Habitly

An offline-first habit and task planner with local reminders and optional cloud synchronization.

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Overview

A mobile planner for daily habits, scheduled progress, recurring tasks, subtasks, and statistics. Guest onboarding and local storage let people start tracking without creating an account.

Expo Router screens use feature logic and repositories backed by SQLite. Database triggers queue local edits in a revision-aware outbox. Optional Firebase accounts synchronize those changes with Firestore, while each account keeps its own local database and device-specific reminders.

Key features

  • Habit schedules, daily entries, streaks, history, and progress statistics
  • Tasks with subtasks, recurrence, and local notifications
  • Offline-first SQLite storage with versioned migrations
  • Google sign-in and optional Firestore synchronization
  • Separate local databases for guest and signed-in accounts
  • Appearance settings, search, and JSON export

Tech stack

ExpoReact NativeTypeScriptExpo RouterSQLiteFirebase AuthFirestoreNativeWindReanimatedExpo Notifications

Product walkthrough

Habitly — product walkthrough

Today

Habitly — today
Habitly — today

Habits

Habitly — habits
Habitly — habits

Profile

Habitly — profile
Habitly — profile

Tasks

Habitly — tasks
Habitly — tasks

Stats

Habitly — stats
Habitly — stats

Architectural Diagram

Open full diagram: Architectural Diagram (opens in a new tab)PNG: download Architectural Diagram
SQLite is the center of the mobile app. Cloud identity and synchronization are optional services, while notifications stay specific to each device.

Arrows show direction. Dashed connections indicate conditional or supporting paths.

Read diagram as text
Mobile screens
Expo · React Native · Expo Router
Account lifecycle
Firebase Auth · Google sign-in
Application & domain logic
React contexts · habits, tasks, statistics
Device reminders
Expo Notifications · native OS scheduling
Local repositories
Expo SQLite · per-account database
Change outbox
SQLite triggers · operation and revision
Cloud sync service
Network / foreground retry · listeners
Cloud records
Firestore · per-user collections

Connections

  • Mobile screens → Application & domain logic: user actions.
  • Account lifecycle → Application & domain logic: account.
  • Application & domain logic → Device reminders: schedule.
  • Application & domain logic → Local repositories: read / write.
  • Local repositories → Change outbox: SQL triggers.
  • Change outbox → Cloud sync service: flush.
  • Cloud sync service ↔ Cloud records: sync.
  • Guest data uses its own database; switching accounts changes the database owner and reconciles local reminders.
  • Account deletion additionally calls an external server endpoint; that server is outside the mobile repository.

Workflow Diagram

Open full diagram: Workflow Diagram (opens in a new tab)PNG: download Workflow Diagram
Habit tracking stays usable offline. Signing in adds cloud synchronization without moving local interactions behind a network request.

Arrows show direction. Dashed connections indicate conditional or supporting paths.

Read diagram as text
Start or sign in
Guest onboarding or Google / Firebase
Plan the routine
Create habits, schedules, tasks, reminders
Record today's progress
Check in, log a value, or complete a task
Save on the device
SQLite transaction · update local UI
Review progress
Streaks · history · statistics
Cloud available?
Signed in and connected
Keep edits queued
Offline or guest: continue locally
Synchronize the account
Push outbox · pull / listen · refresh

Connections

  • Start or sign in → Plan the routine: ready.
  • Plan the routine → Record today's progress: daily use.
  • Record today's progress → Save on the device: local write.
  • Save on the device → Review progress: read local data.
  • Save on the device → Cloud available?: sync check.
  • Cloud available? → Keep edits queued: no (conditional or supporting).
  • Cloud available? → Synchronize the account: yes.
  • Local reminders are scheduled through the device OS rather than sent as cloud push notifications.
  • Google sign-in needs a native development/production build on mobile; guest mode does not require Firebase configuration.

Feature Deep Dive: Offline Sync Outbox

Open full diagram: Feature Deep Dive: Offline Sync Outbox (opens in a new tab)PNG: download Feature Deep Dive: Offline Sync Outbox
An operation revision prevents an older upload from removing a newer pending edit. Remote application is guarded so it does not create another outgoing change.

Arrows show direction. Dashed connections indicate conditional or supporting paths.

Read diagram as text
Change a local record
Insert, update, or delete in SQLite
Queue the operation
Trigger upserts entity + ID + revision
Connected & signed in?
Network, foreground, or timer event
Retain pending edits
Retry later; local UI remains usable
Upload current state
Firestore payload or deletion tombstone
Acknowledge this revision
Remove outbox row only if revision matches
Receive remote changes
Initial pull or Firestore snapshot listener
Apply only safe changes
Skip pending local edits; suppress triggers

Connections

  • Change a local record → Queue the operation: write transaction.
  • Queue the operation → Connected & signed in?: pending operation.
  • Connected & signed in? → Retain pending edits: no (conditional or supporting).
  • Connected & signed in? → Upload current state: yes.
  • Upload current state → Acknowledge this revision: successful write.
  • Acknowledge this revision → Receive remote changes: hydrate / listen.
  • Receive remote changes → Apply only safe changes: check local outbox.
  • Newer local edits retain their outbox row when an older upload completes. Failed uploads remain pending.
  • Remote imports set the importing guard, preventing echo writes; reminder identifiers are reconciled per device.