Which class of QGC handles failsafe(Low battery and RC Loss)?

Hello, I have been in touch with QGC for about 100 days, and I am a developer who is bad at drones, open source, linux, git, Qt, and English. (Yes. It feels like a joke to me, too.)

I tried debugging the QGC source code for the first time with the F9, F5, and F10 buttons on QtCreator a few days ago (link), and before that, I was debugging with Ctrl+F and qDebug() message prints.

About a month ago, I started looking for the part that processes battery information in QGC, and I only recently found it (link), and now I’m trying to find the part that processes RTL(when a by user command or fail safety triggered) and RC loss occur, but I feel that my primitive level of debugging skill is not enough. I wish I could get a hint.

You can’t find it because it doesn’t exist. The firmware handles failsafe. In general QGC is just either a vehicle setup tool or a telemetry display tool. It doesn’t do much to actively control the vehicle. Except for simple things like say changing a flight mode through user interaction. -Don Gagne 2022.11.14

According to the answer obtained from the Dronecode Foundation’s discord channel, Firmware handles failsafe.
QGC dose not handle it.