# Stream‑Mode AI Agent

A lightweight LangChain agent that prints its output **as it is generated** using the `.stream()` API.
The project demonstrates how to replace a single `.invoke()` call with streaming so that users see partial responses in real time.

> **Why stream?**  
> When an LLM produces long answers or calls multiple tools, waiting for the whole result can feel like a freeze. Streaming gives instant feedback and improves UX.

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## 📦 Project Structure

```
.
├── agent.py   # Agent definition with streaming support
├── client.py  # Simple CLI to interact with the agent
└── README.md
```

- **agent.py** – creates an agent that uses a single tool (`get_price`) and streams its output.  
- **client.py** – runs the agent in a loop, reading user queries from stdin.

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## ⚙️ Prerequisites

| Item | Version |
|------|---------|
| Python | 3.10+ |
| pip | latest |
| LangChain | `>=0.2.0` |
| Rich | `>=13.0` |

> **Tip:** Use a virtual environment to keep dependencies isolated.

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## 🚀 Installation

```bash
# Clone the repo (or copy the files)
git clone https://github.com/your-username/stream-agent.git
cd stream-agent

# Create and activate a venv (optional but recommended)
python -m venv .venv
source .venv/bin/activate   # Windows: .venv\Scripts\activate

# Install dependencies
pip install --upgrade pip
pip install langchain rich
```

> If you plan to use an OpenAI model, set the API key:
> ```bash
> export OPENAI_API_KEY="sk-..."
> ```

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## 📖 Usage

Run the client script and type your questions. The agent will stream its answer token‑by‑token.

```bash
python client.py
```

Example session:

```
$ python client.py
Enter your query (Ctrl+C to exit):
> What is the price of Bitcoin today?

Agent: Checking price...
Agent: Current BTC price is $42,300.00
```

The output appears progressively as the LLM generates it.

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## 🛠️ Customization

- **Add more tools** – decorate a function with `@tool` and pass it to `create_agent`.
- **Change model** – modify the `model_name` argument in `agent.py`.
- **Adjust streaming format** – tweak the `stream()` call or use Rich’s live rendering for fancy UI.

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## 📄 License

MIT © 2026

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