If we’re talking specifically about executable scripts, here is #bash’s (libera.chat) factoid on the matter:

Don’t use extensions for your scripts. Scripts define new commands that you can run, and commands are generally not given extensions. Do you run ls.elf? Also: bash scripts are not sh scripts (so don’t use .sh) and the extension will only cause dependencies headaches if the script gets rewritten in another language. See http://www.talisman.org/~erlkonig/documents/commandname-extensions-considered-harmful

It’s for these reasons that I keep my executable scripts named without extensions (e.g. install).

I sometimes have non-executable scripts: they’re chmod -x, they don’t have a shebang, and they’re explicitly made for source-ing (e.g. library functions). For these, I give them an extension depending on what shell I wrote them for (and thus, what shell you need to use to source them), e.g. library.bash or library.zsh.

Yeah, I use weechat.

But in the interest of sharing something new: I do also like ii, which is a minimal filesystem-based IRC client. To tail a channel’s messages, for example, you could do

tail -f #vim/out

Then to send a message,

echo 'Hello, world!' > #vim/in

Fun for the first five minutes just pulling together a makeshift IRC client with tmux panes and the above, but then you realize the depth of the iceberg with its scriptability with standard Unix pipelines. Tail out into a perl script that pipes back into in for example and you have a bot.