Updated
New AI coding model launches: adoption and first bug rates
As of Nov 1, 2026, the newest AI coding model on Bug Bench is GPT-6.1 Sol, released Sep 29, 2026. Of the 6 launched in the last 90 days, GPT-6 Luna has the lowest bug rate (0.34, #1 overall).
Launched in the last 90 days
Line = weekly share of AI-written code
GPT-6.1 Sol
Released Sep 29, 2026First seen week of Sep 28vs GPT-5.6 Sol →
#2 · 0.86
12.5% last week
Claude Sonnet 5.5
Released Sep 28, 2026First seen week of Sep 28
#3 · 0.88
4.5% last week
Claude Opus 5.5
Released Sep 22, 2026First seen week of Sep 21vs Claude Opus 5 →
#6 · 1.25
59.7% last week
GPT-6 Luna
Released Sep 22, 2026First seen week of Sep 21
#1 · 0.34
1.7% last week
GPT-6 Astra
Released Sep 4, 2026First seen week of Aug 31
#5 · 1.04
5.9% last week
Claude Fable 5.1
Released Sep 1, 2026First seen week of Aug 31vs Claude Fable 5 →
#4 · 1.02
4.1% last week
Questions and answers
- What is the newest AI coding model on Bug Bench?
- GPT-6.1 Sol, released Sep 29, 2026. It wrote 12.5% of the AI-written code reviewed by cubic last week.
- Which AI coding model released in the last 90 days has the lowest bug rate?
- GPT-6 Luna, at 0.34 (#1 overall).
- Which new AI coding model is used the most?
- Claude Opus 5.5, with 59.7% of the AI-written code reviewed by cubic in the week of Oct 19, 2026.