Outputs are keyed by port, so a bare value cannot be one. The single mapping point every caller routes through raised a bare AttributeError from retval.items(); it now names the problem, and the message reaches the node the way its other errors do. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01H7LwYgJfpkbLCTeiAf8U4A