Enum ChainEvent 

pub enum ChainEvent {
    IterationStart {
        iteration: usize,
        limit: usize,
        messages: Vec<Message>,
    },
    IterationEnd {
        iteration: usize,
        usage: Option<Usage>,
        cumulative_usage: Option<Usage>,
        tool_calls: Vec<ToolCall>,
    },
    BudgetExhausted {
        cumulative_usage: Usage,
        budget: u64,
    },
}

Event emitted during chain loop execution for observability.

Variants

IterationStart

Emitted before the provider is called for an iteration.

Fields

iteration: usize

1-based iteration number.

limit: usize

The chain limit.

messages: Vec<Message>

Current message history being sent to the provider.

IterationEnd

Emitted after an iteration completes (chunks collected, tool calls extracted).

Fields

iteration: usize

1-based iteration number.

usage: Option<Usage>

Per-iteration token usage, if the provider reported it.

cumulative_usage: Option<Usage>

Cumulative usage across all iterations up to and including this one.

tool_calls: Vec<ToolCall>

Tool calls extracted from this iteration’s response.

BudgetExhausted

Emitted when the budget is exhausted (after completing the current iteration).

Fields

cumulative_usage: Usage

Cumulative usage at the point the budget was exceeded.

budget: u64

The budget limit that was exceeded.

Trait Implementations

impl Clone for ChainEvent

fn clone(&self) -> ChainEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ChainEvent

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

Formats the value using the given formatter.