Scaffold Exercises

Create exercise directory structures that pass pnpm ai-hero-cli internal lint, then commit with git commit.

Directory naming

• Sections: XX-section-name/ inside exercises/ (e.g., 01-retrieval-skill-building)
• Exercises: XX.YY-exercise-name/ inside a section (e.g., 01.03-retrieval-with-bm25)
• Section number = XX, exercise number = XX.YY
• Names are dash-case (lowercase, hyphens)

Exercise variants

Each exercise needs at least one of these subfolders:

• problem/ - student workspace with TODOs
• solution/ - reference implementation
• explainer/ - conceptual material, no TODOs