> Things no program does or should do: change command-line processing, semantic behavior, or similar.

Arguably ripgrep breaks this rule. :-) Compare `echo foo | rg foo` and `rg foo`. The former will search stdin. The latter will search the current working directory.

In any case, I bring this up, because I've heard from folks that ripgrep changing its output format is "bad practice" and that it should "follow standard Unix conventions and not change the output format." And that's when I bring up `ls`. :-)