Validate hourly forecast time bounds

internal/adapters/weatherapi/client.go

@@ -224,6 +224,11 @@ func (b *bundleBuilder) fetchHourly(ctx context.Context) error {
 	if len(hourly.Periods) == 0 {
 		return fmt.Errorf("hourly forecast from %s contains no periods", source.Endpoint)
 	}
+	for i, period := range hourly.Periods {
+		if !period.HasUsableTimeBounds() {
+			return fmt.Errorf("hourly forecast from %s has unusable time bounds for period %d", source.Endpoint, i+1)
+		}
+	}
 	source.IssuedAt = &hourly.IssuedAt
 	source.UpdatedAt = hourly.UpdatedAt
 	b.bundle.Hourly = &hourly

internal/adapters/weatherapi/client_test.go

@@ -501,6 +501,66 @@ func TestRequiredHourlyForecast(t *testing.T) {
 	}
 }
 
+func TestRequiredHourlyForecastValidatesPeriodBounds(t *testing.T) {
+	tests := []struct {
+		name    string
+		body    string
+		wantErr bool
+	}{
+		{
+			name: "valid period",
+			body: `{"data":{"periods":[{"startTime":"2026-05-29T13:00:00Z","endTime":"2026-05-29T14:00:00Z"}]}}`,
+		},
+		{
+			name:    "missing start",
+			body:    `{"data":{"periods":[{"endTime":"2026-05-29T14:00:00Z"}]}}`,
+			wantErr: true,
+		},
+		{
+			name:    "missing end",
+			body:    `{"data":{"periods":[{"startTime":"2026-05-29T13:00:00Z"}]}}`,
+			wantErr: true,
+		},
+		{
+			name:    "empty range",
+			body:    `{"data":{"periods":[{"startTime":"2026-05-29T13:00:00Z","endTime":"2026-05-29T13:00:00Z"}]}}`,
+			wantErr: true,
+		},
+		{
+			name:    "reversed range",
+			body:    `{"data":{"periods":[{"startTime":"2026-05-29T14:00:00Z","endTime":"2026-05-29T13:00:00Z"}]}}`,
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var requested []string
+			server := fixtureServer(t, map[string]handlerOverride{
+				"/forecast/hourly": {status: http.StatusOK, body: tt.body},
+			}, &requested)
+			client := newTestClient(t, server.URL+"/", nil)
+
+			bundle, err := client.FetchBundle(context.Background())
+			if tt.wantErr {
+				if err == nil || !strings.Contains(err.Error(), "hourly forecast") || !strings.Contains(err.Error(), "time bounds") {
+					t.Fatalf("FetchBundle() error = %v, want hourly time-bounds failure", err)
+				}
+				if got := countPath(requested, "/forecast/hourly"); got != 1 {
+					t.Fatalf("hourly requests = %d, want no retry; all requests = %v", got, requested)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("FetchBundle() error = %v", err)
+			}
+			if bundle.Hourly == nil || len(bundle.Hourly.Periods) != 1 {
+				t.Fatalf("Hourly = %#v, want accepted hourly period", bundle.Hourly)
+			}
+		})
+	}
+}
+
 func TestNullAlertsMeansNoActiveAlerts(t *testing.T) {
 	server := fixtureServer(t, map[string]handlerOverride{
 		"/alerts/active": {status: http.StatusOK, body: `{"data": null}`},