A light node that follows an Activeledger network from its supernodes without taking part in consensus. It keeps an embedded store (no CouchDB), serves its own read and submit API, and relays the transactions it is sent to a supernode.
It does not trust the supernodes it follows. Every transaction is checked against the signed votes and commit attestations of the network's nodes, and every contract is run locally. When the result differs from what was committed the hybrid repairs the stream from the network and writes a divergence record.
The supernodes need build 40300. See the documentation for the network settings (hybrid.admission, hybrid.required, hybrid.minVersion), the hybrid.json options, the local API and what contract authors need to know (isSupernode(), adoptFromSupernode()).