Poolside has released Laguna S 2.1, a 118B parameter Mixture-of-Experts (MoE) model that achieves competitive performance on long-horizon coding benchmarks despite its relatively small size. The model supports a context window of up to 1M tokens and has two thinking modes: off and max. Laguna S 2.1 was trained in under nine weeks and has demonstrated capabilities in areas such as building a browser engine from scratch and solving mathematical problems. The model's performance is notable for its size, and its developers attribute its success to improved behaviors such as verification and persistence.