Enum AgUiEvent 

pub enum AgUiEvent {
    RunStarted {
        run_id: String,
        thread_id: Option<String>,
        timestamp: u64,
    },
    StepStarted {
        run_id: String,
        step_name: String,
        timestamp: u64,
    },
    StepFinished {
        run_id: String,
        step_name: String,
        timestamp: u64,
    },
    RunFinished {
        run_id: String,
        timestamp: u64,
    },
    RunError {
        run_id: String,
        code: String,
        message: String,
        timestamp: u64,
    },
    TextMessageStart {
        run_id: String,
        message_id: String,
        role: String,
        timestamp: u64,
    },
    TextMessageContent {
        run_id: String,
        message_id: String,
        delta: String,
        timestamp: u64,
    },
    TextMessageEnd {
        run_id: String,
        message_id: String,
        timestamp: u64,
    },
    ToolCallStart {
        run_id: String,
        tool_call_id: String,
        tool_name: String,
        timestamp: u64,
    },
    ToolCallArgs {
        run_id: String,
        tool_call_id: String,
        delta: String,
        timestamp: u64,
    },
    ToolCallEnd {
        run_id: String,
        tool_call_id: String,
        timestamp: u64,
    },
    ToolCallResult {
        run_id: String,
        tool_call_id: String,
        result: Value,
        timestamp: u64,
    },
    StateSnapshot {
        run_id: String,
        snapshot: Value,
        timestamp: u64,
    },
    StateDelta {
        run_id: String,
        delta: Value,
        timestamp: u64,
    },
    MessagesSnapshot {
        run_id: String,
        messages: Value,
        timestamp: u64,
    },
    Raw {
        run_id: String,
        source: String,
        payload: Value,
        timestamp: u64,
    },
    Custom {
        run_id: String,
        name: String,
        payload: Value,
        timestamp: u64,
    },
    Unknown,
}

AG-UI event emitted by an agent run.

Events are tagged by the type field using the AG-UI protocol’s screaming-snake-case naming (e.g. RUN_STARTED, TEXT_MESSAGE_CONTENT). All variants carry a timestamp (ms since epoch) and a run_id for correlation.

Variants

RunStarted

A new agent run has started.

Fields

run_id: String

Unique identifier for this run (UUID or opaque token).

thread_id: Option<String>

Conversation/thread the run belongs to.

timestamp: u64

Milliseconds since the Unix epoch.

StepStarted

A logical step inside a run has started (e.g. prefetch, tool_loop).

Fields

run_id: String

Run identifier.

step_name: String

Human-readable step name, e.g. "prefetch", "compaction", "tool_loop".

timestamp: u64

Milliseconds since the Unix epoch.

StepFinished

A logical step inside a run has finished.

Fields

run_id: String

Run identifier.

step_name: String

Step name that matches a prior STEP_STARTED.

timestamp: u64

Milliseconds since the Unix epoch.

RunFinished

The run has completed successfully.

Fields

run_id: String

Run identifier.

timestamp: u64

Milliseconds since the Unix epoch.

RunError

The run has terminated with an error.

Fields

run_id: String

Run identifier.

code: String

Short machine-readable error code.

message: String

Human-readable error message.

timestamp: u64

Milliseconds since the Unix epoch.

TextMessageStart

Start of a streamed assistant text message.

Fields

run_id: String

Run identifier.

message_id: String

Unique identifier for the streamed message (used to correlate CONTENT chunks).

role: String

Author role (typically "assistant").

timestamp: u64

Milliseconds since the Unix epoch.

TextMessageContent

Streamed text delta for an open TEXT_MESSAGE_START.

Fields

run_id: String

Run identifier.

message_id: String

Message identifier that matches a prior TEXT_MESSAGE_START.

delta: String

Delta text to append. Clients should concatenate deltas in order.

timestamp: u64

Milliseconds since the Unix epoch.

TextMessageEnd

End of a streamed assistant text message.

Fields

run_id: String

Run identifier.

message_id: String

Message identifier that matches a prior TEXT_MESSAGE_START.

timestamp: u64

Milliseconds since the Unix epoch.

ToolCallStart

The agent has decided to invoke a tool.

Fields

run_id: String

Run identifier.

tool_call_id: String

Unique identifier for this tool call (used to correlate ARGS/END/RESULT).

tool_name: String

Name of the tool being invoked.

timestamp: u64

Milliseconds since the Unix epoch.

ToolCallArgs

Streamed tool-call argument delta (typically used when arguments are generated token-by-token by the LLM).

Fields

run_id: String

Run identifier.

tool_call_id: String

Tool call identifier that matches a prior TOOL_CALL_START.

delta: String

Delta of the serialized JSON arguments.

timestamp: u64

Milliseconds since the Unix epoch.

ToolCallEnd

Tool invocation has completed (arguments fully formed, execution dispatched).

Fields

run_id: String

Run identifier.

tool_call_id: String

Tool call identifier that matches a prior TOOL_CALL_START.

timestamp: u64

Milliseconds since the Unix epoch.

ToolCallResult

Tool execution produced a result.

Fields

run_id: String

Run identifier.

tool_call_id: String

Tool call identifier that matches a prior TOOL_CALL_START.

result: Value

Result payload as an opaque JSON value (provider-specific).

timestamp: u64

Milliseconds since the Unix epoch.

StateSnapshot

Full snapshot of the agent’s shared state.

Fields

run_id: String

Run identifier.

snapshot: Value

Full state document as an opaque JSON value.

timestamp: u64

Milliseconds since the Unix epoch.

StateDelta

Incremental state update as a JSON Patch (RFC 6902) document.

Fields

run_id: String

Run identifier.

delta: Value

JSON Patch array describing the delta.

timestamp: u64

Milliseconds since the Unix epoch.

MessagesSnapshot

Full snapshot of the current message list.

Fields

run_id: String

Run identifier.

messages: Value

Messages as an opaque JSON array.

timestamp: u64

Milliseconds since the Unix epoch.

Raw

Raw, provider-specific event passthrough. Clients that understand the source may consume payload; generic clients should ignore it.

Fields

run_id: String

Run identifier.

source: String

Provider label, e.g. "gemini", "groq", "copilot_headless".

payload: Value

Raw payload as an opaque JSON value.

timestamp: u64

Milliseconds since the Unix epoch.

Custom

Custom application-defined event. Useful for channel-specific affordances (e.g. Telegram typing indicator hints, web UI tooltips).

Fields

run_id: String

Run identifier.

name: String

Custom event name.

payload: Value

Arbitrary payload as an opaque JSON value.

timestamp: u64

Milliseconds since the Unix epoch.

Unknown

Forward-compat catch-all for wire-format events whose type field does not match any variant above.

When a newer AG-UI implementation adds an event kind the current embacle release does not know about, deserialization still succeeds and produces this variant. Producers never emit it; consumers typically ignore it. The original type string and payload are dropped because serde’s #[serde(other)] mandates a unit variant — callers that need the raw JSON should deserialize into serde_json::Value first and hand-dispatch.

Implementations

impl AgUiEvent

pub const fn kind(&self) -> AgUiEventKind

Return the discriminant kind without cloning the event.

pub fn run_id(&self) -> &str

Return the run identifier this event belongs to, or "" for the forward-compat Self::Unknown variant which has no recoverable fields.

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

Convenience constructor for RUN_STARTED.

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

Convenience constructor for STEP_STARTED.

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

Convenience constructor for STEP_FINISHED.

pub fn run_finished(run_id: impl Into<String>) -> Self

Convenience constructor for RUN_FINISHED.

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

Convenience constructor for RUN_ERROR.

pub fn tool_call_start( run_id: impl Into<String>, tool_call_id: impl Into<String>, tool_name: impl Into<String>, ) -> Self

Convenience constructor for TOOL_CALL_START.

pub fn tool_call_result( run_id: impl Into<String>, tool_call_id: impl Into<String>, result: Value, ) -> Self

Convenience constructor for TOOL_CALL_RESULT.

Trait Implementations

impl Clone for AgUiEvent

fn clone(&self) -> AgUiEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AgUiEvent

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for AgUiEvent

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for AgUiEvent

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

where __S: Serializer,

Serialize this value into the given Serde serializer.