"This isn't a tutorial," he said, zooming in on a recycle loop. "This is a negotiation. You propose a flowsheet. The machine calculates the physics. Where you meet—that's the answer. If there's no meeting point, your physics is wrong."

Chloe leaned forward, her nose almost touching the screen. "Why didn't it converge?"

Marcus blinked. He had been so used to the ritual of tweaking damping factors and re-initializing from a saved backup that he had stopped listening . He re-read the error log. She was right.

He clicked and dragged. A . A Heater . A RadFrac column. The canvas filled with blue blocks and green streams. Chloe scribbled furiously.