Fix H3/M33/L25/L32: fix probe dependency, correct ipc comment, throttle taskbar, memoize palette

H3: probe.ts now imports fmtBytes from lib/formatters instead of download.ts,
    breaking the circular probe->download dependency direction.
M33: ipc.ts comment corrected to reflect that no batch cap exists; notes the
     known M33 issue for future implementation.
L25: App.tsx taskbar subscriber skips IPC when fraction/mode/badge unchanged,
     eliminating redundant roundtrips on every progress tick.
L32: paletteActions wrapped in useMemo so CommandPalette sees a stable array
     reference; only rebuilds when isDark changes.

typecheck + 242 tests + eslint + prettier green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/renderer/src/App.tsx

@@ -1,4 +1,4 @@
-import { useState, useEffect } from 'react'
+import { useState, useEffect, useMemo } from 'react'
 import { FluentProvider, makeStyles, tokens } from '@fluentui/react-components'
 import { Sidebar, type TabValue } from './components/Sidebar'
 import { DownloadsView } from './components/DownloadsView'
@@ -56,44 +56,68 @@ function App(): React.JSX.Element {
 
   // Mirror overall queue progress onto the Windows taskbar. Subscribe to the store
   // directly (not via a selector) so taskbar updates don't re-render the app.
+  // Compare against the last IPC call and skip when nothing changed — the store
+  // fires on every progress tick and this avoids one IPC roundtrip per tick (L25).
   useEffect(() => {
+    let lastFraction = -1
+    let lastMode = ''
+    let lastBadge = -1
     function push(items: ReturnType<typeof useDownloads.getState>['items']): void {
       const s = summarizeQueue(items)
       const mode = s.active ? (s.failed > 0 ? 'error' : 'normal') : 'none'
+      if (s.progress === lastFraction && mode === lastMode && s.downloading === lastBadge) return
+      lastFraction = s.progress
+      lastMode = mode
+      lastBadge = s.downloading
       window.api?.setTaskbarProgress?.({ fraction: s.progress, mode, badgeCount: s.downloading })
     }
     push(useDownloads.getState().items)
     return useDownloads.subscribe((st) => push(st.items))
   }, [])
 
-  const paletteActions: PaletteAction[] = [
-    {
-      id: 'go-downloads',
-      label: 'Go to Downloads',
-      hint: 'Navigate',
-      run: () => setTab('downloads')
-    },
-    { id: 'go-library', label: 'Go to Library', hint: 'Navigate', run: () => setTab('library') },
-    { id: 'go-history', label: 'Go to History', hint: 'Navigate', run: () => setTab('history') },
-    { id: 'go-terminal', label: 'Go to Terminal', hint: 'Navigate', run: () => setTab('terminal') },
-    { id: 'go-settings', label: 'Go to Settings', hint: 'Navigate', run: () => setTab('settings') },
-    {
-      id: 'new-download',
-      label: 'New download',
-      hint: 'Focus URL',
-      run: () => {
-        setTab('downloads')
-        // Wait for the download bar to mount after the tab switch, then focus.
-        setTimeout(() => document.getElementById('aerofetch-url')?.focus(), 60)
+  // Memoized so CommandPalette sees a stable array reference between renders —
+  // only rebuilds when the theme label needs to change (L32).
+  const paletteActions = useMemo<PaletteAction[]>(
+    () => [
+      {
+        id: 'go-downloads',
+        label: 'Go to Downloads',
+        hint: 'Navigate',
+        run: () => setTab('downloads')
+      },
+      { id: 'go-library', label: 'Go to Library', hint: 'Navigate', run: () => setTab('library') },
+      { id: 'go-history', label: 'Go to History', hint: 'Navigate', run: () => setTab('history') },
+      {
+        id: 'go-terminal',
+        label: 'Go to Terminal',
+        hint: 'Navigate',
+        run: () => setTab('terminal')
+      },
+      {
+        id: 'go-settings',
+        label: 'Go to Settings',
+        hint: 'Navigate',
+        run: () => setTab('settings')
+      },
+      {
+        id: 'new-download',
+        label: 'New download',
+        hint: 'Focus URL',
+        run: () => {
+          setTab('downloads')
+          // Wait for the download bar to mount after the tab switch, then focus.
+          setTimeout(() => document.getElementById('aerofetch-url')?.focus(), 60)
+        }
+      },
+      {
+        id: 'toggle-theme',
+        label: isDark ? 'Switch to light theme' : 'Switch to dark theme',
+        hint: 'Appearance',
+        run: () => updateSettings({ theme: isDark ? 'light' : 'dark' })
       }
-    },
-    {
-      id: 'toggle-theme',
-      label: isDark ? 'Switch to light theme' : 'Switch to dark theme',
-      hint: 'Appearance',
-      run: () => updateSettings({ theme: isDark ? 'light' : 'dark' })
-    }
-  ]
+    ],
+    [isDark, setTab, updateSettings]
+  )
 
   // AeroFetch's own version, shown in the sidebar. Loaded once over IPC.
   const [version, setVersion] = useState('')