Smart Overpass fetching, SQLite node cache, and rate-limit handling

lib/app_state.dart

@@ -16,6 +16,7 @@ import 'models/search_result.dart';
 import 'services/offline_area_service.dart';
 import 'services/map_data_provider.dart';
 import 'services/node_data_manager.dart';
+import 'services/node_spatial_cache.dart';
 import 'services/tile_preview_service.dart';
 import 'services/changelog_service.dart';
 import 'services/operator_profile_service.dart';
@@ -160,6 +161,7 @@ class AppState extends ChangeNotifier {
   bool get proximityAlertsEnabled => _settingsState.proximityAlertsEnabled;
   int get proximityAlertDistance => _settingsState.proximityAlertDistance;
   bool get networkStatusIndicatorEnabled => _settingsState.networkStatusIndicatorEnabled;
+  bool get showCoverageOverlay => _settingsState.showCoverageOverlay;
   int get suspectedLocationMinDistance => _settingsState.suspectedLocationMinDistance;
 
   // Messages state
@@ -239,10 +241,13 @@ class AppState extends ChangeNotifier {
 
     // Note: Re-auth check will be triggered from home screen after init
 
-    // Initialize OfflineAreaService to ensure offline areas are loaded
-    await OfflineAreaService().ensureInitialized();
-
-    // Preload offline nodes into cache for immediate display
+    // Initialize offline areas and node cache in parallel (independent)
+    await Future.wait([
+      OfflineAreaService().ensureInitialized(),
+      NodeSpatialCache().initPersistence(),
+    ]);
+
+    // Overlay offline area nodes (depends on both above)
     await NodeDataManager().preloadOfflineNodes();
 
     // Start uploader if conditions are met
@@ -737,6 +742,11 @@ class AppState extends ChangeNotifier {
     await _settingsState.setNetworkStatusIndicatorEnabled(enabled);
   }
 
+  /// Set coverage overlay visibility
+  Future<void> setShowCoverageOverlay(bool enabled) async {
+    await _settingsState.setShowCoverageOverlay(enabled);
+  }
+
 
 
   /// Set suspected location minimum distance from real nodes

lib/localizations/de.json

@@ -435,7 +435,9 @@
     "success": "Überwachungsdaten geladen",
     "nodeDataSlow": "Überwachungsdaten langsam",
     "rateLimited": "Server-Limitierung",
-    "networkError": "Netzwerkfehler"
+    "networkError": "Netzwerkfehler",
+    "showCoverageOverlay": "Datenabdeckung anzeigen",
+    "showCoverageOverlaySubtitle": "Zeigt an, welche Kartenbereiche Daten geladen haben"
   },
   "nodeLimitIndicator": {
     "message": "Zeige {rendered} von {total} Geräten",

lib/localizations/en.json

@@ -472,7 +472,9 @@
     "success": "Surveillance data loaded",
     "nodeDataSlow": "Surveillance data slow",
     "rateLimited": "Rate limited by server",
-    "networkError": "Network error"
+    "networkError": "Network error",
+    "showCoverageOverlay": "Data coverage overlay",
+    "showCoverageOverlaySubtitle": "Show which map areas have loaded data"
   },
   "nodeLimitIndicator": {
     "message": "Showing {rendered} of {total} devices",

lib/localizations/es.json

@@ -472,7 +472,9 @@
     "success": "Datos de vigilancia cargados",
     "nodeDataSlow": "Datos de vigilancia lentos",
     "rateLimited": "Limitado por el servidor",
-    "networkError": "Error de red"
+    "networkError": "Error de red",
+    "showCoverageOverlay": "Superposición de cobertura de datos",
+    "showCoverageOverlaySubtitle": "Mostrar qué áreas del mapa tienen datos cargados"
   },
   "nodeLimitIndicator": {
     "message": "Mostrando {rendered} de {total} dispositivos",

lib/localizations/fr.json

@@ -472,7 +472,9 @@
     "success": "Données de surveillance chargées",
     "nodeDataSlow": "Données de surveillance lentes",
     "rateLimited": "Limité par le serveur",
-    "networkError": "Erreur réseau"
+    "networkError": "Erreur réseau",
+    "showCoverageOverlay": "Couverture des données",
+    "showCoverageOverlaySubtitle": "Afficher les zones de la carte dont les données sont chargées"
   },
   "nodeLimitIndicator": {
     "message": "Affichage de {rendered} sur {total} appareils",

lib/localizations/it.json

@@ -472,7 +472,9 @@
     "success": "Dati di sorveglianza caricati",
     "nodeDataSlow": "Dati di sorveglianza lenti",
     "rateLimited": "Limitato dal server",
-    "networkError": "Errore di rete"
+    "networkError": "Errore di rete",
+    "showCoverageOverlay": "Sovrapposizione copertura dati",
+    "showCoverageOverlaySubtitle": "Mostra quali aree della mappa hanno dati caricati"
   },
   "nodeLimitIndicator": {
     "message": "Mostra {rendered} di {total} dispositivi",

lib/localizations/nl.json

@@ -472,7 +472,9 @@
     "success": "Surveillance data geladen",
     "nodeDataSlow": "Surveillance data traag",
     "rateLimited": "Snelheid beperkt door server",
-    "networkError": "Netwerk fout"
+    "networkError": "Netwerk fout",
+    "showCoverageOverlay": "Datadekking overlay",
+    "showCoverageOverlaySubtitle": "Toon welke kaartgebieden geladen data hebben"
   },
   "nodeLimitIndicator": {
     "message": "{rendered} van {total} apparaten getoond",

lib/localizations/pl.json

@@ -472,7 +472,9 @@
     "success": "Dane nadzoru załadowane",
     "nodeDataSlow": "Dane nadzoru powolne",
     "rateLimited": "Ograniczone przez serwer",
-    "networkError": "Błąd sieci"
+    "networkError": "Błąd sieci",
+    "showCoverageOverlay": "Nakładka pokrycia danymi",
+    "showCoverageOverlaySubtitle": "Pokaż które obszary mapy mają załadowane dane"
   },
   "nodeLimitIndicator": {
     "message": "Pokazuje {rendered} z {total} urządzeń",

lib/localizations/pt.json

@@ -472,7 +472,9 @@
     "success": "Dados de vigilância carregados",
     "nodeDataSlow": "Dados de vigilância lentos",
     "rateLimited": "Limitado pelo servidor",
-    "networkError": "Erro de rede"
+    "networkError": "Erro de rede",
+    "showCoverageOverlay": "Sobreposição de cobertura de dados",
+    "showCoverageOverlaySubtitle": "Mostrar quais áreas do mapa têm dados carregados"
   },
   "nodeLimitIndicator": {
     "message": "Mostrando {rendered} de {total} dispositivos",

lib/localizations/tr.json

@@ -472,7 +472,9 @@
     "success": "Gözetleme verisi yüklendi",
     "nodeDataSlow": "Gözetleme verisi yavaş",
     "rateLimited": "Sunucu tarafından hız sınırlandı",
-    "networkError": "Ağ hatası"
+    "networkError": "Ağ hatası",
+    "showCoverageOverlay": "Veri kapsama katmanı",
+    "showCoverageOverlaySubtitle": "Hangi harita alanlarının yüklenmiş veriye sahip olduğunu göster"
   },
   "nodeLimitIndicator": {
     "message": "{total} cihazdan {rendered} tanesi gösteriliyor",

lib/localizations/uk.json

@@ -472,7 +472,9 @@
     "success": "Дані спостереження завантажено",
     "nodeDataSlow": "Повільні дані спостереження",
     "rateLimited": "Обмежено швидкість сервером",
-    "networkError": "Помилка мережі"
+    "networkError": "Помилка мережі",
+    "showCoverageOverlay": "Накладення покриття даними",
+    "showCoverageOverlaySubtitle": "Показати, які області карти мають завантажені дані"
   },
   "nodeLimitIndicator": {
     "message": "Показано {rendered} з {total} пристроїв",

lib/localizations/zh.json

@@ -472,7 +472,9 @@
     "success": "监控数据已加载",
     "nodeDataSlow": "监控数据缓慢",
     "rateLimited": "服务器限流",
-    "networkError": "网络错误"
+    "networkError": "网络错误",
+    "showCoverageOverlay": "数据覆盖范围",
+    "showCoverageOverlaySubtitle": "显示哪些地图区域已加载数据"
   },
   "nodeLimitIndicator": {
     "message": "显示 {rendered} / {total} 设备",

lib/screens/advanced_settings_screen.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'settings/sections/max_nodes_section.dart';
+import 'settings/sections/network_status_section.dart';
 import 'settings/sections/proximity_alerts_section.dart';
 import 'settings/sections/suspected_locations_section.dart';
 import 'settings/sections/tile_provider_section.dart';
@@ -32,8 +33,8 @@ class AdvancedSettingsScreen extends StatelessWidget {
             Divider(),
             SuspectedLocationsSection(),
             Divider(),
-            // NetworkStatusSection(), // Commented out - network status indicator now defaults to enabled
-            // Divider(),
+            NetworkStatusSection(),
+            Divider(),
             TileProviderSection(),
           ],
         ),

lib/screens/settings/sections/network_status_section.dart

@@ -34,6 +34,17 @@ class NetworkStatusSection extends StatelessWidget {
               },
               contentPadding: EdgeInsets.zero,
             ),
+
+            // Coverage overlay toggle
+            SwitchListTile(
+              title: Text(locService.t('networkStatus.showCoverageOverlay')),
+              subtitle: Text(locService.t('networkStatus.showCoverageOverlaySubtitle')),
+              value: appState.showCoverageOverlay,
+              onChanged: (enabled) {
+                appState.setShowCoverageOverlay(enabled);
+              },
+              contentPadding: EdgeInsets.zero,
+            ),
           ],
         );
       },

lib/services/map_data_provider.dart

@@ -60,8 +60,16 @@ class MapDataProvider {
       throw OfflineModeException("Cannot fetch remote nodes for offline area download in offline mode.");
     }
 
-    // For downloads, always fetch fresh data (don't use cache)
-    return _nodeDataManager.fetchWithSplitting(bounds, profiles);
+    // For downloads, always fetch fresh data (don't use cache).
+    // Note: passes null generation, so downloads are never cancelled by stale-fetch
+    // detection and will hold semaphore slots until complete. This is intentional —
+    // offline downloads should run to completion — but means concurrent downloads
+    // can block foreground map fetches via the shared semaphore.
+    return _nodeDataManager.fetchWithSplitting(
+      bounds,
+      profiles,
+      isUserInitiated: true,
+    );
   }
 
   /// Fetch tile image bytes. Default is to try local first, then remote if not offline. Honors explicit source.

lib/services/map_data_submodules/tiles_from_local.dart

@@ -1,11 +1,11 @@
 import 'dart:io';
-import 'dart:math';
 
 import 'package:flutter_map/flutter_map.dart' show LatLngBounds;
 import 'package:flutter/foundation.dart' show visibleForTesting;
 
 import '../offline_area_service.dart';
 import '../offline_areas/offline_area_models.dart';
+import '../offline_areas/offline_tile_utils.dart' show latLonToTileRaw;
 import '../../app_state.dart';
 
 /// Fetch a tile from the newest offline area that matches the given provider, or throw if not found.
@@ -58,28 +58,21 @@ Future<List<int>> fetchLocalTile({
 
 /// O(1) check whether tile (z, x, y) falls within the given lat/lng bounds.
 ///
-/// Uses the same Mercator projection math as [latLonToTile] in
-/// offline_tile_utils.dart, but only computes the bounding tile range
-/// instead of enumerating every tile at that zoom level.
+/// Reuses [latLonToTileRaw] from offline_tile_utils.dart for the Mercator
+/// projection, computing only the bounding tile range instead of enumerating
+/// every tile at that zoom level.
 ///
 /// Note: Y axis is inverted in tile coordinates — north = lower Y.
 @visibleForTesting
 bool tileInBounds(LatLngBounds bounds, int z, int x, int y) {
-  final n = pow(2.0, z);
-  final west = bounds.west;
-  final east = bounds.east;
-  final north = bounds.north;
-  final south = bounds.south;
+  final swTile = latLonToTileRaw(bounds.south, bounds.west, z);
+  final neTile = latLonToTileRaw(bounds.north, bounds.east, z);
 
-  final minX = ((west + 180.0) / 360.0 * n).floor();
-  final maxX = ((east + 180.0) / 360.0 * n).floor();
+  final minX = swTile[0].floor();
+  final maxX = neTile[0].floor();
   // North → lower Y (Mercator projection inverts latitude)
-  final minY = ((1.0 - log(tan(north * pi / 180.0) +
-          1.0 / cos(north * pi / 180.0)) /
-      pi) / 2.0 * n).floor();
-  final maxY = ((1.0 - log(tan(south * pi / 180.0) +
-          1.0 / cos(south * pi / 180.0)) /
-      pi) / 2.0 * n).floor();
+  final minY = neTile[1].floor();
+  final maxY = swTile[1].floor();
 
   return x >= minX && x <= maxX && y >= minY && y <= maxY;
 }

lib/services/network_status.dart

@@ -20,7 +20,12 @@ class NetworkStatus extends ChangeNotifier {
 
   NetworkRequestStatus _status = NetworkRequestStatus.idle;
   Timer? _autoResetTimer;
-
+
+  /// Rate limit countdown: seconds until slot should be free (from Overpass /api/status)
+  int _rateLimitWaitSeconds = 0;
+
+  int get rateLimitWaitSeconds => _rateLimitWaitSeconds;
+
   /// Current network status
   NetworkRequestStatus get status => _status;
 
@@ -50,7 +55,8 @@ class NetworkStatus extends ChangeNotifier {
         });
         break;
       case NetworkRequestStatus.rateLimited:
-        _autoResetTimer = Timer(const Duration(minutes: 2), () {
+        // Use actual wait time + 1s buffer so countdown finishes before reset
+        _autoResetTimer = Timer(Duration(seconds: _rateLimitWaitSeconds + 1), () {
           _setStatus(NetworkRequestStatus.idle);
         });
         break;
@@ -86,9 +92,16 @@ class NetworkStatus extends ChangeNotifier {
     _setStatus(NetworkRequestStatus.timeout);
   }
 
-  /// Rate limited by API
-  void setRateLimited() {
-    debugPrint('[NetworkStatus] Rate limited by API');
+  /// Rate limited by API, with countdown duration from Overpass /api/status
+  void setRateLimited({int waitSeconds = 5}) {
+    debugPrint('[NetworkStatus] Rate limited by API (${waitSeconds}s)');
+    final waitChanged = _rateLimitWaitSeconds != waitSeconds;
+    _rateLimitWaitSeconds = waitSeconds;
+    // If already rate-limited but wait time changed, force a status transition
+    // so the auto-reset timer and countdown UI are updated.
+    if (_status == NetworkRequestStatus.rateLimited && waitChanged) {
+      _status = NetworkRequestStatus.idle; // allow _setStatus to re-enter
+    }
     _setStatus(NetworkRequestStatus.rateLimited);
   }