from concurrent.futures import ThreadPoolExecutor


IO_POOL_MAX_WORKERS: int = 4
IO_POOL_THREAD_NAME_PREFIX: str = "controller-io"


def make_io_pool(max_workers: int = IO_POOL_MAX_WORKERS) -> ThreadPoolExecutor:
 """Create the shared AppController I/O pool.

 4 worker threads, named "controller-io-N". Used for warmup, log pruning,
 disk-bound subsystem init, and any other background work that should
 not spin up its own thread.

 Caller is responsible for shutdown (e.g. controller.shutdown()).
 """
 return ThreadPoolExecutor(
  max_workers=max_workers,
  thread_name_prefix=IO_POOL_THREAD_NAME_PREFIX,
 )