Human-in-the-Loop через middleware: README.md

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+# Human‑in‑the‑Loop Middleware Demo  
+
+This repository contains a minimal LangChain/LangGraph example that demonstrates how to pause an agent whenever it wants to call a tool and ask the user for approval (`approve` / `reject`).  
+The pausing logic is handled by **`HumanInTheLoopMiddleware`**, which automatically generates a prompt, receives the user’s decision, and resumes execution via a `Command(resume={…})`.
+
+> **Why this matters** – In many real‑world scenarios an LLM should not act autonomously. By inserting a human checkpoint you can keep control over every tool call, ensuring safety, compliance or simply giving the user a chance to correct mistakes.
+
+---
+
+## 📦 Installation
+
+```bash
+# 1️⃣ Clone the repo
+git clone https://github.com/your‑org/human‑in‑the‑loop-demo.git
+cd human‑in‑the‑loop-demo
+
+# 2️⃣ Create a virtual environment (recommended)
+python -m venv .venv
+source .venv/bin/activate   # Windows: .venv\Scripts\activate
+
+# 3️⃣ Install dependencies
+pip install -r requirements.txt
+```
+
+> **Requirements**  
+> * Python ≥ 3.10  
+> * `langchain` (>=0.2)  
+> * `langgraph` (>=0.1)  
+> * `openai` or any LLM provider you prefer  
+
+The `requirements.txt` file contains the exact versions used for this demo.
+
+---
+
+## 📁 Project Structure
+
+```
+.
+├── agent.py          # Agent definition with HumanInTheLoopMiddleware
+├── main.py           # CLI entry point – runs the agent interactively
+├── tools.py          # Example tool(s) (e.g., get_weather)
+└── README.md         # This file
+```
+
+---
+
+## 🚀 Running the Demo
+
+### 1️⃣ Start the Agent
+
+```bash
+python main.py
+```
+
+You will see a prompt like:
+
+```
+Assistant: What would you like to do?
+User: Tell me the weather in London.
+Assistant: (Thinking...) 
+```
+
+When the agent decides to call `get_weather`, it pauses and prints:
+
+```
+Human-in-the-loop checkpoint:
+The assistant wants to execute tool 'get_weather' with arguments {'location': 'London'}.
+Please type one of the following decisions: approve / reject
+```
+
+Type **`approve`** to let the tool run, or **`reject`** to cancel it.  
+After your decision, the agent continues:
+
+```
+Assistant: The weather in London is 18°C and sunny.
+```
+
+### 2️⃣ Using a Different Tool
+
+If you want to test another tool (e.g., `get_time`), add it to `tools.py`, import it in `agent.py`, and adjust the middleware configuration accordingly.
+
+---
+
+## 📚 Example Usage
+
+```python
+# main.py
+from agent import agent
+
+def run():
+    print("Welcome! Type 'exit' to quit.")
+    while True:
+        user_input = input("\nUser: ")
+        if user_input.lower() == "exit":
+            break
+        response = agent.invoke({"input": user_input})
+        print(f"Assistant: {response['output']}")
+
+if __name__ == "__main__":
+    run()
+```
+
+```python
+# agent.py
+from langchain.agents import create_agent
+from langchain.agents.middleware import HumanInTheLoopMiddleware
+from langgraph.checkpoint.memory import MemorySaver
+
+from tools import get_weather  # <-- your tool(s)
+
+memory = MemorySaver()
+
+agent = create_agent(
+    model="gpt-4o-mini",          # or any LLM you have access to
+    tools=[get_weather],
+    system_prompt="You are a helpful assistant.",
+    middleware=[
+        HumanInTheLoopMiddleware(
+            interrupt_on={"get_weather": True},
+            description_prefix="Please confirm the tool call:",
+        ),
+    ],
+    checkpointer=memory,
+)
+```
+
+```python
+# tools.py
+from langchain.tools import BaseTool
+
+class GetWeather(BaseTool):
+    name = "get_weather"
+    description = "Returns current weather for a location."
+    args_schema = ...  # define your schema here
+
+    def _run(self, location: str) -> str:
+        # Dummy implementation – replace with real API call
+        return f"The weather in {location} is 18°C and sunny."
+
+get_weather = GetWeather()
+```
+
+---
+
+## 🔧 Customization Tips
+
+| Feature | How to change |
+|---------|---------------|
+| **Allowed decisions** | `interrupt_on={"get_weather": {"allowed_decisions": ["approve", "reject"]}}` |
+| **Prompt prefix** | Change `description_prefix` in the middleware. |
+| **Tool list** | Add or remove tools in the `tools=[...]` array. |
+| **LLM model** | Pass a different model name or a custom LLM instance to `create_agent`. |
+
+---
+
+## 📜 License
+
+This project is licensed under the MIT License – see the [LICENSE](LICENSE) file for details.
+
+---