"""GBNF loader. We use the built-in JSON grammar from llama.cpp because the
full Pydantic schema produces a very large GBNF that slows sampling.
For production we keep a moderate JSON grammar; the fine-tuned model is the
real guarantee of schema-correctness."""
from llama_cpp import LlamaGrammar
import pathlib

_GBNF = pathlib.Path(__file__).parent / "elysium_schema.gbnf"


def load_grammar():
    if _GBNF.exists():
        try:
            return LlamaGrammar.from_string(_GBNF.read_text())
        except Exception as e:
            print(f"[grammar] load failed: {e}")
    return None