🔗 FIX Session

Watch a FIX session open, survive, break and come back — every message drawn as an arrow between two lifelines, with each side's sequence counters visible as they drift apart. Four models cover the Logon handshake and why silence is the bad signal, sequence gaps and the resend that patches them, what one flag decides when you reconnect after an outage, and the question none of the session machinery can answer: did my order actually get through? Each step lights up the matching line of Go and TypeScript.