It claimed to run the pipeline with no engine involved, and could not: the node bodies it called save and load artifacts, which raise outside a node by design. Each node is now a thin wrapper over a plain function — make_rows, train_curve, score — and __main__ calls those, which is the split the sandbox already demonstrates and the one worth copying. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>