diff --git a/client/lib/screens/connect_page.dart b/client/lib/screens/connect_page.dart
index de7c6d8..f8aa63f 100644
--- a/client/lib/screens/connect_page.dart
+++ b/client/lib/screens/connect_page.dart
@@ -33,8 +33,8 @@ class ConnectPage extends ConsumerWidget {
     final isFree = ref.watch(isFreePlanProvider);
     final quota = ref.watch(quotaProvider);
     final stats = ref.watch(vpnStatsProvider).valueOrNull;
-    final down = _mbps(stats?.downloadSpeed);
-    final up = _mbps(stats?.uploadSpeed);
+    final down = _speed(stats?.downloadSpeed);
+    final up = _speed(stats?.uploadSpeed);
     // 延迟来源:连接后用内核 urltest 实测(代理真实 RTT,TCP 探针被隧道吞掉时仍准);
     // 未连接时用节点 TCP 探针 ping。0/无 → 显示 —。
     final livePing = conn.phase == VpnPhase.on ? _bestUrltest(stats) : node.ping;
@@ -201,9 +201,16 @@ class ConnectPage extends ConsumerWidget {
   }
 }
 
-/// 字节/秒 → Mb/s 字符串(null = 未取到,显示 —)。
-String _mbps(double? bytesPerSec) =>
-    bytesPerSec == null ? '—' : (bytesPerSec * 8 / 1000000).toStringAsFixed(1);
+/// 字节/秒 → 动态单位 (数值, 单位):B/s · KB/s · MB/s · GB/s(小数据也看得清)。
+/// null = 未取到,显示 —。
+(String, String) _speed(double? bytesPerSec) {
+  if (bytesPerSec == null) return ('—', 'KB/s');
+  final b = bytesPerSec;
+  if (b < 1024) return (b.toStringAsFixed(0), 'B/s');
+  if (b < 1024 * 1024) return ((b / 1024).toStringAsFixed(1), 'KB/s');
+  if (b < 1024 * 1024 * 1024) return ((b / (1024 * 1024)).toStringAsFixed(1), 'MB/s');
+  return ((b / (1024 * 1024 * 1024)).toStringAsFixed(2), 'GB/s');
+}
 
 /// 内核 urltest 各出站中的最小正延迟(ms);无则 0。
 int _bestUrltest(VpnStatsEvent? s) {
@@ -216,16 +223,16 @@ int _bestUrltest(VpnStatsEvent? s) {
 class _SpeedRow extends StatelessWidget {
   const _SpeedRow({required this.t, required this.down, required this.up, required this.latency});
   final AppText t;
-  final String down;
-  final String up;
+  final (String, String) down;
+  final (String, String) up;
   final String latency;
 
   @override
   Widget build(BuildContext context) {
     final c = context.pangolin;
     final metrics = [
-      (PangolinIcons.arrowDown, t.download, down, 'Mb/s'),
-      (PangolinIcons.arrowUp, t.upload, up, 'Mb/s'),
+      (PangolinIcons.arrowDown, t.download, down.$1, down.$2),
+      (PangolinIcons.arrowUp, t.upload, up.$1, up.$2),
       (PangolinIcons.zap, t.latency, latency, 'ms'),
     ];
     return Row(children: [
diff --git a/server/internal/usage/handler.go b/server/internal/usage/handler.go
index 156e487..96371ec 100644
--- a/server/internal/usage/handler.go
+++ b/server/internal/usage/handler.go
@@ -6,19 +6,17 @@ import (
 	"strconv"
 
 	"github.com/wangjia/pangolin/server/internal/apierr"
+	"github.com/wangjia/pangolin/server/internal/codes"
 )
 
-// ctxKey is the context key type for request-scoped values.  Defined here to
-// avoid an import cycle; the JWT auth middleware sets the same key.
-type ctxKey string
-
-// CtxKeyUserID is the context key carrying the authenticated int64 user ID.
-const CtxKeyUserID ctxKey = "user_id"
-
 // userIDFromContext extracts the authenticated user ID set by the auth
 // middleware, or 0 if absent.
+//
+// 关键:必须读 codes.CtxKeyUserID —— auth.RequireAuth 正是把 user id 存在这个键
+// 下。此前本包自定义了同名常量 ctxKey("user_id"),但 Go 的 context key 按
+// 「类型+值」比较,命名类型不同 → 取不到 → /v1/usage 恒 401(统计页全 0)。
 func userIDFromContext(r *http.Request) int64 {
-	id, _ := r.Context().Value(CtxKeyUserID).(int64)
+	id, _ := r.Context().Value(codes.CtxKeyUserID).(int64)
 	return id
 }