#!/usr/bin/env node
/**
 * enforce-parallel-session-lock — PreToolUse wrapper around the pure
 * parallel-session-lock module (router-gate v4 Stream H Task 7).
 *
 * Prevents two Claude sessions on the same workspace from concurrently
 * mutating files. When session B tries a mutating tool while session A
 * holds a fresh (non-stale) lock, B is blocked with a message naming A's
 * pid for human triage.
 *
 * Activation: settings.json registration is deferred to Phase H-α/H-β
 * batch step. main() is a no-op (exit 0) until then.
 */
import { acquire, release, refresh, computeWorkspaceHash } from './parallel-session-lock.mjs';

/**
 * Pure decision: given an acquire() result, decide block/allow.
 *
 * @param {object} args
 * @param {object|null|undefined} args.acquireResult - from parallel-session-lock.acquire()
 * @param {string} args.sessionId - current session id
 * @returns {{block: boolean, reason?: string}}
 */
export function decide({ acquireResult, sessionId }) {
  // Fail-open if no acquire result (treat as internal error — never lockout).
  if (!acquireResult || typeof acquireResult !== 'object') return { block: false };
  if (acquireResult.acquired) return { block: false };
  const holder = acquireResult.holder || {};
  return {
    block: true,
    reason: `parallel session lock held by ${holder.session_id || 'unknown'} (pid ${holder.pid || '?'}) — wait or close that session first`,
  };
}

async function main() {
  // No-op until settings.json registration + Stop-hook release wiring lands
  // in the deferred Phase H-α/H-β batch step. Activating this hook before
  // the release pathway is wired would lock the user out of their own
  // session on first abnormal exit.
  let input = '';
  for await (const chunk of process.stdin) input += chunk;
  process.exit(0);
}

if (import.meta.url === `file://${process.argv[1].replace(/\\/g, '/')}` || (process.argv[1] || '').endsWith('enforce-parallel-session-lock.mjs')) {
  main().catch(() => process.exit(0));
}