This would be a GAME CHANGER for me. I understand TheBrain uses an External AI tool to generate its responses and that it does not use the content of the brain as a custom large language model (though that should be a long term aim!). However, it should surely be easy to create a custom prompt that retrieves information from the Brain that can form part of the prompt that is sent externally.
For example, with AI tools I am currently creating prompts like, "Summarise the following", "Show any common threads in" etc and then I copy paste the content from multiple thoughts and put them in the prompt. With the right prompt this works REALLY well.
It would be so much more convenient of The Brain did that copy paste function for me. Ideally, the user interface would allow me to select which Thoughts I want to use as input to the prompt and perhaps allow me to edit before submitting.
I then use the output of the AI to form new Thoughts in TheBrain and start the cycle again.
The reason this would be a Game Changer is that anyone can use generative AI tools, but competitive advantage today is being smart about how to form your prompts to really leverage the power of the LLMs on offer. I'm increasingly seeing the Brain as a giant and superior way of thinking through what you are trying to get out of the AI and to form superior prompts.