Should you support GFM and/or frontmatter here? Is so, you should use remark-gfm / remark-frontmatter.

Unless you need options passed into the function, I recommend to define the processor once outside of the function. This way plugins can cache some of the heavy lifting. This isn’t really applicable to your case, but IMO it’s a good practice. If you use GFM/frontmatter, this also allows you to keep the processor in sync with the stringify processor you use below.

const processor = unified()
 .use(remarkParse)
 .use(remarkFrontmatter)
 .use(remarkGfm)
 .use(remarkStringify)
// ...
let ast = processor.parse(changelog)

If you don’t want any of that, the remark abstractions don’t really offer much. You might as well use the slightly lower level mdast-util-from-markdown and mdast-util-to-markdown.

Thanks for the review! ❤️