Chollet: GPT-6 Astra is a 'step-function change' on ARC-AGI-3

François Chollet's X thread on Sept 3, 2026: GPT-6 Astra is a step-function change for interactive reasoning, scoring 66% on ARC-AGI-3 with the standard harness and nearly 100% with a continuous-conversation harness and custom compaction, at roughly $360 per game; he describes the model building efficient symbolic world models with its own shorthand DSL. In follow-ups he says saturation came about 2x faster than his one-year prediction (x.com/fchollet/status/2095601829367480386) and that ARC Prize is not claiming this is AGI (x.com/fchollet/status/2095599835932135919). The ARC Prize blog "OpenAI's GPT-6 Astra on ARC-AGI-3" (arcprize.org/blog/astra, Greg Kamradt) reports 62.7% standard vs 99.9% with a provider adapter, beating the median human's action count on 96% of levels; Mike Knoop: "we lack evidence to call this AGI yet". The Decoder reported Astra pulled Chollet's AGI forecast forward. Verified via the X syndication endpoint (fchollet, 2026-09-03T19:42Z).

GPT-6 Astra represents a step-function change in model capability for interactive reasoning problems. It scores 66% on ARC-AGI-3 using our standard harness, and nearly 100% with a continuous conversation harness and custom compaction, at a cost of roughly $360 per game.

In fact, the continuous harness version significantly outperforms our human baseline in action efficiency across almost all levels. When we examined the reasoning chains to understand how the model operates, we found it performing highly efficient, on-the-fly symbolic world modeling for each game and level. It goes as far as developing its own shorthand DSL to represent in-game situations -- essentially a game-specific algebraic notation.

Overall, Astra exhibits symbolic modeling behaviors we had previously only seen with sophisticated harnesses -- so harness capabilities are increasingly shifting into the model itself.

We see Astra as a major breakthrough in model intelligence.

Read our post on Astra and what these results mean: https://arcprize.org/blog/astra

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Archived 2026-09-29 via fxtwitter (unofficial).