Struct Message 

pub struct Message {
    pub role: MessageRole,
    pub content: MessageContent,
    pub reasoning: Option<String>,
    pub reasoning_details: Option<Vec<Value>>,
    pub tool_calls: Option<Vec<ToolCall>>,
    pub tool_call_id: Option<String>,
    pub phase: Option<AssistantPhase>,
    pub origin_tool: Option<String>,
}

Universal message structure supporting both text and image content

Fields

role: MessageRole

content: MessageContent

Content can be a string (for backward compatibility) or an array of content parts

reasoning: Option<String>

reasoning_details: Option<Vec<Value>>

tool_calls: Option<Vec<ToolCall>>

tool_call_id: Option<String>

phase: Option<AssistantPhase>

Optional assistant-only phase metadata used by OpenAI Responses workflows.

origin_tool: Option<String>

Optional origin tool name for tracking which tool generated this message Used in tool-aware context retention to preserve results from recently-active tools

Implementations

impl Message

pub fn estimate_tokens(&self) -> usize

Estimate the number of tokens in this message (rough approximation).

pub const fn base(role: MessageRole, content: MessageContent) -> Self

Helper to create a base message with common defaults. Public for use in provider implementations.

pub fn user(content: String) -> Self

Create a user message with text content

pub fn user_with_parts(content_parts: Vec<ContentPart>) -> Self

Create a user message with multiple content parts (text and images)

pub fn assistant(content: String) -> Self

Create an assistant message with text content

pub fn assistant_with_parts(content_parts: Vec<ContentPart>) -> Self

Create an assistant message with multiple content parts

pub fn assistant_with_tools(content: String, tool_calls: Vec<ToolCall>) -> Self

Create an assistant message with tool calls Based on OpenAI Cookbook patterns for function calling

pub fn assistant_with_tools_and_parts( content_parts: Vec<ContentPart>, tool_calls: Vec<ToolCall>, ) -> Self

Create an assistant message with tool calls and multiple content parts

pub fn assistant_with_tools_and_reasoning( content: String, tool_calls: Vec<ToolCall>, reasoning_details: Option<Vec<Value>>, ) -> Self

Create an assistant message with tool calls and reasoning details Used for preserving reasoning state in multi-turn conversations

pub fn system(content: String) -> Self

Create a system message

pub fn tool_response(tool_call_id: String, content: String) -> Self

Create a tool response message This follows the exact pattern from OpenAI Cookbook:

{
  "role": "tool",
  "tool_call_id": "call_123",
  "content": "Function result"
}

pub fn tool_response_with_name( tool_call_id: String, _function_name: String, content: String, ) -> Self

Create a tool response message with function name (for compatibility) Some providers might need the function name in addition to tool_call_id

pub fn tool_response_with_origin( tool_call_id: String, content: String, origin_tool: String, ) -> Self

Create a tool response message with origin tool tracking The origin_tool field helps with tool-aware context retention

pub async fn user_with_local_image<P: AsRef<Path>>( file_path: P, ) -> Result<Self, Error>

Create a user message with image from a local file

pub async fn user_with_text_and_local_image<P: AsRef<Path>>( text: String, file_path: P, ) -> Result<Self, Error>

Create a user message with text and a local image

pub fn with_reasoning(self, reasoning: Option<String>) -> Self

Attach provider-visible reasoning trace for archival without affecting payloads.

pub fn with_tool_calls(self, tool_calls: Vec<ToolCall>) -> Self

Attach tool calls to this message.

pub fn with_reasoning_details( self, reasoning_details: Option<Vec<Value>>, ) -> Self

Attach reasoning details for providers that support structured reasoning

pub fn with_phase(self, phase: Option<AssistantPhase>) -> Self

Attach assistant phase metadata for providers that support it.

pub fn validate_for_provider(&self, provider: &str) -> Result<(), String>

Validate this message for a specific provider Based on official API documentation constraints

pub fn has_tool_calls(&self) -> bool

Check if this message has tool calls

pub fn get_tool_calls(&self) -> Option<&[ToolCall]>

Get the tool calls if present

pub fn is_tool_response(&self) -> bool

Check if this is a tool response message

pub fn get_text_content(&self) -> Cow<'_, str>

Get the text content of the message (for backward compatibility)

pub fn has_images(&self) -> bool

Check if this message contains images

pub fn get_images(&self) -> Vec<&ContentPart>

Get all images in this message

Trait Implementations

impl Clone for Message

fn clone(&self) -> Message

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Message

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Message

fn default() -> Message

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Message

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<&Message> for SessionMessage

fn from(message: &Message) -> Self

Converts to this type from the input type.

impl From<&SessionMessage> for Message

fn from(message: &SessionMessage) -> Self

Converts to this type from the input type.

impl PartialEq for Message

fn eq(&self, other: &Message) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Message

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Message