GPT-6.1 Sol's no-CoT runs close 80% of the gap to Astra
Rauno Arike's own runs show 6.1 Sol closing 80% of the no-CoT gap to Astra; if the looped-architecture hypothesis holds, monitorability is affected.
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GPT-6.1 Sol closes 80% of the no-CoT gap between GPT-6 Sol and GPT-6 Astra, according to researcher Rauno Arike's own runs across 27 tasks.
Previously, models in the no-CoT tier lagged Astra clearly, and there was little independent testing of that tier.
The runs reuse the task suite from an earlier Astra no-CoT evaluation, one sample per question; 6.1 Sol sits closer to Astra than to 6 Sol on 24 of 27 tasks. The 50% time-horizon estimate rises from 4 minutes for 6 Sol to 35 minutes, though most benchmarks saturate and the intervals are wide.
The author hypothesizes that 6.1 Sol is a looped transformer, possibly Astra Minor released under a different name, based on circumstantial evidence such as an Azure registry path; OpenAI has not confirmed this. The results are one researcher's own runs, and the Astra and GPT-5.5 scores were taken from the earlier post rather than re-run.