Lesson 4: Prompt, retrieve or fine-tune: where facts should live

Module 6 · Lesson 4 · About 40 minutes · Needs: Lesson 3 (what fine-tuning changes), Module 0 (calling a model)

The situation

Dev liked Lesson 3. "Lesson 3's fine-tune sorted tickets in seconds. Let's fine-tune on everything." Two messages arrive. Priya says the returns window may drop from 30 days to 14 next month. Marta asks what each option costs to build, to run and to keep right.

Module 6 ends with a written decision: should BrightCart prompt, retrieve or fine-tune? This lesson makes it with one question, "How many days do I have to return an item?", run on every rung with real output, and a cost table built from published prices.