TL;DR: Mistral Medium 3.5 is a 128B open-weight model released April 29, 2026, with a 256K context window, configurable reasoning, and native multimodal input. It scores 77.6% on SWE-Bench Verified — close but not ahead of Claude Sonnet 4.6 — and ships alongside Vibe, a cloud coding agent that submits pull requests directly to GitHub without you babysitting it. API pricing is $1.50 per million input tokens. Open weights under a modified MIT license that routes high-revenue enterprises through Mistral's paid channel. It's a serious model with a real killer feature. But the pricing math is complicated. 77.6%. That's Mistral Medium 3.5's score on SWE-Bench Verified. For context: Claude Sonnet 4.6 scores 79.6% on the same benchmark. So Medium 3.5 is close — very close — but it doesn't actually beat the current best.…