Weather Controller

controllers/weather retrieves and persists weather independently of Streamlit, Tkinter, or any other frontend.

Components

• WeatherSnapshot is the typed location, retrieval time, and forecast.
• WeatherSnapshotCache owns JSON serialization and validation.
• OpenMeteoWeatherController owns Open-Meteo requests and freshness policy.
• GpsdWeatherLocationProvider preserves GPS-based location when a fix exists.
• PersistentCache supplies atomic byte storage underneath the domain cache.

CarUi refreshes a snapshot in a daemon worker after normal startup. The weather Streamlit process reads the same disk cache, allowing it to render the latest forecast without repeating location, reverse-geocoding, and forecast requests during its initial browser session.

CarUi prefers a GPSD fix and falls back to the configured controller location when GPSD or a fix is unavailable. Reverse geocoding is intentionally absent from the launch path; GPS coordinates remain visible as the location name. When enabled, CarUi also checks the shared last-known position snapshot before falling back to static coordinates.

The default cache is:

~/.cache/openroadcode/weather

If a refresh fails, refresh_if_stale() returns an older snapshot when one is available. This provides useful offline behavior while preserving the age in WeatherSnapshot.fetched_at.

Run its tests from the repository root:

venv/bin/python -m unittest discover \
  -s controllers/weather/unit_test -p 'test_*.py'