Note on Rio 3.5 Open

NOTE ON RIO 3.5 OPEN In recent days, Rio 3.5 Open has received far more attention than we anticipated. Along with it came analyses and, of course, criticisms and questions. First, we want to clarify that the model is not foundational, trained from scratch, nor was it ever communicated as such. It is a post-training project built on open models, following classical approaches and some experiments. We started with open baseweights and applied various techniques, including merging, OPD, and finally used inference with SwiReasoning. It was precisely thanks to the community's attention that we identified an operational error in the publication process. We ended up making available an intermediate checkpoint that had not yet completed all the final validation and optimization steps. This generated interpretations that, looking back now, we fully understand. The checkpoint has been removed. We tried to recover the final model, but it was not possible. It will only be released after the new training and all external validations are completed. We also want to correct an important attribution point. Our team used public models provided by Alibaba, through Qwen 3.5, and by Nex-AGI, through Nex-N2 Pro, as a basis. In the initial documentation, we did not include Nex's important contribution. Correctly recognizing who builds these foundations is part of the open development process. Thank you, Nex, for your work and for contributing to advancing the state of the art in open models. It is worth contextualizing that there was no official release of that version of the model. The project ended up gaining traction organically and unexpectedly while it was still undergoing independent validations. In any case, this shows that there is interest and that Brazil has more space in this conversation than we usually imagine. We hope to see more initiatives emerging in Latin America, India, Africa, and other places that seek to expand their technological sovereignty, especially at a time when Fable has been closed to the rest of the world and access to frontier models has become part of the global strategic debate. Rio 3.5 Open is just the beginning. We will correct what is necessary, continue developing openly, and share what we learn along the way. Our goal is to show that the Brazilian public sector can also learn, build openly, and contribute to the forefront of current technological research.