Function ensureTaskListLockFile

src/utils/tasks.ts:511–523

* Ensures the lock file exists for a task list

(taskListId: string)

 * Ensures the lock file exists for a task list
 */
async function ensureTaskListLockFile(taskListId: string): Promise<string> {
  await ensureTasksDir(taskListId)
  const lockPath = getTaskListLockPath(taskListId)
  // proper-lockfile requires the target file to exist. Create it with the
  // 'wx' flag (write-exclusive) so concurrent callers don't both create it,
  // and the first one to create wins silently.
  try {
    await writeFile(lockPath, '', { flag: 'wx' })
  } catch {
    // EEXIST or other — file already exists, which is fine.
  }
  return lockPath
}

export type ClaimTaskOptions = {
  /**