Struct LangfuseInterceptor 

pub struct LangfuseInterceptor<T: Tracer + Send + Sync> { /* private fields */ }

Langfuse interceptor for OpenTelemetry-based observability.

This interceptor automatically creates spans for API calls. Spans are maintained across before_request and after_response using a global registry and request metadata, requiring no user code changes.

The tracer must be configured externally - this interceptor only instruments API calls.

Implementations

impl<T: Tracer + Send + Sync> LangfuseInterceptor<T>

where T::Span: Send + Sync + 'static,

pub fn new(tracer: T, config: LangfuseConfig) -> Self

Create a new Langfuse interceptor with the given tracer.

The tracer should be configured to export to Langfuse using opentelemetry_langfuse::ExporterBuilder.

Example

use opentelemetry::global;
use opentelemetry::trace::TracerProvider;
use opentelemetry_langfuse::ExporterBuilder;
use opentelemetry_sdk::runtime::Tokio;
use opentelemetry_sdk::trace::span_processor_with_async_runtime::BatchSpanProcessor;
use opentelemetry_sdk::trace::SdkTracerProvider;

// Build exporter
let exporter = ExporterBuilder::from_env()?.build()?;

// Create tracer provider with batch processor
let provider = SdkTracerProvider::builder()
    .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
    .build();

// Set as global provider
global::set_tracer_provider(provider.clone());

// Get tracer for interceptor
let tracer = provider.tracer("openai-ergonomic");

// Create interceptor with tracer
use openai_ergonomic::langfuse_interceptor::{LangfuseInterceptor, LangfuseConfig};
let interceptor = LangfuseInterceptor::new(tracer, LangfuseConfig::new());

Examples found in repository

examples/langfuse_simple.rs (line 50)

async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    println!(" Initializing OpenAI client with Langfuse observability...\n");

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor = LangfuseInterceptor::new(tracer, LangfuseConfig::new());

    // 4. Create the OpenAI client and add the Langfuse interceptor
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor))
        .build();

    println!(" Client initialized successfully!");
    println!(" Traces will be sent to Langfuse for monitoring\n");

    // Make a simple chat completion - tracing is automatic!
    println!(" Making a simple chat completion request...");
    let request = client
        .chat_simple("What is 2 + 2? Answer with just the number.")
        .build()?;
    let response = client.execute_chat(request).await?;

    println!(" Response: {:?}", response.content());

    println!("\n Done! Check your Langfuse dashboard to see the traces.");
    println!("   - Look for traces with the operation name 'chat'");
    println!("   - Each trace includes request/response details and token usage");

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

examples/langfuse_streaming.rs (line 55)

async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    println!("🚀 Initializing OpenAI client with Langfuse streaming observability...\n");

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor = LangfuseInterceptor::new(tracer, LangfuseConfig::new());

    // 4. Create the OpenAI client and add the Langfuse interceptor
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor))
        .build();

    println!("✅ Client initialized successfully!");
    println!("📊 Streaming traces will be sent to Langfuse for monitoring\n");

    // Example 1: Basic streaming with tracing
    println!("=== Example 1: Basic Streaming ===");
    basic_streaming(&client).await?;

    // Example 2: Streaming with parameters
    println!("\n=== Example 2: Streaming with Parameters ===");
    streaming_with_parameters(&client).await?;

    // Example 3: Collect full content
    println!("\n=== Example 3: Collect Full Content ===");
    collect_content(&client).await?;

    println!("\n✅ Done! Check your Langfuse dashboard to see the streaming traces.");
    println!("   - Look for traces with operation names 'chat' or 'responses'");
    println!("   - Each trace includes:");
    println!("     • before_request: Initial request details");
    println!("     • on_stream_chunk: Each chunk as it arrives (real-time)");
    println!("     • on_stream_end: Final token usage and duration");

    // Give spawned interceptor tasks time to complete
    tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

examples/langfuse.rs (line 54)

async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor =
        std::sync::Arc::new(LangfuseInterceptor::new(tracer, LangfuseConfig::new()));

    // 4. Create the OpenAI client and add the Langfuse interceptor
    // Keep a reference to the interceptor so we can update context later
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor.clone()))
        .build();

    println!(" OpenAI client initialized with Langfuse observability");
    println!(" Traces will be sent to Langfuse for monitoring\n");

    // Example 1: Simple chat completion
    println!("Example 1: Simple chat completion");
    println!("---------------------------------");
    let chat_builder = client
        .chat_simple("What is the capital of France? Answer in one word.")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 2: Chat completion with builder pattern
    println!("Example 2: Chat with builder pattern");
    println!("-------------------------------------");
    let chat_builder = client
        .chat()
        .system("You are a helpful assistant that speaks like a pirate.")
        .user("Tell me about the ocean in 2 sentences.")
        .temperature(0.7)
        .max_tokens(100)
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 3: Multiple messages in a conversation
    println!("Example 3: Conversation");
    println!("-----------------------");
    let chat_builder = client
        .chat()
        .system("You are a math tutor.")
        .user("What is 2 + 2?")
        .assistant("2 + 2 equals 4.")
        .user("And what about 3 + 3?")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 4: Error handling (intentionally trigger an error)
    println!("Example 4: Error handling");
    println!("-------------------------");
    // Create a builder with a non-existent model
    let chat_builder = ChatCompletionBuilder::new("non-existent-model")
        .user("This should fail")
        .build()?;
    let result = client.execute_chat(chat_builder).await;

    match result {
        Ok(_) => println!("Unexpected success"),
        Err(e) => println!("Expected error captured: {e}\n"),
    }

    // Example 5: Embeddings
    println!("Example 5: Embeddings");
    println!("--------------------");
    let embeddings_builder = client.embeddings().text(
        "text-embedding-ada-002",
        "The quick brown fox jumps over the lazy dog",
    );
    let embeddings = client.embeddings().create(embeddings_builder).await?;
    println!("Generated {} embedding(s)\n", embeddings.data.len());

    // Example 6: Using custom metadata via interceptor context
    println!("Example 6: Custom metadata via interceptor context");
    println!("---------------------------------------------------");

    // Set session and user IDs on the interceptor's context
    langfuse_interceptor.set_session_id("demo-session-123");
    langfuse_interceptor.set_user_id("demo-user-456");
    langfuse_interceptor.add_tags(vec!["example".to_string(), "demo".to_string()]);

    let chat_builder = client
        .chat_simple("Say 'Hello from custom session!'")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response with custom metadata: {:?}\n", response.content());

    // Clear context for subsequent calls
    langfuse_interceptor.clear_context();

    println!(" All examples completed!");
    println!(" Check your Langfuse dashboard to see the traces");
    println!("   - Look for traces with operation name 'chat'");
    println!("   - Each trace includes request/response details, token usage, and timing");
    println!("   - Example 6 will have custom session_id, user_id, and tags");

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

pub fn set_session_id(&self, session_id: impl Into<String>)

Set the session ID for traces created by this interceptor.

Examples found in repository

examples/langfuse.rs (line 129)

async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor =
        std::sync::Arc::new(LangfuseInterceptor::new(tracer, LangfuseConfig::new()));

    // 4. Create the OpenAI client and add the Langfuse interceptor
    // Keep a reference to the interceptor so we can update context later
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor.clone()))
        .build();

    println!(" OpenAI client initialized with Langfuse observability");
    println!(" Traces will be sent to Langfuse for monitoring\n");

    // Example 1: Simple chat completion
    println!("Example 1: Simple chat completion");
    println!("---------------------------------");
    let chat_builder = client
        .chat_simple("What is the capital of France? Answer in one word.")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 2: Chat completion with builder pattern
    println!("Example 2: Chat with builder pattern");
    println!("-------------------------------------");
    let chat_builder = client
        .chat()
        .system("You are a helpful assistant that speaks like a pirate.")
        .user("Tell me about the ocean in 2 sentences.")
        .temperature(0.7)
        .max_tokens(100)
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 3: Multiple messages in a conversation
    println!("Example 3: Conversation");
    println!("-----------------------");
    let chat_builder = client
        .chat()
        .system("You are a math tutor.")
        .user("What is 2 + 2?")
        .assistant("2 + 2 equals 4.")
        .user("And what about 3 + 3?")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 4: Error handling (intentionally trigger an error)
    println!("Example 4: Error handling");
    println!("-------------------------");
    // Create a builder with a non-existent model
    let chat_builder = ChatCompletionBuilder::new("non-existent-model")
        .user("This should fail")
        .build()?;
    let result = client.execute_chat(chat_builder).await;

    match result {
        Ok(_) => println!("Unexpected success"),
        Err(e) => println!("Expected error captured: {e}\n"),
    }

    // Example 5: Embeddings
    println!("Example 5: Embeddings");
    println!("--------------------");
    let embeddings_builder = client.embeddings().text(
        "text-embedding-ada-002",
        "The quick brown fox jumps over the lazy dog",
    );
    let embeddings = client.embeddings().create(embeddings_builder).await?;
    println!("Generated {} embedding(s)\n", embeddings.data.len());

    // Example 6: Using custom metadata via interceptor context
    println!("Example 6: Custom metadata via interceptor context");
    println!("---------------------------------------------------");

    // Set session and user IDs on the interceptor's context
    langfuse_interceptor.set_session_id("demo-session-123");
    langfuse_interceptor.set_user_id("demo-user-456");
    langfuse_interceptor.add_tags(vec!["example".to_string(), "demo".to_string()]);

    let chat_builder = client
        .chat_simple("Say 'Hello from custom session!'")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response with custom metadata: {:?}\n", response.content());

    // Clear context for subsequent calls
    langfuse_interceptor.clear_context();

    println!(" All examples completed!");
    println!(" Check your Langfuse dashboard to see the traces");
    println!("   - Look for traces with operation name 'chat'");
    println!("   - Each trace includes request/response details, token usage, and timing");
    println!("   - Example 6 will have custom session_id, user_id, and tags");

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

pub fn set_user_id(&self, user_id: impl Into<String>)

Set the user ID for traces created by this interceptor.

Examples found in repository

examples/langfuse.rs (line 130)

async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor =
        std::sync::Arc::new(LangfuseInterceptor::new(tracer, LangfuseConfig::new()));

    // 4. Create the OpenAI client and add the Langfuse interceptor
    // Keep a reference to the interceptor so we can update context later
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor.clone()))
        .build();

    println!(" OpenAI client initialized with Langfuse observability");
    println!(" Traces will be sent to Langfuse for monitoring\n");

    // Example 1: Simple chat completion
    println!("Example 1: Simple chat completion");
    println!("---------------------------------");
    let chat_builder = client
        .chat_simple("What is the capital of France? Answer in one word.")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 2: Chat completion with builder pattern
    println!("Example 2: Chat with builder pattern");
    println!("-------------------------------------");
    let chat_builder = client
        .chat()
        .system("You are a helpful assistant that speaks like a pirate.")
        .user("Tell me about the ocean in 2 sentences.")
        .temperature(0.7)
        .max_tokens(100)
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 3: Multiple messages in a conversation
    println!("Example 3: Conversation");
    println!("-----------------------");
    let chat_builder = client
        .chat()
        .system("You are a math tutor.")
        .user("What is 2 + 2?")
        .assistant("2 + 2 equals 4.")
        .user("And what about 3 + 3?")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 4: Error handling (intentionally trigger an error)
    println!("Example 4: Error handling");
    println!("-------------------------");
    // Create a builder with a non-existent model
    let chat_builder = ChatCompletionBuilder::new("non-existent-model")
        .user("This should fail")
        .build()?;
    let result = client.execute_chat(chat_builder).await;

    match result {
        Ok(_) => println!("Unexpected success"),
        Err(e) => println!("Expected error captured: {e}\n"),
    }

    // Example 5: Embeddings
    println!("Example 5: Embeddings");
    println!("--------------------");
    let embeddings_builder = client.embeddings().text(
        "text-embedding-ada-002",
        "The quick brown fox jumps over the lazy dog",
    );
    let embeddings = client.embeddings().create(embeddings_builder).await?;
    println!("Generated {} embedding(s)\n", embeddings.data.len());

    // Example 6: Using custom metadata via interceptor context
    println!("Example 6: Custom metadata via interceptor context");
    println!("---------------------------------------------------");

    // Set session and user IDs on the interceptor's context
    langfuse_interceptor.set_session_id("demo-session-123");
    langfuse_interceptor.set_user_id("demo-user-456");
    langfuse_interceptor.add_tags(vec!["example".to_string(), "demo".to_string()]);

    let chat_builder = client
        .chat_simple("Say 'Hello from custom session!'")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response with custom metadata: {:?}\n", response.content());

    // Clear context for subsequent calls
    langfuse_interceptor.clear_context();

    println!(" All examples completed!");
    println!(" Check your Langfuse dashboard to see the traces");
    println!("   - Look for traces with operation name 'chat'");
    println!("   - Each trace includes request/response details, token usage, and timing");
    println!("   - Example 6 will have custom session_id, user_id, and tags");

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

pub fn add_tags(&self, tags: Vec<String>)

Add tags to traces created by this interceptor.

Examples found in repository

examples/langfuse.rs (line 131)

async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor =
        std::sync::Arc::new(LangfuseInterceptor::new(tracer, LangfuseConfig::new()));

    // 4. Create the OpenAI client and add the Langfuse interceptor
    // Keep a reference to the interceptor so we can update context later
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor.clone()))
        .build();

    println!(" OpenAI client initialized with Langfuse observability");
    println!(" Traces will be sent to Langfuse for monitoring\n");

    // Example 1: Simple chat completion
    println!("Example 1: Simple chat completion");
    println!("---------------------------------");
    let chat_builder = client
        .chat_simple("What is the capital of France? Answer in one word.")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 2: Chat completion with builder pattern
    println!("Example 2: Chat with builder pattern");
    println!("-------------------------------------");
    let chat_builder = client
        .chat()
        .system("You are a helpful assistant that speaks like a pirate.")
        .user("Tell me about the ocean in 2 sentences.")
        .temperature(0.7)
        .max_tokens(100)
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 3: Multiple messages in a conversation
    println!("Example 3: Conversation");
    println!("-----------------------");
    let chat_builder = client
        .chat()
        .system("You are a math tutor.")
        .user("What is 2 + 2?")
        .assistant("2 + 2 equals 4.")
        .user("And what about 3 + 3?")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 4: Error handling (intentionally trigger an error)
    println!("Example 4: Error handling");
    println!("-------------------------");
    // Create a builder with a non-existent model
    let chat_builder = ChatCompletionBuilder::new("non-existent-model")
        .user("This should fail")
        .build()?;
    let result = client.execute_chat(chat_builder).await;

    match result {
        Ok(_) => println!("Unexpected success"),
        Err(e) => println!("Expected error captured: {e}\n"),
    }

    // Example 5: Embeddings
    println!("Example 5: Embeddings");
    println!("--------------------");
    let embeddings_builder = client.embeddings().text(
        "text-embedding-ada-002",
        "The quick brown fox jumps over the lazy dog",
    );
    let embeddings = client.embeddings().create(embeddings_builder).await?;
    println!("Generated {} embedding(s)\n", embeddings.data.len());

    // Example 6: Using custom metadata via interceptor context
    println!("Example 6: Custom metadata via interceptor context");
    println!("---------------------------------------------------");

    // Set session and user IDs on the interceptor's context
    langfuse_interceptor.set_session_id("demo-session-123");
    langfuse_interceptor.set_user_id("demo-user-456");
    langfuse_interceptor.add_tags(vec!["example".to_string(), "demo".to_string()]);

    let chat_builder = client
        .chat_simple("Say 'Hello from custom session!'")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response with custom metadata: {:?}\n", response.content());

    // Clear context for subsequent calls
    langfuse_interceptor.clear_context();

    println!(" All examples completed!");
    println!(" Check your Langfuse dashboard to see the traces");
    println!("   - Look for traces with operation name 'chat'");
    println!("   - Each trace includes request/response details, token usage, and timing");
    println!("   - Example 6 will have custom session_id, user_id, and tags");

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

pub fn add_tag(&self, tag: impl Into<String>)

Add a single tag to traces created by this interceptor.

pub fn set_metadata(&self, metadata: Value)

Set metadata for traces created by this interceptor.

pub fn clear_context(&self)

Clear all context attributes.

Examples found in repository

examples/langfuse.rs (line 140)

async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize tracing for logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("openai_ergonomic=debug".parse()?),
        )
        .init();

    // 1. Build Langfuse exporter from environment variables
    let exporter = ExporterBuilder::from_env()?.build()?;

    // 2. Create tracer provider with batch processor
    let provider = SdkTracerProvider::builder()
        .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
        .build();

    // Set as global provider
    global::set_tracer_provider(provider.clone());

    // 3. Get tracer and create interceptor
    let tracer = provider.tracer("openai-ergonomic");
    let langfuse_interceptor =
        std::sync::Arc::new(LangfuseInterceptor::new(tracer, LangfuseConfig::new()));

    // 4. Create the OpenAI client and add the Langfuse interceptor
    // Keep a reference to the interceptor so we can update context later
    let client = Client::from_env()?
        .with_interceptor(Box::new(langfuse_interceptor.clone()))
        .build();

    println!(" OpenAI client initialized with Langfuse observability");
    println!(" Traces will be sent to Langfuse for monitoring\n");

    // Example 1: Simple chat completion
    println!("Example 1: Simple chat completion");
    println!("---------------------------------");
    let chat_builder = client
        .chat_simple("What is the capital of France? Answer in one word.")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 2: Chat completion with builder pattern
    println!("Example 2: Chat with builder pattern");
    println!("-------------------------------------");
    let chat_builder = client
        .chat()
        .system("You are a helpful assistant that speaks like a pirate.")
        .user("Tell me about the ocean in 2 sentences.")
        .temperature(0.7)
        .max_tokens(100)
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 3: Multiple messages in a conversation
    println!("Example 3: Conversation");
    println!("-----------------------");
    let chat_builder = client
        .chat()
        .system("You are a math tutor.")
        .user("What is 2 + 2?")
        .assistant("2 + 2 equals 4.")
        .user("And what about 3 + 3?")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response: {:?}\n", response.content());

    // Example 4: Error handling (intentionally trigger an error)
    println!("Example 4: Error handling");
    println!("-------------------------");
    // Create a builder with a non-existent model
    let chat_builder = ChatCompletionBuilder::new("non-existent-model")
        .user("This should fail")
        .build()?;
    let result = client.execute_chat(chat_builder).await;

    match result {
        Ok(_) => println!("Unexpected success"),
        Err(e) => println!("Expected error captured: {e}\n"),
    }

    // Example 5: Embeddings
    println!("Example 5: Embeddings");
    println!("--------------------");
    let embeddings_builder = client.embeddings().text(
        "text-embedding-ada-002",
        "The quick brown fox jumps over the lazy dog",
    );
    let embeddings = client.embeddings().create(embeddings_builder).await?;
    println!("Generated {} embedding(s)\n", embeddings.data.len());

    // Example 6: Using custom metadata via interceptor context
    println!("Example 6: Custom metadata via interceptor context");
    println!("---------------------------------------------------");

    // Set session and user IDs on the interceptor's context
    langfuse_interceptor.set_session_id("demo-session-123");
    langfuse_interceptor.set_user_id("demo-user-456");
    langfuse_interceptor.add_tags(vec!["example".to_string(), "demo".to_string()]);

    let chat_builder = client
        .chat_simple("Say 'Hello from custom session!'")
        .build()?;
    let response = client.execute_chat(chat_builder).await?;
    println!("Response with custom metadata: {:?}\n", response.content());

    // Clear context for subsequent calls
    langfuse_interceptor.clear_context();

    println!(" All examples completed!");
    println!(" Check your Langfuse dashboard to see the traces");
    println!("   - Look for traces with operation name 'chat'");
    println!("   - Each trace includes request/response details, token usage, and timing");
    println!("   - Example 6 will have custom session_id, user_id, and tags");

    // Shutdown the tracer provider to flush all spans
    println!("\n⏳ Flushing spans to Langfuse...");
    provider.shutdown()?;

    Ok(())
}

pub fn context(&self) -> &Arc<LangfuseContext>

Get a reference to the Langfuse context.

Trait Implementations

impl<T: Tracer + Send + Sync> Interceptor<LangfuseState<<T as Tracer>::Span>> for LangfuseInterceptor<T>

where T::Span: Send + Sync + 'static,

fn before_request<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, ctx: &'life1 mut BeforeRequestContext<'life2, LangfuseState<T::Span>>, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called before a request is sent.

fn after_response<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, ctx: &'life1 AfterResponseContext<'life2, LangfuseState<T::Span>>, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called after a successful non-streaming response is received.

fn on_stream_chunk<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, _ctx: &'life1 StreamChunkContext<'life2, LangfuseState<T::Span>>, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called for each chunk in a streaming response.

fn on_stream_end<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, ctx: &'life1 StreamEndContext<'life2, LangfuseState<T::Span>>, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a streaming response completes successfully.

fn on_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, ctx: &'life1 ErrorContext<'life2, LangfuseState<T::Span>>, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when an error occurs at any stage.