mosh VS widecharwidth

there is a fork with port forwarding support https://github.com/rinne/mosh and a PR with a long discussion https://github.com/mobile-shell/mosh/pull/696 on why it's not merged

you can compile them yourself or if you want to skip the step I recently set up GitHub actions to compile linux binaries of this [1][2], tested by a sample of 1 so no guarantees it works, was planning on doing a tap PR/tap of it at some point

also the official developers have been involved a project to solve this while improving the whole-agent approval things also https://github.com/StanfordSNR/guardian-agent , but I couldn't get it to work which is why I tried the fork and got that working

[1] https://github.com/gnyman/mosh/actions/runs/1068715036

>For example, iTerm2 considers the "rosette" emoji to have width 1

The reason for this is quite possibly that Unicode 9 changed the width for some codepoints (mostly emoji) from 1 to 2, and iTerm until very recently (don't know if it's released yet) defaulted to the Unicode 8 widths, with an opt-in escape sequence to change to Unicode 9.

>This approach comes from the wcwidth utility, and the comment at the top of the C source file provides further insight into the difficulties faced here.

That's link goes to Markus Kuhn's implementation from 2007. It supports Unicode 5, and is by now woefully out of date. You don't want to use it anymore.

Most terminals have their own definition, and the annoying part is that the client application and the terminal need to have theirs in sync or they get weird glitches when moving the cursor.

Shameless plug: Fish's solution is widecharwidth[0], which is a python script that parses the Unicode data files and generates a wcwidth for C++, Javascript and Rust. It's still a wcwidth, meaning that it has issues with joining code points, but it's at least a start. It's up-to-date with Unicode 14 and, unless they change the data format (again) should be easy to update to future Unicode releases.

It's public domain and used by at least fish and WezTerm.

[0]: https://github.com/ridiculousfish/widecharwidth

With fish we've made the experience that relying on libc isn't good enough.

Specifically in the case of connecting to a server that typically has an old libc with old unicode information, from a desktop that has a much newer system, or in case of ambiguous characters, where libc will just give you one width that might not match what the terminal actually renders (and they frequently have configuration options to change it!).

So we've made something we call widecharwidth (https://github.com/ridiculousfish/widecharwidth), which is a python script that parses the unicode datafiles (UnicodeData.txt, emoji-data.txt and friends) and generates a header you can #include.

And someone's opened a PR to mosh to integrate it: https://github.com/mobile-shell/mosh/pull/1143