Which AI model writes the most bugs in Ruby?

As of Sep 30, 2026, GPT-6 Astra had the highest relative bug rate in Ruby code (1.47, 47% more counted bugs than the Ruby average), statistically tied with Claude Opus 5.5, Claude Opus 5, and GPT-5.6 Sol.

Updated Sep 30, 2026

Best AI model for Ruby code

As of Sep 30, 2026, Claude Fable 5.1 had the lowest relative bug rate in Ruby code (0.49, 51% fewer counted bugs than the Ruby average), statistically tied with Claude Opus 4.8, among 6 ranked models.

Models ranked by relative bug rate in Ruby code. Lower values are better.
Rank	Model	Rate
1= (statistically tied)	Claude Fable 5.1	0.49
2= (statistically tied)	Claude Opus 4.8	0.57
3= (statistically tied)	Claude Opus 5.5	0.86
4= (statistically tied)	Claude Opus 5	1.28
5= (statistically tied)	GPT-5.6 Sol	1.37
6= (statistically tied)	GPT-6 Astra	1.47

1.00 = Ruby average · lower is better · = statistically tied

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Questions and answers

Which AI model writes the most bugs in Ruby?: As of Sep 30, 2026, GPT-6 Astra had the highest relative bug rate in Ruby code (1.47, 47% more counted bugs than the Ruby average), statistically tied with Claude Opus 5.5, Claude Opus 5, and GPT-5.6 Sol.