/** A token that names one process for its whole life and changes when the pid
 *  is reused: the kernel start time (Linux: /proc/<pid>/stat field 22 plus the
 *  boot id; elsewhere: `ps -o lstart=`). Undefined when it can't be read. */
export declare function processStartId(pid: number): string | undefined;
/** Whether two start identities name the same process: true or false when
 *  they can be compared, undefined when they can't — they were read by
 *  different methods (procfs vs ps, e.g. one side had no /proc), which says
 *  nothing about the process. A missing boot id on either side compares the
 *  start time alone. */
export declare function sameStartId(recorded: string, now: string): boolean | undefined;
/** This process's start identity, read once — what persistState records. */
export declare function ownStartId(): string | undefined;
/** - `alive` — the recorded process is still running.
 *  - `dead` — nothing has that pid any more.
 *  - `reused` — the pid now belongs to a different process. */
export type PidLiveness = 'alive' | 'dead' | 'reused';
/** Liveness of the process a record names by `pid` and, when the record has
 *  one, `pidStart`. A record written before #573 has no start identity; its
 *  pid is then trusted as before (kill -0), since there is nothing to compare. */
export declare function recordedPidLiveness(pid: unknown, pidStart?: unknown): PidLiveness;
/** True only when the record's pid is alive AND its start identity was read
 *  and matches — proof the run is still there, not just a pid that answers.
 *  A record without `pidStart` (pre-#573) never proves it: its pid may since
 *  belong to anything. */
export declare function recordedPidVerified(pid: unknown, pidStart?: unknown): boolean;
/** Short reason for a record whose pid is no longer its process. */
export declare function deadPidReason(pid: unknown, liveness: PidLiveness): string;
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