The fact that a terminal multiplexer can not be created just as a sidecar project is exactly the reason why it is better to build them as a whole. The editor do

The fact that a terminal multiplexer can not be created just as a sidecar project is exactly the reason why it is better to build them as a whole. The editor does need a lot of terminal multiplexer features, and instead of letting them grow into a mess, it's better to do it systematically from the beginning. To put it another way: If you are going to have an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp anyway, why not just have Common Lisp as part of the program when you start?