[endrix]

What

After a node moves, its edges keep the routes the layout gave them and only their ends follow the ports. The router runs only for an edge whose kept route would not do.

Why

ELK routes edges together, so edges into one port share a trunk. After a move the server routed the moved node's edges anew with its own router, each edge on its own and each in its own channel, so the trunk came back as a comb of parallel lines with a knot at the port. A move of a few pixels (4px counts, so does an arrow key on a selected node) scrambled the picture, and only a new Layout undid it.

How

• The dead-zone slide, which kept a route only for a move under 5px and only when every incident edge could be slid, now applies at any distance and edge by edge. The end goes to the port's anchor; the bend next to it follows on the movement axis so the stub stays straight.
• An edge goes to the router only when the kept route would not do: no interior bend (a slid straight line is a diagonal), a stub turned back through its own node, a segment through a node (the moved node included), or a non-orthogonal result.
• A foreign edge is rerouted only when the moved node covers it, not when it came within the router's 15px padding.
• Only the node that moved counts as moved: the end whose port anchor left the route's end. Before, both ends of every incident edge counted, so edges near the far-end node were rerouted too.

Checked

• On the gemmini state document that showed the comb: of the nine edges of the moved node, eight keep ELK's trunk, the ninth (a straight edge) is routed; no other edge changes.
• reroute-keeps-the-layouts-trunk.test.ts: five tests, two fail on the old handler.
• Server 440, client 351 tests pass; typecheck passes.

https://claude.ai/code/session_01EToj6RJRMSSHQiqGNMU9wv