Vibe-coded with GPT-6 Astra in Codex.

English | 日本語

I built this out of curiosity. I don't plan to actively develop or maintain it. I may make changes if something sparks my interest, but otherwise expect this repository to remain mostly untouched.

An experimental Galaxy Z Fold7 app that uses hinge angle to create a frosted-glass transition between the cover and inner screens. It holds an app's image in place with parallax and blur while the phone folds, then hands over to the app on the other display. It works with regular apps without replacing your launcher.

Download v0.1.21

• Galaxy Z Fold7 SM-F966Z only. Display control is disabled on other models.
• Tested on Android 16 / One UI 8.5, build F966ZSCS1BZH4.
• Shizuku, installed and running. Tested with 13.6.0.r1086.2650830c.
• The supported Samsung stock interactive wallpaper, configured as described below.

No root required. Once set up, it can run without USB if Shizuku is started through wireless debugging. Shizuku must be restarted after a reboot. Long-term stability without USB has not been verified.

Folduo supports English and Japanese. At the top of the app, tap Language / 言語 and choose English, 日本語, or System default. The choice is saved and also appears in Android’s app language settings. Japanese devices use Japanese by default; other devices use English.

Follow the official setup guide to install and start Shizuku using wireless debugging or a computer.

Fine-grained angles come from Samsung's interactive wallpaper through a Shizuku helper. On the tested device, the standard hinge sensor mainly reported 0°, 90° and 180°. This app does not estimate the angle using two gyroscopes.

1. Stop Folduo and any other fold-animation or display-control helpers.
2. Set the inner home screen to the Samsung stock interactive wallpaper identified internally as video_002.mp4. The cover home screen must use its matching stock image, sub_wallpaper_002. Wallpaper names in Settings vary by OS version.
3. To get fine-grained angles on the cover screen too, use the helper below to apply the same stock interactive wallpaper there. This changes the cover home wallpaper in One UI as well. Keep your original wallpaper if you want to restore it later.

Download and extract folduo-wallpaper-setup-0.1.21.zip from the release. Install Python 3 and Android SDK platform-tools (ADB). Connect one phone with USB debugging authorized, then run these commands in the extracted folder:

python3 cover-wallpaper.py status
python3 cover-wallpaper.py apply

status checks the wallpaper without changing it. apply changes the cover home wallpaper only, not the lock screen. Add --adb /path/to/adb if ADB is not on your PATH, or --serial DEVICE_SERIAL if multiple devices are connected.

The helper refuses to overwrite unsupported or custom wallpapers. If it reports other wallpaper or Expected inner angle-aware wallpaper unavailable, the required wallpaper is not configured. It uses assets already installed on your phone; no Samsung wallpaper files are included here.

To build the helper yourself, prepare the build environment, then run from the repository root:

python3 tools/build-wallpaper-helper.py
python3 tools/cover-wallpaper.py status
python3 tools/cover-wallpaper.py apply

1. Install Folduo-0.1.21.apk from the release. With ADB: adb install -r Folduo-0.1.21.apk.
2. Open Folduo, tap Connect Shizuku, and grant access.
3. Tap Allow display over other apps. Allow notifications too.
4. Read the screen-capture explanation, then tap Allow temporary screen access and enable.
5. With the phone unlocked, close it fully once to initialize. Open an app such as Calculator and slowly fold and unfold the phone.

The cover screen uses Samsung's normal navigation. The inner screen has a small custom bar for Recents, Home, Back and Settings. Native navigation gestures and the notification/quick-settings shade are not fully available on the inner screen. Use the custom bar, the cover screen, or stop the app when you need the normal controls.

• Both displays are kept on while active, increasing battery use. Normal display control resumes when stopped or locked.
• The transition uses a frozen image. Video and games do not keep playing in that image.
• Home, Recents and other system screens are not handled like regular app tasks. Protected screens and apps that refuse display migration are unsupported.
• App resizing can still cause layout shifts. Samsung's private APIs and wallpaper responses may change after OS updates.
• If Shizuku stops, the animation stops. Automatic recovery is not guaranteed.

To use the included launcher, tap Use Folduo as the home app in Folduo settings and select Folduo. Tap an icon to open an app, long-press to replace it, or use All apps to browse installed apps. Tap the Folduo button on the home screen to return to settings. English and Japanese are supported.

On the tested Fold7, Samsung redirects new app launches from the inner display to the cover display. Folduo home moves only the selected app to the inner display and restores the selected home when returning. This does not fix other launchers.

Three Calculator/home round trips, moving the home between both displays, long-press selection and opening settings passed on the phone with both displays held on by the helper. The final check with physical folding is still pending. If an app does not open after unfolding, close the phone and launch it from the cover home screen.

• Stop: open the app and tap Stop and release display control. Do this before uninstalling.
• Resume: make sure Shizuku is running, then use Resume in the notification or Resume animation in the app. Unlock and close the phone fully once.
• After a reboot: start Shizuku again, then resume the app if needed.
• If the display or controls get stuck: close the phone and stop the app from the cover screen. If that is not possible, reboot and disable the app's always-on mode before restarting Shizuku.
• Restore your wallpaper: stop the app and choose a wallpaper in Android Settings. To restore the specific stock cover image changed by the helper, run this in the extracted helper folder:

python3 cover-wallpaper.py restore-stock

From a source checkout, use python3 tools/cover-wallpaper.py restore-stock. This restores the known stock image, not an arbitrary previous wallpaper. It refuses to overwrite a different wallpaper selected since setup.

Use Git, JDK 17 and the Android SDK. Set JAVA_HOME to your JDK and ANDROID_HOME to your SDK; add platform-tools to PATH for ADB.

sdkmanager "platforms;android-37.0" "build-tools;36.0.0" "platform-tools"
sdkmanager --licenses

git clone https://github.com/bunkaich/Folduo.git
cd Folduo
git checkout v0.1.21
./gradlew :app:assembleRelease :app:testDebugUnitTest :app:lintRelease

Output: app/build/outputs/apk/release/app-release.apk. Use gradlew.bat on Windows. Builds were verified on macOS with Java 17; Windows and Linux have not been tested end to end.

The wrapper pins Gradle 9.5.1 and verifies its checksum. AGP is 9.2.1; compile SDK is 37, target SDK is 36, and minimum SDK is 33. Initial builds need internet access to download dependencies. The wallpaper helper also needs Python 3.

The release APK uses the existing experimental debug signing certificate. Signing keys are not published. Your own build uses your local certificate and cannot directly replace the release APK. Stop and uninstall the existing app before switching signatures; settings and permissions will need to be configured again. Uninstalling does not restore the wallpaper.

Release downloads include SHA256SUMS. Compare the APK with shasum -a 256 Folduo-0.1.21.apk on macOS or sha256sum Folduo-0.1.21.apk on Linux.

Shizuku grants ADB shell-level access. Captured images are used in memory and are not saved or uploaded by the app. Protected screens are excluded. The app has no internet permission, analytics or ads. Do not post private screenshots, device serials or unedited diagnostic logs in public issues.

Original code: MIT. See third-party notices for dependencies. No Apple or Samsung UI assets, wallpapers or videos are distributed. This project is not affiliated with Apple, Samsung or Shizuku.