Eggdrop [0] and BitchX [1] come to mind. Irssi [2] has a plugin that enables Tcl scripting.

I'm currently fiddling with TkCAD [3] in order to put a small CNC machine to use here, it needs some small adaptations to work on Linux, but I think it's a nice find!

[0] https://eggheads.org/

[1] http://bitchx.sourceforge.net/

[2] https://irssi.org/

[3] https://github.com/revarbat/TkCAD