A diagram is data, not a drawing

I gave one model the same 44-node architecture twice. The first time I asked for raw SVG — place every box, route every edge, hand me the coordinates. The second time I asked it to describe the same system as typed JSON and let a layout engine draw it. Same model, same session, same brief. The only thing I changed was the output boundary. The boxes are fine in both. I want to be upfront about that, because the usual version of this pitch is out of date. Models place labeled boxes well now. If you ask a current frontier model for a six-box flowchart as SVG you get a clean six-box flowchart, and if that's what you need, go do that — it's the right tool and I'm not going to pretend otherwise. What broke was the edges. With no routing algorithm the model just drew long diagonals straight through unrelated boxes. Not a few — everywhere the graph got dense. And when I changed one node, the entire hand-placed coordinate layout had to be regenerated, and came back different. That second part is the one that actually annoyed me. It's not a rendering bug you can squint past. The picture is a dead artifact: you can't diff it, you can't edit one box, you can't get the same one twice. Every change is a full regeneration and a fresh roll of the dice. This isn't a "wait for a better model" problem Here's the part I'd push back on if someone else wrote it, so let me make the case. Routing a connector around obstacles across a nested graph is global constraint optimization. It's the specific thing layout engines like ELK exist to solve. A model emitting SVG has to commit to an x/y for every point, in order, with no way to backtrack once it sees the whole picture — it's predicting the next token, not solving a layout. So a better model gives you nicer boxes, not untangled edges . The failure is structural, and I'd expect it to reproduce across models past a couple dozen nodes. If you don't buy that, the honest move is to test it: throw a 40-node architecture at whatever model you tru