Uncommon but useful static site generator features

Roughly 25 years ago, I released my first static site generator. Compared to back then, we now live in a world of embarrassing SSG abundance, where there seems to be a handful of quality SSGs for every language, framework, or mental model I can imagine. Other than the mess of non-portable Markdown extensions, it feels like a golden age. Yet, there are still numerous features I rely on that aren't widely supported in popular SSGs. Here are the features I wish were more common. (And, yes, I have implemented these in luasmith.) Relative link translation Let's say you have a link between two files in your site's source. In Markdown, this could be a source file named post1.md with a link like [some other post](post2.md). In the process of converting to HTML, these files' extensions might change to .html (or they might be placed into subdirectories like post2/index.html). My opinion is that any link that worked before conversion to HTML should work after. Unfortunately, many SSGs don't…