And because the thinking, which does makes it better at achieving outcomes, contains naughty words and information (e.g. private information). https://stolen-thoughts.com/

Yes. I've not used Opus 5 much directly, but when it was Fable and Opus 4.8, I found Fable did this all the time and it was maddening. It'd say stuff like "Oh, I mentioned that between tool calls" or something.

I’m pretty sure this is a Claude code bug - if you do ctrl+o you can see those hidden responses from Fable. Fable doesn’t know the harness is bugged, so I added instruction to my Claude.md to save all commentary for final message.