from __future__ import annotations

import cv2
import numpy as np


def frame_to_jpeg_bytes(frame: np.ndarray, *, quality: int = 85) -> bytes:
    """Encode BGR frame to JPEG bytes for model services expecting image bytes."""
    params = [int(cv2.IMWRITE_JPEG_QUALITY), int(quality)]
    ok, buf = cv2.imencode(".jpg", frame, params)
    if not ok or buf is None:
        raise RuntimeError("cv2.imencode failed for JPEG")
    return buf.tobytes()