observability.md described a single collector holding the upstream
credential. It also said endpoint and protocol are what agents are
handed; agents get the derived first hop, which has been true since the
collector was introduced.
The swarm tier is documented beside its sibling swarm services rather
than here, and the one line an operator must not miss - swarm.otel.url
on a hive that does not run them - is called out in both places, since
leaving it unset loses telemetry silently.
Review feedback: the metrics pair had nothing writing into it, and it sat
outside the switch that turns on every other swarm-wide service.
The collector now exports to VictoriaMetrics as well as upstream — a
fan-out, not a choice: a local store is for looking at this swarm, an
upstream is for whoever aggregates across swarms.
That makes a local store a complete destination on its own, so
`otel.endpoint` is no longer required when it runs here; a hive with
neither is still refused. The assertion only ever relaxes, so every
config that evaluated before still does.
`enableRequiredServices` now derives both halves, alongside matrix,
authelia and nats. They derive together because a store with no UI is
unreadable and a UI with no store is empty.
`docs/swarm.md` becomes `docs/swarm/README.md` and the shared-services
material moves to `docs/swarm/services.md`, following the shape
`docs/turn-loop/` and `docs/web-ui/` already use. The README keeps a
pointer so the reading path is unbroken.
Every referrer moved with it — five docs pages, two option descriptions
in swarm.nix, and CLAUDE.md's reading path. A pointer to a file that
moved is worse than one to a file that was deleted: the content still
exists, so the reader concludes the note is wrong rather than the path.
