There isn't a screenshot of this in Stephen's blog, but he does mention[1] the ability to evaluate a single 'ChatInput' multiple times, which preserves all previous evaluations and allows you to tab through them to pick the best one. (You can see a screenshot of what the arrow tab switcher looks like on the left side of this[2] example in the Chatbook README.md).

One of the nice advantages of a notebook interface to LLMs is that you can easily go back and edit and rearrange the chat history in the normal ways that any cell in a notebook can be edited, moved, deleted, etc.

So e.g. if you want to go back to an earlier point, you can simply move your cursor between cells at an earlier position in the "physical" chat history, insert a new chat cell, and you're done.

[1]: https://writings.stephenwolfram.com/2023/06/introducing-chat...

[2]: https://github.com/WolframResearch/Chatbook#generate-immedia...