Enum LoopbackEvent 

pub enum LoopbackEvent {
    Chunk(String),
    Flush,
    FullMessage(String),
    Status(String),
    ToolStart {
        tool_name: String,
        tool_call_id: String,
        params: Option<Value>,
        parent_tool_use_id: Option<String>,
        started_at: Instant,
    },
    ToolOutput {
        tool_name: String,
        display: String,
        diff: Option<DiffData>,
        filter_stats: Option<String>,
        kept_lines: Option<Vec<usize>>,
        locations: Option<Vec<String>>,
        tool_call_id: String,
        is_error: bool,
        terminal_id: Option<String>,
        parent_tool_use_id: Option<String>,
        raw_response: Option<Value>,
        started_at: Option<Instant>,
    },
    Usage {
        input_tokens: u64,
        output_tokens: u64,
        context_window: u64,
    },
    SessionTitle(String),
    Plan(Vec<(String, PlanItemStatus)>),
    ThinkingChunk(String),
    Stop(StopHint),
}

Events emitted by the agent side toward the A2A caller.

Variants

Chunk(String)

Flush

FullMessage(String)

Status(String)

ToolStart

Emitted immediately before tool execution begins.

Fields

tool_name: String

tool_call_id: String

params: Option<Value>

Raw input parameters passed to the tool (e.g. {"command": "..."} for bash).

parent_tool_use_id: Option<String>

Set when this tool call is made by a subagent; identifies the parent’s tool_call_id.

started_at: Instant

Wall-clock instant when the tool call was initiated; used to compute elapsed time.

ToolOutput

Fields

tool_name: String

display: String

diff: Option<DiffData>

filter_stats: Option<String>

kept_lines: Option<Vec<usize>>

locations: Option<Vec<String>>

tool_call_id: String

is_error: bool

terminal_id: Option<String>

Terminal ID for shell tool calls routed through the IDE terminal.

parent_tool_use_id: Option<String>

Set when this tool output belongs to a subagent; identifies the parent’s tool_call_id.

raw_response: Option<Value>

Structured tool response payload for ACP intermediate tool_call_update notifications.

started_at: Option<Instant>

Wall-clock instant when the corresponding ToolStart was emitted; used for elapsed time.

Usage

Token usage from the last LLM turn.

Fields

input_tokens: u64

output_tokens: u64

context_window: u64

SessionTitle(String)

Generated session title (emitted after the first agent response).

Plan(Vec<(String, PlanItemStatus)>)

Execution plan update.

ThinkingChunk(String)

Thinking/reasoning token chunk from the LLM.

Stop(StopHint)

Non-default stop condition detected by the agent loop.

Emitted immediately before Flush. When absent, the stop reason is EndTurn.

Trait Implementations

impl Clone for LoopbackEvent

fn clone(&self) -> LoopbackEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for LoopbackEvent

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

Formats the value using the given formatter.