Main content (8,000–12,000 words) - **exercises.md** — 25–40 practice problems (⭐ to ⭐⭐⭐⭐) - **quiz.md** — 20–25 self-assessment questions with answers - **case-study-01.md** — Primary case study (2,000–3,500 words) - **case-study-02.md** — Secondary case study or application exercise - **key-takeaw