Struct Event 

pub struct Event {
    pub id: String,
    pub timestamp: DateTime<Utc>,
    pub invocation_id: String,
    pub branch: String,
    pub author: String,
    pub llm_response: LlmResponse,
    pub actions: EventActions,
    pub long_running_tool_ids: Vec<String>,
    pub llm_request: Option<String>,
    pub provider_metadata: HashMap<String, String>,
}

Core traits and types.

Always available regardless of feature flags. Includes:

• Agent - The fundamental trait for all agents
• Tool / Toolset - For extending agents with capabilities
• Session / State - For managing conversation context
• Event - For streaming agent responses
• AdkError / Result - Unified error handling Event represents a single interaction in a conversation. This struct embeds LlmResponse to match ADK-Go’s design pattern.

Fields

id: String

timestamp: DateTime<Utc>

invocation_id: String

branch: String

author: String

llm_response: LlmResponse

The LLM response containing content and metadata. Access content via event.llm_response.content.

actions: EventActions

long_running_tool_ids: Vec<String>

IDs of long-running tools associated with this event.

llm_request: Option<String>

LLM request data for UI display (JSON string)

provider_metadata: HashMap<String, String>

Provider-specific metadata (e.g., GCP Vertex, Azure OpenAI). Keeps the core Event struct provider-agnostic.

Implementations

impl Event

pub fn new(invocation_id: impl Into<String>) -> Event

Available on crate feature sessions only.

pub fn with_id(id: impl Into<String>, invocation_id: impl Into<String>) -> Event

Available on crate feature sessions only.

Create an event with a specific ID. Use this for streaming events where all chunks should share the same event ID.

pub fn content(&self) -> Option<&Content>

Available on crate feature sessions only.

Convenience method to access content directly.

pub fn set_content(&mut self, content: Content)

Available on crate feature sessions only.

Convenience method to set content directly.

pub fn is_final_response(&self) -> bool

Available on crate feature sessions only.

Returns whether the event is the final response of an agent.

An event is considered final if:

• It has skip_summarization set, OR
• It has long_running_tool_ids (indicating async operations), OR
• It has no function calls, no function responses, is not partial, and has no trailing code execution results.

Note: When multiple agents participate in one invocation, there could be multiple events with is_final_response() as true, for each participating agent.

pub fn function_call_ids(&self) -> Vec<String>

Available on crate feature sessions only.

Extracts function call IDs from this event’s content. Used to identify which function calls are associated with long-running tools.

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<(), Error>

Formats the value using the given formatter.

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

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Event

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.