Function is_hydrated 

pub fn is_hydrated(pref: Pref) -> bool

Has pref been reconciled with the relays yet this session?

The publish gate. These lists are whole-list newest-wins projections of local state, so publishing one before the relay copy has been applied would overwrite another device’s prefs with this device’s emptier view — a fresh login that mutes one chat before the subscription replay lands would erase every block, mute and nickname set elsewhere. Reconcile, THEN publish.