Enum AgentEvent 

pub enum AgentEvent {
    TextStart,
    TextDelta(String),
    TextEnd,
    ThinkingStart,
    ThinkingDelta(String),
    ThinkingEnd,
    ToolCallsBegin(Vec<ToolCall>),
    ToolCallsStart(Vec<ToolCall>),
    ToolResult {
        call_id: String,
        output: Result<String, String>,
        duration_ms: u64,
    },
    ToolCallsComplete,
    UserSteered {
        content: String,
    },
    Compact {
        summary: String,
    },
    Done(AgentResponse),
}

A fine-grained event emitted during agent execution.

Yielded by Agent::run_stream() or emitted via Hook::on_event() for real-time status reporting to clients.

Text and thinking deltas are bracketed by explicit TextStart/TextEnd and ThinkingStart/ThinkingEnd markers so clients can render coherent segments without inferring boundaries from neighboring events. Only one segment is open at a time — transitions emit the closing event of the previous segment before the opening of the next.

Variants

TextStart

A text segment is starting; subsequent TextDeltas belong to it.

TextDelta(String)

Text content delta from the model.

TextEnd

The current text segment has ended.

ThinkingStart

A thinking segment is starting; subsequent ThinkingDeltas belong to it.

ThinkingDelta(String)

Thinking/reasoning content delta from the model.

ThinkingEnd

The current thinking segment has ended.

ToolCallsBegin(Vec<ToolCall>)

Early notification: model is generating tool calls (names only, args incomplete).

ToolCallsStart(Vec<ToolCall>)

Model is calling tools (with the complete tool calls).

ToolResult

A single tool completed execution.

output is Ok for normal tool output and Err for a failure — either a dispatch-level error (no sender, channel closed) or a handler-reported failure. The inner string carries the text in both cases so UIs can render it; the distinction lets clients style errors differently and lets agents make retry decisions.

Fields

call_id: String

The tool call ID this result belongs to.

output: Result<String, String>

Success or error output from the tool.

duration_ms: u64

Wall-clock duration of the tool dispatch in milliseconds.

ToolCallsComplete

All tools completed, continuing to next iteration.

UserSteered

User steering message injected at turn boundary.

Fields

content: String

Compact

Context was compacted — carries the compaction summary.

Fields

summary: String

Done(AgentResponse)

Agent finished with final response.

Trait Implementations

impl Clone for AgentEvent

fn clone(&self) -> AgentEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AgentEvent

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

Formats the value using the given formatter.