// Read process identity without treating an unreadable /proc entry as death.
import { readFileSync } from 'node:fs';
export function processState(pid) {
  if (!Number.isSafeInteger(pid) || pid <= 0) throw new Error('invalid pid');
  let raw;
  try { raw = readFileSync(`/proc/${pid}/stat`, 'utf8'); }
  catch (e) {
    if (e.code !== 'ENOENT' && e.code !== 'ESRCH') throw e;
    // Signal zero only probes existence; it delivers no signal. A missing or
    // restricted proc mount must never make a live process appear dead.
    try { process.kill(pid, 0); } catch (probe) { if (probe.code === 'ESRCH') return { alive: false }; throw probe; }
    throw new Error('process exists but proc identity is unavailable');
  }
  const end = raw.lastIndexOf(')');
  const fields = raw.slice(end + 2).trim().split(/\s+/);
  if (end < 0 || fields.length < 20 || !/^\d+$/.test(fields[19])) throw new Error('unreadable process identity');
  return fields[0] === 'Z' || fields[0] === 'X' ? { alive: false } : { alive: true, startTime: fields[19] };
}