Comment by mananaysiempre

At one point I was wondering if there was a preexisting protocol for a character-based framebuffer of some sort, that we could then use to slice the problem in a different way: a framebuffer multipliexer running terminal emulators inside it instead of a terminal multiplexer emulating multiple terminals into a framebuffer and then translating it back into terminal controls for the parent.

Unfortunately, my conclusion was that the only independent character-based terminal tradition is IBM’s 3270 stuff, but even setting aside IBM weirdness it’s simply not that. (Yes, there’s also such a protocol within tmux but it’s not really compatible with anything else.)