Lab: A versioned prompt, tested on two models

Module 2 · Lab · About 60 minutes · Needs: lessons 1 and 2 (rule checks, the pushback test, the six prompt sections, the OUTCOME: contract)

What you are building

Lesson 2 ended with a prompt built inside a notebook. Dev's question still stands: where does it live, and who can change it? This lab gives the answer a team can review. The prompt becomes a file, returns_desk/prompts/system_v1.md, with placeholders where the numbers go, so every limit still comes from code. A loader fills it, names it by a hash, and refuses a file that changed without a new version. Seven fixed cases, including Tom pushing back and Tom miscounting his days, run against the course model and a second model, and a short report says whether the swap is safe. Everything at BrightCart is simulated.