Tutorials, deep dives and product notes — built for developers.
GPT-6.1 Sol replaced GPT-6 Sol after seven days: +4 index points, +12 on Terminal-Bench 4.0, and a cache rate halved to $0.10. It also dropped the "none" reasoning setting, uses 10-30% more output tokens, and is measurably slower.
Across all six effort levels, GPT-6 Sol scores within a point of GPT-5.6 Sol and costs about half as much per task. Same-harness data on both, the full effort ladder, where coding improved, where knowledge work regressed, and the November price cliff.
OpenAI shipped GPT-6 Sol 90 minutes after Claude Opus 5.5, at half the token price. Artificial Analysis ran both on the same tests: Sol is cheaper to any index score up to about 44, then runs out of headroom. Every benchmark, both effort ladders and the real bill.
Terminal-Bench 4.0 checked Oct 6, 2026: Claude Opus 5.5 (64.8%) and Sonnet 5.5 (61.8%) now top the public tbench.ai board, with GPT-6 Astra and GPT-6.1 Sol tied at 58.2%. Vendor runs and Artificial Analysis results are reported separately, with harness, tokens and cost per row.
FrontierCode 1.1 Main: Opus 5.5 leads at 54.6%; new Cognition entries GPT-6.1 Sol (50.2%) and Claude Haiku 5.5 (46.4%) include effort, rollout spend, API rates and token details. Updated October 9, 2026.
DeepSWE v1.1: Datacurve's standardized leaderboard is kept separate from provider runs. Adds Google-reported Gemini 4 Argon at 77.9% and Ornith-1.5-397B at 56.0%; per-task costs are marked unavailable. Updated October 9, 2026.