OpenAI's Responses API Compaction Pushes GPT-6 Astra to Full Marks on ARC-AGI-3

OpenAI engineer Steven Heidel introduced Compaction in the Responses API, which compresses long conversation state. With it enabled, GPT-6 Astra scored full marks on ARC-AGI-3, though some noted the benchmark conditions were not entirely fair.

2026-09-04 ~ 2026-09-04 · 3 related posts

• OpenAI Ships Responses API Compaction as GPT-6 Astra Maxes Out ARC-AGI-3 — stevenheidel · 2026-09-04
• OpenAI's Heidel: compaction in Responses API lets GPT-6 Astra max out ARC-AGI-3 — stevenheidel · 2026-09-04
• GPT-6 Astra maxes ARC-AGI-3 with compaction, but harnesses differ — mhmazur · 2026-09-04