Function place_document_anchor 

pub fn place_document_anchor(
    anchor: &ReviewAnchor,
    lines: &[String],
) -> AnchorPlacement

A document anchor placed against the document’s whole current lines: the thread’s FIRST captured line is the key, looked for by content.

A document has no hunks, and a rendered block’s neighbours are not the anchor’s neighbours the way a code line’s are, so the code resolver’s neighbourhood rule is not this one. Identity is the captured line’s own text: in place at the recorded number, otherwise one unique match moves it, and two matches are a guess the placement refuses exactly as the code rule does.