App stability and the tracing algorithm filters are improved for a better and accurate scanning result.
A place is defined as a safe when the number of scanned devices is less than 4, low density crowd when between 4 and 8, and if the scan result returns more than 8 devices, the place is defined as a high density crowd.
The tracing algorithm, filters out the devices which has a signal strength higher than -90dB.
Keep in mind that the algorithm is not very precise because different manufacturers has a different blueotooth hardware, or bacause the number of nearby bluetooth devices is not associated as 1:1 relation with a person.
The tracing algorithm is set to scan every 5 minutes and the scanning duration is set 5 seconds (chosen after debugging during different tests).
The generated apk is signed, so if you see an error from Play Store Protection, it it beacause the organization details is not registred on Google Play Console.
Feel free to open a pull request for any kind of bug.