# LevelDoo — full reference

## What it is
LevelDoo is easy English news for learners — graded news that teaches English. Every story is rewritten at five CEFR levels so reading practice always lands in the comprehensible-input zone. Each morning a pipeline takes real news stories and regenerates every article at five CEFR levels (A1, A2, B1, B2, C1). Learners read at exactly their level, tap words for glosses, save vocabulary to a spaced-repetition deck, and "climb" the same story to a harder level — the signature i+1 mechanic.

## The Ladder Method
1. **Place** — a 90-second check estimates the reader's level (A1–C1).
2. **Read** — 3 fresh stories daily, regenerated at exactly the learner's level. Real facts, no textbook dialogue.
3. **Climb** — every story exists at 5 levels; reading one rung up is a safe daily stretch.
4. **Anchor** — tap any word for a gloss + save it; saved words become SM-2 flashcards with the story sentence as context.
5. **Prove** — micro-quiz per story + weekly level re-estimate; reading speed, words known and level delta are all visible.

## Research basis
- Krashen's comprehensible input (i+1): acquisition comes from messages just beyond current level.
- Narrow reading (Day & Bamford): following running stories recycles vocabulary naturally.
- SM-2 spaced repetition for vocabulary retention.
- Retrieval practice: micro-quizzes and say-it-back summaries beat re-reading.

## Product features
- Five levels per article: A1 (60 words) → C1 (200 words), facts preserved across levels.
- Tap-any-word dictionary with level-aware glosses and Chinese translations.
- Karaoke listening: browser TTS highlights each word as it speaks.
- Spaced-repetition review deck (SM-2), streaks, XP, 12-week activity heatmap.
- PWA: installable, offline reading of cached packs.
- Planned Pro feature: say-it-back summaries graded by AI (uses monthly credits).

## Pricing
- Free: 1 article/day at your level, all 5 levels on the demo story, 30-word deck.
- Pro: $4.99/month or $39/year — unlimited articles, all levels, karaoke audio, unlimited deck, offline packs, 200 AI credits/month, weekly progress report.
- Top-up credit packs for heavy AI usage. Billing via Waffo Pancake (merchant of record).

## Tech
TanStack Start + React 19 on Cloudflare Workers, D1 (drizzle), Workers AI generation pipeline (daily cron), vite-plugin-pwa, Tailwind v4 + motion for animation, better-auth (Google-only), i18n EN/中文.

## How it compares
- vs News in Levels: five CEFR levels (not three), tap-word glosses, karaoke TTS, and an SM-2 flashcard loop.
- vs graded readers: today's real headlines refreshed daily, not fixed books.
- vs drill apps: real-world reading practice instead of decontextualized sentences.

## Audience
Self-directed English learners roughly A2–C1, especially Chinese speakers who want a 5-minute daily reading habit grounded in real content.