Manual:Coding_conventions/CSS proposes some standards for CSS and LESS files. Projects should be able to opt in to the enforcement of these standards by adding a CSS linter to their build checks, similar to how they run jshint and phpcs for JavaScript and PHP coding conventions. Several projects have a csslint rule in Gruntfile.json, but csslint isn't aware of LESS syntax.
Possibilities:
- There is a LESS Lint Grunt plugin that works by compiling LESS files into CSS using the npm less and running csslint on its output. But that output may not match the CSS generated by the PHP LESS compiler (leafo/lessphp) that MediaWiki's ResourceLoader uses.
- recess is a native LESS linter.