Enum StreamEvent 

pub enum StreamEvent {
    TextStart {
        id: String,
        execution_id: Option<String>,
    },
    TextDelta {
        id: String,
        delta: String,
    },
    TextEnd {
        id: String,
    },
    StartStep {
        step_id: Option<String>,
    },
    FinishStep {
        step_id: Option<String>,
    },
    ToolInputStart {
        tool_call_id: String,
        tool_name: String,
    },
    ToolInputDelta {
        tool_call_id: String,
        input_text_delta: String,
    },
    ToolInputAvailable {
        tool_call_id: String,
        tool_name: String,
        input: Value,
    },
    ToolOutputAvailable {
        tool_call_id: String,
        output: Value,
    },
    PermissionRequest {
        execution_id: String,
        tool_name: String,
        arguments: Value,
        policy: String,
        timestamp: i64,
    },
    Start {
        message_id: String,
        execution_id: Option<String>,
    },
    Finish {
        message_id: String,
        final_output: Option<String>,
    },
    Error {
        error: ExecutionError,
    },
    ExecutionStart {
        execution_id: String,
        parent_id: Option<String>,
        parent_type: Option<String>,
        timestamp: i64,
    },
    ExecutionEnd {
        execution_id: String,
        final_output: Option<String>,
        duration_ms: u64,
        timestamp: i64,
    },
    ExecutionFailed {
        execution_id: String,
        error: ExecutionError,
        timestamp: i64,
    },
    ExecutionPaused {
        execution_id: String,
        reason: String,
        timestamp: i64,
    },
    ExecutionResumed {
        execution_id: String,
        timestamp: i64,
    },
    ExecutionCancelled {
        execution_id: String,
        reason: String,
        timestamp: i64,
    },
    StepStart {
        execution_id: String,
        step_id: String,
        step_type: String,
        name: String,
        timestamp: i64,
    },
    StepEnd {
        execution_id: String,
        step_id: String,
        output: Option<String>,
        duration_ms: u64,
        timestamp: i64,
    },
    StepFailed {
        execution_id: String,
        step_id: String,
        error: ExecutionError,
        timestamp: i64,
    },
    StepDiscovered {
        execution_id: String,
        step_id: String,
        discovered_by: Option<String>,
        source_type: String,
        reason: String,
        depth: u32,
        timestamp: i64,
    },
    ArtifactCreated {
        execution_id: String,
        step_id: String,
        artifact_id: String,
        artifact_type: String,
        timestamp: i64,
    },
    StateSnapshot {
        execution_id: String,
        step_id: Option<String>,
        state: Value,
        timestamp: i64,
    },
    CheckpointSaved {
        execution_id: String,
        step_id: Option<String>,
        checkpoint_id: String,
        state_hash: String,
        timestamp: i64,
    },
    GoalEvaluated {
        execution_id: String,
        step_id: Option<String>,
        goal_id: String,
        status: String,
        score: Option<f64>,
        reason: Option<String>,
        timestamp: i64,
    },
    InboxMessage {
        execution_id: String,
        message_id: String,
        message_type: String,
        timestamp: i64,
    },
    PolicyDecision {
        execution_id: String,
        step_id: Option<String>,
        tool_name: String,
        decision: String,
        reason: Option<String>,
        timestamp: i64,
    },
    LlmCallStart {
        execution_id: String,
        step_id: Option<String>,
        callable_name: String,
        model: Option<String>,
        history_length: usize,
        timestamp: i64,
    },
    LlmCallEnd {
        execution_id: String,
        step_id: Option<String>,
        duration_ms: u64,
        prompt_tokens: Option<u32>,
        completion_tokens: Option<u32>,
        total_tokens: Option<u32>,
        timestamp: i64,
    },
    LlmCallFailed {
        execution_id: String,
        step_id: Option<String>,
        error: String,
        duration_ms: Option<u64>,
        timestamp: i64,
    },
    TokenUsageRecorded {
        execution_id: String,
        step_id: Option<String>,
        prompt_tokens: u32,
        completion_tokens: u32,
        total_tokens: u32,
        cumulative_tokens: u64,
        cost_usd: Option<f64>,
        cumulative_cost_usd: Option<f64>,
        timestamp: i64,
    },
    MemoryRecalled {
        execution_id: String,
        step_id: Option<String>,
        query: String,
        memories_count: usize,
        duration_ms: u64,
        session_id: Option<String>,
        timestamp: i64,
    },
    MemoryStored {
        execution_id: String,
        step_id: Option<String>,
        memory_type: String,
        session_id: Option<String>,
        timestamp: i64,
    },
    GuardrailEvaluated {
        execution_id: String,
        step_id: Option<String>,
        guardrail_name: String,
        decision: String,
        reason: Option<String>,
        score: Option<f64>,
        timestamp: i64,
    },
    ReasoningTrace {
        execution_id: String,
        step_id: Option<String>,
        reasoning_type: String,
        content: String,
        truncated: Option<bool>,
        timestamp: i64,
    },
    ContextSnapshot {
        execution_id: String,
        step_id: Option<String>,
        message_count: usize,
        estimated_tokens: u32,
        max_tokens: Option<u32>,
        utilization_pct: f64,
        timestamp: i64,
    },
    FeedbackReceived {
        execution_id: String,
        step_id: Option<String>,
        feedback_type: String,
        score: Option<f64>,
        comment: Option<String>,
        user_id: Option<String>,
        timestamp: i64,
    },
}

StreamEvent - All streaming events with data-* prefix

Events are tagged for direct SSE serialization. UI adapters can consume these directly or transform as needed.

Variants

TextStart

Text generation started

Fields

id: String

execution_id: Option<String>

TextDelta

Incremental text chunk

Fields

id: String

delta: String

TextEnd

Text generation ended

Fields

id: String

StartStep

Step boundary start (AI SDK step concept)

Fields

step_id: Option<String>

FinishStep

Step boundary end (AI SDK step concept)

Fields

step_id: Option<String>

ToolInputStart

Tool input started

Fields

tool_call_id: String

tool_name: String

ToolInputDelta

Tool input delta (streaming input)

Fields

tool_call_id: String

input_text_delta: String

ToolInputAvailable

Tool input available (complete input)

Fields

tool_call_id: String

tool_name: String

input: Value

ToolOutputAvailable

Tool output available

Fields

tool_call_id: String

output: Value

PermissionRequest

Human-in-the-loop permission request before tool execution

Fields

execution_id: String

tool_name: String

arguments: Value

policy: String

timestamp: i64

Start

Stream/message start

Fields

message_id: String

execution_id: Option<String>

Finish

Stream/message finish

Fields

message_id: String

final_output: Option<String>

Error

Error occurred

Fields

error: ExecutionError

ExecutionStart

Execution started

Fields

execution_id: String

parent_id: Option<String>

parent_type: Option<String>

timestamp: i64

ExecutionEnd

Execution completed successfully

Fields

execution_id: String

final_output: Option<String>

duration_ms: u64

timestamp: i64

ExecutionFailed

Execution failed

Fields

execution_id: String

error: ExecutionError

timestamp: i64

ExecutionPaused

Execution paused

Fields

execution_id: String

reason: String

timestamp: i64

ExecutionResumed

Execution resumed

Fields

execution_id: String

timestamp: i64

ExecutionCancelled

Execution cancelled

Fields

execution_id: String

reason: String

timestamp: i64

StepStart

Step started (with full metadata)

Fields

execution_id: String

step_id: String

step_type: String

name: String

timestamp: i64

StepEnd

Step completed

Fields

execution_id: String

step_id: String

output: Option<String>

duration_ms: u64

timestamp: i64

StepFailed

Step failed

Fields

execution_id: String

step_id: String

error: ExecutionError

timestamp: i64

StepDiscovered

Step discovered during execution (dynamic discovery for agentic loops)

Fields

execution_id: String

step_id: String

discovered_by: Option<String>

source_type: String

reason: String

depth: u32

timestamp: i64

ArtifactCreated

Artifact created

Fields

execution_id: String

step_id: String

artifact_id: String

artifact_type: String

timestamp: i64

StateSnapshot

State snapshot captured

Fields

execution_id: String

step_id: Option<String>

state: Value

timestamp: i64

CheckpointSaved

Checkpoint saved (Goal-driven persistence)

Fields

execution_id: String

step_id: Option<String>

checkpoint_id: String

state_hash: String

timestamp: i64

GoalEvaluated

Goal evaluated

Fields

execution_id: String

step_id: Option<String>

goal_id: String

status: String

score: Option<f64>

reason: Option<String>

timestamp: i64

InboxMessage

Inbox message received (INV-INBOX-003: audit trail)

Fields

execution_id: String

message_id: String

message_type: String

timestamp: i64

PolicyDecision

Policy decision made (audit trail for tool policy evaluation)

Fields

execution_id: String

step_id: Option<String>

tool_name: String

decision: String

reason: Option<String>

timestamp: i64

LlmCallStart

LLM call started

Fields

execution_id: String

step_id: Option<String>

callable_name: String

model: Option<String>

history_length: usize

timestamp: i64

LlmCallEnd

LLM call completed

Fields

execution_id: String

step_id: Option<String>

duration_ms: u64

prompt_tokens: Option<u32>

completion_tokens: Option<u32>

total_tokens: Option<u32>

timestamp: i64

LlmCallFailed

LLM call failed

Fields

execution_id: String

step_id: Option<String>

error: String

duration_ms: Option<u64>

timestamp: i64

TokenUsageRecorded

Token usage recorded (cumulative)

Fields

execution_id: String

step_id: Option<String>

prompt_tokens: u32

completion_tokens: u32

total_tokens: u32

cumulative_tokens: u64

cost_usd: Option<f64>

cumulative_cost_usd: Option<f64>

timestamp: i64

MemoryRecalled

Memory recalled (retrieved from memory store)

Fields

execution_id: String

step_id: Option<String>

query: String

memories_count: usize

duration_ms: u64

session_id: Option<String>

timestamp: i64

MemoryStored

Memory stored

Fields

execution_id: String

step_id: Option<String>

memory_type: String

session_id: Option<String>

timestamp: i64

GuardrailEvaluated

Guardrail evaluated

Fields

execution_id: String

step_id: Option<String>

guardrail_name: String

decision: String

reason: Option<String>

score: Option<f64>

timestamp: i64

ReasoningTrace

Reasoning trace captured

Fields

execution_id: String

step_id: Option<String>

reasoning_type: String

content: String

truncated: Option<bool>

timestamp: i64

ContextSnapshot

Context window snapshot

Fields

execution_id: String

step_id: Option<String>

message_count: usize

estimated_tokens: u32

max_tokens: Option<u32>

utilization_pct: f64

timestamp: i64

FeedbackReceived

Feedback received

Fields

execution_id: String

step_id: Option<String>

feedback_type: String

score: Option<f64>

comment: Option<String>

user_id: Option<String>

timestamp: i64

Implementations

impl StreamEvent

pub fn text_start(execution_id: Option<&ExecutionId>) -> Self

Create a text-start event

pub fn text_delta(id: impl Into<String>, delta: impl Into<String>) -> Self

Create a text-delta event

pub fn text_end(id: impl Into<String>) -> Self

Create a text-end event

pub fn start( message_id: impl Into<String>, execution_id: Option<&ExecutionId>, ) -> Self

Create a start event

pub fn finish( message_id: impl Into<String>, final_output: Option<String>, ) -> Self

Create a finish event

pub fn error(error: ExecutionError) -> Self

Create an error event

pub fn start_step(step_id: Option<&StepId>) -> Self

Create a start-step event (AI SDK)

pub fn finish_step(step_id: Option<&StepId>) -> Self

Create a finish-step event (AI SDK)

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

Create a tool-input-start event

pub fn tool_input_available( tool_call_id: impl Into<String>, tool_name: impl Into<String>, input: Value, ) -> Self

Create a tool-input-available event

pub fn tool_output_available( tool_call_id: impl Into<String>, output: Value, ) -> Self

Create a tool-output-available event

pub fn permission_request( execution_id: &ExecutionId, tool_name: impl Into<String>, arguments: Value, policy: impl Into<String>, ) -> Self

Create a permission-request event

pub fn execution_start(execution_id: &ExecutionId) -> Self

Create an execution-start event

pub fn execution_start_with_parent( execution_id: &ExecutionId, parent_id: impl Into<String>, parent_type: impl Into<String>, ) -> Self

Create an execution-start event with parent

pub fn execution_end( execution_id: &ExecutionId, final_output: Option<String>, duration_ms: u64, ) -> Self

Create an execution-end event

pub fn execution_failed( execution_id: &ExecutionId, error: ExecutionError, ) -> Self

Create an execution-failed event

pub fn execution_paused( execution_id: &ExecutionId, reason: impl Into<String>, ) -> Self

Create an execution-paused event

pub fn execution_resumed(execution_id: &ExecutionId) -> Self

Create an execution-resumed event

pub fn execution_cancelled( execution_id: &ExecutionId, reason: impl Into<String>, ) -> Self

Create an execution-cancelled event

pub fn step_start( execution_id: &ExecutionId, step_id: &StepId, step_type: StepType, name: impl Into<String>, ) -> Self

Create a step-start event

pub fn step_end( execution_id: &ExecutionId, step_id: &StepId, output: Option<String>, duration_ms: u64, ) -> Self

Create a step-end event

pub fn step_failed( execution_id: &ExecutionId, step_id: &StepId, error: ExecutionError, ) -> Self

Create a step-failed event

pub fn step_discovered( execution_id: &ExecutionId, step_id: &StepId, discovered_by: Option<&StepId>, source_type: StepSourceType, reason: impl Into<String>, depth: u32, ) -> Self

Create a step-discovered event

Emitted when a new step is dynamically discovered during agentic execution. This enables full audit trails for discovered steps (doc-30 Resource Discovery).

pub fn artifact_created( execution_id: &ExecutionId, step_id: &StepId, artifact_id: &ArtifactId, artifact_type: impl Into<String>, ) -> Self

Create an artifact-created event

pub fn inbox_message( execution_id: &ExecutionId, message_id: &str, message_type: InboxMessageType, ) -> Self

Create an inbox-message event for audit trail

Invariant INV-INBOX-003

All inbox messages MUST emit events for audit trail.

pub fn policy_decision_allow( execution_id: &ExecutionId, step_id: Option<&StepId>, tool_name: impl Into<String>, ) -> Self

Create a policy-decision event for audit trail

Records tool policy evaluation decisions for compliance and audit.

pub fn policy_decision_deny( execution_id: &ExecutionId, step_id: Option<&StepId>, tool_name: impl Into<String>, reason: impl Into<String>, ) -> Self

Create a policy-decision deny event

pub fn policy_decision_warn( execution_id: &ExecutionId, step_id: Option<&StepId>, tool_name: impl Into<String>, message: impl Into<String>, ) -> Self

Create a policy-decision warn event

pub fn llm_call_start( execution_id: &ExecutionId, step_id: Option<&StepId>, callable_name: impl Into<String>, model: Option<String>, history_length: usize, ) -> Self

Create an llm-call-start event

pub fn llm_call_end( execution_id: &ExecutionId, step_id: Option<&StepId>, duration_ms: u64, prompt_tokens: Option<u32>, completion_tokens: Option<u32>, total_tokens: Option<u32>, ) -> Self

Create an llm-call-end event

pub fn llm_call_failed( execution_id: &ExecutionId, step_id: Option<&StepId>, error: impl Into<String>, duration_ms: Option<u64>, ) -> Self

Create an llm-call-failed event

pub fn token_usage_recorded( execution_id: &ExecutionId, step_id: Option<&StepId>, prompt_tokens: u32, completion_tokens: u32, cumulative_tokens: u64, cost_usd: Option<f64>, cumulative_cost_usd: Option<f64>, ) -> Self

Create a token-usage-recorded event

pub fn memory_recalled( execution_id: &ExecutionId, step_id: Option<&StepId>, query: impl Into<String>, memories_count: usize, duration_ms: u64, session_id: Option<String>, ) -> Self

Create a memory-recalled event

pub fn memory_stored( execution_id: &ExecutionId, step_id: Option<&StepId>, memory_type: impl Into<String>, session_id: Option<String>, ) -> Self

Create a memory-stored event

pub fn guardrail_evaluated( execution_id: &ExecutionId, step_id: Option<&StepId>, guardrail_name: impl Into<String>, decision: impl Into<String>, reason: Option<String>, score: Option<f64>, ) -> Self

Create a guardrail-evaluated event

pub fn reasoning_trace( execution_id: &ExecutionId, step_id: Option<&StepId>, reasoning_type: impl Into<String>, content: impl Into<String>, truncated: Option<bool>, ) -> Self

Create a reasoning-trace event

pub fn context_window_snapshot( execution_id: &ExecutionId, step_id: Option<&StepId>, message_count: usize, estimated_tokens: u32, max_tokens: Option<u32>, utilization_pct: f64, ) -> Self

Create a context-window-snapshot event

pub fn feedback_received( execution_id: &ExecutionId, step_id: Option<&StepId>, feedback_type: impl Into<String>, score: Option<f64>, comment: Option<String>, user_id: Option<String>, ) -> Self

Create a feedback-received event

pub fn is_control_event(&self) -> bool

Check if this is a control event (pause/resume/cancel)

pub fn is_delta_event(&self) -> bool

Check if this is a delta/streaming event

pub fn is_summary_event(&self) -> bool

Check if this is a summary-level event (not a delta)

pub fn to_sse(&self) -> String

Serialize to SSE format: data: {...}\n\n

pub fn done() -> String

Create a [DONE] termination signal

Trait Implementations

impl Clone for StreamEvent

fn clone(&self) -> StreamEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StreamEvent

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for StreamEvent

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for StreamEvent

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

where __S: Serializer,

Serialize this value into the given Serde serializer.