feat(monitor): aggregate nationwide fleet by province

vehicle-data-platform/apps/api/internal/platform/service.go

@@ -373,6 +373,7 @@ const (
 	monitorVehicleLimit       = 10000
 	monitorPointLimit         = 2000
 	monitorPointZoom          = 11
+	monitorProvinceMaxZoom    = 5
 	monitorClusterGridPixels  = 64
 	vehicleSearchKeywordLimit = 100
 )
@@ -606,17 +607,19 @@ func buildMonitorMapResponse(vehicles Page[VehicleRealtimeRow], query url.Values
 	if zoom > 20 {
 		zoom = 20
 	}
+	provinceMode := zoom <= monitorProvinceMaxZoom
 	bounds, hasBounds, err := parseMonitorBounds(query.Get("bounds"))
 	if err != nil {
 		return MonitorMapResponse{}, err
 	}
 	result := MonitorMapResponse{
-		Mode:      "clusters",
-		Zoom:      zoom,
-		Truncated: vehicles.Total > len(vehicles.Items),
-		Points:    []MonitorMapPoint{},
-		Clusters:  []MonitorMapCluster{},
-		AsOf:      time.Now().UTC().Format(time.RFC3339),
+		Mode:           "clusters",
+		Zoom:           zoom,
+		Truncated:      vehicles.Total > len(vehicles.Items),
+		Points:         []MonitorMapPoint{},
+		Clusters:       []MonitorMapCluster{},
+		ProvincePoints: []MonitorMapProvincePoint{},
+		AsOf:           time.Now().UTC().Format(time.RFC3339),
 	}
 	points := make([]MonitorMapPoint, 0, len(vehicles.Items))
 	for _, vehicle := range vehicles.Items {
@@ -627,7 +630,17 @@ func buildMonitorMapResponse(vehicles Page[VehicleRealtimeRow], query url.Values
 			continue
 		}
 		result.Total++
-		if hasBounds && !bounds.contains(vehicle.Longitude, vehicle.Latitude) {
+		status := monitorVehicleStatus(vehicle)
+		if provinceMode {
+			result.ProvincePoints = append(result.ProvincePoints, MonitorMapProvincePoint{
+				Longitude: vehicle.Longitude,
+				Latitude:  vehicle.Latitude,
+				Status:    status,
+			})
+		}
+		// Nationwide province counts describe the complete filtered fleet, not
+		// only the current slippy-map rectangle. Bounds resume after drill-down.
+		if hasBounds && !provinceMode && !bounds.contains(vehicle.Longitude, vehicle.Latitude) {
 			continue
 		}
 		points = append(points, MonitorMapPoint{
@@ -637,7 +650,7 @@ func buildMonitorMapResponse(vehicles Page[VehicleRealtimeRow], query url.Values
 			ReportIntervalMs: vehicle.ReportIntervalMs,
 			LocationSource:   vehicle.LocationSource,
 			LocationConflict: vehicle.LocationConflict,
-			Status:           monitorVehicleStatus(vehicle),
+			Status:           status,
 		})
 	}
 	if zoom >= monitorPointZoom && len(points) <= monitorPointLimit {
@@ -708,6 +721,9 @@ func buildMonitorMapResponse(vehicles Page[VehicleRealtimeRow], query url.Values
 			result.Mode = "points"
 		}
 	}
+	if provinceMode {
+		result.Mode = "provinces"
+	}
 	return result, nil
 }