Folders called "cache" aren't always cache
TL;DR: Folders named cache or depots inside an app's data directory can hold the installed build: deleting C:\ProgramData\LGHUB\depots broke Logitech G HUB. Check the app's manifests before deleting, and prefer the app's own cleanup.
The system SSD was nearly full, so I went through C:\ProgramData looking for big folders that sounded disposable. Logitech G HUB had gigabytes in depots and cache. They sounded like old downloads, so I deleted them. G HUB stopped working.
What depots really was
A current.json next to it listed the depot of the installed build with state "PRESENT". The app runs out of that folder and checks it. It held the current version, not leftovers. A reinstall over the top fixed it.
The rule I use now
- Inside an app's own data folder, a name like cache, depots or downloads proves nothing. Look for manifests or version files that reference the folder first.
- Prefer the app's own cleanup option or its uninstaller.
- If you can't tell, file it under "might need a reinstall", not "safe".
- Generic caches are still fair game: npm, pip, shader caches,
%TEMP%. Those rebuild themselves by design.