The app indexes the photos in the folders you choose, and only those. The choice can be changed at any time from the Sync screen.
The app asks Android's MediaStore for every image and groups them by folder. MediaStore is the only way to find photos without broad storage access, and it already leaves out files that are still being written and files in the trash.
Folders are shown the way Android names them, relative to the phone's storage: DCIM/Camera/, Pictures/Screenshots/, Pictures/WhatsApp/. A folder includes every folder below it, so ticking DCIM/ covers DCIM/Camera/ too.
On first run every folder under DCIM, where the camera saves by default, is ticked for you. Untick it or browse to others before tapping Continue.
Folders are opened one level at a time, not listed all at once: a library kept as year, month and day is thousands of folders, and a flat list of them is unusable.
- Each row is one folder, with the number of photos in it and in everything below it, and an arrow when there is something below to open.
- The line above says where you are — All folders / DCIM / 2015 — and a tap on any step goes back up to it.
- Ticking a folder takes that folder and every folder under it. Its subfolders then read Already included by… and cannot be ticked separately, and any of them you had ticked before is dropped, since the parent already covers them.
- What you have chosen is listed above the button at the bottom.
Browsing costs nothing: the tree is built from the same list of folders the app already read from MediaStore, so walking into a folder asks Android nothing new.
- Open the Sync screen and tap Change folders.
- Browse to the folders you want, tick and untick, then tap Save and sync.
- A sync starts: photos in newly ticked folders are added, and photos from unticked folders leave the index.
Each photo's id is the md5 of its path inside the phone's storage, for example md5("DCIM/Camera/PXL_20260801_101500.jpg") for /storage/emulated/0/DCIM/Camera/PXL_20260801_101500.jpg. One function in the app computes it, for indexing and for every Re-Sync, so the ids on the phone and in the index are always built the same way, and the same folders on another phone keep every photo's identity.
- A photo moved or renamed gets a new id: the old document is deleted and the photo is added again.
- A folder that disappears (a memory card taken out, a permission withdrawn) simply has no photos at the next Re-Sync, and its photos leave the index. Put the card back and the next sync adds them again, from the phone's cache where possible.