---
description: gnet EventLoop rules for the TCP transport.
globs: internal/transport/tcp/**/*.go
alwaysApply: false
---

# TCP / gnet

EventLoop may: parse PROXY (before TLS), TLS, decode Frame, heartbeat, PUSH_ACK, rate-limit check, `TaskPool.Submit`, `AsyncWrite`.

EventLoop must not: MySQL, Redis, upload, group member expand, deliver fanout.

Heartbeat / PUSH_ACK stay in the loop. `AUTH` / `SEND_MESSAGE` / `SYNC_*` / `READ` / `RECALL` go to TaskPool.

`TaskPool` is a bounded channel. Full → `errs.ErrBusy`, client retries with the same `client_msg_id`. Do not block `OnTraffic` on MySQL.

Business modules send via `session.Manager`, never `gnet.Conn`.

Same `device_id` kicks the old connection. Do not close a connection solely because PUSH_ACK timed out.

gnet options: Multicore, 16MB buffers, TCPKeepAlive 30s. IdleTimeout 120s. Align with Nginx `proxy_timeout`.