Is it possible to write a kde/kwin extension that brings one of the windows in the current desktop/workspace to the front, based on some internal logic? This extension will need to get the list of windows and currently focused window, and somehow bring one of those windows to the front. Can it be done without maintaining a slightly modified fork of kwin? If yes, what apis do I use for this. (I haven't programmed for kde before).

What internal logic are you interested in? Without knowing the details, it is hard to decide if you need to modify the KWin sources.

If this is simply about matching text in the title or the X11 window class, you can use wmctrl and/or xdotool in a bash script.

More control is available via KWin scripting, see https://techbase.kde.org/Development/Tu ... /Scripting