Enum EventType 

pub enum EventType {
    TextMessageStart,
    TextMessageContent,
    TextMessageEnd,
    TextMessageChunk,
    ThinkingTextMessageStart,
    ThinkingTextMessageContent,
    ThinkingTextMessageEnd,
    ToolCallStart,
    ToolCallArgs,
    ToolCallEnd,
    ToolCallChunk,
    ToolCallResult,
    ThinkingStart,
    ThinkingEnd,
    StateSnapshot,
    StateDelta,
    MessagesSnapshot,
    ActivitySnapshot,
    ActivityDelta,
    Raw,
    Custom,
    RunStarted,
    RunFinished,
    RunError,
    StepStarted,
    StepFinished,
}

Event types for the AG-UI protocol.

This enum enumerates all possible event types in the protocol. Event types are serialized using SCREAMING_SNAKE_CASE (e.g., TEXT_MESSAGE_START).

Event Categories

• Text Messages: TextMessageStart, TextMessageContent, TextMessageEnd, TextMessageChunk
• Thinking Messages: ThinkingTextMessageStart, ThinkingTextMessageContent, ThinkingTextMessageEnd
• Tool Calls: ToolCallStart, ToolCallArgs, ToolCallEnd, ToolCallChunk, ToolCallResult
• Thinking Steps: ThinkingStart, ThinkingEnd
• State: StateSnapshot, StateDelta
• Messages: MessagesSnapshot
• Run Lifecycle: RunStarted, RunFinished, RunError
• Step Lifecycle: StepStarted, StepFinished
• Other: Raw, Custom

Variants

TextMessageStart

Start of a text message from the assistant.

TextMessageContent

Content chunk of a text message (streaming delta).

TextMessageEnd

End of a text message.

TextMessageChunk

Complete text message chunk (non-streaming alternative).

ThinkingTextMessageStart

Start of a thinking text message (extended thinking).

ThinkingTextMessageContent

Content chunk of a thinking text message.

ThinkingTextMessageEnd

End of a thinking text message.

ToolCallStart

Start of a tool call.

ToolCallArgs

Arguments chunk for a tool call (streaming).

ToolCallEnd

End of a tool call.

ToolCallChunk

Complete tool call chunk (non-streaming alternative).

ToolCallResult

Result of a tool call execution.

ThinkingStart

Start of a thinking step (chain-of-thought).

ThinkingEnd

End of a thinking step.

StateSnapshot

Complete state snapshot.

StateDelta

Incremental state update (JSON Patch RFC 6902).

MessagesSnapshot

Complete messages snapshot.

ActivitySnapshot

Complete activity snapshot.

ActivityDelta

Incremental activity update (JSON Patch RFC 6902).

Raw

Raw event from the underlying provider.

Custom

Custom application-specific event.

RunStarted

Agent run has started.

RunFinished

Agent run has finished successfully.

RunError

Agent run encountered an error.

StepStarted

A step within a run has started.

StepFinished

A step within a run has finished.

Implementations

impl EventType

pub fn as_str(&self) -> &'static str

Returns the string representation of the event type.

Trait Implementations

impl Clone for EventType

fn clone(&self) -> EventType

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for EventType

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for EventType

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for EventType

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

Formats the value using the given formatter.

impl Hash for EventType

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for EventType

fn eq(&self, other: &EventType) -> 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 EventType

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 Copy for EventType

impl Eq for EventType

impl StructuralPartialEq for EventType