feat: 把 A 端的 Session/KCP/视频/控制 都收口到一个本地 daemon 进程里，Django 和输入发送端都改成通过本机 UDS HTTP 去访问它，同时补齐了观测、性能和可用性上的几个关键问题。

third_party/kcp/ikcp.c

@@ -298,6 +298,10 @@ ikcpcb *ikcp_create(IUINT32 conv, void *user)
     kcp->fastlimit = IKCP_FASTACK_LIMIT;
     kcp->nocwnd = 0;
     kcp->xmit = 0;
+    kcp->fast_retrans_xmit = 0;
+    kcp->early_retrans_xmit = 0;
+    kcp->lost_xmit = 0;
+    kcp->repeat_xmit = 0;
     kcp->dead_link = IKCP_DEADLINK;
     kcp->output = NULL;
     kcp->writelog = NULL;
@@ -788,6 +792,7 @@ void ikcp_parse_data(ikcpcb *kcp, IKCPSEG *newseg)
     }
     else
     {
+        kcp->repeat_xmit++;
         ikcp_segment_delete(kcp, newseg);
     }
 
@@ -1192,6 +1197,7 @@ void ikcp_flush(ikcpcb *kcp)
             needsend = 1;
             segment->xmit++;
             kcp->xmit++;
+            kcp->lost_xmit++;
             if (kcp->nodelay == 0)
             {
                 segment->rto += _imax_(segment->rto, (IUINT32)kcp->rx_rto);
@@ -1211,6 +1217,7 @@ void ikcp_flush(ikcpcb *kcp)
             {
                 needsend = 1;
                 segment->xmit++;
+                kcp->fast_retrans_xmit++;
                 segment->fastack = 0;
                 segment->resendts = current + segment->rto;
                 change++;

third_party/kcp/ikcp.h

@@ -300,6 +300,10 @@ struct IKCPCB
     IINT32 rx_rttval, rx_srtt, rx_rto, rx_minrto;
     IUINT32 snd_wnd, rcv_wnd, rmt_wnd, cwnd, probe;
     IUINT32 current, interval, ts_flush, xmit;
+    IUINT32 fast_retrans_xmit;
+    IUINT32 early_retrans_xmit;
+    IUINT32 lost_xmit;
+    IUINT32 repeat_xmit;
     IUINT32 nrcv_buf, nsnd_buf;
     IUINT32 nrcv_que, nsnd_que;
     IUINT32 nodelay, updated;