Plumtree push-lazy gossip (Leitão, Pereira, Rodrigues 2007 — Part 3 §7.2).

Disseminates realm-scoped messages over HyParView's active view with a tree-emergent topology and lazy-push recovery.

State

• eager_push — peers receiving full GOSSIP payloads. The eager-push set is the Plumtree spanning tree.
• lazy_push — peers receiving only IHAVE announcements. They graft into eager_push when they GRAFT in response to an IHAVE.
• received — MsgId => Payload map of messages we've delivered locally. Used to dedup repeat GOSSIPs and to answer GRAFTs.
• missing — MsgId => [Peer] for peers who sent IHAVE for messages we have not yet received in full.

Message handling

• Local publish — record the message, deliver locally, GOSSIP to every eager peer, IHAVE to every lazy peer.
• Receive GOSSIP — if first time: deliver, remove from missing, eager-forward to every other eager peer, IHAVE-forward to every lazy peer, ensure sender is eager. If duplicate: PRUNE the sender + move sender from eager to lazy.
• Receive IHAVE — if already received, ignore. Else: record sender in missing and emit a GRAFT to the sender right away (Phase 5.3 MVP — a real deployment delays the GRAFT briefly to give the eager push a chance to win the race; the MVP eager-grafts which is correct but slightly heavier).
• Receive GRAFT — sender becomes eager; reply with the GOSSIP payload if we have it, drop silently if not.
• Receive PRUNE — move sender from eager to lazy.

This module is pure. The wrapping process is responsible for transmitting the action list and feeding deliveries to the local consumer.

Reference: plans/PLAN_MACULA_V2_PART3_DISCOVERY.md §7.2; plans/PLAN_PHASE_5_BREAKDOWN.md Session 5.3.