def infer_mime_type_from_storage_key(storage_key: str) -> str:
    lower_filename = storage_key.rsplit("/", 1)[-1].lower()
    if lower_filename.endswith(".mov"):
        return "video/quicktime"
    if lower_filename.endswith((".mp4", ".m4v", ".avi", ".mkv", ".webm")):
        return "video/mp4"
    return "image/jpeg"
