[0xcadams]

What

Add the first transport gate for the relay-first native rewrite: one end-to-end QUIC session keeps its application streams and real TCP target connection while encrypted packet delivery changes between two relays and direct UDP. This layer follows #455 and will feed the authorization and role migration layers below final integration PR #470.

Why

The existing relay stream forwarder cannot move an established application connection to P2P. The rewrite needs evidence that packet delivery can change without reconnecting a database or replaying application bytes, including when only TCP relay transport is available.

Changes

• Add a shared transport-owned packet endpoint with warm relay fallback, authenticated direct-path probes, bounded queues, fixed fragment reassembly, and joined cancellation.
• Keep the handwritten packet wire contract in tunnelv1 on protocol 1 and existing /1 ALPNs. Fragment 1200-byte inner packets into frames that fit minimum-size outer QUIC datagrams.
• Prove relay A → direct → relay B and return through relay A using real QUIC datagram or TLS/TCP-yamux relay legs, a monotonic TCP application exchange, and preserved half-close. Also prove all-TCP fallback with direct UDP blocked throughout.
• Bound one blocked TCP carrier to 64 queued frames (67,136 frame bytes) and independently recover through its sibling. Local race-qualified recovery was roughly 250–310 ms with a 150 ms path timeout; an unread TCP carrier escaped head-of-line blocking in roughly 100 ms under the shorter fault-test settings. These are local proof measurements.
• Passed task go:test:peer-transport -- -race, task go:test, task go:lint, task generate-check, task format, and task format-check. Production integration adds shared-socket STUN/ICE, shared relay demultiplexing, and control-authorized lifetimes around this owner.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-26T18:05:40.809280Z	9454a33	PR opened
🔒 Security Review	✅ Completed 2026-10-26T18:07:16.658367Z	9454a33	PR opened

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