Browser console will print one line on the first snap arrival showing the wire roster, then a line every time the local `others` map gains or loses a handle. Lets us correlate client-side visibility against server-side join/leave + 5s rate dumps to pin down the mutual-vis bug. Drop once mutual visibility is solid. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>