`webhook.ALLOWED_HOST_LIST` named `external` plus the HIVE domain. The
swarm-controller's webhooks target the SWARM domain, which is a different host
on the same private gateway IP — so `external` denied it and the hive entry did
not cover it. Every swarm-controller delivery has been failing there.
Found from the sender's log, which names the host and the rule it broke:
deny 'constellation.darkest.space(10.42.0.1:443)'
webhook can only call allowed HTTP servers (check your
webhook.ALLOWED_HOST_LIST setting)
This is the layer under the DNS fix: resolution now succeeds and reaches
10.42.0.1:443, and forgejo refuses to dial it. The two failures look identical
from the receiving end — no delivery, no log line — which is why reading the
sender was what separated them.
`optional` because a hive with no swarm has no such domain; `unique` because an
all-local deployment can legitimately set both to the same string.