Human-in-the-Loop AI Agents with Google ADK and Telegram

Google's Agent Development Kit (ADK) provides a human_in_loop sample demonstrating how to pause agents for human approval using LongRunningFunctionTool. This post extends the concept into a production-like async pipeline with a browser chat UI, FastAPI backend, and Telegram bot that sends approve/reject buttons to a manager's phone, replacing the original simulated approval with real human interaction via Telegram callbacks and background polling.