Transformers' proposed MIC fixtures would have caught UMT5 future-token attention bug introduced with PyTorch SDPA
On July 30, 2026, Transformers switched T5 to use PyTorch's scaled dot-product attention (SDPA), and that change allowed the UMT5 decoder to attend to future tokens during training. The project describes Model Integration Contracts (transformers-mic): small, pinned fixtures plus runnable usage paths and recorded baselines run on cheap CPU runners; replaying MICs over commits shows the UMT5 fixture would have flagged the regression from its introduction until its fix on September 28, 2026.