DeepSeek v4.1 Flash Tested Across 8 Coding Harnesses: Performs Best in Minimal Setups

mariofilhoml · x · 2026-09-11

DeepSeek evaluated its new v4.1 flash model under 8 different harness configurations: it performs best in minimal harnesses (mini-SWE and DeepSeek's own minimal harness) but underperforms in both Claude Code and Codex. A replier notes this is likely explained by RL checkpoint selection against DeepSWE-like benchmarks — an eval-harness selection bias.

Related event: DeepSeek Releases Harness v0.1.5, Evaluates V4.1 Flash Across Configs(3 posts)→

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