Pick two sessions to compare
Both left and right need a session to diff. Use the dropdowns above; the URL (/ui/diff?left=X&right=Y) is bookmarkable once you pick.
Compare sessions
Pick two sessions and see what each touched that the other didn't. Set diff over processes, sensitive-path flags, DNS queries and TCP targets — useful for "is this flagged session actually different from yesterday's clean one", or "does agent A do anything agent B doesn't".