Crate lc_callbacks 

Callback and tracing system

This module provides callbacks for observability, tracing, and monitoring.

Quick Start

use lc_callbacks::{CallbackManager, StdOutHandler, LangSmithHandler};
use std::sync::Arc;

// Create callback manager with handlers
let manager = CallbackManager::new()
    .add_handler(Arc::new(StdOutHandler::new()))
    .add_handler(Arc::new(LangSmithHandler::from_env()?));

// Use with LLM or Agent
let llm = OpenAIChat::new(config);
// llm.with_callbacks(Arc::new(manager));

Environment Variables for LangSmith

• LANGSMITH_API_KEY: API key (required, starts with “ls_”)
• LANGSMITH_TRACING: Enable tracing (default: “true”)
• LANGSMITH_PROJECT: Project name (default: “default”)
• LANGSMITH_ENDPOINT: API endpoint (default: LangSmith official)
• LANGSMITH_WORKSPACE_ID: Workspace ID (required for org accounts)

Re-exports

pub use handlers::FileCallbackHandler;

pub use handlers::LangSmithHandler;

pub use handlers::LogFormat;

pub use handlers::StdOutHandler;

pub use tracing::clear_span_stack;

pub use tracing::init_task_span_stack;

pub use tracing::ConsoleTracingBackend;

pub use tracing::InMemoryTracingBackend;

pub use tracing::SpanGuard;

pub use tracing::SpanId;

pub use tracing::SpanKind;

pub use tracing::SpanStatus;

pub use tracing::SpanTokenUsage;

pub use tracing::TraceNode;

pub use tracing::TraceSpan;

pub use tracing::Tracer;

pub use tracing::TracingBackend;

Modules

handlers

Built-in callback handlers

tracing

Agent observability / deep tracing system

Structs

CallbackManager

Callback manager that handles multiple handlers

LangSmithClient

LangSmith API client

LangSmithConfig

LangSmith configuration

RunCreate

Simplified run structure for API requests

RunTree

Run tree node for tracing

RunUpdate

Run update structure for PATCH requests

Enums

LangSmithError

LangSmith error type

RunType

Run type for tracing

Traits

CallbackHandler

Callback handler trait for tracing and monitoring