Hands-on drill for Lesson 1 — The combinatorial trap. Before anyone writes a handler, the dependency graph itself goes under test: you declare the direct edges of the quote calculator, the workbench derives what each input transitively dirties, and one check pins the edge from the lesson's diagram that everyone forgets.
- 🟢 Easy · Map the dirty sets — six direct edges in, three dirty sets out. Ships red; the check battery knows the graph better than your handlers will.
Your editable copy is installed with the course — open the drill from Your exercises on the lesson page and work directly in your own space.