ag-ui-dotnet

Expose client-side (frontend) tools to an AG-UI agent with the AG-UI .NET SDK — C# functions that run in the CLIENT app (read local state, GPS, UI, device APIs), where the client executes the call and returns the result so the run continues. USE FOR: declaring an AIFunction in the client and passing it via ChatOptions.Tools to AGUIChatClient; having the client execute a tool the model requested and feed the result back automatically; understanding why no UseFunctionInvocation is needed on the client (AGUIChatClient already invokes functions); what the server must do (UseFunctionInvocation + TerminateOnUnknownCalls) so it forwards an unknown/client tool instead of erroring. DO NOT USE FOR: tools that run on the server/backend (use agui-dotnet-server-tools); pausing for human approval/input before acting (interrupts / human-in-the-loop); plain chat (use agui-dotnet-streaming-chat); shared state, generative UI, multimodal, or protobuf.

Pause an AG-UI agent run for a human, then resume it, with the AG-UI .NET SDK — gate a sensitive tool behind explicit approval, or interrupt a run to collect free-form input from the user before continuing. USE FOR: requiring human approval before a tool executes (ApprovalRequiredAIFunction + ToolApprovalRequestContent/ToolApprovalResponseContent, resume by appending the request + CreateResponse(approved)); pausing a run to ask the user a question and resuming with their answer (InterruptRequestContent / InterruptResponseContent, RunAgentInput.Resume); how a paused run surfaces as RUN_FINISHED outcome=interrupt and how the client detects and answers it. DO NOT USE FOR: tools that run without approval on the server (use agui-dotnet-server-tools) or in the client (use agui-dotnet-client-tools); plain chat (use agui-dotnet-streaming-chat); shared state, generative UI, multimodal, or protobuf.

Send images and other binary/file content to an AG-UI agent with the AG-UI .NET SDK — attach pictures (or audio, PDFs, etc.) to a user message so a multimodal model can see them. USE FOR: building a user ChatMessage with mixed content parts (TextContent plus DataContent for inline bytes, or UriContent for a hosted URL); choosing inline bytes vs a URL reference; setting the correct media type; sending the message through AGUIChatClient so the content parts cross the AG-UI wire to a vision/multimodal model. DO NOT USE FOR: plain text chat (use agui-dotnet-streaming-chat); tool calls (use agui-dotnet-server-tools / agui-dotnet-client-tools); structured shared state (use agui-dotnet-shared-state); reasoning traces, interrupts, generative UI, or protobuf.

Use the protobuf wire transport (instead of the default Server-Sent Events) for an AG-UI connection with the AG-UI .NET SDK — a compact binary event stream negotiated via the Accept header. USE FOR: making an AGUIChatClient prefer protobuf by wiring an AGUIEventStreamHandler with ProtobufEventStreamFormatter (then SseEventStreamFormatter as fallback) into the HttpClient; enabling a server to answer protobuf by registering ProtobufEventStreamFormatter and negotiating the response format from the request Accept header; understanding the protobuf-or-SSE fallback. DO NOT USE FOR: the default SSE transport or first-time setup (use agui-dotnet-streaming-chat); JSON event serialization questions; tools, state, interrupts, multimodal, or generative UI.

Surface a reasoning/thinking model's intermediate thoughts separately from its final answer with the AG-UI .NET SDK — so a client can show the agent "thinking" before it responds, and handle that reasoning trace correctly across turns. USE FOR: distinguishing the model's reasoning trace from its answer on the client by matching TextReasoningContent vs TextContent in each ChatResponseUpdate's Contents; rendering thinking and answer in different ways as they stream; deciding whether to carry the reasoning text into later turns (whether to append/resend the model's reasoning back into conversation history). DO NOT USE FOR: plain text streaming with no reasoning display (use agui-dotnet-streaming-chat); tools, shared state, interrupts, multimodal, generative UI, or protobuf.