You may feel better to know that the web server is not part of the shell itself. It's a separate Python script that does its work by invoking fish and sending it commands. Its source is here: https://github.com/fish-shell/fish-shell/blob/master/share/t...
You guys keep beating around the bush and keep downvoting me! Is the web server built-in? Yes, it is. Why do you keep finding excuses and why do you keep downvoting the voice of reasons - a shell should not have a web server in its codebase, period. Put this into an optional package and make everybody happy!
You are just shouting that a shell should not have a web server in it's codebase, but you are giving no reasons why. I am using vim in the console to this day, and I don't mind my shell having a web interface for the most common use cases.
Some people do find the web interface useful, otherwise it wouldn't be there. On the other hand, you are not providing any reasons why a web server is harmful, why would anybody listen to you as the voice of reason, if your axiom is "a shell should not have a web server in its codebase, period"?
Fish is a deviant. There are thousands of *nix projects out there, many with a much more desperate need for a web UI, but they simply don't do it, because they know that they shouldn't cross that line.
