Lifecycle

Create one LangfuseClient for the process or worker and derive observers and service clients from it.

const langfuse = new LangfuseClient()
const tracing = langfuse.observer({ captureMode: 'safe' })

try {
  await runWork(tracing)
  await langfuse.flush()
} finally {
  await langfuse.close()
}

flush() drains traces and queued scores without closing the client. close() performs final delivery and resource shutdown. Do not create one client per request in a long-running service.

Process signals do not unwind an await using scope. On SIGINT or SIGTERM, stop accepting work, abort and await active Agent runs, then call langfuse.close(). Core can then finish each root observation with status: 'cancelled' before Langfuse flushes it. When Studio owns the runs, put langfuse.close() in Studio.serve({ onShutdown }).