State and maintenance

echo-words has no database and needs no database backup. Only ECHOWORDS_DATA_DIR matters: it holds the Anki collection, the voice models, the broker state, and the cached audio.

The collection itself is replicated through AnkiWeb, so even that directory is not the only copy of your cards.

What is deliberately not persisted

Server job state, undo, session counters, and the accepted-submission receipt map live in memory and reset when the backend restarts. This is by design: the durable record of every lookup is the Anki note it produced.

The PWA keeps the last 50 answers in the browser's IndexedDB. A server restart does not erase them, but controls tied to the old process still expire. A fresh browser database starts with empty history; it never downloads the server's recent entries. Reconnects recover only locally known unfinished jobs.

The language lists and directory are also cached in IndexedDB. Startup reads local data without waiting for the server. Automatic refresh attempts are limited to once per 24 hours, including failed attempts, and preserve the old snapshot on failure. Editing a language invalidates the affected lists immediately.

App updates retain the same browser database. Persistent storage is requested where supported, with localStorage as a fallback if IndexedDB is unavailable. Keep the same HTTPS origin across deployments to retain device data; explicitly clearing site data also clears local history.

The Stats screen shows this split directly — Today, Last 7 days, and All time are counted from the collection, while Since startup: N without a card is the in-memory session counter.

The audio cache

ECHOWORDS_DATA_DIR/audio/ keeps one small MP3 per looked-up word and has no cleanup policy. These files are safe to delete at any time: Anki reviews play the separate copy in the collection's own media directory.

Health

GET /api/health answers with the running version and is what inv deploy gates on. The Status screen adds the operational picture: usable LLM providers, missing provider keys, paid calls spent against the daily cap, the last AnkiWeb sync and any sync error, and the last call each language made.