> ## Documentation Index
> Fetch the complete documentation index at: https://docs.upsonic.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Chat

> Build stateful conversational sessions with memory and metrics

## Overview

Chat enables you to build stateful conversational sessions with automatic memory management, cost tracking, and session analytics. It wraps an Agent with session persistence, memory integration, and usage metrics.

## Key Features

* **Session Management**: Unique session/user identification with state tracking
* **Memory Integration**: Conversation history, summarization, and user profile analysis
* **Cost Tracking**: Real-time token usage and cost monitoring
* **Streaming Support**: Both blocking and streaming response modes
* **History Manipulation**: Delete messages, remove attachments
* **Error Handling**: Built-in retry mechanisms with exponential backoff

## Example

```python theme={null}
import asyncio
from upsonic import Agent, Chat


async def main():
    agent = Agent("anthropic/claude-sonnet-4-5")

    chat = Chat(
        session_id="user123_session1",
        user_id="user123",
        agent=agent
    )

    response = await chat.invoke("Hello, how are you?")
    print(response)

    print(f"Total cost: ${chat.total_cost:.4f}")
    print(f"Messages: {len(chat.all_messages)}")


if __name__ == "__main__":
    asyncio.run(main())
```

## Navigation

* [Attributes](/concepts/chat/attributes) - Configuration options
* [Creating a Chat](/concepts/chat/creating-a-chat) - Initialization and configuration
* [Running a Chat](/concepts/chat/running-a-chat) - Sending messages and streaming
* [Metrics](/concepts/chat/metrics) - Cost and session analytics
* [History Management](/concepts/chat/history-management) - Message and attachment manipulation
* [Storage Backends](/concepts/chat/storage-backends) - Persistence options
* [Advanced](/concepts/chat/advanced/memory-strategies) - Advanced configuration
* [Examples](/concepts/chat/examples/basic) - Complete working examples