Building

1. Root your phone with Magisk

2. Fetch framework.jar and android.hidl.base-V1.0-java.jar

   This app needs system/hidden functions, and this was the easiest/simplest way I could find to make them available. If you know a better way, please tell me!

   mkdir app/system_libs
   cd app/system_libs
   
   # retrieve from running phone
   adb pull /system/framework/framework.jar .
   adb pull /system/framework/android.hidl.base-V1.0-java.jar .
   
   # convert to .class files, ignoring actual code (basically "headers" only)
   dex2jar framework.jar -nc
   dex2jar android.hidl.base-V1.0-java.jar -nc
   
   # (optional) delete the original jar files
   rm framework.jar android.hidl.base-V1.0-java.jar

3. Build and install with Android Studio (probably easier) or ./gradlew installDebug

4. Build the Magisk module with ./gradlew magisk_module, and install build/open_aguiExtModule_permissions.zip with Magisk on the phone