The document is addressed as structure, not raw text. It pulls the heading outline out of a long document before deciding where to work, and searches for an exact passage rather than guessing at the first thing that looks similar.
When it changes a sentence, it can record that change as a tracked edit rather than a silent overwrite, so what moved stays visible and reversible. It also works inside the comment thread itself — reading what is open, replying, and resolving a thread only once the edit it asked for is actually in the document.