lastActivity
A static method that returns when a conversation last moved, so a browser can restore its idle clock after a reload. Without it a widget restarts the clock at zero: a tab closed for 55 minutes of a 60-minute timeout would wait another hour before warning, while the conversation ends in five.
The service stamps messages in microseconds; this converts to seconds. Every role counts, not only
the ones visibleMessages() keeps, because the service’s idle clock moves on any
write. Messages without a positive integer timestamp are skipped.
Parameters
messages
Messages as log() returns them in messages.
Returns
number | null — epoch seconds of the newest dated message, or null when none is dated.