- Добавлен device_type (1 байт, CLIENT_TYPE_*) в INIT_REQUEST и INIT_RESPONSE
- Добавлен keepalive_interval (2 байта) в INIT_RESPONSE
- STCP handshake расширен с 43 до 46 байт (device_type+keepalive)
- negotiate_keepalive(): оба desktop/server → min, иначе (есть mobile) → max
- keepalive_interval вынесен в UTUN_INSTANCE для использования в handshake
- stcp_client_connect() принимает device_type и keepalive_interval
- peer_device_type/peer_keepalive_interval передаются через stcp_link в ETCP_LINK
- u_async.c: process immediate_queue BEFORE epoll_wait in uasync_poll
- stcp_link.c: defensive NULL etcp_conn/etcp_link in stcp_link_close
- utun_instance.c: move stcp_server_list_destroy_all to Phase J (before ETCP),
add deferred drain in both Phase J and L
- stcp.h/c: STCP_HS_ENC_CLIENT 6→38, STCP_HS_ENC_SERVER 7→39,
exchange ed25519_pubkey in both handshake directions
- etcp_connections.c: copy peer_ed25519 from STCP to ETCP_CONN in
etcp_link_enter_ready_tcp; guard link->etcp in tcp_link_close_cb
- chat_sync.c: fix lk->conn NULL dereference for TCP links
- test_stcp.c: update stcp_server_create/stcp_client_connect callsites
- tools/chat_tcp_test: change transport udp→tcp
evgeny
Evgeny