00 Setup

Learner guide: 00 Setup

Instructor notes

• Use checkpoint/00-setup as the stable base-app checkout. It should be equivalent to checkpoint/01-base-app, not the complete reference app.
• main contains the complete reference implementation, but learners should use the checkpoint so setup and base-app orientation share the same starting state.
• Make learners confirm both URLs: Vite on 127.0.0.1:3333, Express on 127.0.0.1:8787.
• Emphasize the EU Langfuse host value: LANGFUSE_BASE_URL=https://cloud.langfuse.com.
• Have learners configure Project Settings → LLM Connections and save a default evaluator model before the monitoring chapter. LLM-as-a-judge evaluators will otherwise stop at the "No default model set" screen.
• Keep key handling explicit: real API keys go only into .env or Langfuse secret fields, never into shared transcripts, notes, or chat.
• After one successful chat turn, have learners switch to checkpoint/02-tracing for the first build step.

Watch for

• Missing .env values. The app may render while model calls fail.
• Missing Langfuse LLM connection or default evaluator model. The app can run and trace correctly while LLM-as-a-judge setup is still blocked.
• People expecting traces on checkpoint/00-setup or checkpoint/01-base-app. Both are intentionally untraced; tracing starts only after the 02-tracing edits.
• People staying on main for tracing. main is already the finished reference implementation.

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