# Stream‑Mode AI Agent

A lightweight demo of a LangChain agent that streams its output token‑by‑token instead of waiting for the entire response.  
The project showcases how to replace a single `.invoke()` call with `.stream()`, so you can see the answer appear in real time.

---

## 📖 Description

- **Stack**: `LangChain`, `create_agent`, `@tool`, `rich`
- **Files**:
  - `agent.py` – defines tools and creates an agent that streams its output.
  - `client.py` – simple CLI to interact with the agent.

The agent can call external tools (e.g., a calculator) while streaming, making it feel more interactive for long answers or multi‑step reasoning.

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## ⚙️ Prerequisites

| Item | Version |
|------|---------|
| Python | ≥ 3.10 |
| pip | Latest |
| Virtual environment (recommended) | Any |

The project uses the following packages:

```bash
langchain==0.2.*          # LangChain core
rich==13.*                # Pretty console output
```

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## 🚀 Installation

1. **Clone the repository**

   ```bash
   git clone https://github.com/your-username/stream-ai-agent.git
   cd stream-ai-agent
   ```

2. **Create a virtual environment (optional but recommended)**

   ```bash
   python -m venv .venv
   source .venv/bin/activate      # On Windows: .venv\Scripts\activate
   ```

3. **Install dependencies**

   ```bash
   pip install -r requirements.txt
   ```

> If you don't have a `requirements.txt`, create one with:
>
> ```
> langchain>=0.2,<0.3
> rich>=13,<14
> ```

---

## 🏃‍♂️ Running the Agent

```bash
python client.py
```

You will see a prompt:

```
Enter your question (or type 'exit' to quit):
```

Type any query, e.g.:

```
What is 12 * 8?
```

The agent will stream its answer token by token, and if it needs to use the calculator tool, you’ll see the intermediate tool call printed in real time.

---

## 📌 Example Session

```text
$ python client.py
Enter your question (or type 'exit' to quit): What is 12 * 8?

> Calculating...
> 96
Answer: 96
```

The `>` lines are produced by the `rich` library, showing tool calls and partial outputs as they arrive.

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## 🔧 Extending the Agent

- **Add more tools**: Decorate a function with `@tool(name="...", description="...")`.
- **Change LLM**: Pass a different model to `create_agent(..., llm=...)`.
- **Custom streaming logic**: Override the default stream handling in `agent.py`.

---

## 📄 License

MIT © 2026

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