The hub waited only 5s (the request manager default) for stats over
WebSocket and closed the connection on any error. On hosts where
`zpool list` stalls (seen on Proxmox, up to its 10s timeout), collection
exceeded that limit, so the hub sent a close (code 1000) and the agent
reconnected. The refresh ran every other cycle, which caused a
disconnect roughly every 2 minutes.
Hub:
- Wait up to 30s for WebSocket stats responses.
- Keep the connection open when a stats request times out; only close
it (and fall back to SSH) for other errors.
Agent:
- After the first collection, refresh `zpool list` pool stats and
`zfs list` dataset usage in the background and serve cached values
meanwhile, so a hung utility cannot delay the stats response.
