In this case the code is public and you can see they are not cheating in that sense.
Here is the ARC-AGI-3 specific harness by the way - lots of challenge information encoded inside: https://github.com/symbolica-ai/ARC-AGI-3-Agents/blob/symbol...
1. https://github.com/symbolica-ai/ARC-AGI-3-Agents/blob/symbol...