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+# RFCP Iteration 10.4 — Fix Stadia Maps 401 Error on Mobile
+
+**Date:** 2025-01-30  
+**Status:** Ready for Implementation  
+**Priority:** Medium  
+**Estimated Effort:** 10-15 minutes
+
+---
+
+## Problem Statement
+
+On mobile Safari (iOS), the Topo/Elev map tiles show:
+```
+401 Error
+Invalid Authentication
+docs.stadiamaps.com/authentication
+```
+
+**Root Cause:** Stadia Maps requires API key authentication for production use. Desktop browsers may work due to referrer/caching, but mobile Safari enforces stricter policies.
+
+**Affected Features:**
+- Topo button (topographic map layer)
+- Elev button (elevation/terrain layer)
+
+---
+
+## Solution
+
+Replace Stadia Maps tiles with **OpenTopoMap** — a free, open-source topographic map that requires no authentication.
+
+### Why OpenTopoMap?
+
+| Feature | Stadia (Stamen) | OpenTopoMap |
+|---------|-----------------|-------------|
+| API Key Required | Yes | **No** |
+| Rate Limits | 200k/month | None (fair use) |
+| Mobile Support | Requires auth | **Works everywhere** |
+| Contour Lines | Stylized | **More detailed** |
+| Style | Artistic | Technical/Professional |
+| Best For | Design | **RF Planning** ✓ |
+
+OpenTopoMap is actually **better suited** for RF coverage planning — more technical appearance with detailed elevation contours.
+
+---
+
+## Implementation
+
+### File to Modify
+
+`/opt/rfcp/frontend/src/components/map/Map.tsx`
+
+### Find Current Stadia URLs
+
+Look for URLs containing:
+- `tiles.stadiamaps.com`
+- `stamen_terrain`
+- `stamen_toner`
+
+### Replace With OpenTopoMap
+
+**Before (Stadia Maps):**
+```typescript
+const topoLayer = L.tileLayer(
+  'https://tiles.stadiamaps.com/tiles/stamen_terrain/{z}/{x}/{y}{r}.png',
+  {
+    attribution: '© Stamen Design, © OpenMapTiles, © OpenStreetMap',
+    maxZoom: 18,
+  }
+);
+```
+
+**After (OpenTopoMap):**
+```typescript
+const topoLayer = L.tileLayer(
+  'https://tile.opentopomap.org/{z}/{x}/{y}.png',
+  {
+    attribution: 'Map data: &copy; <a href="https://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://viewfinderpanoramas.org">SRTM</a> | Map style: &copy; <a href="https://opentopomap.org">OpenTopoMap</a> (<a href="https://creativecommons.org/licenses/by-sa/3.0/">CC-BY-SA</a>)',
+    maxZoom: 17,  // OpenTopoMap max zoom is 17
+  }
+);
+```
+
+### Also Check for Elevation Layer
+
+If there's a separate elevation/terrain layer, replace similarly:
+
+**Before:**
+```typescript
+'https://tiles.stadiamaps.com/tiles/stamen_terrain_background/{z}/{x}/{y}{r}.png'
+```
+
+**After:**
+```typescript
+'https://tile.opentopomap.org/{z}/{x}/{y}.png'
+```
+
+### Alternative: Keep Both Options
+
+If you want to keep Stadia as an option (for desktop users who like the style), you could:
+
+1. Try OpenTopoMap first
+2. Fallback to Stadia if user has API key configured
+3. Or just replace completely (simpler)
+
+**Recommendation:** Just replace completely — OpenTopoMap is better for this use case anyway.
+
+---
+
+## Testing Checklist
+
+- [ ] Desktop Chrome: Topo button shows OpenTopoMap tiles
+- [ ] Desktop Chrome: Elev button works (if separate from Topo)
+- [ ] Mobile Safari: No 401 errors
+- [ ] Mobile Safari: Topo/terrain tiles load correctly
+- [ ] Mobile Chrome: Same tests
+- [ ] Zoom levels 1-17 work correctly
+- [ ] Attribution displays properly
+- [ ] Coverage heatmap overlays correctly on new tiles
+
+---
+
+## Verification Commands
+
+After implementation:
+
+```bash
+cd /opt/rfcp/frontend
+
+# Check for any remaining Stadia references
+grep -r "stadiamaps" src/
+
+# Should return empty (no matches)
+
+# Build and deploy
+npm run build
+sudo systemctl reload caddy
+```
+
+---
+
+## Rollback Plan
+
+If OpenTopoMap has issues (unlikely), can switch to other free providers:
+
+1. **Esri World Topo:**
+   ```
+   https://server.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer/tile/{z}/{y}/{x}
+   ```
+
+2. **CartoDB Voyager:**
+   ```
+   https://{s}.basemaps.cartocdn.com/rastertiles/voyager/{z}/{x}/{y}{r}.png
+   ```
+
+---
+
+## Notes
+
+- OpenTopoMap maxZoom is 17 (not 18 like Stadia)
+- OpenTopoMap servers are in Germany — may be slightly slower for Ukraine, but still fast
+- Fair use policy: don't hammer the servers with excessive requests
+- HTTPS required (already using it)
+
+---
+
+## Reference
+
+- OpenTopoMap: https://opentopomap.org/
+- Leaflet Providers: https://leaflet-extras.github.io/leaflet-providers/preview/
+- Previous iteration: RFCP-Iteration10.3.2-Fix-Boundary-Rendering.md