feat(Q3): Open-Meteo weather fetcher with hourly caching

vigilar/detection/weather.py

@@ -0,0 +1,57 @@
+"""Open-Meteo weather fetcher with in-memory caching."""
+
+import logging
+import time
+
+import requests
+
+log = logging.getLogger(__name__)
+
+_WMO_CODES = {
+    0: "Clear sky", 1: "Mainly clear", 2: "Partly cloudy", 3: "Overcast",
+    45: "Fog", 48: "Depositing rime fog",
+    51: "Light drizzle", 53: "Moderate drizzle", 55: "Dense drizzle",
+    61: "Light rain", 63: "Moderate rain", 65: "Heavy rain",
+    66: "Light freezing rain", 67: "Heavy freezing rain",
+    71: "Light snow", 73: "Moderate snow", 75: "Heavy snow", 77: "Snow grains",
+    80: "Light showers", 81: "Moderate showers", 82: "Violent showers",
+    85: "Light snow showers", 86: "Heavy snow showers",
+    95: "Thunderstorm", 96: "Thunderstorm with light hail", 99: "Thunderstorm with heavy hail",
+}
+
+CACHE_TTL_S = 3600
+
+
+def _weather_code_to_text(code: int) -> str:
+    return _WMO_CODES.get(code, "Unknown")
+
+
+class WeatherFetcher:
+    def __init__(self):
+        self._cache: dict[str, tuple[dict, float]] = {}
+
+    def get_conditions(self, lat: float, lon: float) -> dict | None:
+        cache_key = f"{lat:.2f},{lon:.2f}"
+        if cache_key in self._cache:
+            data, ts = self._cache[cache_key]
+            if time.time() - ts < CACHE_TTL_S:
+                return data
+        try:
+            resp = requests.get(
+                "https://api.open-meteo.com/v1/forecast",
+                params={"latitude": lat, "longitude": lon, "current": "temperature_2m,weather_code"},
+                timeout=10,
+            )
+            if resp.status_code != 200:
+                return None
+            j = resp.json()
+            current = j.get("current", {})
+            result = {
+                "temperature_c": current.get("temperature_2m"),
+                "conditions": _weather_code_to_text(current.get("weather_code", -1)),
+            }
+            self._cache[cache_key] = (result, time.time())
+            return result
+        except Exception:
+            log.debug("Weather fetch failed", exc_info=True)
+            return None