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AG-UI: Stateful human in the loop

This sample is a human-in-the-loop chatbot that asks the user a frontend question before continuing to a model response.

Choose this when​

Use this sample when a workflow needs explicit user input, approval, or a UI choice before the model continues.

What it demonstrates​

  • A FrontendToolCall node that asks a question in the UI.
  • A stateful conversation workflow that can resume after user input.
  • Routing successful tool input to a ModelCall node.
  • Sending a fallback assistant message from a Code node when the input does not match the expected tool result path.

How it works​

The workflow starts by calling the frontend ask_a_question tool and stores the result at output.toolResult. If the tool result is returned, execution continues into the ModelCall node. Other input follows the alternate branch and emits a simple assistant error message. The frontend tool call does not write its function call or result into input.chat; the returned choice is workflow control-flow data rather than model tool-call history.

Setup notes​

Create a connector and model before running this sample, then select that model in the ModelCall node. It needs the Sharpy client sample because it understands the ask_a_question tool call and how to present it to the user. When using Sharpy, make sure you uncheck the Send All Messages checkbox and put the workflow ID into the input with the same name.