Greptile Summary

This PR implements a sophisticated marker decluttering system for the map screen. When multiple contacts share nearby GPS positions, their markers overlap and become unreadable. The solution uses a Union-Find algorithm to detect overlapping markers (within 60px threshold) and spreads them radially around their centroid with adaptive radius scaling based on cluster size.

Key implementation details:

• MarkerDeclutter.kt provides a pure, testable algorithm with no MapLibre dependency
• MapScreen integration recalculates positions dynamically on camera idle (zoom/pan)
• GeoJSON sources/layers for pins (small dots at true GPS) and connecting lines to offset markers
• Symmetric bitmap padding ensures iconAnchor("center") positions circles correctly
• User-configurable toggle in Map settings (default: enabled)

Test coverage: 15 unit tests for core algorithm + bitmap symmetry test + deduplication test + UI tests

Architecture highlights:

• Clean separation: algorithm is MapLibre-agnostic via ScreenToLatLng interface
• Proper reactive flow: Settings → DataStore → ViewModel → UI
• Efficient updates: only recalculates on camera idle, not every frame

Confidence Score: 5/5

• This PR is safe to merge with high confidence
• Well-architected implementation with comprehensive testing (15+ unit tests), clean separation of concerns, proper reactive flows, and no security concerns. The O(n²) lookup performance issue was already noted in a previous review. Code follows established patterns and includes proper documentation.
• No files require special attention

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[User toggles declutter in Settings] --> B[SettingsViewModel.setMapMarkerDeclutterEnabled]
    B --> C[SettingsRepository saves to DataStore]
    C --> D[mapMarkerDeclutterEnabledFlow emits]
    D --> E[MapViewModel collects flow]
    E --> F[MapState.mapMarkerDeclutterEnabled updates]
    F --> G[MapScreen LaunchedEffect triggers]
    
    H[Contact markers update] --> G
    I[Camera idle pan/zoom] --> J[onCameraIdleListener]
    J --> K[updateDeclutterSources]
    G --> K
    
    K --> L{declutterEnabled?}
    L -->|Yes| M[Project markers to screen space]
    M --> N[MarkerDeclutter.calculateDeclutteredPositions]
    N --> O[Union-Find groups overlapping markers]
    O --> P[Spread groups radially with adaptive radius]
    P --> Q[Convert back to lat/lng]
    Q --> R[Update marker GeoJSON with display positions]
    R --> S[Create pin/line GeoJSON for offset markers]
    
    L -->|No| T[Use original GPS positions]
    T --> R
    S --> U[Render map with decluttered markers]

_{Last reviewed commit: 49e26d4}

Codecov Report

✅ All modified and coverable lines are covered by tests.

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I really dislike this. Please make a option to not have it turned on when you do not like it.
When there are many markers on the map, i zoom into the map further and put them apart by doing so. The only reason to have such a thing is when i reached the max zoom-in and there are still two markers that overlap each other because they have both the same coordinates.
When i zoom out on the map, i can see where the most markers on the map are by having this visual blob build of many markers.

Where would you set the option ?

Settings -> Map Sources

In combination with a separate PR renaming 'Map Sources' to 'Map'

done