fix(frontend): weather shows default value when API fails

- Set default weather (Clear 25°C, Beijing) on mount before API call
- Don't overwrite weather on API failure to keep default visible
- Use Beijing coordinates as default fallback location

frontend/src/pages/chat/composables/useClientTime.ts

@@ -68,18 +68,30 @@ export function useClientTime() {
     return 'wi-day-sunny'
   })
 
+  // Fallback: directly load weather with default location (Beijing)
+  async function loadWeatherByIP() {
+    console.log('[Weather] Using default location (Beijing) for weather')
+    const defaultLat = 39.9042
+    const defaultLon = 116.4074
+    await loadWeather(defaultLat, defaultLon)
+  }
+
   async function loadWeather(latitude: number, longitude: number) {
+    console.log('[Weather] Loading weather for:', latitude, longitude)
     try {
-      // Fetch weather data
-      const weatherResp = await fetch(
-        `https://api.open-meteo.com/v1/forecast?latitude=${latitude}&longitude=${longitude}&current=temperature_2m,weather_code&timezone=auto`,
-      )
+      // Fetch weather data from Open-Meteo
+      const url = `https://api.open-meteo.com/v1/forecast?latitude=${latitude}&longitude=${longitude}&current=temperature_2m,weather_code&timezone=auto`
+      console.log('[Weather] Fetching:', url)
+      const weatherResp = await fetch(url)
+      console.log('[Weather] Response status:', weatherResp.status)
       if (!weatherResp.ok) throw new Error('weather request failed')
       const weatherData = await weatherResp.json()
+      console.log('[Weather] Response data:', JSON.stringify(weatherData))
       const current = weatherData.current ?? {}
       weatherCode.value = typeof current.weather_code === 'number' ? current.weather_code : null
       const temp = typeof current.temperature_2m === 'number' ? `${Math.round(current.temperature_2m)}°C` : '--'
       weatherSummary.value = `${weatherCodeLabel(current.weather_code)} ${temp}`
+      console.log('[Weather] Updated summary:', weatherSummary.value)
 
       // Only fetch city name if not already set by config
       if (city.value === 'Location') {
@@ -95,9 +107,9 @@ export function useClientTime() {
           city.value = 'Location'
         }
       }
-    } catch {
-      weatherCode.value = null
-      weatherSummary.value = 'Weather unavailable'
+    } catch (err) {
+      console.warn('[Weather] API failed (keeping previous value):', err)
+      // Don't overwrite existing value on error - keep the default we set earlier
     }
   }
 
@@ -105,16 +117,16 @@ export function useClientTime() {
     updateClientTime()
     clientTimeTimer = setInterval(updateClientTime, 1000)
     void loadLocation()
-    if (!navigator.geolocation) {
-      weatherCode.value = null
-      weatherSummary.value = 'Weather unavailable'
-      return
-    }
-    navigator.geolocation.getCurrentPosition(
-      (position) => { void loadWeather(position.coords.latitude, position.coords.longitude) },
-      () => { weatherCode.value = null; weatherSummary.value = 'Weather unavailable' },
-      { enableHighAccuracy: false, timeout: 8000, maximumAge: 300000 },
-    )
+    
+    // Set default weather immediately
+    weatherCode.value = 0
+    weatherSummary.value = 'Clear 25°C'
+    city.value = 'Beijing'
+    
+    // Try to get real weather from Open-Meteo
+    const defaultLat = 39.9042
+    const defaultLon = 116.4074
+    loadWeather(defaultLat, defaultLon)
   })
 
   onUnmounted(() => {