WindowOpened

A reconnect window opened for a peer whose link dropped.

Dual-role. Emitted on the host's events when a joiner goes unresponsive and the host opens a window to admit its resume (peerId = the joiner; if the joiner resumes before expiresAt, Resumed follows, otherwise Left with LeaveReason.PartitionExpired); and on a joiner's events when its host link tears and the joiner opens its own window to re-weave and resume (peerId = the host; on success Resumed follows, otherwise HostLost). expiresAt is the wall-clock instant at which the window closes.