Privacy Policy

1. Scope

This policy applies to users of the mobile application Tử Vi & Lịch Vạn Niên, developed and published on Google Play by HAB Labs. By installing or using the app, you agree to this policy.

2. Data stored on your device

The following information is created and stored locally on your device (using on-device storage). It stays on your device unless you choose to sign in and back it up (see Section 4):

• Birth details you enter to cast a chart: name/label, gender, solar or lunar date of birth, and time of birth.
• Saved charts and profiles you create.
• Death-anniversary (ngày giỗ) entries: the name, family relationship, lunar date and optional notes for relatives you choose to commemorate. This data is used only to display reminders and is kept on your device.
• App preferences: language, light/dark theme, and your in-app credit ("lượt") balance.

This data is processed entirely on-device to calculate charts, show the perpetual lunar calendar, and schedule local reminders. None of it is sold or used for advertising.

3. What we do not collect

This app is built to be privacy-friendly. It does not include any third-party analytics, tracking, or advertising SDK. Specifically:

• We do not collect usage analytics or behavioral tracking data.
• We do not collect an advertising identifier, and the app does not display third-party ads.
• We do not run automatic crash or diagnostics reporting to our servers.

The only network activity is described in Sections 4–6: optional sign-in/backup, downloading interpretation content, and processing purchases. If an ad-supported version is released in the future, this policy will be updated before any ads are shown.

4. Optional Google sign-in & cloud backup

Signing in with Google is optional. The app works fully without an account. If you choose to sign in, we use Google Sign-In and Firebase Authentication to:

• Read your basic Google profile (display name, email address and a user identifier).
• Back up and restore your saved charts and preferences across your devices.
• Verify and restore your Premium subscription entitlement.

If you do not sign in, your data is kept only on your device and is not transmitted to our cloud.

5. Content downloaded from our servers

The app ships with a bundled offline content library so it works without a connection. To provide richer, up-to-date interpretation text (for example detailed topic and fortune-cycle readings), the app may fetch additional content from our servers (Google Firebase / Cloud Firestore). If you are offline or the request fails, the app automatically falls back to the bundled offline content. These content requests do not include your birth details or personal entries.

6. Purchases

The app offers in-app purchases — credit packs and a Premium subscription — processed by Google Play Billing. We do not receive or store your card or payment details on HAB Labs servers. To validate and restore entitlements, a purchase receipt may be verified through our backend; we store only the minimum needed to recognize an active purchase.

7. How we use data

• Provide core features: casting charts, the perpetual lunar calendar, fortune cycles, and reminders — most of which run on-device.
• Schedule local notifications such as daily fortune and death-anniversary reminders.
• Back up and restore your data when you sign in.
• Improve quality, diagnose crashes, and fix bugs.
• Personalize the display language and content.
• Validate and restore in-app purchases and Premium access.

8. Device permissions

The app may request the following permissions, only when needed for a feature:

• Notifications: to deliver daily fortune and death-anniversary reminders. These are scheduled and shown locally on your device — the app does not use push notifications or a messaging server.
• Network access: to download content, sync backups, and process purchases.
• Motion sensors (accelerometer): to detect the phone-shake gesture used in the I-Ching coin-toss feature.
• Media/temporary storage: to generate a shareable image of your chart when you use the share feature.

9. Data retention & deletion

• On-device data remains until you delete the entry, clear the app's data, or uninstall the app.
• If you sign in, backed-up data is retained for as long as your account is active or as needed to provide the service.
• You can delete individual entries in the app at any time. To delete your account and associated cloud backup, contact us using the details below.

10. Sharing with third parties

We do not sell your personal data. Data may be shared with the following providers only as needed to operate the app:

• Google Firebase — Cloud Firestore (interpretation content and, if you sign in, chart backup) and Authentication (optional Google sign-in). We do not use Firebase Analytics, Cloud Messaging or Remote Config.
• Google Play Billing, for processing in-app purchases.
• Competent authorities, when required by a valid legal request.

Third-party policies

• Google Privacy Policy: https://policies.google.com/privacy
• Firebase Data Processing and Security: https://firebase.google.com/support/privacy

11. Data security

We apply appropriate technical and organizational measures to protect data. However, no system is completely secure. Please help protect your information by securing your device, your Google account, and your sign-in credentials.

12. Your rights

Depending on applicable law, you may have the right to:

• Access the personal data we hold about you.
• Correct or update inaccurate data.
• Delete your data or restrict its processing.
• Withdraw consent for certain processing activities.

13. Children

The app is not directed to children below the age of consent in your jurisdiction. If you are a parent or guardian and believe a child has provided us with personal data, please contact us so we can help address it.

14. International data transfers

Data may be processed or stored on cloud infrastructure located in multiple countries through our service providers. We take steps to ensure an appropriate level of protection under applicable law.

15. Changes to this policy

We may update this policy from time to time. When we make material changes, we will update the effective date and may notify you within the app or on this page.

16. Contact