Adds `debug snapshot --id <int>` to query a running instance's current
attribute values and alarm states without the subscribe/stream overhead
of the debug view. Routes through ManagementActor → CommunicationService
→ site DeploymentManager → InstanceActor using the existing remote query
pattern.
Central and site clusters now communicate via ClusterClient/
ClusterClientReceptionist instead of direct ActorSelection. Both
CentralCommunicationActor and SiteCommunicationActor are registered
with their cluster's receptionist. Central creates one ClusterClient
per site using NodeA/NodeB contact points from the DB. Sites configure
multiple CentralContactPoints for automatic failover between central
nodes. ISiteClientFactory enables test injection.
Central now resolves site Akka remoting addresses from the Sites DB table
(NodeAAddress/NodeBAddress) instead of relying on runtime RegisterSite
messages. Eliminates the race condition where sites starting before central
had their registration dead-lettered. Addresses are cached in
CentralCommunicationActor with 60s periodic refresh and on-demand refresh
when sites are added/edited/deleted via UI or CLI.
New components 18-19: ManagementService (Akka.NET actor on Central exposing
all admin operations via ClusterClientReceptionist) and CLI (console app using
ClusterClient for scripting). Updated HighLevelReqs, CLAUDE.md, README,
Component-Host, Component-Communication, Component-Security.
Add per-pattern message timeouts with sensible defaults (120s for deployments, 30s
for queries/commands). Configure Akka.NET transport heartbeat explicitly rather than
relying on framework defaults. Document per-site message ordering guarantee. Specify
that in-flight messages on disconnect result in timeout error (no central buffering)
and debug streams die on any disconnect.
