feat: initial scaffold with context adapters and litellm pkg

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pkg/litellm/telemetry.go

@@ -0,0 +1,71 @@
+package litellm
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.36.0"
+	"google.golang.org/adk/telemetry"
+)
+
+// SetupTelemetry wires ADK OTLP tracing from environment variables.
+//
+// Reads:
+//   - OTLP_ENDPOINT       full URL base, e.g. http://jaeger.d-ma.be:4318 (skip if empty)
+//   - ADK_SERVICE_NAME    service name in Jaeger (default: "agent")
+//   - ADK_SERVICE_VERSION semver label (default: "0.1.0")
+//
+// Returns a shutdown func to call on exit with a short-timeout context.
+// No-op (nil error, noop shutdown) when OTLP_ENDPOINT is unset.
+func SetupTelemetry(ctx context.Context) (shutdown func(context.Context) error, err error) {
+	endpoint := os.Getenv("OTLP_ENDPOINT")
+	if endpoint == "" {
+		return func(context.Context) error { return nil }, nil
+	}
+
+	svcName := os.Getenv("ADK_SERVICE_NAME")
+	if svcName == "" {
+		svcName = "agent"
+	}
+	svcVersion := os.Getenv("ADK_SERVICE_VERSION")
+	if svcVersion == "" {
+		svcVersion = "0.1.0"
+	}
+
+	exporter, err := otlptracehttp.New(ctx,
+		otlptracehttp.WithEndpointURL(endpoint+"/v1/traces"),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("otlp exporter: %w", err)
+	}
+
+	res, err := resource.New(ctx,
+		resource.WithAttributes(
+			semconv.ServiceName(svcName),
+			semconv.ServiceVersion(svcVersion),
+		),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("resource: %w", err)
+	}
+
+	providers, err := telemetry.New(ctx,
+		telemetry.WithSpanProcessors(sdktrace.NewBatchSpanProcessor(exporter)),
+		telemetry.WithResource(res),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("telemetry.New: %w", err)
+	}
+	providers.SetGlobalOtelProviders()
+
+	return func(ctx context.Context) error {
+		shutCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+		defer cancel()
+		return providers.Shutdown(shutCtx)
+	}, nil
+}