/** Whether a process is still running. Signal 0 checks without delivering. */
export declare function processAlive(pid: number): boolean;
/** Slots with at least one live claimant, so a caller can avoid them. */
export declare function busySlots(): Set<string>;
/**
 * Slots THIS process already holds.
 *
 * Its own claim must not push it onto a new slot: re-attaching in one session
 * should come back to the browser it is already running, not start a second.
 */
export declare function ownSlots(): Set<string>;
/** Take a claim on `slot`. Returns the token to release it with. */
export declare function claim(slot: string): string;
/**
 * Give up this process's claim.
 *
 * Returns true when nobody is left, which is the caller's signal to stop the
 * container. Returns false while another live session still holds it — stopping
 * then would pull the browser out from under them.
 */
export declare function release(slot: string, token: string): boolean;