digraph architecture{
  node [shape = invhouse]; Eth2RPC GossipSub WeakSubjectivitySync;
  node [shape = octagon]; SyncManager SyncProtocol RequestManager;
  SyncManager [label="SyncManager (Sync in)"];
  node [shape = doubleoctagon] SharedBlockQueue;
  {rank = same; SyncManager RequestManager;}
  {rank = same; Eth2RPC GossipSub WeakSubjectivitySync;}

  WeakSubjectivitySync [label="WeakSubjectivitySync (impl TBD)"];

  node [shape = octagon]; Eth2Processor RequestManager;
  node [shape = octagon]; ChainDAG Quarantine Clearance;

  Eth2RPC -> SyncProtocol [dir=both]
  SyncProtocol -> SyncManager [dir=both, label="beaconBlocksByRange() (mixin)"]

  GossipSub -> Eth2Processor [label="node.topicBeaconBlocks: blockValidator->validateBeaconBlock (no transition or signature check yet)\nthen enqueued in blockQueue"];
  GossipSub -> Eth2Processor [dir=back, label="node.topicBeaconBlocks: blockValidator()->ValidationResult.Accept->libp2p/gossipsub.nim\nvalidate() in rpcHandler()"];

  Eth2Processor -> Clearance [label="storeBlock(): enqueue in clearance/quarantine and callback to fork choice"];
  SyncProtocol -> RequestManager [dir=both, label="fetchAncestorBlocksFromNetwork()"];

  SyncManager -> SharedBlockQueue [dir=both, label="Eth2Processor.blockQueue\n== SyncManager.outQueue (shared state!)"];
  Eth2Processor -> SharedBlockQueue [dir=both, label="Eth2Processor.blockQueue\n== RequestManager.outQueue (shared state!)"];
  SharedBlockQueue -> RequestManager [dir=both, label="SyncManager.outQueue\n== RequestManager.outQueue (shared state!)"];

  LocalValidatorDuties -> Clearance

  RequestManager -> Quarantine [dir=back, label="Retrieve missing ancestors"]
  Clearance -> Quarantine
  Clearance -> ChainDAG

  Eth2Processor -> ForkChoice
  LocalValidatorDuties -> ForkChoice

  node [shape = cylinder]; BeaconChainDB;
  ChainDAG -> BeaconChainDB [dir=both]

  SyncProtocol -> ChainDAG [dir=back, label="Sync out: getBlockRange()\nbeaconBlocksByRoot()\n"]
}