too much, sorry

lib/services/map_data_submodules/nodes_from_overpass.dart

@@ -47,6 +47,13 @@ Future<List<OsmNode>> _fetchOverpassNodesWithSplitting({
       profiles: profiles,
       maxResults: maxResults,
     );
+  } on OverpassRateLimitException catch (e) {
+    // Rate limits should NOT be split - just fail with extended backoff
+    debugPrint('[fetchOverpassNodes] Rate limited - using extended backoff, not splitting');
+    
+    // Wait longer for rate limits before giving up entirely  
+    await Future.delayed(const Duration(seconds: 30));
+    rethrow; // Let caller handle as a regular failure
   } on OverpassNodeLimitException {
     // If we've hit max split depth, give up to avoid infinite recursion
     if (splitDepth >= maxSplitDepth) {
@@ -99,16 +106,31 @@ Future<List<OsmNode>> _fetchSingleOverpassQuery({
       final errorBody = response.body;
       debugPrint('[fetchOverpassNodes] Overpass API error: $errorBody');
       
-      // Check if it's a node limit exceeded error
-      if (errorBody.contains('too many') || 
-          errorBody.contains('50000') || 
-          errorBody.contains('50,000') ||
-          errorBody.contains('limit') ||
-          errorBody.contains('runtime error')) {
-        debugPrint('[fetchOverpassNodes] Detected node limit error, will attempt splitting');
+      // Check if it's specifically the 50k node limit error (HTTP 400)
+      // Exact message: "You requested too many nodes (limit is 50000)"
+      if (errorBody.contains('too many nodes') && 
+          errorBody.contains('50000')) {
+        debugPrint('[fetchOverpassNodes] Detected 50k node limit error, will attempt splitting');
         throw OverpassNodeLimitException('Query exceeded node limit', serverResponse: errorBody);
       }
       
+      // Check for timeout errors that indicate query complexity (should split)
+      // Common timeout messages from Overpass
+      if (errorBody.contains('timeout') || 
+          errorBody.contains('runtime limit exceeded') ||
+          errorBody.contains('Query timed out')) {
+        debugPrint('[fetchOverpassNodes] Detected timeout error, will attempt splitting to reduce complexity');
+        throw OverpassNodeLimitException('Query timed out', serverResponse: errorBody);
+      }
+      
+      // Check for rate limiting (should NOT split - needs longer backoff)
+      if (errorBody.contains('rate limited') || 
+          errorBody.contains('too many requests') ||
+          response.statusCode == 429) {
+        debugPrint('[fetchOverpassNodes] Rate limited by Overpass API - needs extended backoff');
+        throw OverpassRateLimitException('Rate limited by server', serverResponse: errorBody);
+      }
+      
       NetworkStatus.instance.reportOverpassIssue();
       return [];
     }

lib/services/map_data_submodules/tiles_from_remote.dart

@@ -3,6 +3,8 @@ import 'dart:io';
 import 'dart:async';
 import 'package:http/http.dart' as http;
 import 'package:flutter/foundation.dart';
+import 'package:latlong2/latlong.dart';
+import 'package:flutter_map/flutter_map.dart';
 import 'package:deflockapp/dev_config.dart';
 import '../network_status.dart';
 
@@ -18,6 +20,77 @@ void clearRemoteTileQueue() {
   }
 }
 
+/// Clear only tile requests that are no longer visible in the given bounds
+void clearRemoteTileQueueSelective(LatLngBounds currentBounds) {
+  final clearedCount = _tileFetchSemaphore.clearStaleRequests((z, x, y) {
+    // Return true if tile should be cleared (i.e., is NOT visible)
+    return !_isTileVisible(z, x, y, currentBounds);
+  });
+  
+  if (clearedCount > 0) {
+    debugPrint('[RemoteTiles] Selectively cleared $clearedCount non-visible tile requests');
+  }
+}
+
+/// Calculate retry delay using configurable backoff strategy.
+/// Uses: initialDelay * (multiplier ^ (attempt - 1)) + randomJitter, capped at maxDelay
+int _calculateRetryDelay(int attempt, Random random) {
+  // Calculate exponential backoff: initialDelay * (multiplier ^ (attempt - 1))
+  final baseDelay = (kTileFetchInitialDelayMs * 
+    pow(kTileFetchBackoffMultiplier, attempt - 1)).round();
+  
+  // Add random jitter to avoid thundering herd
+  final jitter = random.nextInt(kTileFetchRandomJitterMs + 1);
+  
+  // Apply max delay cap
+  return (baseDelay + jitter).clamp(0, kTileFetchMaxDelayMs);
+}
+
+/// Convert tile coordinates to lat/lng bounds for spatial filtering
+class _TileBounds {
+  final double north, south, east, west;
+  _TileBounds({required this.north, required this.south, required this.east, required this.west});
+}
+
+/// Calculate the lat/lng bounds for a given tile
+_TileBounds _tileToBounds(int z, int x, int y) {
+  final n = pow(2, z);
+  final lon1 = (x / n) * 360.0 - 180.0;
+  final lon2 = ((x + 1) / n) * 360.0 - 180.0;
+  final lat1 = _yToLatitude(y, z);
+  final lat2 = _yToLatitude(y + 1, z);
+  
+  return _TileBounds(
+    north: max(lat1, lat2),
+    south: min(lat1, lat2),
+    east: max(lon1, lon2),
+    west: min(lon1, lon2),
+  );
+}
+
+/// Convert tile Y coordinate to latitude
+double _yToLatitude(int y, int z) {
+  final n = pow(2, z);
+  final latRad = atan(_sinh(pi * (1 - 2 * y / n)));
+  return latRad * 180.0 / pi;
+}
+
+/// Hyperbolic sine function: sinh(x) = (e^x - e^(-x)) / 2
+double _sinh(double x) {
+  return (exp(x) - exp(-x)) / 2;
+}
+
+/// Check if a tile intersects with the current view bounds
+bool _isTileVisible(int z, int x, int y, LatLngBounds viewBounds) {
+  final tileBounds = _tileToBounds(z, x, y);
+  
+  // Check if tile bounds intersect with view bounds
+  return !(tileBounds.east < viewBounds.west ||
+           tileBounds.west > viewBounds.east ||
+           tileBounds.north < viewBounds.south ||
+           tileBounds.south > viewBounds.north);
+}
+
 
 
 /// Fetches a tile from any remote provider, with in-memory retries/backoff, and global concurrency limit.
@@ -31,16 +104,10 @@ Future<List<int>> fetchRemoteTile({
   const int maxAttempts = kTileFetchMaxAttempts;
   int attempt = 0;
   final random = Random();
-  final delays = [
-    kTileFetchInitialDelayMs + random.nextInt(kTileFetchJitter1Ms),
-    kTileFetchSecondDelayMs + random.nextInt(kTileFetchJitter2Ms),
-    kTileFetchThirdDelayMs + random.nextInt(kTileFetchJitter3Ms),
-  ];
-  
   final hostInfo = Uri.parse(url).host; // For logging
 
   while (true) {
-    await _tileFetchSemaphore.acquire();
+    await _tileFetchSemaphore.acquire(z: z, x: x, y: y);
     try {
       // Only log on first attempt or errors
       if (attempt == 1) {
@@ -71,7 +138,7 @@ Future<List<int>> fetchRemoteTile({
         rethrow;
       }
       
-      final delay = delays[attempt - 1].clamp(0, 60000);
+      final delay = _calculateRetryDelay(attempt, random);
       if (attempt == 1) {
         debugPrint("[fetchRemoteTile] Attempt $attempt for $z/$x/$y from $hostInfo failed: $e. Retrying in ${delay}ms.");
       }
@@ -97,28 +164,42 @@ Future<List<int>> fetchOSMTile({
   );
 }
 
-/// Simple counting semaphore, suitable for single-thread Flutter concurrency
+/// Enhanced tile request entry that tracks coordinates for spatial filtering
+class _TileRequest {
+  final int z, x, y;
+  final VoidCallback callback;
+  
+  _TileRequest({required this.z, required this.x, required this.y, required this.callback});
+}
+
+/// Spatially-aware counting semaphore for tile requests
 class _SimpleSemaphore {
   final int _max;
   int _current = 0;
-  final List<VoidCallback> _queue = [];
+  final List<_TileRequest> _queue = [];
   _SimpleSemaphore(this._max);
 
-  Future<void> acquire() async {
+  Future<void> acquire({int? z, int? x, int? y}) async {
     if (_current < _max) {
       _current++;
       return;
     } else {
       final c = Completer<void>();
-      _queue.add(() => c.complete());
+      final request = _TileRequest(
+        z: z ?? -1, 
+        x: x ?? -1, 
+        y: y ?? -1, 
+        callback: () => c.complete(),
+      );
+      _queue.add(request);
       await c.future;
     }
   }
 
   void release() {
     if (_queue.isNotEmpty) {
-      final callback = _queue.removeAt(0);
-      callback();
+      final request = _queue.removeAt(0);
+      request.callback();
     } else {
       _current--;
     }
@@ -130,4 +211,17 @@ class _SimpleSemaphore {
     _queue.clear();
     return clearedCount;
   }
+  
+  /// Clear only tiles that don't pass the visibility filter
+  int clearStaleRequests(bool Function(int z, int x, int y) isStale) {
+    final initialCount = _queue.length;
+    _queue.removeWhere((request) => isStale(request.z, request.x, request.y));
+    final clearedCount = initialCount - _queue.length;
+    
+    if (clearedCount > 0) {
+      debugPrint('[SimpleSemaphore] Cleared $clearedCount stale tile requests, kept ${_queue.length}');
+    }
+    
+    return clearedCount;
+  }
 }