Type a Bluesky handle. It loads every mutual (people it follows who follow it back), then reads every mutual's whole post history looking for replies between them. The result is a grid: for every pair of mutuals, who broke the ice first by replying to the other. Sparked by @norvid-studies.bsky.social asking how to build exactly this, tagged to life by @bisks.net — and it also builds the "void graph" @norvid-studies.bsky.social asked for in the same thread: the listing of mutuals who've never spoken to each other at all.
reads Bluesky's public graph and repos in your browser — no login, nothing uploaded. can take a while for handles with a lot of mutuals.
Rows and columns are the same list — every mutual, plus the handle you searched. A cell lights up when the row replied to the column at least once; gold means that reply happened before the reverse one (or the reverse hasn't happened yet) — the one who broke the ice. Click a lit cell to open the actual reply.
@norvid-studies.bsky.social's other idea from the same thread — not who raced whom, but which of your mutuals have never spoken to each other at all, no reply in either direction, ever. Every node below is you or one of your mutuals, arranged in a circle; a line connects two who've exchanged at least one reply. A red node has never replied to, or been replied to by, anyone else in this circle.