Struct OutputMessageStartedData 

pub struct OutputMessageStartedData {
    pub turn_id: TurnId,
    pub message_id: MessageId,
    pub model: Option<String>,
    pub iteration: Option<u32>,
    pub phase: Option<ExecutionPhase>,
}

Data for output.message.started event

Emitted when the LLM starts generating a response. UI can show a “thinking” indicator until output.message.delta or output.message.completed events arrive.

Fields

turn_id: TurnId

Turn ID this output belongs to

message_id: MessageId

Stable public ID for this assistant message across its streaming lifecycle. This is the same identifier as OutputMessageCompletedData.message.id.

model: Option<String>

Optional model name being used

iteration: Option<u32>

Current iteration number within this turn (1-based). Useful for UI to show progress during multi-step tool-calling flows.

phase: Option<ExecutionPhase>

Best-effort streamed phase hint (EVE-774).

None means “not yet classified — treat as ordinary assistant text”, NEVER “thinking”. A missing/unknown phase must fall back to the assistant-text channel, never the reasoning channel. Only populated when the provider stream reveals a native phase before this event is emitted; today output.message.started is emitted before the LLM call, so this is generally None at start. The authoritative classification remains the completed Message.phase. See specs/events.md.

Trait Implementations

impl Clone for OutputMessageStartedData

fn clone(&self) -> OutputMessageStartedData

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for OutputMessageStartedData

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for OutputMessageStartedData

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<OutputMessageStartedData> for EventData

fn from(data: OutputMessageStartedData) -> Self

Converts to this type from the input type.

impl Serialize for OutputMessageStartedData

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

where __S: Serializer,

Serialize this value into the given Serde serializer.