SubscribeToEvents' sourceId is the manager HANDLE, not a NodeState — the same
object-typed trap as ContinuationPoint.NodeToBrowse, found the same way. The
`sourceId as NodeState` cast compiled, always yielded null, and silently
disabled the gate: an ungranted session could subscribe to an equipment's event
notifier and receive every alarm it raises, including the condition fields,
while every value on it was refused.
Now uses the SDK's own IsHandleInNamespace, which cannot be wrong about the type.
The new test passes a null monitored item deliberately: the gate must deny
without touching the item, which also makes the test a discriminator rather than
a restatement — against the broken cast the call falls through to the base
implementation, which does dereference it, so the test fails loudly.
Claude-Session: https://claude.ai/code/session_015p7wGqy3YpZNCpDzTpGMKo
Joseph Doherty
8cdbcb9823