Enum Message 

pub enum Message {
    System(SystemMessage),
    Assistant(AssistantMessage),
    User(UserMessage),
    Result(ResultMessage),
    StreamEvent(StreamEvent),
}

Top-level message enum — the primary type consumers work with.

Every message emitted by the SDK during a session is one of these variants. Consumers typically match on this enum to route messages to their appropriate handlers.

Example

match message {
    Message::System(sys) => println!("session: {}", sys.session_id),
    Message::Assistant(asst) => {
        if let Some(text) = Message::Assistant(asst).assistant_text() {
            println!("{}", text);
        }
    }
    Message::Result(r) if r.is_error => eprintln!("error turn"),
    Message::StreamEvent(ev) => { /* rich streaming data */ }
    _ => {}
}

Variants

System(SystemMessage)

Synthesized initialization message, emitted once per session.

Assistant(AssistantMessage)

An assistant response containing one or more content blocks.

User(UserMessage)

A user message (present in session history / resume replay).

Result(ResultMessage)

Terminal message for a completed prompt turn.

StreamEvent(StreamEvent)

Rich streaming event for data that does not map to a content block (tool call lifecycle, plan updates, usage deltas, etc.).

Implementations

impl Message

pub fn session_id(&self) -> Option<&str>

Returns the session ID carried by this message, if present.

All current variants carry a session_id. This method returns Some(&str) for every variant; the Option wrapper exists for forward-compatibility with future variants that may omit it.

pub fn is_error_result(&self) -> bool

Returns true if this is a ResultMessage with is_error = true.

pub fn is_stream_event(&self) -> bool

Returns true if this is a StreamEvent.

pub fn assistant_text(&self) -> Option<String>

Extracts concatenated text from all ContentBlock::Text blocks in an AssistantMessage. Returns None for any other variant, and None when the assistant message contains no text blocks.

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<'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