Instead of 1 1-click link, make it a handshake, 2 1-click links: 1. Godelski shares 1-click link with Brigandish. 2. Brigandish clicks link and that registers

Instead of 1 1-click link, make it a handshake, 2 1-click links: 1. Godelski shares 1-click link with Brigandish. 2. Brigandish clicks link and that registers Brigandish's Signal account with Godelski's Signal account, but no communication can take place yet. 3. Brigandish shares 1-click link with Godelski. 4. Godelski clicks the link, if Godelski has a registration waiting for Brigandish's Signal account then the handshake is complete. I came up with this right now, I'm sure someone else can find a problem with it beyond it being a tad more bothersome than usual.