Get started with the AG-UI .NET SDK: bootstrap and run your first streaming-chat app (client + server) with the AG-UI .NET NuGet packages (AGUI.Client, AGUI.Server, AGUI.Formatting, AGUI.Abstractions). USE FOR: which packages to install and how to wire them; constructing an AGUIChatClient against an endpoint and streaming the reply as Microsoft.Extensions.AI IChatClient / ChatResponseUpdate; hosting an AG-UI POST endpoint yourself over any IChatClient; running a single- or multi-turn conversation; STATELESS agents (client owns history, resends it every turn) vs HOSTED / conversation-holding agents (server keeps the session, client pins a thread id). DO NOT USE FOR: changing the AG-UI .NET SDK itself (use the agui-dotnet-* contributor skills); server tools (agui-dotnet-server-tools); client tools (agui-dotnet-client-tools); interrupts / human-in-the-loop; shared state; generative UI; multimodal; or protobuf transport.