Project 19: Flashcard Learning App

📋 Project Brief

Build a spaced-repetition flashcard app using the SM-2 algorithm (Anki-style). Cards are scheduled based on how well the user remembers them, with intervals increasing for well-known cards and decreasing for difficult ones. Includes 3D flip animations and a progress dashboard.

✅ Feature Requirements

Feature 1: 3D Card Flip

Acceptance Criteria:

• Clicking a card triggers a CSS 3D flip animation (transform: rotateY(180deg))
• The front shows the question; the back shows the answer
• The flip must use perspective and backface-visibility: hidden
• Flip duration: ~400ms with an ease-in-out curve
• Clicking again (or pressing Space) flips back

Feature 2: SM-2 Spaced Repetition

Acceptance Criteria:

• After viewing the answer, the user rates difficulty: "Again" (Hard), "Good," or "Easy"
• Again: Card reappears in 1 minute, then 10 minutes
• Good: Interval doubles from the previous interval (1d → 2d → 4d → 8d...)
• Easy: Interval triples
• Each card stores: interval, ease_factor, repetition_count, next_review_date
• On app open, show only cards where next_review_date ≤ today

Feature 3: Markdown Support

Acceptance Criteria:

• Card content supports Markdown: bold, italic, code blocks, lists
• Code snippets render with syntax highlighting
• Math formulas supported via basic LaTeX notation (stretch)
• Images can be embedded via URL

Feature 4: Progress Dashboard

Acceptance Criteria:

• Circular progress chart: "Cards Mastered" (interval > 21 days) vs. "Learning" vs. "New"
• Daily review count: "Reviewed 15 cards today"
• Streak tracker: consecutive days of reviews completed
• Forecast: "You have ~8 cards due tomorrow, ~12 in 3 days"

Feature 5: Deck Import

Acceptance Criteria:

• Import decks from CSV or JSON files
• CSV format: front,back (one card per row)
• JSON format: [{ "front": "...", "back": "..." }]
• Show a preview of the first 5 cards before confirming import
• Duplicate detection: skip cards that already exist in the deck

📊 SM-2 Algorithm Reference

Rating	Effect on Interval	Effect on Ease Factor
Again (0-1)	Reset to 1 minute	Decrease by 0.2 (min: 1.3)
Good (3)	Previous interval × Ease Factor	No change
Easy (5)	Previous interval × Ease Factor × 1.3	Increase by 0.15

🧪 Testing Checklist

• Unit test SM-2 interval calculations for all ratings
• Unit test ease factor clamping (never below 1.3)
• Unit test "due today" filtering logic
• Unit test CSV/JSON parsing
• Integration test: rating a card updates its next review date correctly

🚀 Stretch Goals

• Add audio pronunciation for language learning cards
• Implement card tags/categories for organized study
• Add a "Cram Mode" that shows all cards regardless of schedule
• Implement cloud sync for cross-device study sessions