Close Reading is the rage. Coding is the rage. Why not mix the two? You want your students to “mark up” the text with metacognitive markers? Why not use HTML or Markdown? You’d be killing two birds with one stone without having them touch a computer at all.
My advice? Make sure that students have interactive notebooks for the complex texts that they’re reading so that they’ll have plenty of space to “code” their thoughts. After all, coding is just a language and language is used to express yourself.