Function place_anchor_in_lines 

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

One seat-tree anchor placed against a file’s whole current lines - the files page’s resolution. The scope’s numbering IS the file’s own (the seat’s tree is where the comment was written), so unlike a diff scope whose numbering may belong to another base, the recorded line is trusted: in place when it still carries the anchor’s text, otherwise re-found by content plus neighbours, and Gone / Ambiguous as the diff resolver reports them.