feat: add OWM alerts, UV index support, and provider info UI

- Parse OWM One Call 3.0 weather alerts and map to Warning structs
- Map hourly UVI from OWM response to HourlyForecast.UVIndex
- Add severity helper mapping OWM alert tags to severity levels
- Extract UVIndex through compute layer to timeline slots
- Smart warnings: use provider-supplied alerts, fall back to DWD
- Show UV index in dashboard timeline tooltips
- Add provider description below forecast dropdown with i18n

internal/compute/compute.go

@@ -122,6 +122,7 @@ func BuildDashboard(req ComputeRequest) (DashboardData, error) {
 		cloudPct := 50.0
 		sunMin := 0.0
 		pressureHpa := 0.0
+		uvIndex := 0.0
 		if i < len(dayForecasts) {
 			if dayForecasts[i].CloudCoverPct != nil {
 				cloudPct = *dayForecasts[i].CloudCoverPct
@@ -132,6 +133,9 @@ func BuildDashboard(req ComputeRequest) (DashboardData, error) {
 			if dayForecasts[i].PressureHpa != nil {
 				pressureHpa = *dayForecasts[i].PressureHpa
 			}
+			if dayForecasts[i].UVIndex != nil {
+				uvIndex = *dayForecasts[i].UVIndex
+			}
 		}
 
 		budgets, worstStatus, worstMode := computeRoomBudgets(req, h.Hour, h.TempC, cloudPct, sunMin, toggles)
@@ -144,6 +148,7 @@ func BuildDashboard(req ComputeRequest) (DashboardData, error) {
 			TempC:        h.TempC,
 			HumidityPct:  h.HumidityPct,
 			PressureHpa:  pressureHpa,
+			UVIndex:      uvIndex,
 			RiskLevel:    dayRisk.Level.String(),
 			BudgetStatus: worstStatus.String(),
 			IndoorTempC:  indoorTempC,

internal/compute/compute_test.go

@@ -30,6 +30,17 @@ func makeForecasts(baseTime time.Time, temps []float64) []Forecast {
 	return forecasts
 }
 
+func makeForecastsWithUVI(baseTime time.Time, temps []float64, uvis []float64) []Forecast {
+	forecasts := makeForecasts(baseTime, temps)
+	for i := range forecasts {
+		if i < len(uvis) {
+			uv := uvis[i]
+			forecasts[i].UVIndex = &uv
+		}
+	}
+	return forecasts
+}
+
 func TestBuildDashboard_NoForecasts(t *testing.T) {
 	req := ComputeRequest{
 		Profile: Profile{Name: "Test", Timezone: "Europe/Berlin"},
@@ -850,3 +861,40 @@ func TestBuildDashboard_MultipleRooms(t *testing.T) {
 		t.Errorf("got %d room budgets, want 2", len(data.RoomBudgets))
 	}
 }
+
+func TestBuildDashboard_UVIndex(t *testing.T) {
+	loc, _ := time.LoadLocation("UTC")
+	base := time.Date(2025, 7, 15, 0, 0, 0, 0, loc)
+
+	temps := make([]float64, 24)
+	uvis := make([]float64, 24)
+	for i := range temps {
+		temps[i] = 30
+		if i >= 10 && i <= 14 {
+			uvis[i] = 8.5
+		}
+	}
+
+	req := ComputeRequest{
+		Profile:   Profile{Name: "Test", Timezone: "UTC"},
+		Forecasts: makeForecastsWithUVI(base, temps, uvis),
+		Toggles:   map[string]bool{},
+		Date:      "2025-07-15",
+	}
+
+	data, err := BuildDashboard(req)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(data.Timeline) != 24 {
+		t.Fatalf("got %d timeline slots, want 24", len(data.Timeline))
+	}
+	// Hour 12 should have UVI 8.5
+	if data.Timeline[12].UVIndex != 8.5 {
+		t.Errorf("Timeline[12].UVIndex = %v, want 8.5", data.Timeline[12].UVIndex)
+	}
+	// Hour 0 should have UVI 0
+	if data.Timeline[0].UVIndex != 0 {
+		t.Errorf("Timeline[0].UVIndex = %v, want 0", data.Timeline[0].UVIndex)
+	}
+}

internal/compute/types.go

@@ -99,6 +99,7 @@ type Forecast struct {
 	SunshineMin   *float64  `json:"sunshineMin"`
 	ApparentTempC *float64  `json:"apparentTempC"`
 	PressureHpa   *float64  `json:"pressureHpa"`
+	UVIndex       *float64  `json:"uvIndex"`
 }
 
 // Warning holds a weather warning sent from the client.
@@ -172,6 +173,7 @@ type TimelineSlotData struct {
 	TempC        float64      `json:"tempC"`
 	HumidityPct  float64      `json:"humidityPct"`
 	PressureHpa  float64      `json:"pressureHpa"`
+	UVIndex      float64      `json:"uvIndex"`
 	RiskLevel    string       `json:"riskLevel"`
 	BudgetStatus string       `json:"budgetStatus"`
 	IndoorTempC  float64      `json:"indoorTempC"`

internal/weather/openmeteo_test.go

@@ -70,6 +70,16 @@ func TestOpenMeteoFetchForecast(t *testing.T) {
 	if resp.Daily[0].TempMaxC != 35.5 {
 		t.Errorf("Daily[0].TempMaxC = %v, want 35.5", resp.Daily[0].TempMaxC)
 	}
+
+	// Open-Meteo does not provide alerts — Warnings must be nil
+	if resp.Warnings != nil {
+		t.Errorf("Warnings = %v, want nil (Open-Meteo has no alerts)", resp.Warnings)
+	}
+
+	// Open-Meteo does not provide hourly UVI — must be zero
+	if resp.Hourly[0].UVIndex != 0 {
+		t.Errorf("Hourly[0].UVIndex = %v, want 0 (Open-Meteo has no hourly UVI)", resp.Hourly[0].UVIndex)
+	}
 }
 
 func TestOpenMeteoServerError(t *testing.T) {

internal/weather/openweathermap.go

@@ -73,9 +73,19 @@ type owmDaily struct {
 	UVI       float64           `json:"uvi"`
 }
 
+type owmAlert struct {
+	SenderName  string   `json:"sender_name"`
+	Event       string   `json:"event"`
+	Start       int64    `json:"start"`
+	End         int64    `json:"end"`
+	Description string   `json:"description"`
+	Tags        []string `json:"tags"`
+}
+
 type owmResponse struct {
 	Hourly []owmHourly `json:"hourly"`
 	Daily  []owmDaily  `json:"daily"`
+	Alerts []owmAlert  `json:"alerts"`
 }
 
 func (o *OpenWeatherMap) FetchForecast(ctx context.Context, lat, lon float64, timezone string) (*ForecastResponse, error) {
@@ -83,7 +93,7 @@ func (o *OpenWeatherMap) FetchForecast(ctx context.Context, lat, lon float64, ti
 		return nil, fmt.Errorf("openweathermap: API key required")
 	}
 
-	reqURL := fmt.Sprintf("%s?lat=%.4f&lon=%.4f&appid=%s&units=metric&exclude=minutely,alerts",
+	reqURL := fmt.Sprintf("%s?lat=%.4f&lon=%.4f&appid=%s&units=metric&exclude=minutely",
 		o.baseURL, lat, lon, o.apiKey)
 
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
@@ -125,6 +135,7 @@ func (o *OpenWeatherMap) FetchForecast(ctx context.Context, lat, lon float64, ti
 			WindSpeedMs:     h.WindSpeed,
 			WindDirectionDeg: h.WindDeg,
 			PressureHpa:     h.Pressure,
+			UVIndex:         h.UVI,
 			SunshineMin:     (1 - h.Clouds/100) * 60,
 		}
 		if h.Rain != nil {
@@ -144,5 +155,33 @@ func (o *OpenWeatherMap) FetchForecast(ctx context.Context, lat, lon float64, ti
 		})
 	}
 
+	for _, a := range raw.Alerts {
+		result.Warnings = append(result.Warnings, Warning{
+			EventType:   a.Event,
+			Severity:    owmTagsToSeverity(a.Tags),
+			Headline:    a.Event,
+			Description: a.Description,
+			Onset:       time.Unix(a.Start, 0).In(loc),
+			Expires:     time.Unix(a.End, 0).In(loc),
+		})
+	}
+
 	return result, nil
 }
+
+func owmTagsToSeverity(tags []string) string {
+	for _, tag := range tags {
+		switch tag {
+		case "Extreme temperature value", "Extreme weather":
+			return "Extreme"
+		case "Flood", "Tornado", "Hurricane":
+			return "Severe"
+		case "Thunderstorm", "Wind", "Rain", "Snow":
+			return "Moderate"
+		}
+	}
+	if len(tags) > 0 {
+		return "Minor"
+	}
+	return "Minor"
+}

internal/weather/openweathermap_test.go

@@ -53,6 +53,16 @@ const owmTestJSON = `{
       "wind_deg": 210,
       "uvi": 8.1
     }
+  ],
+  "alerts": [
+    {
+      "sender_name": "DWD",
+      "event": "Heat Warning",
+      "start": 1752616800,
+      "end": 1752660000,
+      "description": "Extreme heat expected in the region.",
+      "tags": ["Extreme temperature value"]
+    }
   ]
 }`
 
@@ -120,11 +130,19 @@ func TestOpenWeatherMapFetchForecast(t *testing.T) {
 		t.Errorf("Hourly[0].SunshineMin = %v, want 45", h0.SunshineMin)
 	}
 
+	// UV index
+	if h0.UVIndex != 7.2 {
+		t.Errorf("Hourly[0].UVIndex = %v, want 7.2", h0.UVIndex)
+	}
+
 	// Second hour: no rain field
 	h1 := resp.Hourly[1]
 	if h1.PrecipitationMm != 0 {
 		t.Errorf("Hourly[1].PrecipitationMm = %v, want 0 (missing field)", h1.PrecipitationMm)
 	}
+	if h1.UVIndex != 8.1 {
+		t.Errorf("Hourly[1].UVIndex = %v, want 8.1", h1.UVIndex)
+	}
 
 	// Daily
 	if len(resp.Daily) != 1 {
@@ -146,6 +164,27 @@ func TestOpenWeatherMapFetchForecast(t *testing.T) {
 	if d0.Sunset.IsZero() {
 		t.Error("Daily[0].Sunset is zero")
 	}
+
+	// Warnings from alerts
+	if len(resp.Warnings) != 1 {
+		t.Fatalf("Warnings len = %d, want 1", len(resp.Warnings))
+	}
+	w0 := resp.Warnings[0]
+	if w0.Headline != "Heat Warning" {
+		t.Errorf("Warnings[0].Headline = %q, want %q", w0.Headline, "Heat Warning")
+	}
+	if w0.Severity != "Extreme" {
+		t.Errorf("Warnings[0].Severity = %q, want %q", w0.Severity, "Extreme")
+	}
+	if w0.Description != "Extreme heat expected in the region." {
+		t.Errorf("Warnings[0].Description = %q", w0.Description)
+	}
+	if w0.Onset.IsZero() {
+		t.Error("Warnings[0].Onset is zero")
+	}
+	if w0.Expires.IsZero() {
+		t.Error("Warnings[0].Expires is zero")
+	}
 }
 
 func TestOpenWeatherMapMissingAPIKey(t *testing.T) {
@@ -203,4 +242,36 @@ func TestOpenWeatherMapMissingOptionalFields(t *testing.T) {
 	if resp.Hourly[0].DewPointC != 0 {
 		t.Errorf("DewPointC = %v, want 0", resp.Hourly[0].DewPointC)
 	}
+	if resp.Hourly[0].UVIndex != 0 {
+		t.Errorf("UVIndex = %v, want 0", resp.Hourly[0].UVIndex)
+	}
+	if resp.Warnings != nil {
+		t.Errorf("Warnings = %v, want nil", resp.Warnings)
+	}
+}
+
+func TestOwmTagsToSeverity(t *testing.T) {
+	tests := []struct {
+		tags []string
+		want string
+	}{
+		{[]string{"Extreme temperature value"}, "Extreme"},
+		{[]string{"Extreme weather"}, "Extreme"},
+		{[]string{"Flood"}, "Severe"},
+		{[]string{"Tornado"}, "Severe"},
+		{[]string{"Hurricane"}, "Severe"},
+		{[]string{"Thunderstorm"}, "Moderate"},
+		{[]string{"Wind"}, "Moderate"},
+		{[]string{"Rain"}, "Moderate"},
+		{[]string{"Snow"}, "Moderate"},
+		{[]string{"Fog"}, "Minor"},
+		{[]string{}, "Minor"},
+		{nil, "Minor"},
+	}
+	for _, tt := range tests {
+		got := owmTagsToSeverity(tt.tags)
+		if got != tt.want {
+			t.Errorf("owmTagsToSeverity(%v) = %q, want %q", tt.tags, got, tt.want)
+		}
+	}
 }

internal/weather/types.go

@@ -16,6 +16,7 @@ type HourlyForecast struct {
 	SunshineMin     float64
 	ShortwaveRadW   float64
 	PressureHpa     float64
+	UVIndex         float64
 	IsDay           bool
 	Condition       string
 }
@@ -32,9 +33,10 @@ type DailyForecast struct {
 
 // ForecastResponse holds the full forecast response from a provider.
 type ForecastResponse struct {
-	Hourly []HourlyForecast
-	Daily  []DailyForecast
-	Source string
+	Hourly   []HourlyForecast
+	Daily    []DailyForecast
+	Warnings []Warning
+	Source   string
 }
 
 // Warning represents a weather warning.