> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/marimo-team/marimo/llms.txt
> Use this file to discover all available pages before exploring further.

# ChatMessage

A message in a chat.

## Usage

```python theme={null}
import marimo as mo

# Create a user message
message = mo.ai.ChatMessage(
    role="user",
    content="Hello, how are you?",
    id="msg-1"
)
```

```python theme={null}
# Create an assistant message with parts
message = mo.ai.ChatMessage(
    role="assistant",
    content="I'm doing well, thank you!",
    id="msg-2",
    parts=[
        {"type": "text", "text": "I'm doing well, thank you!"}
    ]
)
```

```python theme={null}
# Create a message with attachments
attachment = mo.ai.ChatAttachment(
    url="https://example.com/image.png",
    name="example.png"
)

message = mo.ai.ChatMessage(
    role="user",
    content="Look at this image",
    id="msg-3",
    attachments=[attachment]
)
```

## Signature

```python theme={null}
mo.ai.ChatMessage(
    role: Literal["user", "assistant", "system"],
    content: Any,
    id: str = "",
    parts: list[ChatPart] = [],
    attachments: Optional[list[ChatAttachment]] = None,
    metadata: Any | None = None
)
```

## Parameters

<ParamField path="role" type="Literal['user', 'assistant', 'system']" required>
  The role of the message.
</ParamField>

<ParamField path="content" type="Any" required>
  The content of the message. This can be a rich Python object.
</ParamField>

<ParamField path="id" type="str" default="''">
  The id of the message.
</ParamField>

<ParamField path="parts" type="list[ChatPart]" default="[]">
  Parts from AI SDK Stream Protocol (must be serializable to JSON).
</ParamField>

<ParamField path="attachments" type="Optional[list[ChatAttachment]]" default="None">
  Optional attachments to the message.
</ParamField>

<ParamField path="metadata" type="Any | None" default="None">
  Optional metadata.
</ParamField>

## Part Types

### TextPart

Represents a text content part.

**Attributes:**

* `type` (Literal\["text"]): Part type
* `text` (str): The text content

### ReasoningPart

Represents a reasoning content part.

**Attributes:**

* `type` (Literal\["reasoning"]): Part type
* `text` (str): The reasoning text
* `details` (Optional\[list\[ReasoningDetails]]): Optional reasoning details

### ToolInvocationPart

Represents a tool invocation part from the AI SDK.

**Attributes:**

* `type` (str): Starts with "tool-"
* `tool_call_id` (str): The tool call identifier
* `state` (Union\[str, Literal\["output-available"]]): The state of the invocation
* `input` (dict\[str, Any]): The input to the tool
* `output` (Optional\[Any]): The output from the tool

**Properties:**

* `tool_name`: Returns the tool name (extracted from type)

### FilePart

Represents a FileUIPart from the AI SDK.

**Attributes:**

* `type` (Literal\["file"]): Part type
* `media_type` (str): The media type
* `url` (str): The file URL
* `filename` (Optional\[str]): Optional filename