"""Authentication headers for LangGraph-to-Gateway internal calls."""

from __future__ import annotations

import os


def internal_service_token() -> str:
    return (
        os.environ.get("EVOSCIENTIST_BACKEND_SERVICE_TOKEN", "").strip()
        or os.environ.get("AI4SCI_EVO_RUNTIME_GRANT_SECRET", "").strip()
    )


def internal_service_headers() -> dict[str, str]:
    token = internal_service_token()
    return {"X-Ai4Sci-Service-Token": token} if token else {}