[FEATURE REQUEST] Custom Folder Syncs

Is your feature request related to a problem? Please describe.

In the Android app, it's currently not possible to select custom local folders for synchronization. The app appears to use a default folder or location, which limits flexibility for users who store data across different directories. This is especially problematic for those who want to sync specific project folders, external storage (SD cards), or app-specific data folders.

Describe the solution you'd like

I would love to see support for adding one or more custom folders in the Android app that can be selected for synchronization. This could be implemented via a simple file/folder picker in the app’s UI, with support for granting proper storage permissions (including access to external storage or SD cards).

Each selected folder should be:

• Watched for changes
• Synced independently
• Removable from the sync list at any time

This feature would give users complete control over what data gets synchronized and from where.

Describe alternatives you've considered

• Manually moving or copying files to the app’s default sync folder (not practical, especially for automation)
• Creating symbolic links (not supported or reliable on Android without root)
• Using other sync tools that support custom folders (but losing the benefits of this app)

None of these workarounds offer the seamless experience users expect from a modern synchronization app on Android.

Additional context

This feature would be especially useful for:

• Users with files in specific app directories (e.g., documents, downloads, audio projects, etc.)
• Those who use external SD cards
• Developers or power users working across multiple folders

Other apps like Syncthing or FolderSync already offer this flexibility, and having it in Gitter would make the Android app far more powerful and user-friendly.

✅ TASKS

• Research Android storage access APIs (especially SAF and scoped storage)
• Create branch feature/custom-folder-sync-android
• Development tasks
  • Add folder picker UI
  • Request and handle storage permissions properly
  • Enable multiple folder selections
  • Adjust sync logic to support multiple folders
  • Implement unit/integration tests (as needed)
• Code review and feedback
• Test plan design (include SD cards, internal storage, and various folder types)
• QA
• Merge feature/custom-folder-sync-android into main

Start by reviewing the Android app's current folder-selection UI and sync logic, along with the SAF and scoped-storage requirements named in the issue. The work is complete when users can select, authorize, independently sync, and remove multiple folders, with unit or integration coverage and testing across internal storage, SD cards, and varied folder types.