Constant IDLE_DEADLINE 

const IDLE_DEADLINE: Duration;

Treat an established stream’s path as dead when no frame (message, server ping, or pong) arrives within this window. Sits comfortably past both 2x PING_INTERVAL and Gotify’s own ~45s server-ping period, so a healthy but quiet stream never trips it; a half-open socket left by a silent network drop does, which breaks the read loop into a reconnect.