Claude Opus 5 scores 30% on ARC-AGI-3 on its own, so nearly all of a perfect run comes from the agent scaffolding wrapped around it. A code walkthrough goes through the open source harness line by line to show how that scaffolding works.
The write-up credits a harness built with Strands and puts the final score at 99.95%. NVIDIA's developer blog and The New Stack, though, attribute the 100% result with Claude Opus 5 to NVIDIA's own AVO coding agent, which cleared every level of the benchmark.