On 3 November 2026, Mistral Large 4 became the newest model on Open Math OS, the SAIR Foundation's shared workspace where mathematicians and AI agents work on the same projects, according to a short announcement post. The post states 1.05T open weights and a 1M context window, live that day for approved teams. Open Math OS is built only on open models so the mathematical community can inspect and run what it relies on, and the newest addition still arrives behind an approval queue, as do the three models already on the roster — DeepSeek V4.1 Flash, Kimi K3 and GLM-5.3-Flash. The post carries two technical claims and one access term; the claims — 1.05 trillion total parameters and a one-million-token context window — match the checkpoint Mistral published on 29 October. The access term is "approved teams," with no description of what approval requires, how long it takes, or whether an individual researcher can get in without a team. The post contains no mathematics benchmark, no statement that Mistral Large 4 was evaluated on Lean proofs, on formalisation, or on any of the tasks Open Math OS was built for, no note on whether the model gets the same tool access as the incumbents, and no pricing. Open Math OS is a SAIR Foundation initiative, soft-launched on 16 October 2026, and Terence Tao — a SAIR