Module topology 

Core-level topology-change notification primitive.

The topology sink receives events when nodes are registered, torn down, or have their deps mutated. This is the substrate for reactive describe() and reactive observe() at the graph layer.

Topology sinks are NOT nodes — they sit outside the reactive graph to avoid circularity (registering an observer node would itself be a topology change).

Structs

TopologySubscription

RAII handle for a topology subscription. Dropping it unregisters the sink.

Enums

TopologyEvent

What changed in the topology.

Type Aliases

TopologySink

Callback for topology changes. Send + Sync for cross-thread Core usage.