An assistant that answers a wholesale distributor’s staff has to feel like it is thinking out loud — responses render as they arrive rather than appearing complete after a wait. The engineering consequence is that the view re-renders constantly while the user is still reading, so every layout decision has to survive text growing underneath it: no jumping scroll position, no reflowing action buttons, no flicker on the message being written.

State lives in Angular Signals: messages, streaming status, attachments, reactions. The view derives from them instead of being synchronised with them, which removes the entire class of bug where a chat looks stale until you click something. Services stay fully decoupled from the components, so the transport can change without the interface knowing.

Chat interfaces accumulate floating things — context menus, a lightbox for attachments, the sidebar with chat groups, create and delete flows. Handled ad hoc, they fight each other over stacking, focus and dismissal. Centralising them through CDK Overlay gave one set of rules for positioning and closing, which is why the interaction semantics stay predictable no matter how the user got there.

Staff use this between other tasks, often on a phone, so the narrow layout was the starting point rather than a late compression of the desktop one — touch targets, reachable actions, and a sidebar that becomes a gesture instead of a permanent column.