単語カード: Japanese vocab cards
A personal flashcard app for drilling Japanese vocabulary: Claude-generated examples and mnemonics, multiple study modes, and spaced repetition.
- React
- Vite
- Supabase
- Claude API
- Vercel
I study Japanese with Claude, and at the end of a session I'd ask it to export the day's vocabulary as a CSV. 単語カード (tango kādo, "word cards") is where those CSVs go: each import becomes a deck, and the app drills it.
What it does
- Study modes: classic flip cards, multiple choice, and reverse (English → Japanese), with a hint that shows an example sentence in Japanese only.
- AI enrichment on demand: Claude generates example sentences, mnemonics, and related words for any card.
- Spaced repetition: a lightweight score per card that decays over time, so the words you're forgetting come back around.
- Real Japanese text handling: morphological analysis (kuromoji) and kana conversion (WanaKana), so typed answers and conjugations are graded properly instead of by exact match.
What it taught me
After eight phases shipped with every test green, I sat down to actually study and hit a batch of bugs in a single session. The retrospective boiled down to one sentence: "done" meant "tests pass on hand-crafted fixtures," never "works on the real 956-word corpus, on my phone, looking like the wireframe." About 40% of my verb deck turned out to be inflected forms the data model never accounted for.
The fixes were mostly process: test fixtures sampled from the real data, a mobile viewport in the end-to-end tests, and a visual pass against the wireframes before anything counts as done.