Rio de Janeiro's City Government Releases Rio 3.5 Open 397B Under MIT License

Hugging Face / Hacker News·medium signal

IplanRIO, the municipal IT company of Rio de Janeiro, released Rio 3.5 Open 397B on Hugging Face under an MIT license — a 397B-parameter sparse MoE (~17B active) post-trained from Qwen 3.5 397B, with a ~1.01M-token context window and multimodal input. It introduces SwiReasoning, a training-free inference framework that dynamically switches between explicit chain-of-thought and latent-space reasoning via entropy-based confidence signals for better token efficiency. A city government shipping a frontier-class open model is notable, though the benchmark claims still await independent audit.