fix: preserve subscription context in navigation and cache keys

SubscriptionCardActive: passes ?sub= to /connection navigation.
Connection: QR state includes subscriptionId for back-navigation.
ConnectionQR: preserves subscription context on back button.
Dashboard + Subscription: localStorage traffic cache keyed per-subscription
to prevent cooldown bleed between different subscriptions.

src/components/dashboard/SubscriptionCardActive.tsx

@@ -214,7 +214,7 @@ export default function SubscriptionCardActive({
               haptic.notification('error');
               return;
             }
-            navigate('/connection');
+            navigate(`/connection?sub=${subscription.id}`);
           }}
           className={`mb-2.5 flex w-full items-center gap-3.5 rounded-[14px] p-3.5 text-left transition-shadow duration-300${isAtDeviceLimit ? 'cursor-not-allowed opacity-50' : ''}`}
           data-onboarding="connect-devices"

src/pages/Connection.tsx

@@ -43,9 +43,10 @@ export default function Connection() {
       state: {
         url: appConfig?.subscriptionUrl,
         hideLink: appConfig?.hideLink ?? false,
+        subscriptionId: subId,
       },
     });
-  }, [navigate, appConfig?.subscriptionUrl, appConfig?.hideLink, isTelegramWebApp]);
+  }, [navigate, appConfig?.subscriptionUrl, appConfig?.hideLink, isTelegramWebApp, subId]);
 
   useEffect(() => {
     const handleKeyDown = (e: KeyboardEvent) => {

src/pages/ConnectionQR.tsx

@@ -8,6 +8,7 @@ import { AdminBackButton } from '@/components/admin';
 interface ConnectionQRState {
   url: string;
   hideLink: boolean;
+  subscriptionId?: number;
 }
 
 function isValidState(state: unknown): state is ConnectionQRState {
@@ -24,12 +25,14 @@ export default function ConnectionQR() {
 
   const state = location.state as unknown;
   const validState = isValidState(state) ? state : null;
+  const subId = validState?.subscriptionId;
+  const connectionPath = subId ? `/connection?sub=${subId}` : '/connection';
 
   useEffect(() => {
     if (!validState) {
-      navigate('/connection', { replace: true });
+      navigate(connectionPath, { replace: true });
     }
-  }, [validState, navigate]);
+  }, [validState, navigate, connectionPath]);
 
   if (!validState) {
     return null;
@@ -38,7 +41,7 @@ export default function ConnectionQR() {
   return (
     <div className="animate-fade-in">
       <div className="mb-6 flex items-center gap-3">
-        <AdminBackButton to="/connection" replace />
+        <AdminBackButton to={connectionPath} replace />
         <h1 className="text-2xl font-bold text-dark-100">{t('subscription.connection.qrTitle')}</h1>
       </div>
 

src/pages/Dashboard.tsx

@@ -141,7 +141,10 @@ export default function Dashboard() {
         traffic_used_percent: data.traffic_used_percent,
         is_unlimited: data.is_unlimited,
       });
-      localStorage.setItem('traffic_refresh_ts', Date.now().toString());
+      localStorage.setItem(
+        `traffic_refresh_ts_${subscription?.id ?? 'default'}`,
+        Date.now().toString(),
+      );
       if (data.rate_limited && data.retry_after_seconds) {
         setTrafficRefreshCooldown(data.retry_after_seconds);
       } else {
@@ -176,7 +179,7 @@ export default function Dashboard() {
     if (hasAutoRefreshed.current) return;
     hasAutoRefreshed.current = true;
 
-    const lastRefresh = localStorage.getItem('traffic_refresh_ts');
+    const lastRefresh = localStorage.getItem(`traffic_refresh_ts_${subscription?.id ?? 'default'}`);
     const now = Date.now();
     const cacheMs = API.TRAFFIC_CACHE_MS;
 

src/pages/Subscription.tsx

@@ -391,7 +391,10 @@ export default function Subscription() {
         traffic_used_percent: data.traffic_used_percent,
         is_unlimited: data.is_unlimited,
       });
-      localStorage.setItem('traffic_refresh_ts', Date.now().toString());
+      localStorage.setItem(
+        `traffic_refresh_ts_${subscriptionId ?? 'default'}`,
+        Date.now().toString(),
+      );
       if (data.rate_limited && data.retry_after_seconds) {
         setTrafficRefreshCooldown(data.retry_after_seconds);
       } else {
@@ -427,7 +430,7 @@ export default function Subscription() {
     if (hasAutoRefreshed.current) return;
     hasAutoRefreshed.current = true;
 
-    const lastRefresh = localStorage.getItem('traffic_refresh_ts');
+    const lastRefresh = localStorage.getItem(`traffic_refresh_ts_${subscriptionId ?? 'default'}`);
     const now = Date.now();
     const cacheMs = 30 * 1000;
 
@@ -441,7 +444,7 @@ export default function Subscription() {
     }
 
     refreshTrafficMutation.mutate();
-  }, [subscription, refreshTrafficMutation]);
+  }, [subscription, refreshTrafficMutation, subscriptionId]);
 
   const copyUrl = () => {
     if (subscription?.subscription_url) {