feat: solution for 'Human-in-the-loop (interrupt / resume)'

README.md

@@ -0,0 +1,67 @@
+# LangGraph Human-in-the-loop Demo
+
+This project demonstrates how to create a LangGraph that pauses execution to ask the user for confirmation via a custom interrupt. The user is prompted in the console using `questionary`, and the graph resumes once the user provides an answer.
+
+## Features
+
+- **Custom interrupt node**: Triggers a pause and sends a structured payload (type, question, options).
+- **Human-in-the-loop**: The graph waits for user input before continuing.
+- **State persistence**: Uses an in-memory checkpoint to resume execution after the interrupt.
+- **Simple console UI**: Uses `questionary` for interactive prompts.
+
+## Requirements
+
+- Python 3.10 or newer
+- `langgraph`
+- `questionary`
+
+Install the dependencies with:
+
+```bash
+pip install -r requirements.txt
+```
+
+## Running the Demo
+
+```bash
+python src/main.py
+```
+
+You will see a prompt:
+
+```
+Уверены, что хотите продолжить?
+  ❯ approve
+  ❯ reject
+```
+
+Select an option. After you choose, the script will print the final state, which includes the user's answer.
+
+## Project Structure
+
+```
+├── src/
+│   └── main.py          # Main script with graph definition and run loop
+├── requirements.txt    # Python dependencies
+└── README.md            # This file
+```
+
+## How It Works
+
+1. **Graph Definition**  
+   The graph has a single node `ask_user`.  
+   - On first run, it triggers an interrupt with a payload containing a question and options.  
+   - After the user responds, the node receives the answer via the `resume` parameter and stores it in the state.
+
+2. **Interrupt Handling**  
+   The main loop listens for chunks from `graph.stream()`.  
+   - When an interrupt chunk is detected (`"__interrupt__"` key), it displays the question using `questionary.select`.  
+   - The chosen answer is sent back to the graph via `Command(resume=answer)`.
+
+3. **Resuming Execution**  
+   The graph resumes from the same node, now with the answer available in the state.  
+   The final state is printed to the console.
+
+Feel free to extend the graph with more nodes or integrate it with other LangChain components.
+
+Enjoy experimenting with LangGraph and human-in-the-loop workflows!