PowerTools needs to store some things persistently on the local device for functionality. The locations and usages are contained below.
Logs
Release
Logs are written to the /tmp/powertools.log file.
Debug
Logs are written to the ~/powertools.log file.
Settings profiles
The filename format is <app_id>.ron where <app_id> is the game's AppId, or default_settings for no game (main menu settings). The file format is RON with the file structure base defined in file.rs.
Decky
Per-game settings are stored by Steam AppId in ~/homebrew/settings/PowerTools.
Other
Everything is unceremoniously dumped into /tmp.
Cached files
Decky
These are stored along with the per-games settings in ~/homebrew/settings/PowerTools.
Other
These are stored in /tmp.
Executable files
Decky
Decky installs PowerTools to the ~/homebrew/plugins/PowerTools folder.
Other
This is arbitrary i.e. user-defined or defined by the implementation.