The agent can list files in the site folder and in a folder you link. A large folder still lists. Secrets and generated folders stay out of the list.
The empty chat shows prompts for the view you are in. Design, content, assets, and publish each have their own prompts. Type @ to attach a page, a CMS item, a component, or a file.
Open in browser serves the site on your computer. Your own browser loads that address. The page reloads after each save.