Stop packet construction when input callbacks restart the stream

src/transport_layer/etcp.c

@@ -1015,6 +1015,8 @@ struct ETCP_DGRAM* etcp_request_pkt(struct ETCP_CONN* conn) {
         return NULL;
     }
     if (!conn->input_send_q->head) input_queue_try_push(conn);
+    // Callback input_queue мог сменить эпоху при исчерпании seq или OOM; старый проход отправки прекращается.
+    if (conn->close_requested || conn->state == 2 || !conn->initialized || conn->session_required || conn->reinit_pending) return NULL;
     struct INFLIGHT_PACKET* packet = (struct INFLIGHT_PACKET*)conn->input_send_q->head;
     struct ETCP_LINK* link = NULL;
     for (struct ETCP_LINK* candidate = conn->links; candidate; candidate = candidate->next)