Ask HN: How to add executable code logic to Neo4j graph nodes?

I am creating a dynamic "world events" graph that reacts to incoming data streams from a number of sources, but it seems like Neo4j is truly designed as a static data store. Anyone with some deeper knowledge of Neo4j have any idea how I could add dynamic behavior to a given "node" or class of "nodes" without having to write a plugin?

Imagine a lazily computed price graph of assets, with some set of dependencies (a gold future option is dependent on the gold future, as well as the spot price of gold itself, as well as whatever currency you're pricing the derivative in)

It seems like Neo4j would really lend itself to this application but I can't seen to find a way to couple executable code with the state itself within a single node, without using stored procedures or something. Just wanted to ask the community, thanks