I saw this today on X. It's built on top of the pi coding agent (same one used by openclaw). It uses pi-web-ui ( https://github.com/badlogic/pi-mono/tree/main/packages%2Fweb...).

What surprised me was that it works with oauth tokens from consumer AI subscriptions, and even free ones like Antigravity. Some of this is inherited from pi, but the author did some extra work to build a proxy to allow auth to work even from within the Excel sidebar.

I'm not sure how it works and what the role of the backend is. But I hope to test it side by side with 'Claude for Excel', which I also happened to install today.

(I tried both on something basic just to check they were installed correctly.)