Using SQLite to Track Sync State in Rust — Simple, Reliable, Zero Dependencies

All tests run on an 8-year-old MacBook Air. Sync tools need to remember what they've already transferred. Files change. Transfers get interrupted. The app restarts. The naive approach — scan everything on every run — gets slow fast. The right approach: track state in SQLite. The schema One table. One row per file. CREATE TABLE IF NOT EXISTS sync_state ( path TEXT PRIMARY KEY , size INTEGER NOT NULL , modified_at INTEGER NOT NULL , -- Unix timestamp hash TEXT , -- SHA-256, computed lazily synced_