A range or hunk selection covers a stretch of the diff, and restoring only
the cursor left the other end pointing at whatever line the new rendering
happened to put there — with more context lines above, a selected hunk
would grow a tail of context it never covered.
So the other end is remembered by identity too, and put back before the
cursor. If it is a line the re-render dropped, the selection is left as the
single line we landed on: there is no telling which line inherits a
selection's edge, and a wrong guess acts on lines the user never chose.
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>