app/cache.py

# app/app/cache.py
from pathlib import Path
import os, json, tempfile, os
import asyncio

class Cache:
    def __init__(self, filename: str = "cache.json"):
        # bevorzugt /data (persistenter Storage auf HF), sonst /tmp
        base = Path(os.getenv("APP_CACHE_DIR", "/data"))
        if not os.access(base, os.W_OK):
            base = Path("/tmp/app-cache")
        base.mkdir(parents=True, exist_ok=True)

        self.path = base / filename

    def _dump_to_disk(self, data: dict | list | None = None):
        # vorhandenen Zustand laden/ersetzen
        if data is None and self.path.exists():
            try:
                data = json.loads(self.path.read_text(encoding="utf-8"))
            except Exception:
                data = None
        data = data if data is not None else {}

        # atomar schreiben
        with tempfile.NamedTemporaryFile(
            "w", delete=False, dir=self.path.parent, suffix=".tmp", encoding="utf-8"
        ) as tmp:
            json.dump(data, tmp, ensure_ascii=False, indent=2)
            tmp_name = tmp.name
        os.replace(tmp_name, self.path)  # atomar

    async def add(self, measurement: dict):
        # ... füge measurement in deinen Speicher ein ...
        # Beispiel (anpassen, falls du eine Liste etc. führst):
        data = {"last": measurement}
        await asyncio.to_thread(self._dump_to_disk, data)