SWE-Pair Benchmark: DeepSeek V4.1 Flash Outperforms GPT-6 Luna on Dual-Bug Fixing Tasks

·2026.11.11 03:33

Key point

In a new benchmark requiring simultaneous fixes for two real bugs, DeepSeek V4.1 Flash achieved a 90% success rate at a cost of 6 cents per task, surpassing GPT-6 Luna.

Details

  • SWE-Pair is a new coding-agent benchmark consisting of 161 tasks from 69 Python projects, requiring agents to fix two real bugs simultaneously.
  • DeepSeek V4.1 Flash at medium effort solved 90% of tasks at a cost of approximately 6 cents per solved task.
  • GPT-6 Luna at max effort solved 78% of tasks at a cost of approximately 23 cents per solved task.
  • Increasing reasoning effort did not improve performance for DeepSeek; max effort scored 88% (slightly below medium) while costing 1.7x more.
  • The benchmark dataset is available on Hugging Face, and results from every agent run are published on the project's lab site.
  • Users can run their own agents on the benchmark using a single Harbor command.

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