Duolingo for your codebase. An interactive Claude Code skill that quizzes you on your own code — with XP, levels, streaks, badges, and spaced repetition.
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║ 🧠 CODEQUIZ ║
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║ Level 5 • 500 XP • 🔥 7 day streak ║
║ 4 badges • 62% mastered ║
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Teams that rely on AI without understanding their code are worse at using AI. You can't prompt effectively, debug AI output, or catch hallucinations if you don't know how the system works.
CodeQuiz fixes this. It scans your repo, finds the complex parts, and quizzes you on them. You build real understanding — and that makes you 10x better at using AI.
git clone git@github.com:nessielabs/codequiz.git ~/.claude/skills/codequizThat's it. No dependencies, no build step.
Open Claude Code in any git repo and run:
/codequiz
Or just type "quiz me", "test my knowledge", or "codebase quiz" in the Claude Code chat.
Here's what a question looks like:
Question 1/7 — Explain This (State/UI — Novice)
📂 NavigationStore.swift — Part of the navigation state management system
func push(_ destination: AppDestination) {
// Trim forward history when pushing a new destination
if currentIndex < stack.count - 1 {
stack.removeSubrange((currentIndex + 1)...)
}
stack.append(destination)
direction = .forward
currentIndex = stack.count - 1
}
What does push(_:) do, and why does it trim forward history
before appending?
Type your answer, or say skip if you know this, or idk if you
want to see the explanation.
And here's the end of a session:
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║ SESSION COMPLETE ║
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║ ║
║ Questions: 7/7 answered ║
║ Correct: 7/7 (100%) ║
║ XP Earned: +130 XP ║
║ New Level: 1 → 3 (Warming Up) ║
║ Streak: 🔥 1 day ║
║ ║
║ Total XP: 155 ║
║ Overall: Level 3 — Warming Up ║
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KNOWLEDGE RISK MAP
State/UI ███████░░░░░░░░░░░░░ Familiar (0.35)
State/Services ██████░░░░░░░░░░░░░░ Familiar (0.30)
Logic/Operations ███░░░░░░░░░░░░░░░░░ Novice (0.15)
Providers ███░░░░░░░░░░░░░░░░░ Novice (0.15)
Views/Markdown ███░░░░░░░░░░░░░░░░░ Novice (0.15)
Views/ContextChat ███░░░░░░░░░░░░░░░░░ Novice (0.15)
Views/ContextEditor ███░░░░░░░░░░░░░░░░░ Novice (0.15)
Overall Mastery: 29% (2/7 modules at Familiar+)
Suggested Focus: Providers, Views/Markdown, Views/ContextEditor
- Discovery — Claude scans your codebase and identifies technically challenging components
- Quiz — You get short-answer questions grounded in real code
- Learn — Wrong answers get thorough explanations. Discuss further or move on.
- Track — XP, mastery levels, and spaced repetition ensure you actually retain it
| Type | Difficulty | What it tests |
|---|---|---|
| Explain This | Easy | Show code, ask what it does and why |
| What Happens When | Medium | Show code, ask about edge case behavior |
| Connect the Dots | Hard | Ask how two modules interact |
Pick your pace:
- Quick — 3 questions, ~2 min
- Standard — 7 questions, ~5 min
- Deep Dive — 15 questions, ~10 min
- Boss Fight — Multi-part deep dive on one complex subsystem
Earn XP for every correct answer. Level up from Beginner to Codebase Wizard (Level 10).
Each module in your codebase gets its own mastery rating:
KNOWLEDGE RISK MAP
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src/auth/ ████████████████░░░░ Expert (0.92)
src/api/routes/ ████████████░░░░░░░░ Proficient (0.68)
src/database/ ████████░░░░░░░░░░░░ Familiar (0.45)
src/utils/ ████░░░░░░░░░░░░░░░░ Novice (0.22)
src/workers/ ░░░░░░░░░░░░░░░░░░░░ Unknown (0.00)
Overall Mastery: 38%
Suggested Focus: src/utils/, src/workers/
Unlock achievements as you learn:
| Badge | How to earn |
|---|---|
| First Blood | First correct answer |
| Edge Lord | 5 edge-case questions correct |
| Architect | 5 architectural questions correct |
| Streak Master | 7-day streak |
| Deep Diver | Master any module to Expert |
| Boss Slayer | Ace a Boss Fight |
| Perfectionist | 10 correct in a row |
Topics you got wrong come back sooner. Topics you've mastered fade out. Like Anki, but for code.
Say "I know this, skip"? There's a 25% chance you'll get a quick verification question. Pass it for bonus XP. Fail it and the topic goes back into rotation.
This isn't a test — it's a learning tool:
- Wrong answers get full explanations of what the code does and why
- Every question shows the file path and which component of the software it belongs to
- "I don't know" is always an option — no penalty, just learning
- Discuss further if the explanation isn't clear
- Dispute grading if you think you were marked wrong
Your progress is saved at ~/.codequiz/{repo-name}/mastery.json. Per-repo, persistent across sessions, survives after every single question (so quitting mid-session doesn't lose progress).
MIT
