Enum LcelStreamEvent 

pub enum LcelStreamEvent {
    OnLlmStart {
        run_id: Uuid,
        name: String,
        metadata: HashMap<String, Value>,
    },
    OnLlmStream {
        run_id: Uuid,
        name: String,
        token: String,
    },
    OnLlmEnd {
        run_id: Uuid,
        name: String,
        output: Value,
    },
    OnToolEnd {
        run_id: Uuid,
        name: String,
        output: String,
    },
    OnChainEnd {
        run_id: Uuid,
        name: String,
        output: Value,
    },
}

Fine-grained event emitted during LCEL pipeline execution.

v0.9.0 supports 5 core event types:

• OnLlmStart / OnLlmStream / OnLlmEnd: LLM lifecycle
• OnToolEnd: Tool execution completion
• OnChainEnd: Chain execution completion

v0.10.0 will add: OnRetrieverStart/End, OnPromptStart/End, OnToolStart, OnChainStart, OnToolError, OnChainError, etc.

Note: Named LcelStreamEvent to avoid collision with lc_langgraph::StreamEvent (graph execution events).

Variants

OnLlmStart

LLM invocation started.

Fields

run_id: Uuid

Unique run identifier.

name: String

Name of the LLM (e.g. “gpt-4o”, “claude-3-opus”).

metadata: HashMap<String, Value>

Additional metadata.

OnLlmStream

LLM streaming token.

Fields

run_id: Uuid

Unique run identifier.

name: String

Name of the LLM.

token: String

The token text.

OnLlmEnd

LLM invocation completed.

Fields

run_id: Uuid

Unique run identifier.

name: String

Name of the LLM.

output: Value

The full LLM output.

OnToolEnd

Tool execution completed.

Fields

run_id: Uuid

Unique run identifier.

name: String

Name of the tool.

output: String

The tool output.

OnChainEnd

Chain execution completed.

Fields

run_id: Uuid

Unique run identifier.

name: String

Name of the chain.

output: Value

The chain output.

Implementations

impl LcelStreamEvent

pub fn run_id(&self) -> &Uuid

Get the run_id for this event.

pub fn name(&self) -> &str

Get the name associated with this event.

pub fn kind(&self) -> &str

Get the event kind as a string.

Trait Implementations

impl Clone for LcelStreamEvent

fn clone(&self) -> LcelStreamEvent

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for LcelStreamEvent

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

Formats the value using the given formatter.