diff --git a/CODE-AUDIT.md b/CODE-AUDIT.md
index e737ce0..4ad973f 100644
--- a/CODE-AUDIT.md
+++ b/CODE-AUDIT.md
@@ -248,7 +248,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
   [`datetime.ts`](src/renderer/src/datetime.ts) and imported by their views; unit-tested in `test/datetime.test.ts`.*
 - [ ] **M10 — `.url` shortcut parsing duplicated** — `parseUrlFile` (DownloadBar) vs
   `readUrlShortcut` (main/deeplink). Different `URL=` extractors for the same file format.
-- [ ] **M11 — Inconsistent clipboard access.** Reads use `navigator.clipboard.readText` (paste
+- [x] **M11 — Inconsistent clipboard access.** Reads use `navigator.clipboard.readText` (paste
   button) *and* `window.api.readClipboard` (suggestion watcher); writes use
   `navigator.clipboard.writeText` (copy report). Pick one strategy.
 - [x] **M12 — Shared `errorText` style.** `tokens.colorPaletteRedForeground1` is applied inline
@@ -392,7 +392,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
   ambiguous.
 - [x] **L8 — Index/compound list keys.** TerminalView keys log lines by array index; Settings
   Diagnostics keys by `id + occurredAt` while every other list keys by `id` alone.
-- [ ] **L9 — Thumbnail box sizes not shared.** Four hand-tuned 16:9 boxes (120×68, 108×64, 72×44,
+- [x] **L9 — Thumbnail box sizes not shared.** Four hand-tuned 16:9 boxes (120×68, 108×64, 72×44,
   60×34) with no shared aspect/size constant.
 - [ ] **L10 — Scattered magic numbers.** Timeouts/caps spread across modules (probe 60s, indexer
   180s, probeMeta 30s, update-idle 60s; MAX_ENTRIES 500/200, MAX_TEMPLATES 100, MAX_ITEMS 20000).
@@ -434,7 +434,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
 - [x] **L27 — DownloadBar Enter probes, not downloads.** Enter in the URL field triggers
   `fetchFormats`; there's no keyboard path to actually start the download (LibraryView's Enter
   runs its primary action). Inconsistent.
-- [ ] **L28 — Default kind/quality applied once.** DownloadBar seeds from settings via a one-shot
+- [x] **L28 — Default kind/quality applied once.** DownloadBar seeds from settings via a one-shot
   ref; changing the default in Settings while on the Downloads tab isn't reflected until reload.
 - [ ] **L29 — UI constant in the store.** `QUALITY_OPTIONS` lives in `store/downloads.ts` yet is a
   presentational constant imported by views — couples UI to the store module.
diff --git a/src/renderer/src/components/DownloadBar.tsx b/src/renderer/src/components/DownloadBar.tsx
index a5a2b47..ec1f09e 100644
--- a/src/renderer/src/components/DownloadBar.tsx
+++ b/src/renderer/src/components/DownloadBar.tsx
@@ -37,6 +37,7 @@ import { SegmentedControl } from './ui/SegmentedControl'
 import { IconButton } from './ui/IconButton'
 import { useClipboardLink, looksLikeUrl } from '../useClipboardLink'
 import { logError } from '../reportError'
+import { THUMB_LG } from '../thumbSizes'
 
 /** First http(s) URL in a blob of dropped text (one per line; '#' comments skipped). */
 function firstUrl(text: string): string | null {
@@ -104,8 +105,8 @@ const useStyles = makeStyles({
   },
   previewThumb: {
     flexShrink: 0,
-    width: '120px',
-    height: '68px',
+    width: `${THUMB_LG.w}px`,
+    height: `${THUMB_LG.h}px`,
     objectFit: 'cover',
     display: 'flex',
     alignItems: 'center',
@@ -315,15 +316,13 @@ export function DownloadBar(): React.JSX.Element {
     }
   }
 
-  // Apply the saved default format once, when persisted settings first arrive.
-  const appliedDefaults = useRef(false)
+  // When settings load or change, update kind/quality -- but only while the bar
+  // is idle (URL empty) so an in-progress setup isn't unexpectedly reset.
   useEffect(() => {
-    if (settingsLoaded && !appliedDefaults.current) {
-      appliedDefaults.current = true
-      setKind(defaultKind)
-      setQuality(defaultKind === 'audio' ? defaultAudioQuality : defaultVideoQuality)
-    }
-  }, [settingsLoaded, defaultKind, defaultVideoQuality, defaultAudioQuality])
+    if (!settingsLoaded || url.trim()) return
+    setKind(defaultKind)
+    setQuality(defaultKind === 'audio' ? defaultAudioQuality : defaultVideoQuality)
+  }, [settingsLoaded, defaultKind, defaultVideoQuality, defaultAudioQuality, url])
 
   // Probe state for the single-video format picker.
   const [info, setInfo] = useState<MediaInfo | null>(null)
@@ -415,10 +414,10 @@ export function DownloadBar(): React.JSX.Element {
 
   async function paste(): Promise<void> {
     try {
-      const text = await navigator.clipboard.readText()
+      const text = (await window.api?.readClipboard?.()) ?? ''
       if (text) onUrlChange(text.trim())
     } catch {
-      /* clipboard blocked -- ignore in preview */
+      /* ignore in preview */
     }
   }
 
diff --git a/src/renderer/src/components/HistoryView.tsx b/src/renderer/src/components/HistoryView.tsx
index a466db9..7fc627f 100644
--- a/src/renderer/src/components/HistoryView.tsx
+++ b/src/renderer/src/components/HistoryView.tsx
@@ -1,4 +1,4 @@
-import { useMemo, useState } from 'react'
+import { useMemo, useState } from 'react'
 import {
   Text,
   Caption1,
@@ -33,6 +33,7 @@ import { Hint } from './Hint'
 import { Select } from './Select'
 import { ScreenHeader, useScreenStyles } from './ui/Screen'
 import { useFocusStyles } from './ui/focusRing'
+import { THUMB_SM } from '../thumbSizes'
 
 const useStyles = makeStyles({
   root: {
@@ -78,8 +79,8 @@ const useStyles = makeStyles({
   },
   thumb: {
     flexShrink: 0,
-    width: '72px',
-    height: '44px',
+    width: `${THUMB_SM.w}px`,
+    height: `${THUMB_SM.h}px`,
     display: 'flex',
     alignItems: 'center',
     justifyContent: 'center',
diff --git a/src/renderer/src/components/LibraryView.tsx b/src/renderer/src/components/LibraryView.tsx
index d8374d6..ea2ae5d 100644
--- a/src/renderer/src/components/LibraryView.tsx
+++ b/src/renderer/src/components/LibraryView.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useState } from 'react'
+import { useEffect, useMemo, useState } from 'react'
 import {
   Body1,
   Caption1,
@@ -41,6 +41,7 @@ import { VirtualList } from './VirtualList'
 import { ScreenHeader, useScreenStyles } from './ui/Screen'
 import { StatusChip } from './ui/StatusChip'
 import { useFocusStyles } from './ui/focusRing'
+import { THUMB_XS } from '../thumbSizes'
 
 // True in the standalone browser preview (no Electron preload).
 const PREVIEW = typeof window === 'undefined' || !window.electron
@@ -178,8 +179,8 @@ const useStyles = makeStyles({
   },
   plainList: { display: 'flex', flexDirection: 'column' },
   rowThumb: {
-    width: '60px',
-    height: '34px',
+    width: `${THUMB_XS.w}px`,
+    height: `${THUMB_XS.h}px`,
     ...shorthands.borderRadius(tokens.borderRadiusSmall)
   },
   rowMain: { display: 'flex', flexDirection: 'column', minWidth: 0, flexGrow: 1 },
@@ -242,7 +243,7 @@ export function LibraryView(): React.JSX.Element {
     setConfirmRemoveId(null)
   }, [selectedSourceId])
   // Offer a freshly-copied link the way the Downloads tab does, but skip single
-  // videos — a library source is a channel/playlist to sync, not a one-off.
+  // videos -- a library source is a channel/playlist to sync, not a one-off.
   const clip = useClipboardLink(url, (u) => !looksLikeSingleVideo(u))
   const [selected, setSelected] = useState<Set<string>>(new Set())
   const [batchNote, setBatchNote] = useState<string | null>(null)
@@ -372,7 +373,7 @@ export function LibraryView(): React.JSX.Element {
     setSelected(on ? new Set(actionableItems.map((it) => it.id)) : new Set())
   }
 
-  // One click queues every chosen item — maxConcurrent gates how many actually
+  // One click queues every chosen item -- maxConcurrent gates how many actually
   // run, the rest wait in the queue. Selection clears since nothing is held back.
   function downloadSelected(): void {
     if (!selectedSourceId || selectedActionable.length === 0) return
@@ -397,7 +398,7 @@ export function LibraryView(): React.JSX.Element {
     setBatchNote(`Queued ${n} download${n === 1 ? '' : 's'}.`)
   }
 
-  // One row of the item list — a playlist header or a video — shared by the
+  // One row of the item list -- a playlist header or a video -- shared by the
   // inline (small source) and virtualized (large source) render paths.
   function rowKey(row: LibRow): string {
     return row.kind === 'header' ? `h:${row.title}` : row.item.id
@@ -406,7 +407,7 @@ export function LibraryView(): React.JSX.Element {
   function renderRow(row: LibRow): React.JSX.Element {
     if (row.kind === 'header') {
       const open = isGroupOpen(row.title)
-      // "All on" is judged over the ACTIONABLE rows only — downloaded rows aren't
+      // "All on" is judged over the ACTIONABLE rows only -- downloaded rows aren't
       // selectable, so they must not keep the group from reading as fully selected (M36).
       const groupActionableItems = row.items.filter(actionable)
       const groupActionable = groupActionableItems.length
diff --git a/src/renderer/src/components/QueueItem.tsx b/src/renderer/src/components/QueueItem.tsx
index 07b3137..803b14c 100644
--- a/src/renderer/src/components/QueueItem.tsx
+++ b/src/renderer/src/components/QueueItem.tsx
@@ -32,6 +32,7 @@ import { MediaThumb } from './MediaThumb'
 import { Hint } from './Hint'
 import { StatusChip } from './ui/StatusChip'
 import { useFocusStyles } from './ui/focusRing'
+import { THUMB_MD } from '../thumbSizes'
 
 const useStyles = makeStyles({
   root: {
@@ -44,8 +45,8 @@ const useStyles = makeStyles({
   },
   thumb: {
     flexShrink: 0,
-    width: '108px',
-    height: '64px',
+    width: `${THUMB_MD.w}px`,
+    height: `${THUMB_MD.h}px`,
     display: 'flex',
     alignItems: 'center',
     justifyContent: 'center',
diff --git a/src/renderer/src/thumbSizes.ts b/src/renderer/src/thumbSizes.ts
new file mode 100644
index 0000000..4911e53
--- /dev/null
+++ b/src/renderer/src/thumbSizes.ts
@@ -0,0 +1,5 @@
+/** Shared 16:9 thumbnail box dimensions used across queue, history, and library views. */
+export const THUMB_LG = { w: 120, h: 68 } as const
+export const THUMB_MD = { w: 108, h: 64 } as const
+export const THUMB_SM = { w: 72, h: 44 } as const
+export const THUMB_XS = { w: 60, h: 34 } as const