"""Logic for the `dev` domain. Transport-agnostic (D-263)."""

from __future__ import annotations

import time
from collections.abc import Iterator


def slow_work(seconds: float, steps: int = 10) -> Iterator[tuple[int, int]]:
    """Yield (step, total) over roughly `seconds`, so a caller can report progress.

    A generator rather than something that takes a callback, because the service
    must not know how progress is reported — that is the router's business, and
    handing the service a printer is how a service learns it lives in a CLI.
    """
    steps = max(1, steps)
    interval = max(0.0, seconds) / steps
    for step in range(1, steps + 1):
        time.sleep(interval)
        yield step, steps