Application Shell 21 block design & features
ApplicationShell21 is an application shell for AI chat apps built with Shadcn UI. The sidebar starts with the Shadcnblocks logo, a New chat action and chat search, then lists past conversations grouped under Today, Yesterday, Previous 7 days and Previous 30 days. Each conversation reveals a more menu on hover with Share, Rename and Delete. The signed-in user sits in the footer.
The header holds the sidebar trigger, a model picker dropdown with a check beside the selected model, and a Share button. The main column is a centred conversation of skeleton shapes: rounded user bubbles on the right and assistant lines beside an avatar dot on the left.
A composer built from an input group stays pinned under the conversation, with an attach button, a round send button and a short disclaimer. Only the conversation scrolls, so the header and composer are always visible.
On small screens the sidebar closes off-canvas and the conversation and composer take the full width.