L7 · DIG Node peer network
The normative node↔node protocol: mTLS peer identity (peer_id = SHA-256(TLS SPKI DER)), the two RPC tiers (mTLS-authenticated PEER/CONTROL vs anonymous PUBLIC-READ so browsers can retrieve content), the dual-mode public gateway (rpc.dig.net's mTLS front for node-class clients — the dig-store CLI, the SDK, any DIG-identity-key holder — across the full dig.local/localhost/rpc.dig.net ladder, plus its plain-HTTPS+CORS front for browsers, with an ephemeral self-signed client certificate for channel-bound anonymous reads), the ordered NAT-traversal ladder (direct → UPnP → NAT-PMP → PCP → relay-coordinated hole-punch (signalling only) → relayed/TURN transport), the relay's four roles (STUN, introducer, hole-punch signalling, relayed transport), STUN reflexive-address discovery, introducer + gossip peer discovery, PEX peer-exchange (node↔node stream + the RLY-008 relay introducer binding), the Kademlia DHT with provider records that locate which peers hold content (find_node/find_providers/add_provider/ping over a framed dig-nat mTLS stream; content-key = SHA-256(domain-tag ‖ store_id[‖root[‖retrieval_key]])), provider records announced promptly on an inventory gain (whichever path put a capsule on disk — so a reader that caches a capsule becomes a discoverable holder of it) and withdrawn on removal, the holdings-announce wire (gossip-pool broadcast opcode 222 — the signed, batched add/remove statement of a peer's holdings, TLS-leaf-key ECDSA with the `dig:holdings:v1` preimage and fail-closed acceptance), the gossip/peer-RPC port relationship (gossip 9445 = peer 9444 + 1 — translate before dialing), the relay RelayMessage wire (RLY-001..RLY-008), the peer RPC methods (dig.getPeers/dig.announce/dig.getNetworkInfo/dig.getAvailability/dig.listInventory/dig.fetchRange), and the relay-last-fallback invariant (prefer hole-punch signalling over full relaying).