
     *
     * SIGUSR2 rather than SIGUSR1 because Node reserves SIGUSR1 for starting its
     * own inspector, and it is sent to the child alone rather than to its
     * process group: the point is to give the child a chance to shut its own
     * children down in order, not to kill them out from under it. If it doesn't
     * finish in time, kill() escalates through the usual SIGTERM/SIGKILL path.
     */
    suspend(): Promise<void>;
    /** Kill the current child (if any) and resolve once it has actually exited. */
    kill(): Promise<void>;
}
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