Fix interactive tunnel latency and bound connection setup

[acking-you]

Summary

Interactive RPC traffic can stall on the local TCP legs of a tunnel even when the relay sockets already use TCP_NODELAY. Subscriber-to-relay and publisher-to-service connection attempts can also outlive the SDK's control I/O deadline. This fixes both issues found while investigating Pocket-Codex session switching.

Related Issues

Companion Pocket-Codex fix: acking-you/pocket-codex#92.

Change Type

• Bug fix

What Changed

• Disable Nagle on both local TCP forwarding legs, with a socket-level regression test.
• Bound subscriber relay connections and publisher local-service connections with the existing control I/O timeout and error type.
• Exclude credentials from the subscriber tracing span.
• Exercise a 20 MiB transfer followed by 200 small request/response exchanges on the same connection, in both plaintext and codec modes, including half-close and trailing data.

Verification

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace — 207 passed, 3 ignored; the subsequently added tcp_forward_disables_nagle_on_the_local_leg test also passed.
• Manual verification completed

The tunnel integration tests measured small-message P95 around 2.1 ms in both codec modes after the large transfer. A combined build with the Pocket-Codex fixes completed 300 real bridge session switches over a local relay on one WebSocket with zero disconnects: median 13.8 ms, P95 45.5 ms, maximum 63.3 ms.

Compatibility / Risk

No wire-format, CLI, or dependency-version changes. TCP connection attempts now fail within the existing control I/O deadline. Disabling Nagle can increase packet counts for small writes.

The session benchmark used isolated historical fixtures and warm local caches; it is not a public-network latency guarantee or an isolated measurement of the Nagle change. The fixed commit is also available on the dedicated pocket-codex branch. Companion PR acking-you/pocket-codex#92 consumes that Git branch, with the exact commit pinned in Cargo.lock, so it does not need to wait for a registry release.

[chatgpt-codex-connector]

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