Owner decision 2026-11-11: /fleet/diagnostics "Faulted devices" counts DISTINCT
devices across the nodes of the selected node's cluster, Faulted state only.
- DriverHostActor: FaultedDevices = HostState.Faulted only (Stopped no longer
counted); new StoppedDevices + FaultedHostNames. Counting extracted to the
testable DiagnosticsFromHealth.
- DriverInstanceDiagnostics: StoppedDevices (default 0) and FaultedHostNames
(default null) are additive with defaults, so a pre-#786 sender's snapshot
still deserializes over Akka's default JSON serializer (pinned by a test).
- FleetDiagnosticsAggregation (pure): identity key = (driver-instance string
id, HostName), case-insensitive; a single-host driver / nameless pre-#786
count is combined by MAX across nodes, never summed. Cluster peers come from
enabled ClusterNode rows of the selected node's ClusterId.
- FleetDiagnostics.razor: tile fetches the cluster peers and shows the
distinct count + "n of m nodes answered"; per-driver table gains a Stopped
devices column.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Joseph Doherty