diff --git a/src/shared/components/ui/sidebar.test.tsx b/src/shared/components/ui/sidebar.test.tsx
new file mode 100644
index 00000000..c9658f8b
--- /dev/null
+++ b/src/shared/components/ui/sidebar.test.tsx
@@ -0,0 +1,192 @@
+// @vitest-environment jsdom
+import { describe, it, expect, vi } from 'vitest'
+import { render } from '@testing-library/react'
+import { act } from 'react'
+import {
+  SidebarProvider,
+  Sidebar,
+  SidebarContent,
+  SidebarGroup,
+  SidebarGroupContent,
+  SidebarMenu,
+  SidebarMenuItem,
+  SidebarMenuButton,
+} from './sidebar'
+
+type Listener = (event: Event) => void
+
+function SidebarHarness() {
+  return (
+    <SidebarProvider>
+      <Sidebar>
+        <SidebarContent>
+          <SidebarGroup>
+            <SidebarGroupContent>
+              <SidebarMenu>
+                <SidebarMenuItem>
+                  <SidebarMenuButton>Item</SidebarMenuButton>
+                </SidebarMenuItem>
+              </SidebarMenu>
+            </SidebarGroupContent>
+          </SidebarGroup>
+        </SidebarContent>
+      </Sidebar>
+    </SidebarProvider>
+  )
+}
+
+describe('Sidebar event listener lifecycle', () => {
+  const origAdd = window.addEventListener.bind(window)
+  const origRemove = window.removeEventListener.bind(window)
+
+  it('registers and removes the same number of listeners across repeated mount/unmount cycles', () => {
+    let addCount = 0
+    let removeCount = 0
+
+    window.addEventListener = vi.fn((type: string, listener: Listener) => {
+      addCount++
+      origAdd(type, listener)
+    }) as typeof window.addEventListener
+    window.removeEventListener = vi.fn((type: string, listener: Listener) => {
+      removeCount++
+      origRemove(type, listener)
+    }) as typeof window.removeEventListener
+
+    try {
+      for (let i = 0; i < 5; i++) {
+        const result = render(<SidebarHarness />)
+        act(() => result.unmount())
+      }
+      expect(addCount).toBe(removeCount)
+      expect(addCount).toBeGreaterThan(0)
+    } finally {
+      window.addEventListener = origAdd
+      window.removeEventListener = origRemove
+    }
+  })
+
+  it('adds and removes the exact same callback reference for window keydown', () => {
+    const addedCallbacks: Listener[] = []
+    const removedCallbacks: Listener[] = []
+
+    window.addEventListener = vi.fn((type: string, listener: Listener) => {
+      if (type === 'keydown') addedCallbacks.push(listener)
+      origAdd(type, listener)
+    }) as typeof window.addEventListener
+    window.removeEventListener = vi.fn((type: string, listener: Listener) => {
+      if (type === 'keydown') removedCallbacks.push(listener)
+      origRemove(type, listener)
+    }) as typeof window.removeEventListener
+
+    try {
+      const result = render(<SidebarHarness />)
+      act(() => result.unmount())
+
+      expect(addedCallbacks.length).toBeGreaterThanOrEqual(1)
+      expect(removedCallbacks.length).toBeGreaterThanOrEqual(1)
+
+      for (const fn of addedCallbacks) {
+        expect(removedCallbacks).toContain(fn)
+      }
+    } finally {
+      window.addEventListener = origAdd
+      window.removeEventListener = origRemove
+    }
+  })
+
+  it('does not fire stale keyboard handler after unmount', () => {
+    const registered = new Set<Listener>()
+
+    window.addEventListener = vi.fn((type: string, listener: Listener) => {
+      if (type === 'keydown') registered.add(listener)
+      origAdd(type, listener)
+    }) as typeof window.addEventListener
+    window.removeEventListener = vi.fn((type: string, listener: Listener) => {
+      if (type === 'keydown') registered.delete(listener)
+      origRemove(type, listener)
+    }) as typeof window.removeEventListener
+
+    try {
+      const result = render(<SidebarHarness />)
+      const handlersBeforeUnmount = new Set(registered)
+
+      act(() => result.unmount())
+
+      for (const handler of handlersBeforeUnmount) {
+        expect(registered.has(handler)).toBe(false)
+      }
+    } finally {
+      window.addEventListener = origAdd
+      window.removeEventListener = origRemove
+    }
+  })
+
+  it('uses the same function identity for add and remove on window', () => {
+    const pairs = new Map<string, { added: Listener[]; removed: Listener[] }>()
+
+    window.addEventListener = vi.fn((type: string, listener: Listener) => {
+      if (!pairs.has(type)) pairs.set(type, { added: [], removed: [] })
+      pairs.get(type)!.added.push(listener)
+      origAdd(type, listener)
+    }) as typeof window.addEventListener
+    window.removeEventListener = vi.fn((type: string, listener: Listener) => {
+      if (!pairs.has(type)) pairs.set(type, { added: [], removed: [] })
+      pairs.get(type)!.removed.push(listener)
+      origRemove(type, listener)
+    }) as typeof window.removeEventListener
+
+    try {
+      const result = render(<SidebarHarness />)
+      act(() => result.unmount())
+
+      for (const [, { added, removed }] of pairs) {
+        for (const fn of added) {
+          expect(removed).toContain(fn)
+        }
+      }
+    } finally {
+      window.addEventListener = origAdd
+      window.removeEventListener = origRemove
+    }
+  })
+})
+
+describe('useIsMobile matchMedia listener lifecycle', () => {
+  it('cleans up matchMedia change listener on unmount', () => {
+    const added: Listener[] = []
+    const removed: Listener[] = []
+
+    const mockMql = {
+      matches: false,
+      media: '(max-width: 767px)',
+      onchange: null,
+      addListener: vi.fn(),
+      removeListener: vi.fn(),
+      addEventListener: vi.fn((_type: string, handler: Listener) => {
+        added.push(handler)
+      }),
+      removeEventListener: vi.fn((_type: string, handler: Listener) => {
+        const idx = added.indexOf(handler)
+        if (idx >= 0) removed.push(handler)
+      }),
+      dispatchEvent: vi.fn(),
+    }
+
+    const originalMatchMedia = window.matchMedia
+    window.matchMedia = vi.fn().mockReturnValue(mockMql)
+
+    try {
+      const result = render(<SidebarHarness />)
+
+      expect(mockMql.addEventListener).toHaveBeenCalledWith('change', expect.any(Function))
+      const addedCount = added.length
+
+      act(() => result.unmount())
+
+      expect(mockMql.removeEventListener).toHaveBeenCalledWith('change', expect.any(Function))
+      expect(removed.length).toBe(addedCount)
+    } finally {
+      window.matchMedia = originalMatchMedia
+    }
+  })
+})
diff --git a/src/shared/hooks/useOptimisticData.ts b/src/shared/hooks/useOptimisticData.ts
index 03aec6be..66354233 100644
--- a/src/shared/hooks/useOptimisticData.ts
+++ b/src/shared/hooks/useOptimisticData.ts
@@ -256,13 +256,6 @@ export function useOptimisticData<T>(
     }, delay)
   }, [fetchData, maxRetries, baseDelay, clearBackoffTimer])
 
-  const retry = useCallback(() => {
-    if (retryCount < MAX_RETRIES && lastFetchFnRef.current) {
-      setRetryCount((c) => c + 1);
-      fetchData(lastFetchFnRef.current, true);
-    }
-  }, [retryCount, fetchData]);
-
   const clearCache = useCallback(() => {
     cacheRef.current.clear()
   }, [])