105 hidden bugs tested: DeepSeek V4.1 Flash near Opus 5 at 1/28th the cost
PawelHuryn · x · 2026-09-10
PawelHuryn tested DeepSeek V4.1 Flash on two repos containing 105 hidden bugs (find-and-fix), and it lands on the Pareto frontier:
- Opus 5 (max): 27 bugs, $51.33
- Grok 4.6 (max): 27, $16.96
- DeepSeek V4.1 Flash (max): 24, just $1.80
- GPT-5.6 Luna (xhigh): 23, $2.50
- Opus 5 (high): 21, $38.77
Takeaway: at 28x cheaper than Opus 5 (max) while missing only 3 fewer bugs, DeepSeek V4.1 Flash is a very strong everyday model. More effort levels and DeepSeek V4 Pro results are being posted hourly in the thread.
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