import re


def is_valid_file_category_id(category_id):
    """
    Validates a file lifecycle category ID, also known as the categories "category-ext-name".
    A valid category ID should look like: category-00000001 - It should
    always start with "category-" and end with 8 hexadecimal characters in lower
    case.

    :type category_id: str
    :param category_id: The file lifecycle category ID to be validated.

    :rtype: bool
    :return: True or False depending on whether category_id passes validation.
    """
    if category_id is None:
        return False

    match = re.match(r'^category-[0-9a-f]{8}$', category_id)

    if not match:
        return False

    return True