Gen UI Interrupt (Strategy B — Promise-Based)

Inline time-picker rendered in the chat via useFrontendTool with an async handler. The handler returns a Promise that resolves only when the user picks a slot or cancels — equivalent UX to LangGraph's native interrupt() primitive, adapted for the Claude Agent SDK which has no graph-level pause/resume.

How It Works

1. User asks to book a meeting
2. Backend scheduling agent calls schedule_meeting (a frontend tool)
3. Frontend renders TimePickerCard inline in the chat
4. User picks a slot or cancels
5. The Promise resolves with the result, which flows back to the agent
6. Agent confirms the booking in chat

Backend

The Python backend at src/agents/interrupt_agent.py defines only a system prompt and tools=[] — the schedule_meeting tool is registered entirely on the frontend. AG-UI forwards the frontend tool definition to Claude, and the tool call lifecycle resolves the user's choice back through CopilotKit.

Reference

• ms-agent-python gen-ui-interrupt — the reference implementation this port is based on.
• langgraph-python gen-ui-interrupt — the canonical LangGraph version using native interrupt().