from __future__ import annotations
from dataclasses import dataclass, asdict
from typing import Any, Dict
import json

@dataclass
class LocalProblem:
    id: str
    domain: str
    description: str
    version: int = 1

@dataclass
class SharedVariables:
    variables: Dict[str, Any]
    version: int = 1

@dataclass
class PlanDelta:
    delta: Dict[str, Any]
    timestamp: float
    version: int = 1

@dataclass
class PrivacyBudget:
    lambda_privacy: float

@dataclass
class AuditLog:
    entry: str
    signer: str
    timestamp: float
    contract_id: str
    version: int = 1

def to_json(obj: Any) -> str:
    if hasattr(obj, "__dict__"):
        return json.dumps(asdict(obj), default=str)
    return json.dumps(obj, default=str)