Laguna M.1/XS.2 Technical Report
In arXiv preprint · 2026
Abstract
We present Laguna M.1 and Laguna XS.2, two Mixture-of-Experts foundation models built for long-horizon, agentic coding: M.1 has 225.8B total parameters (23.4B activated per token) and XS.2 has 33.4B total (3B activated). Both models were trained from scratch end-to-end inside the same internal system that we refer to as our Model Factory: a tightly-integrated stack of versioned data, training, evaluation, and inference components that turn model development into an industrial process. We describe the principles and design choices of the Model Factory and also detail the end-to-end training process of our models, throughout pre-training data and architecture, post-training stages, evaluation, and quantization. On agentic software engineering and terminal benchmarks (SWE-bench Verified, SWE-bench Multilingual, SWE-Bench Pro, and Terminal-Bench 2.0) M.1 and XS.2 are competitive with state-of-the-art open models in their respective weight classes. Laguna XS.2 weights are released under Apache 2.0.
Cite
@misc{abadji2026lagunam1xs2technicalreport,
title={Laguna M.1/XS.2 Technical Report},
author={Julien Abadji and Marah Abdin and Connor Adams and Eric Alcaide and Mustafa Altun and Michele Artoni and Junze Bao and Uday Barar and Vassilis Bekiaris and Arkadii Bessonov and Benjamin Bütikofer and Jonathan Chang and Yen-Chun Chen and Dmitry Chernenkov and Yang Chi and Filippos Christianos and Fenia Christopoulou and Razvan-Andrei Ciocoiu and Tzachi Cohen and Yohann Coppel and Dmitrii Emelianenko and Brandon Fergerson and Brian Fitzgerald and Matthias Gallé and Alex Golonzovskyi and George Grigorev and Yiyang Hao and Christian Hensel and Jan Huenermann and Ye Ji and Sarthak Joshi and Eiso Kant and Kabir Khandpur and Seonghyeon Kim and Vladimir Kirichenko and Umut Kocasarac and Ilya Kochik and Ivan Komarov and Chaerin Kong and Anurag Koul and François-Joseph Lacroix and Sergei Laktionov and Waren Long and Quentin Malartic and Vadim Markovtsev and Afonso Marques and Robert McHardy and Carlos Mocholí and Dmitry Monakhov and Adam Morris and Martin Muller and Christian Mürtz and Robin Nabel and Thien Nguyen and Rok Novosel and Szymon Ozog and Aalhad Patankar and Aleksei Petrov and Alexandre Piché and Arthur Pignet and Teodor Poncu and Phil Potter and Alexander Rakowski and Pierre-Yves Ritschard and Jay Roberts and Joe Rowell and Piotr Sarna and Pierre-André Savalle and Uladzislau Sazanovich and Nikita Shapovalov and Arsenii Shevchenko and Mikhail Shilkov and Andrei Sokol and Mohamed Soliman and Jack Stephenson and Victor Storchan and Dragos-Constantin Tantaru and Artem Tyurin and Adrian Wälchli and Pengming Wang and Jianxiao Yang and Renat Zayashnikov and Alexander Zelenka Martin and Nikolay Zinov and Caroline Bercier and José Caldeira and Margarida Garcia and Tom George and Kabeer Gharzai and Glenn Hitchcock and Carson Klingenberg and Ivo Pinto and Varun Randery and Noah Smith and Arina Sugako and Jason Warner},
year={2026},
eprint={2605.27605},
archivePrefix={arXiv},
primaryClass={cs.AI},
url={https://arxiv.org/abs/2605.27605},
}