Enum Event 

pub enum Event {
    RunStarted {
        thread_id: String,
        run_id: String,
        parent_run_id: Option<String>,
        input: Option<Value>,
        base: BaseEvent,
    },
    RunFinished {
        thread_id: String,
        run_id: String,
        result: Option<Value>,
        base: BaseEvent,
    },
    RunError {
        message: String,
        code: Option<String>,
        base: BaseEvent,
    },
    StepStarted {
        step_name: String,
        base: BaseEvent,
    },
    StepFinished {
        step_name: String,
        base: BaseEvent,
    },
    TextMessageStart {
        message_id: String,
        role: Role,
        base: BaseEvent,
    },
    TextMessageContent {
        message_id: String,
        delta: String,
        base: BaseEvent,
    },
    TextMessageEnd {
        message_id: String,
        base: BaseEvent,
    },
    TextMessageChunk {
        message_id: Option<String>,
        role: Option<Role>,
        delta: Option<String>,
        base: BaseEvent,
    },
    ReasoningStart {
        message_id: String,
        base: BaseEvent,
    },
    ReasoningMessageStart {
        message_id: String,
        role: Role,
        base: BaseEvent,
    },
    ReasoningMessageContent {
        message_id: String,
        delta: String,
        base: BaseEvent,
    },
    ReasoningMessageEnd {
        message_id: String,
        base: BaseEvent,
    },
    ReasoningMessageChunk {
        message_id: Option<String>,
        delta: Option<String>,
        base: BaseEvent,
    },
    ReasoningEnd {
        message_id: String,
        base: BaseEvent,
    },
    ReasoningEncryptedValue {
        subtype: ReasoningEncryptedValueSubtype,
        entity_id: String,
        encrypted_value: String,
        base: BaseEvent,
    },
    ToolCallStart {
        tool_call_id: String,
        tool_call_name: String,
        parent_message_id: Option<String>,
        base: BaseEvent,
    },
    ToolCallArgs {
        tool_call_id: String,
        delta: String,
        base: BaseEvent,
    },
    ToolCallEnd {
        tool_call_id: String,
        base: BaseEvent,
    },
    ToolCallResult {
        message_id: String,
        tool_call_id: String,
        content: String,
        role: Option<Role>,
        base: BaseEvent,
    },
    ToolCallChunk {
        tool_call_id: Option<String>,
        tool_call_name: Option<String>,
        parent_message_id: Option<String>,
        delta: Option<String>,
        base: BaseEvent,
    },
    StateSnapshot {
        snapshot: Value,
        base: BaseEvent,
    },
    StateDelta {
        delta: Vec<Value>,
        base: BaseEvent,
    },
    MessagesSnapshot {
        messages: Vec<Value>,
        base: BaseEvent,
    },
    ActivitySnapshot {
        message_id: String,
        activity_type: String,
        content: HashMap<String, Value>,
        replace: Option<bool>,
        base: BaseEvent,
    },
    ActivityDelta {
        message_id: String,
        activity_type: String,
        patch: Vec<Value>,
        base: BaseEvent,
    },
    Raw {
        event: Value,
        source: Option<String>,
        base: BaseEvent,
    },
    Custom {
        name: String,
        value: Value,
        base: BaseEvent,
    },
}

AG-UI Protocol Event Types.

These events follow the AG-UI specification for agent-to-frontend communication. See: https://docs.ag-ui.com/concepts/events

Variants

RunStarted

Signals the start of an agent run.

Fields

thread_id: String

run_id: String

parent_run_id: Option<String>

input: Option<Value>

base: BaseEvent

RunFinished

Signals successful completion of an agent run.

Fields

thread_id: String

run_id: String

result: Option<Value>

base: BaseEvent

RunError

Indicates an error occurred during the run.

Fields

message: String

code: Option<String>

base: BaseEvent

StepStarted

Marks the beginning of a step within a run.

Fields

step_name: String

base: BaseEvent

StepFinished

Marks the completion of a step.

Fields

step_name: String

base: BaseEvent

TextMessageStart

Indicates the beginning of a text message stream.

Fields

message_id: String

role: Role

Role is always “assistant” for TEXT_MESSAGE_START.

base: BaseEvent

TextMessageContent

Contains incremental text content.

Fields

message_id: String

delta: String

base: BaseEvent

TextMessageEnd

Indicates the end of a text message stream.

Fields

message_id: String

base: BaseEvent

TextMessageChunk

Combined chunk event for text messages (alternative to Start/Content/End).

Fields

message_id: Option<String>

role: Option<Role>

delta: Option<String>

base: BaseEvent

ReasoningStart

Marks the start of a reasoning phase for a message.

Fields

message_id: String

base: BaseEvent

ReasoningMessageStart

Marks the start of a streamed reasoning message.

Fields

message_id: String

role: Role

base: BaseEvent

ReasoningMessageContent

Contains incremental reasoning text.

Fields

message_id: String

delta: String

base: BaseEvent

ReasoningMessageEnd

Marks the end of a streamed reasoning message.

Fields

message_id: String

base: BaseEvent

ReasoningMessageChunk

Combined reasoning chunk event (alternative to Start/Content/End).

Fields

message_id: Option<String>

delta: Option<String>

base: BaseEvent

ReasoningEnd

Marks the end of a reasoning phase for a message.

Fields

message_id: String

base: BaseEvent

ReasoningEncryptedValue

Attaches an encrypted reasoning value to a message or tool call.

Fields

subtype: ReasoningEncryptedValueSubtype

entity_id: String

encrypted_value: String

base: BaseEvent

ToolCallStart

Signals the start of a tool call.

Fields

tool_call_id: String

tool_call_name: String

parent_message_id: Option<String>

base: BaseEvent

ToolCallArgs

Contains incremental tool arguments.

Fields

tool_call_id: String

delta: String

base: BaseEvent

ToolCallEnd

Signals the end of tool argument streaming.

Fields

tool_call_id: String

base: BaseEvent

ToolCallResult

Contains the result of a tool execution.

Fields

message_id: String

tool_call_id: String

content: String

role: Option<Role>

base: BaseEvent

ToolCallChunk

Combined chunk event for tool calls (alternative to Start/Args/End).

Fields

tool_call_id: Option<String>

tool_call_name: Option<String>

parent_message_id: Option<String>

delta: Option<String>

base: BaseEvent

StateSnapshot

Provides a complete state snapshot.

Fields

snapshot: Value

base: BaseEvent

StateDelta

Contains incremental state changes (RFC 6902 JSON Patch).

Fields

delta: Vec<Value>

Array of JSON Patch operations.

base: BaseEvent

MessagesSnapshot

Provides a complete message history snapshot.

Fields

messages: Vec<Value>

base: BaseEvent

ActivitySnapshot

Provides an activity snapshot.

Fields

message_id: String

activity_type: String

content: HashMap<String, Value>

replace: Option<bool>

base: BaseEvent

ActivityDelta

Contains incremental activity changes (RFC 6902 JSON Patch).

Fields

message_id: String

activity_type: String

patch: Vec<Value>

Array of JSON Patch operations.

base: BaseEvent

Raw

Wraps events from external systems.

Fields

event: Value

source: Option<String>

base: BaseEvent

Custom

Custom application-defined event.

Fields

name: String

value: Value

base: BaseEvent

Implementations

impl Event

pub fn run_started( thread_id: impl Into<String>, run_id: impl Into<String>, parent_run_id: Option<String>, ) -> Self

Create a run-started event.

pub fn run_started_with_input( thread_id: impl Into<String>, run_id: impl Into<String>, parent_run_id: Option<String>, input: Value, ) -> Self

Create a run-started event with input.

pub fn run_finished( thread_id: impl Into<String>, run_id: impl Into<String>, result: Option<Value>, ) -> Self

Create a run-finished event.

pub fn run_error(message: impl Into<String>, code: Option<String>) -> Self

Create a run-error event.

pub fn step_started(step_name: impl Into<String>) -> Self

Create a step-started event.

pub fn step_finished(step_name: impl Into<String>) -> Self

Create a step-finished event.

pub fn text_message_start(message_id: impl Into<String>) -> Self

Create a text-message-start event.

pub fn text_message_content( message_id: impl Into<String>, delta: impl Into<String>, ) -> Self

Create a text-message-content event.

pub fn text_message_end(message_id: impl Into<String>) -> Self

Create a text-message-end event.

pub fn text_message_chunk( message_id: Option<String>, role: Option<Role>, delta: Option<String>, ) -> Self

Create a text-message-chunk event.

pub fn reasoning_start(message_id: impl Into<String>) -> Self

Create a reasoning-start event.

pub fn reasoning_message_start(message_id: impl Into<String>) -> Self

Create a reasoning-message-start event.

pub fn reasoning_message_content( message_id: impl Into<String>, delta: impl Into<String>, ) -> Self

Create a reasoning-message-content event.

pub fn reasoning_message_end(message_id: impl Into<String>) -> Self

Create a reasoning-message-end event.

pub fn reasoning_message_chunk( message_id: Option<String>, delta: Option<String>, ) -> Self

Create a reasoning-message-chunk event.

pub fn reasoning_end(message_id: impl Into<String>) -> Self

Create a reasoning-end event.

pub fn reasoning_encrypted_value( subtype: ReasoningEncryptedValueSubtype, entity_id: impl Into<String>, encrypted_value: impl Into<String>, ) -> Self

Create a reasoning-encrypted-value event.

pub fn tool_call_start( tool_call_id: impl Into<String>, tool_call_name: impl Into<String>, parent_message_id: Option<String>, ) -> Self

Create a tool-call-start event.

pub fn tool_call_args( tool_call_id: impl Into<String>, delta: impl Into<String>, ) -> Self

Create a tool-call-args event.

pub fn tool_call_end(tool_call_id: impl Into<String>) -> Self

Create a tool-call-end event.

pub fn tool_call_result( message_id: impl Into<String>, tool_call_id: impl Into<String>, content: impl Into<String>, ) -> Self

Create a tool-call-result event.

pub fn tool_call_chunk( tool_call_id: Option<String>, tool_call_name: Option<String>, parent_message_id: Option<String>, delta: Option<String>, ) -> Self

Create a tool-call-chunk event.

pub fn state_snapshot(snapshot: Value) -> Self

Create a state-snapshot event.

pub fn state_delta(delta: Vec<Value>) -> Self

Create a state-delta event.

pub fn messages_snapshot(messages: Vec<Value>) -> Self

Create a messages-snapshot event.

pub fn activity_snapshot( message_id: impl Into<String>, activity_type: impl Into<String>, content: HashMap<String, Value>, replace: Option<bool>, ) -> Self

Create an activity-snapshot event.

pub fn activity_delta( message_id: impl Into<String>, activity_type: impl Into<String>, patch: Vec<Value>, ) -> Self

Create an activity-delta event.

pub fn raw(event: Value, source: Option<String>) -> Self

Create a raw event.

pub fn custom(name: impl Into<String>, value: Value) -> Self

Create a custom event.

pub fn with_timestamp(self, timestamp: u64) -> Self

Set timestamp on the event.

pub fn now_millis() -> u64

Get current timestamp in milliseconds.

Trait Implementations

impl Clone for Event

fn clone(&self) -> Event

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Event

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Event

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Event

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

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 Event