Laguna S 2.1

Laguna S 2.1 became available on AI Gateway on July 20, 2026. Laguna S 2.1 is a Mixture-of-Experts (MoE) model with 118 billion total parameters and 8 billion active per token, and it runs in thinking and no-thinking modes. Poolside published the weights on Hugging Face under the OpenMDW-1.1 license. AI Gateway lists two versions: this one, with a context window of 1M tokens, and a free version with a smaller window at laguna-s-2.1-free.

Agentic coding is the focus. With thinking enabled, Laguna S 2.1 scores 70.2% on Terminal-Bench 2.1, 78.5% on SWE-Bench Multilingual, and 59.4% on SWE-Bench Pro (public dataset). Broader agentic evaluations put it at 40.4% on DeepSWE v1.1, 46.2% on SWE Atlas codebase question answering, and 49.7% on Toolathlon Verified. Thinking accounts for a large share of those results. Without it, the Terminal-Bench 2.1 score falls to 60.4% and DeepSWE to 16.5%.

The context window of 1M tokens supports the sessions Laguna S 2.1 is built for. A single agent run accumulates terminal output, file contents, and tool results across many steps before it finishes. In one case study Poolside published, Laguna S 2.1 built a working HTML and CSS rendering engine from an empty folder over 181 steps with no human intervention, then checked its own rendering against a headless browser.

Poolside documented three limitations at release. First, Laguna S 2.1 sometimes relies on a remembered tool interface instead of the schema a third-party agent harness supplies. That usually corrects itself once the harness rejects the call and asks for a retry. Second, tool arguments that expect a JSON array can come back with invalid escaping. Third, Laguna S 2.1 can think for long stretches on competition mathematics before it makes progress. Laguna S 2.1 also accepts text input only, with no image or audio input.

Set the model to poolside/laguna-s-2.1 in the AI SDK, Chat Completions API, Responses API, Messages API, or other API formats, from TypeScript or Python. To use Laguna S 2.1 inside a coding agent, run vercel ai-gateway coding-agents setup, then select poolside/laguna-s-2.1 in the agent's model configuration. AI Gateway serves Laguna S 2.1 through Poolside, with retries and failover, and expanded capacity for both versions after launch. Pricing mirrors the provider with no markup and no platform fee on inference, including on Bring Your Own Key (BYOK) requests.