Anthropic (Claude) Integration

go get github.com/langwatch/langwatch/sdks/go
go get github.com/langwatch/langwatch/sdks/go/instrumentation/anthropic
go get github.com/anthropics/anthropic-sdk-go

package main

import (
	"context"
	"log"
	"os"

	"github.com/anthropics/anthropic-sdk-go"
	"github.com/anthropics/anthropic-sdk-go/option"
	"go.opentelemetry.io/otel"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"

	langwatch "github.com/langwatch/langwatch/sdks/go"
	otelanthropic "github.com/langwatch/langwatch/sdks/go/instrumentation/anthropic"
)

func main() {
	ctx := context.Background()

	// Set up the LangWatch exporter (reads LANGWATCH_API_KEY from env).
	exporter, err := langwatch.NewExporter(ctx)
	if err != nil {
		log.Fatalf("failed to create exporter: %v", err)
	}
	tp := sdktrace.NewTracerProvider(sdktrace.WithBatcher(exporter))
	otel.SetTracerProvider(tp)
	defer tp.Shutdown(ctx) // Critical: ensures traces are flushed.

	// Create an instrumented Anthropic client. By default the middleware
	// captures both request (input) and response (output) content.
	client := anthropic.NewClient(
		option.WithAPIKey(os.Getenv("ANTHROPIC_API_KEY")),
		option.WithMiddleware(otelanthropic.Middleware()),
	)

	message, err := client.Messages.New(ctx, anthropic.MessageNewParams{
		Model:     anthropic.ModelClaudeHaiku4_5,
		MaxTokens: 1024,
		System:    []anthropic.TextBlockParam{{Text: "You are a helpful assistant."}},
		Messages: []anthropic.MessageParam{
			anthropic.NewUserMessage(anthropic.NewTextBlock("Hello, Claude!")),
		},
	})
	if err != nil {
		log.Fatalf("messages call failed: %v", err)
	}

	log.Printf("Response: %v", message)
}