GPT-6 Astra maxes ARC-AGI-3 with compaction, but harnesses differ
mhmazur · x · 2026-09-04
Steven Heidel (OpenAI) showed GPT-6 Astra maxing out ARC-AGI-3 when compaction is enabled in the Responses API, beating Opus 5 and GPT-5.6 Sol. But mhmazur notes the comparison isn't apples to apples: Astra's score uses the new Provider Adapter harness (preserving opaque reasoning across requests and compaction), while Opus 5 and GPT-5.6 Sol were run on the Standard harness.
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