Privacy Policy

1. Information we collect

DeltaSleep does not collect, transmit, or share any personal information. The app operates entirely offline.

• ✓ No account registration. No email address. No user profile.
• ✓ No analytics, crash reporters, or third-party SDKs.
• ✓ No advertising identifiers (GAID or otherwise).
• ✓ No device fingerprinting.

2. Microphone access

The app uses the RECORD_AUDIO permission exclusively to detect movement and snoring while you sleep. Audio processing is performed in real time, on your device, by a native Rust library.

• ✓ Raw audio (PCM) is never written to disk by default.
• ✓ Only derived metrics are stored: sleep phase labels, snore flags, and per-epoch aggregates (RMS, band power).
• ✓ Optional snore clips (up to 10 seconds) can be saved locally if you enable the feature, and are automatically purged according to your retention setting.

3. Data stored on your device

DeltaSleep writes data to a SQLite database in the app's private storage directory — a location that no other app can access without root. The database contains:

• ✓ Per-night session records (start time, stop time)
• ✓ 30-second epoch records (timestamp, sleep phase, snore flag, aggregate audio metrics)
• ✓ Optional short snore audio clips (if the opt-in feature is enabled)
• ✓ App preferences (sensitivity settings, retention period)

Data retention is user-configurable (30, 90, or 365 days, or never). The default is 365 days. Old records are deleted automatically.

4. No internet access

The INTERNET permission is absent from the Android manifest. The OS enforces this: the app cannot open a network socket even if it tried.

This guarantee is verified automatically: the CI pipeline fails if http, socket, URL, or fetch appear in the Kotlin source. You can audit the check in ci.yml.

5. Data export

You can export your sleep data as JSON or CSV at any time. The export is written to a folder you choose via the system file picker. DeltaSleep does not transmit this file anywhere — you control where it goes.

6. Data deletion

You can delete all data at any time from the app's settings screen using the "Nuke all data" action. This overwrites the database before deleting it, so the content cannot be recovered from disk.

Uninstalling the app removes the private storage directory, including the database and any snore clips.

7. Permissions summary

• ✓ RECORD_AUDIO — required to detect sleep phases and snoring
• ✓ FOREGROUND_SERVICE — keeps the tracking service running while your screen is off
• ✓ POST_NOTIFICATIONS — shows the persistent "DeltaSleep is running" notification required by Android for foreground services

No other permissions are requested or used.

8. Children's privacy

DeltaSleep is not directed at children under 13 and does not knowingly collect information from anyone.

9. Changes to this policy

If this policy changes, the updated version will be posted at this URL with a new effective date. Because no data is collected, changes are expected to be minimal.

10. Contact

Questions about this policy? Open an issue on GitHub or email ntufar@gmail.com.