"""
Authentication: per-user isolation via HF OAuth or MOCK_USER.
No global state; username is derived per-request in app.py.
"""
from backend.config import MOCK_USER
from backend.utils import get_username_from_request

__all__ = ["get_username_from_request", "require_username"]


def require_username(request: any) -> str:
    """
    Return username for current request; never empty in practice
    (anonymous used as fallback).
    """
    return get_username_from_request(request) or "anonymous"