Access iCloud shared photo stream files on filesystem I use iCloud's shared photo albums from my iPhone and look at the files from my OSX Photos app on my mac laptop. I would like to know where these files are stored / cached on the file system. I'm able to "import" these files from the shared album and then see them in Finder by looking at at "Photos Library" files in Finder. However, I can't see these files anywhere on my filesystem if I don't "import" them.

Ultimately, I'm trying to use the shared album functionality to create a stream, but cross-post the album on another source (probably Google Photos) automatically for family members who are not on OSX. (I'm aware of the ability to post these albums on iCloud, but am not happy with the generated web album, so I've decided to go down a different path). I'm happy to write a cron job or automator script if necessary to achieve the above.
Ok, I think I found it. Hopefully this is stable over time. Credit goes to Where does Photos store iCloud photos shared with me?

/Users/user/Library/Containers/com.apple.cloudphotosd/Data/Library/Application Support/com.apple.cloudphotosd/services/com.apple.photo.icloud.sharedstreams/assets/