Struct Message 

pub struct Message {
    pub role: Role,
    pub content: Option<Content>,
    pub tool_calls: Option<Vec<ToolCall>>,
    pub tool_call_id: Option<String>,
    pub name: Option<String>,
    pub reasoning: Option<String>,
    pub finish_reason: Option<String>,
}

Conversation message — the fundamental unit of LLM interaction.

Fields

role: Role

content: Option<Content>

tool_calls: Option<Vec<ToolCall>>

tool_call_id: Option<String>

name: Option<String>

Tool name — present on tool result messages

reasoning: Option<String>

Extracted reasoning/thinking content (e.g. from <think> blocks)

finish_reason: Option<String>

Implementations

impl Message

pub fn user(text: &str) -> Self

pub fn assistant(text: &str) -> Self

pub fn system(text: &str) -> Self

pub fn tool_result(tool_call_id: &str, name: &str, content: &str) -> Self

pub fn assistant_with_tool_calls(text: &str, tool_calls: Vec<ToolCall>) -> Self

Assistant message that requested tool calls.

WHY store tool_calls on assistant messages: When rebuilding the chat history for the LLM API, we need to pair each tool result with the assistant message that requested it. Without storing the original tool_calls, we lose the correlation and the LLM can’t understand the conversation flow.

pub fn system_summary(text: String) -> Self

Summary message injected by context compression.

pub fn text_content(&self) -> String

Extract plaintext from content, joining multimodal parts.

pub fn has_tool_calls(&self) -> bool

True if this message has tool call requests from the assistant.

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() -> Self

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 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