Chronos

An hourly activity logger. Every hour during your wake window, Chronos prompts you with a notification — tap it and log, in up to three words, what you spent the last hour on. Over time you build an honest, low-effort picture of where your time actually goes.

The whole point is frequent prompts, tiny entries. Accuracy comes from being asked every hour, not from writing detailed notes.

Status

Early MVP. Android-first. Local-only — entries live in on-device SQLite, nothing is sent to a server.

Core loop

• Notification window (configurable, default 08:00–23:00). On the hour, Chronos fires a local notification asking about the hour that just ended. The first prompt fires one hour after Start (e.g. Start 8 AM → first prompt 9 AM, asking about 8–9 AM); the last prompt fires at End.
• Log modal. Tap the notification → modal opens with the relevant hour preloaded. Type up to three words → save.
• Today timeline. Reverse-chronological list of hours you've logged for the selected day. Empty hours aren't rendered.
• Backfill. A center "+" button on the Today tab opens the modal in pick mode (date + hour range) so missed hours can be filled in later.
• Day picker. ‹ / › chevrons (and a date picker) on the Today tab let you jump to any past day.

Tech

• Expo (~55) with Expo Router for file-based routing
• expo-notifications for hourly scheduled prompts (Android DAILY triggers, one per hour in the window)
• expo-sqlite for local entry + settings storage
• React Native 0.83 / React 19

Running it

Important

Don't use Expo Go. Expo Go strips Notifications.scheduleNotificationAsync, so the entire prompt loop will silently no-op. Use a development build.

npm install
npx expo run:android         # builds & installs the dev client on a connected device/emulator
# or, after the dev client is installed:
npx expo start --dev-client

iOS / web builds compile but aren't actively verified — Android is the priority surface.

Android permissions

On first launch, Chronos routes to a permissions screen and won't proceed until they're granted. There are three things to allow:

1. Notifications (POST_NOTIFICATIONS) — system prompt; Chronos requests it inline.
2. Alarms & reminders (SCHEDULE_EXACT_ALARM, Android 12+) — opens a system page; toggle "Allow" for Chronos.
3. Ignore battery optimization — opens the battery-optimization list; find Chronos and choose "Don't optimize."

Some manufacturers (Samsung, Xiaomi/Redmi, OnePlus, Oppo, Huawei) aggressively kill background scheduled alarms even with the system permission. The permissions screen has per-OEM tips inline. If hourly prompts ever stop firing in real use, that's the first thing to check — battery managers, not the code.

Project layout

src/
  app/
    _layout.tsx            root: init DB, request notifications, gate first-run
    permissions.tsx        permissions screen (first-run + Settings entry)
    log.tsx                log modal (single + batch/pick mode)
    (tabs)/
      _layout.tsx          tab nav (Today / Settings)
      index.tsx            Today: day picker + timeline
      settings.tsx         notification window, permissions link, diagnostics
  components/               themed primitives, day timeline, hour row, app tabs
  lib/
    db.ts                  SQLite schema + queries (entries, settings kv)
    notifications.ts       channel setup, permission helper, schedule loop
    settings.ts            notify window + first-run flag
    time.ts                hour/day math + formatters
  constants/theme.ts       colors, spacing, fonts

Scripts

npm run android      # alias for `expo run:android`
npm start            # `expo start`
npm run lint         # `expo lint`