If the agent was started outside the updater (manually, during dev,
or from a prior systemd unit), there is no agent.pid for _stop_agent
to target, so a successful code install leaves the old in-memory
agent process still serving requests. Scan /proc for any decnet agent
command and SIGTERM all matches so restart is reliable regardless of
how the agent was originally launched.
Adds a separate `decnet updater` daemon on each worker that owns the
agent's release directory and installs tarball pushes from the master
over mTLS. A normal `/update` never touches the updater itself, so the
updater is always a known-good rescuer if a bad agent push breaks
/health — the rotation is reversed and the agent restarted against the
previous release. `POST /update-self` handles updater upgrades
explicitly (no auto-rollback).
- decnet/updater/: executor, FastAPI app, uvicorn launcher
- decnet/swarm/updater_client.py, tar_tree.py: master-side push
- cli: `decnet updater`, `decnet swarm update [--host|--all]
[--include-self] [--dry-run]`, `--updater` on `swarm enroll`
- enrollment API issues a second cert (CN=updater@<host>) signed by the
same CA; SwarmHost records updater_cert_fingerprint
- tests: executor, app, CLI, tar tree, enroll-with-updater (37 new)
- wiki: Remote-Updates page + sidebar + SWARM-Mode cross-link
