Initialize from build-time structure. Deep-clones via JSON round-trip.
OptionalbuildTimeStructure: EngineSerializedPipelineStructureConvert a runtime StageNode into a SerializedPipelineStructure node.
Update structure when dynamic children are discovered at runtime.
OptionalhasSelector: booleanOptionalhasDecider: booleanUpdate structure when a dynamic next chain is discovered at runtime.
Update structure when a dynamic subflow is registered at runtime.
OptionalsubflowName: stringOptionalsubflowBuildTimeStructure: unknownUpdate the iteration count for a node (loop support).
Returns the current runtime structure (mutated during execution).