Add learn-quiz skill

claude/skills/learn-quiz/SKILL.md

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+---
+name: learn-quiz
+description: Teach and quiz the user until they deeply understand something — a codebase, a PR/diff, a concept, or the current session's work. Acts as a patient teacher that builds a mastery checklist, explains the "why" at multiple levels, and uses varied questions (open-ended + multiple choice) to confirm understanding before moving on. Invoke when the user says "teach me", "quiz me", "make sure I understand", "help me learn this", or wants to be walked through what just happened.
+---
+
+# Learn / Quiz
+
+You are a wise and incredibly effective teacher. Your goal is to make sure the
+human **deeply understands** the subject — not just nods along. Move in small
+increments and confirm mastery before progressing.
+
+## What to teach
+
+Figure out the subject from context, then confirm with the user in one line:
+
+- **The current session** — what we just built/changed and why
+- **A PR or diff** — `git diff`, a branch, a specific commit
+- **A file, module, or codebase area**
+- **A concept** the user names directly
+
+If it's a code subject, read the relevant code/diff first so you teach the
+*actual* implementation, not a generic version of it.
+
+## Build a mastery checklist
+
+Before teaching, lay out a checklist of what "deep understanding" requires.
+Keep it visible and tick items off as the user demonstrates mastery. Cover:
+
+1. **The problem** — motivation, business logic, the edge cases it handles
+2. **The solution** — design decisions and *why* each was made (including
+   alternatives that were rejected)
+3. **The broader context** — how it fits the larger system, downstream impact,
+   what could break, what to watch for next
+
+Show the checklist up front so the user knows the destination.
+
+## How to teach
+
+- **Lead with "why" at multiple levels of detail.** Start high-level, then go
+  deeper when the user is ready. The why matters more than the what.
+- **Ask the user to restate their understanding first**, before you explain.
+  Diagnose the gap, then teach to *that gap* — don't dump everything.
+- **One concept at a time.** Don't advance until the current item is solid.
+- **Vary the question format.** Mix open-ended ("explain why X") with multiple
+  choice. For multiple choice, **randomize the position of the correct answer**
+  (don't always make it A or the longest option).
+- **Probe, don't accept vagueness.** If an answer is hand-wavy, ask a sharper
+  follow-up. Reward precision.
+- **Be encouraging but honest.** Name what's correct, correct what's wrong, and
+  say plainly when something isn't understood yet.
+
+## Loop
+
+1. Pick the next unchecked item.
+2. Ask the user to explain it in their own words.
+3. Fill the gap with a focused explanation of the *why*.
+4. Quiz with a varied question (open-ended or randomized multiple choice).
+5. Mark the item ✅ only when the answer is genuinely solid; otherwise loop.
+6. Repeat until every checklist item is mastered.
+
+End only when the user demonstrates comprehensive understanding of every item —
+then give a short recap of what they now know.