Scaffold Exercises

---
name: scaffold-exercises
description: >
  Create exercise directory structures with sections, problems, solutions, and explainers that
  pass linting. Use when user wants to scaffold exercises, create exercise stubs, or set up a new
  course section.
allowed-tools: Read Grep Glob Bash Write Edit
compatibility: >
  Specific to the ai-hero course repository layout. Not a general project scaffolder.
metadata:
  tags: exercise-scaffolding, ai-hero-cli, course-sections, problem-solution, lint-compliant
  platforms: Claude, ChatGPT, Gemini, Codex
  version: "1.0"
  source: mattpocock/skills
  upstream_commit: 3cca18b368ae95cdbdebbff572ccafa662551015
  invocation: model-invoked
---

# Scaffold Exercises

Create exercise directory structures with sections, problems, solutions, and explainers that pass linting. Use when user wants to scaffold exercises, create exercise stubs, or set up a new course section.

This skill is imported from `mattpocock/skills` (MIT) and is **model-invoked** upstream.

## When to use this skill

- Create exercise directory structures with sections, problems, solutions, and explainers that pass linting.
- Use when user wants to scaffold exercises, create exercise stubs, or set up a new course section.

## Instructions

## 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

When stubbing, default to `explainer/` unless the plan specifies otherwise.

### Required files

Each subfolder (`problem/`, `solution/`, `explainer/`) needs a `readme.md` that:

- Is **not empty** (must have real content, even a single title line works)
- Has no broken links

When stubbing, create a minimal readme with a title and a description:

```md
# Exercise Title

Description here
```

If the subfolder has code, it also needs a `main.ts` (>1 line). But for stubs, a readme-only exercise is fine.

### Workflow

1. **Parse the plan** - extract section names, exercise names, and variant types
2. **Create directories** - `mkdir -p` for each path
3. **Create stub readmes** - one `readme.md` per variant folder with a title
4. **Run lint** - `pnpm ai-hero-cli internal lint` to validate
5. **Fix any errors** - iterate until lint passes

### Lint rules summary

The linter (`pnpm ai-hero-cli internal lint`) checks:

- Each exercise has subfolders (`problem/`, `solution/`, `explainer/`)
- At least one of `problem/`, `explainer/`, or `explainer.1/` exists
- `readme.md` exists and is non-empty in the primary subfolder
- No `.gitkeep` files
- No `speaker-notes.md` files
- No broken links in readmes
- No `pnpm run exercise` commands in readmes
- `main.ts` required per subfolder unless it's readme-only

### Moving/renaming exercises

When renumbering or moving exercises:

1. Use `git mv` (not `mv`) to rename directories - preserves git history
2. Update the numeric prefix to maintain order
3. Re-run lint after moves

Example:

```bash
git mv exercises/01-retrieval/01.03-embeddings exercises/01-retrieval/01.04-embeddings
```

### Example: stubbing from a plan

Given a plan like:

```
Section 05: Memory Skill Building
- 05.01 Introduction to Memory
- 05.02 Short-term Memory (explainer + problem + solution)
- 05.03 Long-term Memory
```

Create:

```bash
mkdir -p exercises/05-memory-skill-building/05.01-introduction-to-memory/explainer
mkdir -p exercises/05-memory-skill-building/05.02-short-term-memory/{explainer,problem,solution}
mkdir -p exercises/05-memory-skill-building/05.03-long-term-memory/explainer
```

Then create readme stubs:

```
exercises/05-memory-skill-building/05.01-introduction-to-memory/explainer/readme.md -> "# Introduction to Memory"
exercises/05-memory-skill-building/05.02-short-term-memory/explainer/readme.md -> "# Short-term Memory"
exercises/05-memory-skill-building/05.02-short-term-memory/problem/readme.md -> "# Short-term Memory"
exercises/05-memory-skill-building/05.02-short-term-memory/solution/readme.md -> "# Short-term Memory"
exercises/05-memory-skill-building/05.03-long-term-memory/explainer/readme.md -> "# Long-term Memory"
```

## Examples

- Apply this skill to one narrow scope first, confirm the output matches the shape described above, then widen to the full task.
- When a step needs a fact from the repository or the environment, look it up instead of asking the user for it.

## Best practices

- Keep the upstream procedure intact; record deviations explicitly instead of silently improvising.
- Stop and hand control back to the user at every decision point this skill marks as theirs.
- Prefer small reversible changes, and state assumptions rather than burying them.

## References

- Upstream skill: `mattpocock/skills` `skills/misc/scaffold-exercises/SKILL.md` (commit `3cca18b`, MIT)
- Project standards: `.agent-skills/skill-standardization/SKILL.md`
- Validator script: `.agent-skills/skill-standardization/scripts/validate_skill.sh`