fix: safely fallback to metric unit per city instead of overwriting F to C randomly; allow trend engine to run even if Open-Meteo drops

bot_listener.py

@@ -386,8 +386,8 @@ def start_bot():
                 except Exception:
                     return None
 
-            temp_unit = open_meteo.get("unit", "celsius")
-            temp_symbol = "°F" if temp_unit == "fahrenheit" else "°C"
+            city_is_fahrenheit = city_name.strip().lower() in ["dallas", "new york", "chicago", "miami", "atlanta", "seattle"]
+            temp_symbol = "°F" if city_is_fahrenheit else "°C"
 
             # --- 1. 紧凑 Header (城市 + 时间 + 风险状态) ---
             local_time = open_meteo.get("current", {}).get("local_time", "")

src/analysis/trend_engine.py

@@ -66,11 +66,12 @@ def analyze_weather_trend(
     nws = weather_data.get("nws", {})
 
     empty_result = ("", "", {})
-    if not metar or not open_meteo:
+    if not metar and not mgm:
         return empty_result
 
-    max_so_far = _sf(metar.get("current", {}).get("max_temp_so_far"))
-    cur_temp = _sf(metar.get("current", {}).get("temp"))
+    max_so_far = _sf(metar.get("current", {}).get("max_temp_so_far")) if metar else _sf(mgm.get("current", {}).get("mgm_max_temp"))
+    cur_temp = _sf(metar.get("current", {}).get("temp")) if metar else _sf(mgm.get("current", {}).get("temp"))
+
     daily = open_meteo.get("daily", {})
     hourly = open_meteo.get("hourly", {})
     times = hourly.get("time", [])