Self-optimizing peer-selection middleware for the DIG Node — the pure decision + learning layer between dig-download and the discovery layers (dig-dht / dig-gossip / dig-nat). Maintains a dynamic peer registry, learns each peer's throughput/RTT/reliability + saturation point + a relayed penalty from the REAL measured outcome of every transfer (measured-only, non-gameable), and ranks a candidate subset per content request to minimize P99 latency without thundering-herd. No user-facing knobs; re-uses the transport-verified peer_id = SHA-256(TLS SPKI DER).