> P.S. feature request! If Alice, Bob and Charlie are all contacts with each other, and Alice writes an offline message to Charlie, Alice should be able to opportunisticly hand the encrypted message to Bob on their shared network, and Bob can deliver it to Charlie.

This is intentionally only included in Forum-mode chats in Briar. Over direct message, leaking contacts is considered a breach of security. (Your definition of "leak" may differ.) In group messages, only the group admin is considered trusted, and every message must go directly to or come from them.

In every security tradeoff, Briar chose the option that maximizes security, even considering how the airwave transmission times might be fingerprintable as Briar traffic.

Not saying any of this is a good way to make a useable app for wide adoption, but it is intentional and highly opinionated.