An agent whose freshness is "unknown" is a distinct case, not a
fallback: it reported into the KV bucket but isn't in the swarm-identity
roster. The label used to just reuse the enum name ("unknown"), which
doesn't tell an operator what to do about it. Give it a label that
names the actual situation ("not in swarm identity") plus a tooltip
spelling out the fix (register/migrate it), so an operator scanning the
roster during a migration can immediately tell which agents still need
work.
No backend change needed — GET /api/agents/status already emits a row
for every hive-reported agent outside the roster (AgentStatusReader,
unit-tested as an_agent_outside_the_roster_is_surfaced_as_unknown), and
the page already renders every row it gets back.
8d29ebf53c