I, too, built a POC autothink shortly after the Claude 3.7 release that included the `extended thinking` toggle. It's literally also called autothink:

https://github.com/NiloCK/autothink

https://www.paritybits.me/think-toggles-are-dumb/

My own version took a first pass with an LLM whose job was to assign a 0-100 complexity rating, and then there was more or less a linear scaling of the allocated thinking budget.

The OP effort here is obviously higher grade, and I'm really tickled to see quantitative results. Well done.