The Model Is No Longer the AI: What GPT-6 Astra’s 99.9% ARC-AGI-3 Score Actually Measures
A model in isolation versus the same model embedded in a wider system. Editorial image generated by the author. When OpenAI released GPT-6 Astra, one number inevitably attracted most of the attention: 99.9 percent on ARC-AGI-3. Only a couple of months earlier, GPT-5.6 Sol had scored 7.8 percent on the semi-private evaluation. Read literally, the comparison suggests an almost absurd jump in capability. There is an important qualification. Astra did not score 99.9 percent using ARC Prize’s Standard harness. Under that evaluation its best result was 62.7 percent. The 99.9 percent score came from a Provider Adapter that preserves Astra’s opaque reasoning state between requests and uses context compaction during longer interactions. ARC Prize explicitly treats the two harnesses as answering different evaluation questions . The percentages themselves also need care. ARC-AGI-3 is not scored like an ordinary accuracy test. Its Relative Human Action Efficiency metric combines...