Fix connection accept regression: revert disabled gates, add 409 handling

Previous fix (2139ea8) caused regression: staleTime:0 nuked cache on
every mount, isLoadingIncoming disabled buttons during cold-cache fetch.

Changes:
- Remove staleTime:0 (keep refetchOnMount:'always' for background refresh)
- Revert button gate to pendingRequestIds.has() only (no is_read gate)
- Remove isLoadingIncoming from disabled prop and spinner condition
- Add 409-as-success handling to ConnectionRequestCard (People tab)
- Use axios.isAxiosError() instead of err:any in all 3 catch blocks
- Add markRead() call to 409 branch so notifications clear properly

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/connections/ConnectionRequestCard.tsx

@@ -4,6 +4,7 @@ import { toast } from 'sonner';
 import { formatDistanceToNow } from 'date-fns';
 import { Button } from '@/components/ui/button';
 import { useConnections } from '@/hooks/useConnections';
+import axios from 'axios';
 import { getErrorMessage } from '@/lib/api';
 import { cn } from '@/lib/utils';
 import type { ConnectionRequest } from '@/types';
@@ -33,8 +34,14 @@ export default function ConnectionRequestCard({ request, direction }: Connection
       setResolved(true);
       toast.success(action === 'accept' ? 'Connection accepted' : 'Request declined');
     } catch (err) {
+      // 409 means the request was already resolved (e.g. accepted via toast or notification center)
+      if (axios.isAxiosError(err) && err.response?.status === 409) {
+        setResolved(true);
+        toast.success(action === 'accept' ? 'Connection already accepted' : 'Request already resolved');
+      } else {
         toast.error(getErrorMessage(err, 'Failed to respond'));
       }
+    }
   };
 
   const handleCancel = async () => {

frontend/src/components/notifications/NotificationToaster.tsx

@@ -4,6 +4,7 @@ import { Check, X, Bell, UserPlus } from 'lucide-react';
 import { useQueryClient } from '@tanstack/react-query';
 import { useNotifications } from '@/hooks/useNotifications';
 import { useConnections } from '@/hooks/useConnections';
+import axios from 'axios';
 import { getErrorMessage } from '@/lib/api';
 import type { AppNotification } from '@/types';
 
@@ -36,11 +37,10 @@ export default function NotificationToaster() {
         await respondRef.current({ requestId, action });
         toast.dismiss(loadingId);
         toast.success(action === 'accept' ? 'Connection accepted' : 'Request declined');
-      } catch (err: any) {
+      } catch (err) {
         toast.dismiss(loadingId);
         // 409 means the request was already resolved (e.g. accepted via notification center)
-        const status = err?.response?.status;
-        if (status === 409) {
+        if (axios.isAxiosError(err) && err.response?.status === 409) {
           toast.success(action === 'accept' ? 'Connection already accepted' : 'Request already resolved');
         } else {
           toast.error(getErrorMessage(err, 'Failed to respond to request'));

frontend/src/components/notifications/NotificationsPage.tsx

@@ -8,6 +8,7 @@ import { useNotifications } from '@/hooks/useNotifications';
 import { useConnections } from '@/hooks/useConnections';
 import { Button } from '@/components/ui/button';
 import { cn } from '@/lib/utils';
+import axios from 'axios';
 import { getErrorMessage } from '@/lib/api';
 import { ListSkeleton } from '@/components/ui/skeleton';
 import type { AppNotification } from '@/types';
@@ -31,7 +32,7 @@ export default function NotificationsPage() {
     deleteNotification,
   } = useNotifications();
 
-  const { incomingRequests, respond, isResponding, isLoadingIncoming } = useConnections();
+  const { incomingRequests, respond, isResponding } = useConnections();
   const queryClient = useQueryClient();
   const navigate = useNavigate();
   const [filter, setFilter] = useState<Filter>('all');
@@ -94,8 +95,10 @@ export default function NotificationsPage() {
       toast.success(action === 'accept' ? 'Connection accepted' : 'Request declined');
     } catch (err) {
       // 409 means the request was already resolved (e.g. accepted via toast)
-      const status = (err as any)?.response?.status;
-      if (status === 409) {
+      if (axios.isAxiosError(err) && err.response?.status === 409) {
+        if (!notification.is_read) {
+          await markRead([notification.id]).catch(() => {});
+        }
         toast.success(action === 'accept' ? 'Connection already accepted' : 'Request already resolved');
       } else {
         toast.error(getErrorMessage(err, 'Failed to respond'));
@@ -224,23 +227,22 @@ export default function NotificationsPage() {
                   {/* Connection request actions (inline) */}
                   {notification.type === 'connection_request' &&
                     notification.source_id &&
-                    !notification.is_read &&
-                    (isLoadingIncoming || pendingRequestIds.has(notification.source_id)) && (
+                    pendingRequestIds.has(notification.source_id) && (
                       <div className="flex items-center gap-1.5 shrink-0">
                         <Button
                           size="sm"
                           onClick={(e) => { e.stopPropagation(); handleConnectionRespond(notification, 'accept'); }}
-                          disabled={isResponding || isLoadingIncoming}
+                          disabled={isResponding}
                           className="gap-1 h-7 text-xs"
                         >
-                          {(isResponding || isLoadingIncoming) ? <Loader2 className="h-3 w-3 animate-spin" /> : <Check className="h-3 w-3" />}
+                          {isResponding ? <Loader2 className="h-3 w-3 animate-spin" /> : <Check className="h-3 w-3" />}
                           Accept
                         </Button>
                         <Button
                           variant="ghost"
                           size="sm"
                           onClick={(e) => { e.stopPropagation(); handleConnectionRespond(notification, 'reject'); }}
-                          disabled={isResponding || isLoadingIncoming}
+                          disabled={isResponding}
                           className="h-7 text-xs"
                         >
                           <X className="h-3 w-3" />

frontend/src/hooks/useConnections.ts

@@ -20,7 +20,6 @@ export function useConnections() {
       const { data } = await api.get<ConnectionRequest[]>('/connections/requests/incoming');
       return data;
     },
-    staleTime: 0,
     refetchOnMount: 'always',
   });