# model.py
import cv2
import numpy as np

def predict_mask(image: np.ndarray) -> np.ndarray:
    """
    Simple vessel segmentation (safe fallback).
    Replace later with UNet once weights match.
    """

    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    blur = cv2.GaussianBlur(gray, (5, 5), 0)

    _, mask = cv2.threshold(
        blur, 0, 255,
        cv2.THRESH_BINARY + cv2.THRESH_OTSU
    )

    return mask