Some time ago I found xonsh which is a python-based shell. It had really good multiline support, and I am searching for a shell with sameish multiline support as xonsh. Fish shell also has good multiline support, it is around the same level, but it is not posix compatible. I want a shell that has that kind of level of multiline, but zsh (bash is also fine) compatible.

Does anyone know of one?

edit: based on the replies, I get this is unclear. My problem with zsh is that if i press enter and it starts a new line, I can’t get back to the prevous line, because a new prompt is started. In fish this is possible, all lines are one prompt. But, fish is not posix compatible. So, I guess I want a posix-compatible shell with fish-like lines (multiple line) editing. I wanted zsh support to keep using my custom oh-my-zsh prompt, but remaking it for a new shell is not a big problem. Sorry for being unclear.