Enum Message 

pub enum Message {
    Human(HumanMessage),
    Ai(AiMessage),
    System(SystemMessage),
    Tool(ToolMessage),
}

A single message in an LLM conversation.

Variants

Human(HumanMessage)

User input.

Ai(AiMessage)

Assistant response.

System(SystemMessage)

System prompt or instruction.

Tool(ToolMessage)

Tool execution result.

Implementations

impl Message

Convenience constructors.

pub fn human(content: impl Into<String>) -> Message

Build a Human message with text only.

pub fn human_with_parts( content: impl Into<String>, parts: Vec<ContentPart>, ) -> Message

Build a Human message that carries multimodal parts alongside text. Providers that support multimodal will serialize the parts; others silently ignore them and use the text content alone.

pub fn ai(content: impl Into<String>) -> Message

Build an Ai message with text only (no tool calls, no parts).

pub fn ai_with_parts( content: impl Into<String>, parts: Vec<ContentPart>, ) -> Message

Build an Ai message with multimodal parts alongside text.

pub fn system(content: impl Into<String>) -> Message

Build a System message.

pub fn tool(call_id: impl Into<String>, content: impl Into<String>) -> Message

Build a Tool message.

pub fn content(&self) -> &str

Get the message’s primary text content (empty string for messages that are tool-call-only with no text).

pub fn tool_calls(&self) -> &[ToolCall]

Returns the tool calls if this is an Ai message; empty otherwise.

pub fn has_tool_calls(&self) -> bool

True if this is an Ai message with at least one tool call.

pub fn parts(&self) -> &[ContentPart]

Multimodal parts on a Human or Ai message. Empty for System / Tool (they don’t carry multimodal content).

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<(), Error>

Formats the value using the given formatter.

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

fn deserialize<__D>( __deserializer: __D, ) -> Result<Message, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<&str> for Message

fn from(s: &str) -> Message

Converts to this type from the input type.

impl From<String> for Message

fn from(s: String) -> Message

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 Runnable<Vec<Message>, Message> for Client

fn invoke<'life0, 'async_trait>( &'life0 self, input: Vec<Message>, __arg2: RunnableConfig, ) -> Pin<Box<dyn Future<Output = Result<Message>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

One-shot invocation. The hot path.

fn name(&self) -> &str

Friendly name for telemetry / introspection.

fn batch<'life0, 'async_trait>( &'life0 self, inputs: Vec<I>, config: RunnableConfig, ) -> Pin<Box<dyn Future<Output = Result<Vec<O>, CognisError>> + Send + 'async_trait>>

where 'life0: 'async_trait, I: 'static, O: 'static, Self: Sized + Sync + 'async_trait,

Run multiple inputs in parallel. Defaults to buffer_unordered honouring config.max_concurrency.

fn stream<'life0, 'async_trait>( &'life0 self, input: I, config: RunnableConfig, ) -> Pin<Box<dyn Future<Output = Result<RunnableStream<O>, CognisError>> + Send + 'async_trait>>

where 'life0: 'async_trait, Self: Sized + Sync + 'async_trait,

Stream the final output (chunks of O). Default emits one item via invoke — non-streaming runnables are correct without override.

fn stream_events<'life0, 'async_trait>( &'life0 self, input: I, config: RunnableConfig, ) -> Pin<Box<dyn Future<Output = Result<EventStream, CognisError>> + Send + 'async_trait>>

where 'life0: 'async_trait, I: Serialize, O: Serialize, Self: Sized + Sync + 'async_trait,

Stream structured events. Default emits OnStart + OnEnd around an invoke call. Graph engines override to surface per-node events.

fn input_schema(&self) -> Option<Value>

JSON Schema for the input type, if known.

fn output_schema(&self) -> Option<Value>

JSON Schema for the output type, if known.

impl Serialize for Message

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Message