Ruby code review: which models catch the bugs
Of the 17 models ranked on Ruby code, 5 models tied for the most known bugs: 100%. 9 of the other 12 models have 95% intervals that overlap theirs. Gemini 3.5 Flash-Lite caught the fewest, 0%. Together they caught 69% of known bugs in Ruby code, against 60% for the same 17 across the whole benchmark.
| Model | Caught here | Every bug | Difference |
|---|---|---|---|
| GPT-6.1 Sol | 100% | 89% | +11 pts |
| Gemini 4 Argon | 100% | 82% | +18 pts |
| Claude Sonnet 5.5 | 100% | 77% | +23 pts |
| Gemini 3.8 Flash | 100% | 68% | +32 pts |
| Gemini 3.1 Pro | 100% | 67% | +33 pts |
| Claude Opus 5.5 | 89%[67%–100%] | 90% | −1 pt |
| GPT-5.6 Sol | 67%[0%–100%] | 72% | −5 pts |
| GPT-6 Luna | 67%[0%–100%] | 67% | 0 pts |
| Claude Haiku 5.5 | 67%[0%–100%] | 64% | +3 pts |
| GLM-5.3 Flash (Workers AI) | 67%[33%–100%] | 61% | +6 pts |
| GLM-5.3 (Workers AI) | 67%[0%–100%] | 61% | +6 pts |
| DeepSeek V4 Pro (Workers AI) | 67%[50%–100%] | 54% | +13 pts |
| Gemma 4 26B A4B (Workers AI) | 67%[0%–100%] | 26% | +41 pts |
| DeepSeek V4 Flash (Workers AI) | 44%[0%–67%] | 49% | −5 pts |
| GPT-OSS 120B (Workers AI) | 33%[0%–67%] | 40% | −7 pts |
| Kimi K2.7 Code (Workers AI) | 33%[0%–100%] | 38% | −5 pts |
| Gemini 3.5 Flash-Lite | 0% | 11% | −11 pts |
Ruby was the fifth-easiest of the 12 languages for these models.
Gemma 4 26B A4B gains the most here: 67%, against 26% over every bug.
Gemini 3.5 Flash-Lite drops the most: 0%, against 11% over every bug.
The change “Reimplement Action Cable redis adapter with redis-client” in rails/rails, a change of 100 to 300 lines that landed in June 2026, introduced a logic bug that a later upstream commit fixed.
GPT-6.1 Sol, Gemini 4 Argon, Claude Sonnet 5.5, Gemini 3.8 Flash, GPT-6 Luna, Gemini 3.1 Pro and Gemma 4 26B A4B caught it; Claude Opus 5.5, GLM-5.3 Flash and DeepSeek V4 Pro (Workers AI) caught it in part; GPT-5.6 Sol, Claude Haiku 5.5, GLM-5.3, DeepSeek V4 Flash (Workers AI), GPT-OSS 120B (Workers AI), Kimi K2.7 Code (Workers AI) and Gemini 3.5 Flash-Lite missed it.