A tx-submission inbound side (server, sic!).

Each call to runNextPeerAction atomically inspects the shared state and this peer's local protocol state and returns one of: submit buffered bodies to the mempool, request bodies, request txids (blocking or pipelined), or do nothing. When idle, the server parks on awaitSharedChange until the shared-state generation moves or an optional wake delay expires, then re-evaluates. Body requests are pipelined; in pipelined mode txid requests become non-blocking and the server collects replies via handleReplies.

V2 server state machine.

Depth n tracks outstanding pipelined replies (type-level Nat).

States (non-pipelined, n = 0): serverIdle - park on awaitSharedChange or pick next action serverReqTxIds 0 - send a txid request (blocking or pipelined) submitBufferedTxs - submit buffered bodies, run continuation requestTxBodies - send a pipelined body request, depth + 1

States (pipelined, n > 0): continueAfterReplies - post-reply pick; dispatch action or DoNothing continueAfterBodyRequests - post-body-request pick; same dispatch handleReplies n - block on CollectPipelined for the next reply handleReply (n-1) - apply received txids or bodies, then continueAfterReplies (n-1)

Transitions:

serverIdle [PeerDoNothing] --> awaitSharedChange --> serverIdle [PeerSubmitTxs ks] --> submitBufferedTxs ks serverIdle [PeerRequestTxs ks] --> requestTxBodies 0 ks --> continueAfterBodyRequests 1 [PeerRequestTxIds] when unack queue empty --> blocking wire request, wait for reply --> serverIdle [PeerRequestTxIds] otherwise --> pipelined wire request --> handleReplies 1

handleReplies n --> handleReply (n-1) handleReply [CollectTxIds] --> applyReceivedTxIds --> continueAfterReplies (n-1) [CollectTxs] --> applyReceivedTxs --> continueAfterReplies (n-1)

continueAfterReplies 0 = serverIdle continueAfterReplies n@(>0), continueAfterBodyRequests n [PeerSubmitTxs ks] --> submitBufferedTxs ks (continueAfterReplies n) [PeerRequestTxs ks] --> requestTxBodies n ks [PeerRequestTxIds] --> serverReqTxIds n [PeerDoNothing] --> handleReplies n

Policy for making decisions