A chevron in front of the title toggles it without touching the selection,
and right-click offers Collapse node / Expand node for the whole selection
as one undo step. A collapsed node draws its title bar alone; every link of
one side meets at a single point on it, and hidden links there share one
mark per side, since per-port marks would stack on the same pixels. It has
no ports to grab, so a link dropped on it connects nothing.
Like hiding a link this is drawing only: collapsed is saved on the node and
an expanded node leaves no trace in the project file.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
