Offline-first field app that syncs when the power comes back

Amanzi Meters sends readers to record water meters across Cape Town. Two things keep breaking their current app. Signal drops in many areas, and scheduled power cuts take mobile towers and the office offline for two to four hours at a time. The app they have assumes the network is always there, so readers lose a morning of work when it is not, and sometimes the same reading is uploaded twice and a household is billed oddly.

Each reader records about 120 meters a day: a meter id, a reading, a timestamp and sometimes a photo. The utility needs an app where a reader can work for a whole shift with no network at all, and where everything they recorded reaches the server exactly once when the network returns, even if the app was closed and reopened in between.

You will build the app and a small sync server. The app stores every reading in a local database first and shows the reader whether each one is saved locally, syncing or confirmed by the server. A background sync sends pending readings when the network is available, retries on failure, and uses an id the app generates so the server can reject duplicates. You will generate test readings and simulate flaky network and power cuts, because you cannot take a bus around Cape Town. Done looks like a reader completing a 120-meter shift fully offline, then watching every reading sync once when the network returns, with a counter that proves none were lost and none were duplicated.