8 hours later I actually know now how bitchat works (not every part yet but most of it). it's pretty nifty: every phone is a BLE server and a BLE client at the same time. the app optimistically connects to peers that it can find through a scan. all messages it receives are relayed to all other connections.

I've tried it with a chain of 4 phones each connecting to only their next peer and the message propagates like a lightning payment from one phone to another.

need to implement message chunking (the protocol already defines it but there's no working implementation lol. it's strange because an LLM came up with it but it didn't implement it on neither ios nor android

freaky