"""Fire-and-forget asyncio tasks that are kept alive until they finish."""
from __future__ import annotations

import asyncio
import logging

log = logging.getLogger(__name__)
_BACKGROUND: set[asyncio.Task] = set()


def _done(task: asyncio.Task) -> None:
    _BACKGROUND.discard(task)
    if not task.cancelled() and task.exception() is not None:
        # class name only: exception text may carry paths/URLs/keys
        log.error("background task failed: %s", type(task.exception()).__name__)


def spawn(coro) -> asyncio.Task:
    """create_task + strong reference (the loop only keeps weak ones)."""
    task = asyncio.create_task(coro)
    _BACKGROUND.add(task)
    task.add_done_callback(_done)
    return task