02 Tracing

Learner guide: 02 Tracing

Instructor notes

• Teach the progression in three visible layers: OpenAI generations, one agent root, then tool observations.
• Keep the code changes small and local. The point is to show that Langfuse wraps existing app boundaries instead of forcing an architecture rewrite.
• The user/session propagation section is optional live, but later checkpoints include it so the following chapters have attribution available.

Demo rhythm

1. Add LangfuseSpanProcessor and observeOpenAI, run one turn, show separate generation traces.
2. Wrap runSupportConversationInner with observe(...), run again, show nested generations.
3. Wrap the two local tool helpers, run again, show the full tree.

Watch for

• Learners wrapping the OpenAI client in a separate factory. The workshop intentionally keeps the wrapper inline.
• Missing shutdown flush in index.ts; traces can arrive late without it.

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