Changelog of @hackage/gbnet-hs 0.2.5.0

Changelog

Retransmissions now respect congestion control: Retransmitted reliable messages previously bypassed all flow control (ccCanSend/ccDeductBudget and CWND), allowing unbounded retransmit traffic during congestion. Now gated by the same congestion budget as new sends.

Extract encodeChannelWire and enqueuePayload shared helpers, eliminating duplicated wire encoding between processChannelMessages and processRetransmissions.

Wire reliable channel retransmission: Channel.getRetransmitMessages was implemented and exported but never called from the connection tick loop. Reliable messages that were lost on the wire were never retransmitted, causing silent data loss on any packet drop. Now called from updateConnectedPure after processing outgoing messages — expired unacked messages are re-queued as new Payload packets with fresh sequence numbers.

Fix keepalive regression: drainAllConnectionQueues unconditionally called recordBytesSent even when zero bytes were sent, resetting connLastSendTime every tick. This prevented the keepalive timer from ever triggering, causing connections to silently die on any single packet loss (no ACK feedback, no retransmission). Now only records when actual bytes are sent.

Bandwidth tracking now functional: recordBytesSent and recordBytesReceived were implemented in Connection but never called. Wired into peerTick: outgoing bytes recorded after encryption in drainAllConnectionQueues, incoming bytes recorded per-packet in handlePacket. BandwidthTracker and NetworkStats byte counters now report real values.
Fix O(n^2) list appending in encryptOutgoing and processPacketsPure: replaced acc ++ [x] with reverse-accumulator pattern.
Fix migration cooldowns leak: npMigrationCooldowns map now swept of stale entries in updateConnections, preventing unbounded growth on long-running servers.
Total function compliance: replaced partial Seq.index with Seq.lookup in delta encoding/baseline management.

Codebase-wide elimination of prime-mark variable naming (x', x'') in favour of descriptive names and optics composition across all 31 source files, tests, and benchmarks.
README and EXAMPLES: removed all prime-mark variables, added optics-based configuration examples, fixed section numbering, added LambdaCase pragma.

Congestion bypass for small reliable packets: Small reliable messages (<= 64 bytes) now bypass the congestion window, preventing upgrade/command stalls when heavy unreliable traffic fills the cwnd. Binary rate limit still applies to all traffic.

Refactored processChannelMessages from nested if/else to guards + Maybe-monadic pipeline with named where-helpers

NetworkConfig gains ncEncryptionKey :: !(Maybe EncryptionKey) field (defaults to Nothing)
NetworkStats gains nsDecryptionFailures :: !Word64 field
TestNetConfig gains tncDuplicateChance and tncOutOfOrderChance fields
Connection gains connEncryptionKey, connSendNonce, connRecvNonceMax fields

ChaCha20-Poly1305 AEAD encryption (GBNet.Crypto module): pre-shared key encryption for post-handshake packets with anti-replay nonce tracking
IPv6 socket support: newUdpSocket now detects address family from SockAddr; new helpers localhost6, ipv6, anyAddr6
TestNet simulation: packet duplication (tncDuplicateChance) and out-of-order delivery (tncOutOfOrderChance)

Drop -O2 from benchmark ghc-options (users set optimization in their own cabal.project)
Add automated Hackage publish to CI pipeline (tag-gated with version validation)
Add Hackage badge to README

Initial release.