> ## 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.

# Attributes

> Configuration options for the Chat class

## Constructor Parameters

| Parameter                    | Type                    | Default    | Description                                     |
| ---------------------------- | ----------------------- | ---------- | ----------------------------------------------- |
| `session_id`                 | `str`                   | (required) | Unique identifier for this chat session         |
| `user_id`                    | `str`                   | (required) | Unique identifier for the user                  |
| `agent`                      | `Agent`                 | (required) | The Agent instance to handle conversations      |
| `storage`                    | `Storage`               | `None`     | Storage backend (defaults to InMemoryStorage)   |
| `full_session_memory`        | `bool`                  | `True`     | Store full conversation history                 |
| `summary_memory`             | `bool`                  | `False`    | Enable conversation summarization               |
| `user_analysis_memory`       | `bool`                  | `False`    | Enable user profile analysis                    |
| `user_profile_schema`        | `type`                  | `None`     | Custom Pydantic schema for user profiles        |
| `dynamic_user_profile`       | `bool`                  | `False`    | Auto-generate profile schema from conversations |
| `num_last_messages`          | `int`                   | `None`     | Limit history to last N messages                |
| `feed_tool_call_results`     | `bool`                  | `False`    | Include tool calls in memory                    |
| `user_memory_mode`           | `'update' \| 'replace'` | `'update'` | How to update user profiles                     |
| `debug`                      | `bool`                  | `False`    | Enable debug logging                            |
| `debug_level`                | `int`                   | `1`        | Debug verbosity (1=standard, 2=detailed)        |
| `max_concurrent_invocations` | `int`                   | `1`        | Maximum concurrent invoke calls                 |
| `retry_attempts`             | `int`                   | `3`        | Number of retry attempts for failed calls       |
| `retry_delay`                | `float`                 | `1.0`      | Delay between retry attempts (seconds)          |

## Instance Properties

| Property              | Type                | Description                                                        |
| --------------------- | ------------------- | ------------------------------------------------------------------ |
| `state`               | `SessionState`      | Current session state (IDLE, AWAITING\_RESPONSE, STREAMING, ERROR) |
| `all_messages`        | `List[ChatMessage]` | All messages in the session                                        |
| `input_tokens`        | `int`               | Total input tokens used                                            |
| `output_tokens`       | `int`               | Total output tokens used                                           |
| `total_tokens`        | `int`               | Total tokens (input + output)                                      |
| `total_cost`          | `float`             | Total cost in USD                                                  |
| `total_requests`      | `int`               | Total API requests made                                            |
| `total_tool_calls`    | `int`               | Total tool calls made                                              |
| `run_duration`        | `float`             | Total run duration in seconds                                      |
| `time_to_first_token` | `float`             | Time to first token in seconds                                     |
| `start_time`          | `float`             | Session start time (Unix timestamp)                                |
| `end_time`            | `float`             | Session end time (None if active)                                  |
| `duration`            | `float`             | Session duration in seconds                                        |
| `last_activity`       | `float`             | Time since last activity in seconds                                |
| `is_closed`           | `bool`              | Whether the session is closed                                      |

## 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="session1",
        user_id="user1",
        agent=agent,
        full_session_memory=True,
        summary_memory=True,
        num_last_messages=50,
        retry_attempts=3
    )

    response = await chat.invoke("Hello!")
    print(response)

    print(f"State: {chat.state.value}")
    print(f"Cost: ${chat.total_cost:.4f}")
    print(f"Tokens: {chat.total_tokens}")


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