Stuck, curious, or found something odd? Email atimofeev@reactant.ru and you'll get a reply from the person who builds the app.
How do I make up a missed day? A missed day stays open until the end of the next day — tap it on the calendar to tap it back in. After that it locks, your streak restarts, and every held day stays kept.
Why can I only have three practices? On purpose. Three is what you can return to on a hard day. Rest a practice (its record is kept) to make room for another.
Where is my data? On your device, and — if you're signed in to iCloud — in your private iCloud database. No accounts, nothing shared with the developer. See the privacy policy.
The widget or Live Activity isn't updating? Both follow the app's data automatically; opening the app once refreshes them. Live Activities also need "Allow Live Activities" enabled in Settings → Pebbles.