Open/Close icon for folders is ambiguous

Clicking the up-facing arrow means "expand" when it could just as easily mean "collapse". It's not a big deal but I find myself slowing down cognitively because it's not clear whether up is up or down is down. I suggest considering using the right-facing triangle that rotates to a down-facing triangle (like Notion or Devonthink) or +,- like some outliners. Also, maybe consider putting the open/close on the left like most tools have it.