The diff comment editor is restyled as the shared comment pill (context
line inside the box, auto-growing textarea, round attach button;
Cmd/Ctrl+Enter attaches, Enter breaks the line) and the saved-comment
card matches the composer preview entries. Pierre's gutter utility is
enabled: hovering a line shows a small primary-colored plus that opens
a comment for the line, dragging from it selects a range, and it rides
the bottom of an active selection. Clicking a diff line toggles a
single-line comment, and dragging over content maps to the same line
selection the number column produces — the native text selection is
suppressed once a drag crosses a line boundary — opening the editor for
the range on release. Placeholders and meta lines are dimmed relative
to typed text.