The change feed as Server-Sent Events: one event: change per section of a resolve answer that moved, as it is recorded (data = the event /api/v1/changes returns; id = its feed position). Resume with Last-Event-ID (EventSource does it on reconnect) or ?since=; filters ?domain= and ?section=. A heartbeat comment every 15 s; each connection ends after 5 minutes with retry: 3000 and resumes where it was.