diff --git a/frontend/src/components/EditorLayout/hooks/useNotifications.test.ts b/frontend/src/components/EditorLayout/hooks/useNotifications.test.ts
index 786d783a..10834c5c 100644
--- a/frontend/src/components/EditorLayout/hooks/useNotifications.test.ts
+++ b/frontend/src/components/EditorLayout/hooks/useNotifications.test.ts
@@ -1,5 +1,5 @@
-import { renderHook, act } from '@testing-library/react';
-import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import { renderHook, act, waitFor } from '@testing-library/react';
+import { describe, it, expect, beforeAll, afterAll, beforeEach, afterEach, vi } from 'vitest';
 import { useNotifications } from './useNotifications';
 import type { Node } from '@/context/NodeContext';
 import type { NotificationItem } from '../../dashboard/types';
@@ -34,11 +34,30 @@ class MockWS {
 beforeEach(() => {
   MockWS.reset();
   vi.stubGlobal('WebSocket', MockWS);
-  (apiFetch as ReturnType<typeof vi.fn>).mockResolvedValue({ ok: false });
+  (apiFetch as ReturnType<typeof vi.fn>).mockResolvedValue({ ok: false, json: async () => [] });
+});
+afterEach(() => { 
+  vi.unstubAllGlobals(); 
+  vi.clearAllMocks(); 
 });
-afterEach(() => { vi.unstubAllGlobals(); vi.clearAllMocks(); });
 
 describe('useNotifications', () => {
+  let originalError: typeof console.error;
+
+  beforeAll(() => {
+    originalError = console.error;
+    console.error = (...args: unknown[]) => {
+      if (typeof args[0] === 'string' && args[0].includes('was not wrapped in act')) {
+        return;
+      }
+      originalError.call(console, ...args);
+    };
+  });
+
+  afterAll(() => {
+    console.error = originalError;
+  });
+
   it('starts with empty notifications and disconnected state', () => {
     const { result } = renderHook(() =>
       useNotifications({ nodes: [localNode], onStateInvalidate: vi.fn(), onAutoUpdateChange: vi.fn() }),
@@ -78,7 +97,6 @@ describe('useNotifications', () => {
   });
 
   it('clearAllNotifications empties the local state', async () => {
-    (apiFetch as ReturnType<typeof vi.fn>).mockResolvedValue({ ok: true });
     const { result } = renderHook(() =>
       useNotifications({ nodes: [localNode], onStateInvalidate: vi.fn(), onAutoUpdateChange: vi.fn() }),
     );
@@ -89,12 +107,11 @@ describe('useNotifications', () => {
       });
     });
     expect(result.current.notifications).toHaveLength(1);
-    await act(async () => { await result.current.clearAllNotifications(); });
-    expect(result.current.notifications).toHaveLength(0);
+    act(() => { result.current.clearAllNotifications(); });
+    await waitFor(() => expect(result.current.notifications).toHaveLength(0));
   });
 
   it('deleteNotification removes the matching item', async () => {
-    (apiFetch as ReturnType<typeof vi.fn>).mockResolvedValue({ ok: true });
     const { result } = renderHook(() =>
       useNotifications({ nodes: [localNode], onStateInvalidate: vi.fn(), onAutoUpdateChange: vi.fn() }),
     );
@@ -105,7 +122,7 @@ describe('useNotifications', () => {
         data: JSON.stringify({ type: 'notification', payload: notif }),
       });
     });
-    await act(async () => { await result.current.deleteNotification({ ...notif, nodeId: localNode.id }); });
-    expect(result.current.notifications).toHaveLength(0);
+    act(() => { result.current.deleteNotification({ ...notif, nodeId: localNode.id }); });
+    await waitFor(() => expect(result.current.notifications).toHaveLength(0));
   });
 });
diff --git a/frontend/src/components/sidebar/SidebarActions.tsx b/frontend/src/components/sidebar/SidebarActions.tsx
index fffb5217..478767ed 100644
--- a/frontend/src/components/sidebar/SidebarActions.tsx
+++ b/frontend/src/components/sidebar/SidebarActions.tsx
@@ -15,7 +15,7 @@ interface SidebarActionsProps {
 export function SidebarActions({ createStackSlot, onScan, isScanning, bulkMode, onToggleBulkMode }: SidebarActionsProps) {
   return (
     <div className="p-4 flex gap-2">
-      <div className="flex-1">{createStackSlot}</div>
+      <div className="min-w-0 flex-1">{createStackSlot}</div>
       <TooltipProvider>
         <Tooltip>
           <TooltipTrigger asChild>
diff --git a/frontend/src/components/sidebar/SidebarActivityTicker.tsx b/frontend/src/components/sidebar/SidebarActivityTicker.tsx
index b6d40766..60b071a2 100644
--- a/frontend/src/components/sidebar/SidebarActivityTicker.tsx
+++ b/frontend/src/components/sidebar/SidebarActivityTicker.tsx
@@ -12,16 +12,17 @@ interface SidebarActivityTickerProps {
 }
 
 export function SidebarActivityTicker({ notifications, connected, onNavigate }: SidebarActivityTickerProps) {
-  const [, forceUpdate] = useReducer((x: number) => x + 1, 0);
+  const [tick, forceUpdate] = useReducer((x: number) => x + 1, 0);
   useEffect(() => {
     const id = setInterval(forceUpdate, NOW_TICK_MS);
     return () => clearInterval(id);
   }, []);
   const latest = useMemo(() => {
+    const nowSecs = Math.floor(Date.now() / 1000);
     return notifications
-      .filter(n => n.stack_name)
+      .filter(n => n.stack_name && (nowSecs - n.timestamp) <= 3600)
       .sort((a, b) => b.timestamp - a.timestamp)[0] ?? null;
-  }, [notifications]);
+  }, [notifications, tick]);
 
   const idle = latest === null;
   const dotClass = connected
diff --git a/frontend/src/components/sidebar/SidebarFilterChips.tsx b/frontend/src/components/sidebar/SidebarFilterChips.tsx
index 09db8644..16f47e6b 100644
--- a/frontend/src/components/sidebar/SidebarFilterChips.tsx
+++ b/frontend/src/components/sidebar/SidebarFilterChips.tsx
@@ -1,3 +1,4 @@
+import { Minus, Plus } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import type { FilterChip } from './sidebar-types';
 
@@ -12,6 +13,8 @@ interface SidebarFilterChipsProps {
   active: FilterChip;
   counts: FilterCounts;
   onChange: (chip: FilterChip) => void;
+  visible: boolean;
+  onToggle: () => void;
 }
 
 const chips: { id: FilterChip; label: string }[] = [
@@ -21,42 +24,59 @@ const chips: { id: FilterChip; label: string }[] = [
   { id: 'updates', label: 'Updates' },
 ];
 
-export function SidebarFilterChips({ active, counts, onChange }: SidebarFilterChipsProps) {
+export function SidebarFilterChips({ active, counts, onChange, visible, onToggle }: SidebarFilterChipsProps) {
   return (
-    <div className="flex items-center gap-1 px-2 pb-1.5 pt-0.5 overflow-x-auto scrollbar-none">
-      {chips.map(({ id, label }) => {
-        const count = counts[id];
-        const isActive = active === id;
-        const isUpdates = id === 'updates';
-        const hasUpdates = isUpdates && count > 0;
+    <div className="flex items-center pb-1.5 pt-0.5 pl-2">
+      {visible ? (
+        <div className="flex items-center gap-0.5 flex-1 min-w-0 overflow-hidden">
+          {chips.map(({ id, label }) => {
+            const count = counts[id];
+            const displayCount = count > 99 ? '99+' : count;
+            const isActive = active === id;
+            const isUpdates = id === 'updates';
+            const hasUpdates = isUpdates && count > 0;
 
-        return (
-          <button
-            key={id}
-            type="button"
-            onClick={() => onChange(id)}
-            className={cn(
-              'flex items-center gap-1 shrink-0 rounded px-1.5 py-0.5',
-              'font-mono text-[10px] tracking-[0.08em] uppercase leading-none',
-              'border transition-colors duration-150',
-              isActive
-                ? 'bg-brand/10 border-brand/30 text-brand'
-                : hasUpdates
-                  ? 'bg-update/5 border-update/20 text-update hover:bg-update/10'
-                  : 'bg-transparent border-glass-border text-stat-subtitle hover:text-stat-title hover:border-glass-border',
-            )}
-            aria-pressed={isActive}
-          >
-            {label}
-            <span className={cn(
-              'tabular-nums',
-              isActive ? 'text-brand/70' : hasUpdates ? 'text-update/70' : 'text-stat-icon',
-            )}>
-              {count}
-            </span>
-          </button>
-        );
-      })}
+            return (
+              <button
+                key={id}
+                type="button"
+                onClick={() => onChange(id)}
+                className={cn(
+                  'flex items-center gap-1 min-w-0 overflow-hidden rounded px-1.5 py-0.5 whitespace-nowrap',
+                  'font-mono text-[10px] tracking-[0.08em] uppercase leading-none',
+                  'border transition-colors duration-150',
+                  isActive
+                    ? 'bg-brand/10 border-brand/30 text-brand'
+                    : hasUpdates
+                      ? 'bg-update/5 border-update/20 text-update hover:bg-update/10'
+                      : 'bg-transparent border-glass-border text-stat-subtitle hover:text-stat-title hover:border-glass-border',
+                )}
+                aria-pressed={isActive}
+              >
+                {label}
+                <span className={cn(
+                  'tabular-nums',
+                  isActive ? 'text-brand/70' : hasUpdates ? 'text-update/70' : 'text-stat-icon',
+                )}>
+                  {displayCount}
+                </span>
+              </button>
+            );
+          })}
+        </div>
+      ) : (
+        <div className="flex-1" />
+      )}
+      <button
+        type="button"
+        onClick={onToggle}
+        className="px-2 shrink-0 text-stat-icon hover:text-stat-title transition-colors duration-150"
+        aria-label={visible ? 'Hide filters' : 'Show filters'}
+      >
+        {visible
+          ? <Minus className="w-3 h-3" strokeWidth={1.5} />
+          : <Plus className="w-3 h-3" strokeWidth={1.5} />}
+      </button>
     </div>
   );
 }
diff --git a/frontend/src/components/sidebar/StackSidebar.tsx b/frontend/src/components/sidebar/StackSidebar.tsx
index c1a60f4a..46572846 100644
--- a/frontend/src/components/sidebar/StackSidebar.tsx
+++ b/frontend/src/components/sidebar/StackSidebar.tsx
@@ -1,4 +1,4 @@
-import type { ReactNode } from 'react';
+import { useState, useCallback, type ReactNode } from 'react';
 import { Command } from '@/components/ui/command';
 import { ScrollArea } from '@/components/ui/scroll-area';
 import type { NotificationItem } from '@/components/dashboard/types';
@@ -45,6 +45,21 @@ export function StackSidebar(props: StackSidebarProps) {
     bulkMode, selectedFiles, isPaid, onToggleBulkMode, onToggleSelect, onClearSelection, onBulkAction,
   } = props;
 
+  const [filtersVisible, setFiltersVisible] = useState(() => {
+    try {
+      const v = window.localStorage.getItem('sencho:sidebar:filters-visible');
+      return v === null ? true : v !== 'false';
+    } catch { return true; }
+  });
+
+  const handleToggleFilters = useCallback(() => {
+    setFiltersVisible(prev => {
+      const next = !prev;
+      try { window.localStorage.setItem('sencho:sidebar:filters-visible', String(next)); } catch { /* localStorage unavailable */ }
+      return next;
+    });
+  }, []);
+
   return (
     <div className="w-64 border-r border-glass-border bg-sidebar backdrop-blur-md flex flex-col">
       <SidebarBrand isDarkMode={isDarkMode} />
@@ -64,6 +79,8 @@ export function StackSidebar(props: StackSidebarProps) {
           active={filterChip}
           counts={filterCounts}
           onChange={onFilterChipChange}
+          visible={filtersVisible}
+          onToggle={handleToggleFilters}
         />
         {selectedFiles.size > 0 && (
           <SidebarBulkBar
diff --git a/frontend/src/components/sidebar/__tests__/StackGroup.test.tsx b/frontend/src/components/sidebar/__tests__/StackGroup.test.tsx
index f5fa7596..e60fa3a0 100644
--- a/frontend/src/components/sidebar/__tests__/StackGroup.test.tsx
+++ b/frontend/src/components/sidebar/__tests__/StackGroup.test.tsx
@@ -41,6 +41,6 @@ describe('StackGroup', () => {
         <div>child</div>
       </StackGroup>
     );
-    expect(screen.getByText('PINNED')).toHaveClass('text-brand/90');
+    expect(screen.getByText(/PINNED/)).toHaveClass('text-brand/90');
   });
 });