The frame that is for the node itself rather than for a task in it. A task
id indexes a Vec, so this is a number that cannot be one. It carries what
must outlive the task it names - a watch and the death it asked about
(crate::world::Event::Node) - and so cannot be addressed to that task.
What a payload that arrived over conn means on this side. An address is the
one value that does not survive a link unchanged: a task the sender called
its own is one on the far side here, and a task it reached through this
link is one of ours, so the two cases swap and the sender’s conn - a name in
its numbering - is discarded. Exact rather than heuristic only because an
address is a host type (Addr) a program cannot forge.
Run a connection as a peer of the node reached through port, answering with
the way in to it. The outbound half comes back rather than registering
itself, so whoever established the connection holds it before anything can
name it: registering by event is a race the caller cannot wait out, since a
task that already knows the far address could send first and be told there
was no such link.
Whether every address in a payload leaving over conn has an image on the
far side - that is, none names a third node. Forwarding one would mean
proxying for a link the receiver does not hold, which has its own lifetime
and failure questions, so it is refused rather than half-built.