"""
Timing utility — context manager and decorator for measuring latency.
"""

from __future__ import annotations

import time
from contextlib import contextmanager
from typing import Iterator


@contextmanager
def timed(label: str = "") -> Iterator[dict]:
    """Context manager that yields a dict and fills it with elapsed ms."""
    info: dict = {"label": label, "elapsed_ms": 0.0}
    t0 = time.perf_counter()
    try:
        yield info
    finally:
        info["elapsed_ms"] = round((time.perf_counter() - t0) * 1000.0, 3)