Guardian Bubble is a live parental control platform. I inherited an existing Flutter codebase and took ownership of its hardest features — location tracking at scale, SOS that fires in killed-app state, and platform-level integrations most Flutter apps never touch.
SOS fires even when the app is killed — FCM wakeup triggers audio-only processing mode without foregrounding. Debugged a production bug where audio codec wasn't initialised on cold boot, causing the first alarm to be silently missed while the second worked. Found via adb logcat after controlled repros.
Flicker-free route rendering on the live map — implemented Douglas-Peucker path simplification and KDE smoothing on raw GPS traces, combined with Google Maps and Mapbox map-matching. Live ETA, distance, and bearing computed in real time.
1,000+ contact sync without blocking the UI — contact parsing runs in a Dart isolate off the main thread, with multi-device session switching maintaining state continuity across a cubit managing multiple child accounts.
Platform-level iOS SOS: critical alerts bypass Do Not Disturb, app-lifecycle-aware dialogs resurface on resume so a parent never misses an active alarm. Synthetic location detection prevents false SOS triggers from mock location apps.
Modernised inherited codebase: migrated deprecated APIs to Clean Architecture, added Husky hooks, and wrote unit tests on API parsing and result processing — caught a pre-release parsing bug that would have broken location history for all users before it shipped.
Live on App Store and Play Store. 99.9% crash-free rate with continuous background location streaming across iOS and Android. SOS system reliable in killed-app state across all tested devices.