Multi-Span Tracing

const result = await lumina.trace('rag_pipeline', async (parentSpan) => {
  parentSpan.setAttribute('user_query', query);

  // Child span 1
  const docs = await lumina.trace('retrieval', async () => {
    return await vectorDB.search(query);
  });

  // Child span 2
  const response = await lumina.traceLLM(
    () => llm.generate(buildPrompt(query, docs)),
    { name: 'synthesis', system: 'anthropic' }
  );

  return response;
});

rag_pipeline (2.5s, $0.05)
├── retrieval (1.8s, $0.01)
│   ├── embedding (0.2s, $0.001)
│   └── vector_search (1.6s, $0.009)
└── synthesis (0.7s, $0.04)

await lumina.trace('operation', async (span) => {
  span.addEvent('step_1_started');

  // Step 1
  await processStep1();

  span.addEvent('step_1_completed');
  span.addEvent('step_2_started');

  // Step 2
  await processStep2();

  span.addEvent('step_2_completed');
});