Friend lists are encrypted data; each friendship is a shared folder; files friends share appear in the newsfeed; a share is a write into your own space, so the server does not learn who follows whom; two friends reading one file is the remaining leak that Tor is meant to close.

It is the privacy claim about contacts made concrete.

Who are your friends? That is data, and it is encrypted like any other data.

Each friendship is a shared folder. What you share with them goes in it.

Files your friends share with you appear in your newsfeed. That feed is those folders, read together.

A share is a write into your own space. The server sees you write. It does not learn who follows whom.

Two friends open the same file. Today, that pair of reads is the one thing that could give them away. Hiding it is the Tor work.

Check yourself. What is a friendship in storage terms, and what is the one access pattern that can still leak?