from __future__ import annotations

from dataclasses import dataclass, field
from typing import Dict, List


@dataclass
class GraphOfContracts:
    """A simple in-memory registry for contract adapters and versions."""
    contracts: Dict[str, Dict[str, str]] = field(default_factory=dict)

    def register(self, contract_id: str, adapter_version: str) -> None:
        self.contracts[contract_id] = {"adapter_version": adapter_version}

    def get_version(self, contract_id: str) -> str | None:
        return self.contracts.get(contract_id, {}).get("adapter_version")