SNGNav

SNGNav is an offline-first navigation architecture built for Flutter, designed to function reliably under degraded conditions such as GPS loss, network failure, or extreme weather. It integrates dead reckoning with Kalman filtering for location continuity during signal loss, supports MBTiles for offline map rendering, and offers dual routing via OSRM or Valhalla — either self-hosted or public endpoints. Weather hazard detection includes black-ice and pre-trip advisories sourced from JMA, MET Norway, and NWS. The system runs on Linux desktop (x64) and has experimental ARM64 support via Yocto/QEMU, though GL rendering remains blocked upstream (flutter#183495). Safety overlays are ASIL-QM compliant, display-only, and render above all UI layers during hazardous conditions. The project consists of 36 independently versioned pub.dev packages, including modules for consent-driven fleet data, simulated environments, and provider configuration via Dart defines. While flutter_map provides the tile rendering foundation, SNGNav adds resilience layers: sensor fusion, offline-capable pipelines, and scenario-based fault tolerance. Demo profiles simulate snowstorms, tunnel navigation, and route hazards. Real hardware deployment (e.g., Raspberry Pi) is unverified. Configuration allows swapping providers without code changes. Offline mode requires manual MBTiles setup; default tile source falls back to online OSM. CI now tests all 36 packages across every branch, with 3,181+ passing tests as of August 2026. Not intended to replace commercial navigation but to serve edge cases where connectivity fails — targeting developers building safety-critical systems for drivers in extreme environments.