workSignal property
The work-signal probe the COMPLETION FENCE proves an inferred completion
with — bound by the composer via StationServices.workSignal; noWorkSignal
(the default) leaves the fence INERT, which is exactly today's behavior.
Only consulted for a capability declaring
CompletionContract.committedWorkspace, and only when the tree actually
carries a real SourceControl + Workspace (see ProcessAllocation).
Implementation
final WorkSignalProbe workSignal;