Start positions for one load. A node that survived the previous layout keeps
its settled position; a NEW node is seeded at the centroid of the neighbours
that have one, because the cold-load box is wrong for it twice over: the
layout spreads far wider than SEED_SPREAD, so an imported paper would start
nowhere near its authors and then cross the canvas under the link force, and
a clump of new nodes at the origin shoves the settled neighbourhood apart
under a viewport an in-place reload deliberately does not reframe.
Start positions for one load. A node that survived the previous layout keeps its settled position; a NEW node is seeded at the centroid of the neighbours that have one, because the cold-load box is wrong for it twice over: the layout spreads far wider than SEED_SPREAD, so an imported paper would start nowhere near its authors and then cross the canvas under the link force, and a clump of new nodes at the origin shoves the settled neighbourhood apart under a viewport an in-place reload deliberately does not reframe.