Reasoning stopped being a product. It became a setting.

Two years ago, buying a model that thinks before it answers meant buying a different model. Today, at four of the five largest publishers, it means passing a parameter — and the separate reasoning lines are being switched off one by one. OpenAI's deprecation page now carries an end date for every surviving member of the o-series. o1, o1-pro, o3-mini and o4-mini shut down on 23 October 2026; o3 and o3-pro follow on 11 December. The recommended replacement in each case is a general model from the GPT-5.6 family, and for the two pro-tier models the replacement is written out as gpt-5.6-sol with reasoning mode set to pro. The premium reasoning tier is now literally a value in a request. Mistral got there first. Its entire Magistral line — the company's only reasoning products — was retired by 31 July 2026, and the migration targets listed by the manufacturer were not further reasoning models but ordinary models of the main line. DeepSeek reached the same place by a different route. Its current price list contains three models, all of them V4, and a single row headed thinking mode: both non-thinking and thinking modes are supported, with thinking as the default. The R1 line that made the company's name in January 2025 has no entry of its own. Alibaba's separate line ended earliest of all, and quietly. QwQ-32B-Preview appeared in November 2024 and QwQ-32B in March 2025; no third model ever followed. From Qwen3 onwards, thinking is a switch inside the general model. QwQ has a profile in this catalogue as of today — as the closing entry of a product category rather than the first entry of a family. Google is the exception that clarifies the rule, because it never made the separation in the first place. Gemini shipped thinking as a budget the caller sets, not as a model you choose, and so has nothing to wind down. For readers the practical consequence is narrow but real. Where a hosted reasoning model is switched off, its published benchmark results become unreproducible — the closed Magistral Medium 1.2 is already in that position. Where the weights were open, the model survives as a download after it stops being a product: QwQ-32B is still pulled tens of thousands of times a month, eighteen months after the line it belongs to quietly ended.