- Replace placeholder-loop comment with the double-render guard explanation
- Use _alarmTimestamps.GetValueOrDefault(binding, DateTimeOffset.MinValue) so the
placeholder timestamp is stable/idempotent across snapshot calls (was UtcNow)
- Add dcl.ExpectMsg<SubscribeAlarmsRequest>() drain in Snapshot_QuietNativeBinding_EmitsPlaceholder
and Snapshot_NativeBindingWithLiveCondition_NoPlaceholder to consume the DCL message
the NativeAlarmActor sends at startup
InstanceActor.BuildAlarmStatesSnapshot now adds an IsConfiguredPlaceholder
row per configured native source binding that currently has no live
condition, so the Debug View tree can show the binding node even when
quiet. A binding is "quiet" when no retained AlarmStateChanged carries its
NativeSourceCanonicalName (DV-1).
Kind derivation: reuses the exact nativeKind value already computed via
ResolveNativeKind(nativeSource.ConnectionName) at the NativeAlarmActor
creation site and stored in a new _nativeAlarmKinds dictionary -- the
accurate per-binding kind (NativeOpcUa vs NativeMxAccess), not the
NativeOpcUa default.
Tests: Snapshot_QuietNativeBinding_EmitsPlaceholder,
Snapshot_NativeBindingWithLiveCondition_NoPlaceholder.