03 Prompt Management

Learner guide: 03 Prompt Management

Instructor notes

• The teaching point is the trace-to-prompt loop: every generation should link to the prompt version that produced it.
• Prefer the UI path first because it mirrors how non-engineers will edit prompts later.
• Keep the local SYSTEM_PROMPT as a resilience fallback, not as the source of truth once the prompt is published.

Demo rhythm

1. Create dad-it-support-agent as a text prompt and label it production.
2. Fetch it with LangfuseClient.
3. Swap the hardcoded system message for the fetched text, keeping SYSTEM_PROMPT as the fallback.
4. Pass langfusePrompt into observeOpenAI.
5. Open a generation and show the Prompt badge.

Watch for

• Prompt name/label mismatches between .env and Langfuse.
• Learners forgetting that the SDK fetches the production label by default.
• The Prompt badge proves linking, not usage. A transcript still sending the local SYSTEM_PROMPT passes every verify step while prompt edits in the UI change nothing — if an edit seems to have no effect, check the generation input.

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