# backends_base.py
from typing import Any, AsyncIterable, Dict

class ChatBackend:
    """Abstract interface for chat backends (OpenAI-compatible)."""
    async def stream(self, request: Dict[str, Any]) -> AsyncIterable[Dict[str, Any]]:
        raise NotImplementedError

class ImagesBackend:
    """Abstract interface for image backends (OpenAI-compatible)."""
    async def generate_b64(self, request: Dict[str, Any]) -> str:
        raise NotImplementedError