feat(audit): Batch 11 — UX behavior gaps (toast surface, sidebar badge)

A new in-app toast surface is the batch's spine, making the silent-failure and
global-status gaps fixable:

- Toast infra: store/toasts.ts (useToasts + toast(); auto-dismiss) + ui/Toaster.tsx
  (non-portal bottom-center stack, avoids the Fluent-portal GPU flicker). Unit-
  tested (test/toasts.test.ts). Mounted at the app root beside LiveRegion.
- UX6: shared renderer reveal.ts revealFile('open'|'folder') awaits the IPC result
  and toasts the main-process reason instead of silently no-oping on a moved/typed-
  out file. safeShowInFolder upgraded to return an error string like safeOpenPath
  (preload/mock/Api types updated).
- UX9 / UI25: a Fluent CounterBadge on the sidebar Downloads nav item shows the
  active (downloading + queued) count from any tab, via a count-only App selector
  that doesn't re-render on progress ticks.
- UX15: cancelAll store action + a "Cancel all (N)" header button.
- UX24: the disabled "Check watched" button uses disabledFocusable + a Hint that
  explains it needs a watched source.
- UX12: the Terminal gate gains an inline "Enable custom commands" button, so it's
  no longer a dead-end pointing at another screen.
- L144: the DownloadBar duplicate guard now also checks history — a URL downloaded
  earlier warns "Already downloaded: …" (dupInHistory) vs "Already in your queue: …".

Deferred with rationale (CODE-AUDIT.md): UX7/UX8 (Settings IA redesign — visual),
UX18/UX26 (subjective/visual polish), L131 (arguably by-design, needs live taskbar),
L142 (history/templates/sources IPC-return reconciliation — a focused own PR).

Verified: typecheck (node+web) + 279 tests + eslint + production build green;
touched files prettier-clean.

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

CODE-AUDIT.md

@@ -169,6 +169,20 @@ electron-store split is deliberate for DPAPI), **CC11** (constants centralized;
 carry a documented standard + deferral rationale. All green: typecheck (node+web) + 275 tests + eslint +
 production build; touched files prettier-clean.
 
+**Session 2026-07-01 pass 8 (Batch 11 — UX behavior gaps):** a new in-app **toast** surface
+([store/toasts.ts](src/renderer/src/store/toasts.ts) + [ui/Toaster.tsx](src/renderer/src/components/ui/Toaster.tsx),
+non-portal bottom-center, +unit-tested) is the batch's spine — it makes **UX6** real: a shared
+[reveal.ts](src/renderer/src/reveal.ts) `revealFile` now surfaces open/reveal failures ("File not found — it
+may have been moved…") instead of the old silent no-op, and `safeShowInFolder` was upgraded to return an error
+string like `safeOpenPath`. Also landed **UX9/UI25** (a `CounterBadge` on the sidebar Downloads nav item shows
+the active count from any tab, via a count-only selector that doesn't re-render on ticks), **UX15** (`cancelAll`
++ a "Cancel all (N)" header button), **UX24** (`disabledFocusable` + `Hint` explains the disabled "Check
+watched"), **UX12** (an inline "Enable custom commands" button on the Terminal gate), and **L144** (the dup
+guard now checks history → "Already downloaded: …"). **Deferred with rationale:** UX7/UX8 (Settings IA
+redesign — visual), UX18/UX26 (subjective/visual polish), L131 (arguably by-design, needs the live taskbar),
+and **L142** (the history/templates/sources IPC-return reconciliation — a focused own-PR, CC14's tail). All
+green: typecheck (node+web) + 279 tests + eslint + production build; touched files prettier-clean.
+
 **Deliberately deferred** (need live-app/visual verification or are larger refactors the
 audit itself defers to 1.x): the wire-or-cut features (M5/M6/UX1), the god-file/store
 refactors (C1, C2, H1), the SIMP* helpers + shared-UI-token work, the CC* consolidations,
@@ -950,6 +964,10 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
   "interrupted"); user-facing ones are capitalized with periods. Fine when interpolated, jarring if shown raw.
 - [ ] **L131 — Taskbar `error` state is ephemeral** — it's driven by live `error` items, so "Clear
   finished" flips the red taskbar bar back to normal even though failures occurred (out of sync with the persisted error log).
+  *Deferred (arguably by-design, needs the live taskbar): the taskbar reflects the *live queue*, so clearing
+  finished items legitimately returns it to idle — the persisted record lives in Diagnostics. Whether the red
+  bar should linger after a clear is a debatable UX call best judged against the real Windows taskbar; left
+  for the watched Windows pass (with Batch 14/15).*
 - [x] **L132 — `clearProbe` + form-reset logic is duplicated** in DownloadBar (`onUrlChange`, `download`, `addPlaylist`).
   *Fixed: a shared `resetForm()` in [useDownloadBar.ts](src/renderer/src/components/downloadBar/useDownloadBar.ts)
   now owns the post-enqueue reset (URL + probe + the one-shot trim/schedule/advanced/incognito/options),
@@ -1017,11 +1035,20 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
 - [ ] **L142 — IPC mutation return values are discarded everywhere.** history/templates/sources/settings
   IPC calls return the authoritative (validated/capped/sanitized) state, but every renderer caller does
   optimistic-only updates and ignores it — client and persisted state can silently diverge until reload (generalizes M34).
+  *Deferred (targeted, own PR): settings already reconcile (M34). Extending "apply the returned authoritative
+  state" to history/templates/sources touches each store's mutation path and each corresponding IPC return
+  shape, and the divergence it guards against is rare (only when main caps/sanitizes differently than the
+  optimistic update) and self-heals on reload. Best done as one focused reconciliation PR with each store
+  verified, not folded into this UX batch. Standard already recorded under CC14.*
 - [ ] **L143 — No in-window "quit anyway."** With a download active (or tray mode), closing only hides;
   quitting requires the tray menu. If the tray ever fails to create, the only exit is Task Manager
   (mitigated today by the embedded fallback tray icon).
-- [ ] **L144 — Duplicate guard checks the queue only, not history.** Re-adding a URL downloaded earlier
+- [x] **L144 — Duplicate guard checks the queue only, not history.** Re-adding a URL downloaded earlier
   (already cleared from the queue) gives no "already downloaded" hint (roadmap notes this as a possible extension).
+  *Fixed: the DownloadBar dup guard ([useDownloadBar.ts](src/renderer/src/components/downloadBar/useDownloadBar.ts))
+  now checks history when a URL isn't in the live queue — if it was downloaded before, the warning banner reads
+  "Already downloaded: …" (vs "Already in your queue: …"), with the same "Download anyway" confirm. A new
+  `dupInHistory` flag drives the wording.*
 - [x] **L145 — `useClipboardLink` re-offers a dismissed link after a tab switch.** `lastSeen` is
   per-hook-instance; switching Downloads↔Library remounts it, so a previously-dismissed clipboard link is offered again.
   *Fixed: `lastSeen` is now a module-level variable (not a per-instance `useRef`), so a dismissed/accepted
@@ -1253,9 +1280,12 @@ are an undefined spacing/radius/type scale and a drift between Fluent components
 - [ ] **UI24 — No context menus anywhere.** Every row exposes actions only as inline buttons;
   right-click does nothing on any screen, despite many per-row actions that conventionally also live on
   right-click. **Standard:** add consistent right-click menus mirroring row actions, or note "none by design."
-- [ ] **UI25 — No in-app global status surface.** Queue progress shows only on the Downloads tab's
+- [x] **UI25 — No in-app global status surface.** Queue progress shows only on the Downloads tab's
   summary strip; on any other tab there's no in-app sign downloads are running (only the OS taskbar).
   **Standard:** a persistent affordance (e.g. a sidebar "Downloads" badge with the active count).
+  *Fixed (with UX9): a `CounterBadge` on the sidebar Downloads nav item shows the active (downloading +
+  queued) count from every tab, and a new in-app toast surface covers transient status. The exact
+  suggested affordance.*
 
 ### Animations & transitions
 
@@ -1388,35 +1418,60 @@ root cause is already filed.
 
 ### Medium — confusion, feedback & organization
 
-- [ ] **UX6 — Silent failures on file actions.** `openFile`/`showInFolder` in the stores call
+- [x] **UX6 — Silent failures on file actions.** `openFile`/`showInFolder` in the stores call
   `window.api.openPath(...)` and ignore the returned error string; [reveal.ts](src/main/reveal.ts)
   refuses missing/moved files or disallowed types and returns an error nobody surfaces. Clicking
   "Open file" on a moved download does nothing, with no message. **Fix:** surface open/reveal errors.
+  *Fixed: a shared renderer helper [reveal.ts](src/renderer/src/reveal.ts) `revealFile('open'|'folder', path)`
+  awaits the IPC result and raises the main-process reason ("File not found — it may have been moved…",
+  "Refusing to open this file type.") as an error **toast** — the new transient-notification surface (see
+  UX9). Both the downloads and history stores route through it. `safeShowInFolder` was upgraded to return an
+  error string like `safeOpenPath` (it previously no-op'd silently), so reveal failures surface too.*
 - [ ] **UX7 — Settings is one long unsegmented scroll** of ~11 cards with no section nav/anchors; the
   only finder is the hide-cards search (M14). Order is arbitrary and related items are split.
   **Fix:** group into sub-sections (or a left rail) with a stable, logical order.
+  *Deferred (visual, own pass): a Settings section-nav / left-rail is a layout redesign whose value is
+  entirely in how it looks and scrolls — it wants the app running and eyeballed, not an unattended edit.
+  Grouped with the visual/UX polish pass.*
 - [ ] **UX8 — "Default format" vs "Format & post-processing" are two places for one concept.** Kind +
   quality live under Downloads; container/codec/subs/SponsorBlock live in a separate card. **Fix:**
   co-locate, or clearly label one "defaults" and the other "advanced post-processing."
-- [ ] **UX9 — No global completion feedback off the Downloads tab** (UI25). If OS notifications are
+  *Deferred (ties to UX7): co-locating or re-labelling these cards is part of the same Settings
+  information-architecture pass; done together there with the app running.*
+- [x] **UX9 — No global completion feedback off the Downloads tab** (UI25). If OS notifications are
   off/suppressed (focus assist) and you're on another tab, a finished download gives no in-app sign.
   **Fix:** a sidebar Downloads badge / lightweight in-app toast.
+  *Fixed (both halves of the suggested fix): a **sidebar Downloads badge** — a Fluent `CounterBadge` on the
+  Downloads nav item shows the active (downloading + queued) count from any tab
+  ([Sidebar.tsx](src/renderer/src/components/Sidebar.tsx)), driven by a count-only selector in App so it
+  updates without re-rendering on every progress tick; and a **lightweight in-app toast** surface
+  ([Toaster.tsx](src/renderer/src/components/ui/Toaster.tsx) + [store/toasts.ts](src/renderer/src/store/toasts.ts)),
+  a non-portal bottom-center stack that any store/component can raise (now used for UX6's file-action errors).
+  Together this closes **UI25**.*
 - [x] **UX10 — Re-download silently changes quality** (H5) — a confusing "I asked for 720p, got Best." *Resolved by H5 (re-download stores `formatId`/`formatHasAudio` and strips compound quality labels).*
 - [ ] **UX11 — Scheduled downloads silently never fire if the app is quit** (M4). The hint is easy to
   miss; the user returns to find nothing happened. **Fix:** warn at schedule time that it requires the
   app running (or persist + relaunch).
-- [ ] **UX12 — Terminal is a dead-end when custom commands are off** (L18). The nav item is always
+- [x] **UX12 — Terminal is a dead-end when custom commands are off** (L18). The nav item is always
   visible; clicking it shows a gate pointing to a setting on another screen. **Fix:** hide/disable the
-  nav item, or let the gate enable the setting inline.
+  nav item, or let the gate enable the setting inline. *Fixed (both fixes): the nav item is already hidden
+  when custom commands are off (Sidebar's `showTerminal` filter, L18), and the gate — still reachable via the
+  command palette — now carries an inline **"Enable custom commands"** button that flips the setting on the
+  spot ([TerminalView.tsx](src/renderer/src/components/TerminalView.tsx)), so it's no longer a dead-end that
+  sends you to another screen.*
 - [x] **UX13 — Backup export warns of nothing; it contains secrets** (M22). A user "backs up settings"
   and ships proxy creds / tokens in cleartext. **Fix:** warn, or mask/omit secrets. *Resolved by M22
   (backup strips proxy / PO-token / update-token; the caption states credentials aren't included).*
 - [x] **UX14 — Duplicate warning can show a placeholder title** (L76): 'Already in your queue:
   "YouTube video (abc123)"' before metadata resolves looks broken. **Fix:** fall back to the URL.
   *Resolved by L76 (the dup warning falls back to the URL when the title is still the placeholder).*
-- [ ] **UX15 — No bulk actions in the Downloads queue.** History has a select-mode + bulk delete;
+- [x] **UX15 — No bulk actions in the Downloads queue.** History has a select-mode + bulk delete;
   Downloads has only per-row remove + "Clear finished." Inconsistent. **Fix:** mirror select/bulk, or
-  add "Cancel all."
+  add "Cancel all." *Fixed (the "Cancel all" option): a `cancelAll` store action + a "Cancel all (N)"
+  header button ([DownloadsView.tsx](src/renderer/src/components/DownloadsView.tsx)) that cancels every
+  active (downloading + queued) item at once — killing the live processes and freeing the queue — shown only
+  when there's something cancelable. (A full History-style select-mode is the heavier alternative; "Cancel
+  all" covers the common bulk need.)*
 
 ### Low — polish & smaller friction
 
@@ -1427,6 +1482,8 @@ root cause is already filed.
 - [ ] **UX17 — Icon-only Fetch/Paste buttons** rely on hover tooltips for meaning (UI a11y; new users on touch/keyboard miss them). **Fix:** labels or `aria`-described affordances.
 - [ ] **UX18 — The quality control morphs after Fetch** (preset list → real formats; label "Quality" →
   "Quality / format") in place — a surprising transform. **Fix:** keep a stable control with a clear "formats loaded" state.
+  *Deferred (subjective visual): the morph is arguably informative (the label change signals real formats
+  loaded); whether it "surprises" is a judgment best made watching it, so it joins the watched visual pass.*
 - [x] **UX19 — Window size/position isn't remembered.** [index.ts](src/main/index.ts) opens a fixed
   920×700 every launch (no bounds persistence). **Fix:** persist + restore window bounds. *Fixed with W2 —
   [windowState.ts](src/main/windowState.ts) persists + restores bounds/maximized with an off-screen guard.*
@@ -1438,13 +1495,18 @@ root cause is already filed.
 - [ ] **UX22 — Onboarding is shallow and one-shot** (L67): three tips, no folder choice, not
   revisitable; the clipboard tip requires a focus event a first-timer won't trigger.
 - [ ] **UX23 — Settings folder paths are read-only** (L71) — no paste; Browse-dialog only.
-- [ ] **UX24 — "Check N watched for new" is disabled with no explanation** when no source is watched —
+- [x] **UX24 — "Check N watched for new" is disabled with no explanation** when no source is watched —
   a user with indexed (but unwatched) sources sees a dead button. **Fix:** tooltip / enable with a hint to watch a source.
+  *Fixed: the button uses `disabledFocusable` (not `disabled`) when nothing is watched, so it stays
+  hover/focus-reachable, and a `Hint` explains why — "Turn on 'Watch' for a channel or playlist below first,
+  then this checks them for new uploads." ([LibraryView.tsx](src/renderer/src/components/LibraryView.tsx)).*
 - [x] **UX25 — Empty-state copy mismatches the flow** (L78): Downloads says "Paste a URL above to get
   started," but the actual path is Fetch/Download. *Resolved by L78 (DownloadsView empty-state copy
   rewritten to match the Fetch/Download flow).*
 - [ ] **UX26 — yt-dlp/ffmpeg version + initial settings load have no skeleton/spinner** — brief blank
   states on boot (plus the documented one-frame theme flash). **Fix:** lightweight loading states.
+  *Deferred (low value, needs eyeballing): the blanks are sub-second on a normal launch; adding skeletons is
+  a perceived-polish tweak worth doing while watching the actual boot, so it joins the visual pass.*
 
 ---
 

src/main/reveal.ts

@@ -53,8 +53,11 @@ export async function safeOpenPath(p: unknown): Promise<string> {
   return shell.openPath(p)
 }
 
-/** Reveal a path in the OS file manager. No-op for missing/invalid paths. */
-export function safeShowInFolder(p: unknown): void {
-  if (typeof p !== 'string' || !isAbsolute(p) || !existsSync(p)) return
+/** Reveal a path in the OS file manager. Returns '' on success, or an error
+ *  string (mirroring safeOpenPath) so the renderer can surface it (UX6). */
+export function safeShowInFolder(p: unknown): string {
+  if (typeof p !== 'string' || !isAbsolute(p)) return 'Invalid path.'
+  if (!existsSync(p)) return 'File not found — it may have been moved or deleted.'
   shell.showItemInFolder(p)
+  return ''
 }

src/preload/index.ts

@@ -80,7 +80,8 @@ const api = {
 
   openUrl: (url: string): Promise<void> => ipcRenderer.invoke(IpcChannels.openUrl, url),
 
-  showInFolder: (path: string): Promise<void> => ipcRenderer.invoke(IpcChannels.showInFolder, path),
+  showInFolder: (path: string): Promise<string> =>
+    ipcRenderer.invoke(IpcChannels.showInFolder, path),
 
   readClipboard: (): Promise<string> => ipcRenderer.invoke(IpcChannels.clipboardRead),
 

src/renderer/src/App.tsx

@@ -9,6 +9,7 @@ import { SettingsView } from './components/SettingsView'
 import { Onboarding } from './components/Onboarding'
 import { CommandPalette, type PaletteAction } from './components/CommandPalette'
 import { LiveRegion } from './components/LiveRegion'
+import { Toaster } from './components/ui/Toaster'
 import { getTheme, pageBackground } from './theme'
 import { SPACE } from './components/ui/tokens'
 import { useSettings } from './store/settings'
@@ -55,6 +56,12 @@ function App(): React.JSX.Element {
   const isDark = useResolvedDark()
   const tab = useNav((s) => s.tab)
   const setTab = useNav((s) => s.setTab)
+  // Active-download count for the sidebar Downloads badge (UX9/UI25), so a run in
+  // progress is visible from any tab. A number selector only re-renders when the
+  // count actually changes -- not on every progress tick.
+  const activeCount = useDownloads(
+    (s) => s.items.filter((i) => i.status === 'downloading' || i.status === 'queued').length
+  )
   const [paletteOpen, setPaletteOpen] = useState(false)
   // Track the element that was focused before the palette opened so we can restore it on close.
   const prePaletteRef = useRef<Element | null>(null)
@@ -225,6 +232,7 @@ function App(): React.JSX.Element {
               collapsed={collapsed}
               onToggleCollapsed={toggleCollapsed}
               showTerminal={showTerminal}
+              downloadCount={activeCount}
             />
 
             <main className={styles.content}>
@@ -248,6 +256,7 @@ function App(): React.JSX.Element {
           </>
         )}
         <LiveRegion />
+        <Toaster />
       </div>
     </FluentProvider>
   )

src/renderer/src/components/DownloadBar.tsx

@@ -52,6 +52,7 @@ export function DownloadBar(): React.JSX.Element {
     scheduleAt,
     dragActive,
     dup,
+    dupInHistory,
     showAdvanced,
     downloadOptions,
     incognito,
@@ -170,7 +171,9 @@ export function DownloadBar(): React.JSX.Element {
             </>
           }
         >
-          <Caption1>Already in your queue: "{dup}".</Caption1>
+          <Caption1>
+            {dupInHistory ? 'Already downloaded' : 'Already in your queue'}: "{dup}".
+          </Caption1>
         </Banner>
       )}
 

src/renderer/src/components/DownloadsView.tsx

@@ -8,7 +8,7 @@
   tokens,
   shorthands
 } from '@fluentui/react-components'
-import { ArrowDownloadRegular, ArrowClockwiseRegular } from '@fluentui/react-icons'
+import { ArrowDownloadRegular, ArrowClockwiseRegular, DismissRegular } from '@fluentui/react-icons'
 import { useDownloads, type DownloadItem } from '../store/downloads'
 import { queueSummaryOf } from '../store/queueStats'
 import { DownloadBar } from './DownloadBar'
@@ -75,6 +75,7 @@ export function DownloadsView(): React.JSX.Element {
   const items = useDownloads((s) => s.items)
   const clearFinished = useDownloads((s) => s.clearFinished)
   const retryAll = useDownloads((s) => s.retryAll)
+  const cancelAll = useDownloads((s) => s.cancelAll)
 
   const summary = queueSummaryOf(items)
   const hasFinished = items.some(
@@ -89,6 +90,9 @@ export function DownloadsView(): React.JSX.Element {
       i.status === 'paused' ||
       i.status === 'saved'
   ).length
+  // Cancelable = the items with a live/pending run (downloading + queued); this is
+  // exactly what "Cancel all" acts on (UX15).
+  const cancelable = items.filter((i) => i.status === 'downloading' || i.status === 'queued').length
 
   return (
     <div className={mergeClasses(styles.root, screen.width)}>
@@ -126,6 +130,11 @@ export function DownloadsView(): React.JSX.Element {
               Retry all failed ({summary.failed})
             </Button>
           )}
+          {cancelable > 0 && (
+            <Button size="small" appearance="subtle" icon={<DismissRegular />} onClick={cancelAll}>
+              Cancel all ({cancelable})
+            </Button>
+          )}
           {hasFinished && (
             <Button size="small" appearance="subtle" onClick={clearFinished}>
               Clear finished

src/renderer/src/components/LibraryView.tsx

@@ -36,6 +36,7 @@ import { thumbUrl } from '../thumb'
 import { relTime } from '../datetime'
 import { MediaThumb } from './MediaThumb'
 import { VirtualList } from './VirtualList'
+import { Hint } from './Hint'
 import { ScreenHeader, useScreenStyles } from './ui/Screen'
 import { StatusChip } from './ui/StatusChip'
 import { SegmentedControl } from './ui/SegmentedControl'
@@ -536,15 +537,28 @@ export function LibraryView(): React.JSX.Element {
       )}
 
       <div className={styles.toolbar}>
+        <Hint
+          label={
+            watchedCount === 0
+              ? 'Turn on "Watch" for a channel or playlist below first, then this checks them for new uploads.'
+              : 'Check your watched sources for new uploads'
+          }
+          placement="top"
+          align="start"
+        >
           <Button
             size="small"
             appearance="subtle"
             icon={syncing ? <Spinner size="tiny" /> : <ArrowSyncRegular />}
             onClick={onCheckNew}
-          disabled={syncing || watchedCount === 0}
+            // disabledFocusable (not disabled) when nothing is watched, so the
+            // button still shows its explanatory tooltip on hover/focus (UX24).
+            disabled={syncing}
+            disabledFocusable={watchedCount === 0}
           >
             Check {watchedCount > 0 ? `${watchedCount} watched` : 'watched'} for new
           </Button>
+        </Hint>
         {syncNote && <Caption1 className={text.muted}>{syncNote}</Caption1>}
         <div className={styles.toolbarSpacer} />
         <span className={styles.switchRow}>

src/renderer/src/components/Sidebar.tsx

@@ -1,4 +1,11 @@
-import { Caption1, makeStyles, mergeClasses, tokens, shorthands } from '@fluentui/react-components'
+import {
+  Caption1,
+  CounterBadge,
+  makeStyles,
+  mergeClasses,
+  tokens,
+  shorthands
+} from '@fluentui/react-components'
 import {
   ArrowDownloadFilled,
   ArrowDownloadRegular,
@@ -88,6 +95,8 @@ const useStyles = makeStyles({
     alignSelf: 'stretch'
   },
   navItem: {
+    // relative so the collapsed count badge can pin to the icon's corner.
+    position: 'relative',
     display: 'flex',
     alignItems: 'center',
     gap: '11px',
@@ -105,6 +114,16 @@ const useStyles = makeStyles({
       backgroundColor: tokens.colorNeutralBackground1Hover
     }
   },
+  // Expanded: the active-download count sits at the far right of the nav row.
+  navBadge: {
+    marginLeft: 'auto'
+  },
+  // Collapsed: pin the count to the top-right corner of the centered icon.
+  navBadgeCollapsed: {
+    position: 'absolute',
+    top: '4px',
+    right: '8px'
+  },
   navItemCollapsed: {
     justifyContent: 'center',
     padding: '9px 0'
@@ -155,6 +174,8 @@ interface SidebarProps {
   onToggleCollapsed: () => void
   /** Show the Terminal nav item (only when custom commands are enabled) */
   showTerminal: boolean
+  /** Active (downloading + queued) count, badged on the Downloads nav item (UX9). */
+  downloadCount: number
 }
 
 export function Sidebar({
@@ -166,7 +187,8 @@ export function Sidebar({
   version,
   collapsed,
   onToggleCollapsed,
-  showTerminal
+  showTerminal,
+  downloadCount
 }: SidebarProps): React.JSX.Element {
   const styles = useStyles()
   const focus = useFocusStyles()
@@ -238,10 +260,23 @@ export function Sidebar({
               }
               onClick={() => onTabChange(n.value)}
               aria-current={active ? 'page' : undefined}
-              aria-label={n.label}
+              aria-label={
+                n.value === 'downloads' && downloadCount > 0
+                  ? `${n.label}, ${downloadCount} active`
+                  : n.label
+              }
             >
               <span className={styles.navIcon}>{n.icon}</span>
               {!collapsed && n.label}
+              {n.value === 'downloads' && downloadCount > 0 && (
+                <CounterBadge
+                  className={collapsed ? styles.navBadgeCollapsed : styles.navBadge}
+                  count={downloadCount}
+                  size="small"
+                  color="brand"
+                  aria-hidden
+                />
+              )}
             </button>
           )
           return collapsed ? (

src/renderer/src/components/TerminalView.tsx

@@ -33,6 +33,10 @@ const MAX_LOG_LINES = 2000
 const useStyles = makeStyles({
   root: { display: 'flex', flexDirection: 'column', gap: SPACE.section, height: '100%' },
   gate: {
+    display: 'flex',
+    flexDirection: 'column',
+    alignItems: 'flex-start',
+    gap: '8px',
     padding: '12px 14px',
     backgroundColor: tokens.colorStatusWarningBackground1,
     color: tokens.colorStatusWarningForeground1,
@@ -75,6 +79,7 @@ export function TerminalView(): React.JSX.Element {
   const styles = useStyles()
   const screen = useScreenStyles()
   const customCommandEnabled = useSettings((s) => s.customCommandEnabled)
+  const updateSettings = useSettings((s) => s.update)
 
   const [args, setArgs] = useState('')
   const [lines, setLines] = useState<Line[]>([])
@@ -158,10 +163,19 @@ export function TerminalView(): React.JSX.Element {
       />
 
       {!customCommandEnabled && (
-        <Body1 className={styles.gate}>
-          The terminal is part of custom commands. Turn on "Run custom commands" in Settings →
-          Custom commands to use it.
+        <div className={styles.gate}>
+          <Body1>
+            The terminal runs the bundled yt-dlp with your own arguments — part of custom commands,
+            which can pass arbitrary yt-dlp flags. Turn it on to use the terminal.
           </Body1>
+          <Button
+            appearance="primary"
+            size="small"
+            onClick={() => updateSettings({ customCommandEnabled: true })}
+          >
+            Enable custom commands
+          </Button>
+        </div>
       )}
 
       <div className={styles.inputRow}>

src/renderer/src/components/downloadBar/useDownloadBar.ts

@@ -9,6 +9,7 @@ import {
   type CommandPreviewResult
 } from '@shared/ipc'
 import { useDownloads, type MediaKind } from '../../store/downloads'
+import { useHistory } from '../../store/history'
 import { QUALITY_OPTIONS } from '../../qualityOptions'
 import { sameVideo } from '../../store/queueStats'
 import { useSettings } from '../../store/settings'
@@ -55,6 +56,8 @@ export interface DownloadBarController {
   setDragActive: Dispatch<SetStateAction<boolean>>
   dup: string | null
   setDup: Dispatch<SetStateAction<string | null>>
+  /** true when the duplicate was found in history (already downloaded) vs the live queue (L144). */
+  dupInHistory: boolean
   // advanced / preview
   showAdvanced: boolean
   setShowAdvanced: Dispatch<SetStateAction<boolean>>
@@ -141,6 +144,9 @@ export function useDownloadBar(): DownloadBarController {
 
   // Duplicate guard: warn before enqueuing a URL already in the active queue.
   const [dup, setDup] = useState<string | null>(null)
+  // Whether the duplicate matched a history entry (already downloaded) rather than
+  // a live queue item (L144) — the banner wording differs.
+  const [dupInHistory, setDupInHistory] = useState(false)
   const confirmDup = useRef(false)
 
   // Per-download options (M5/M6/UX1): advanced features.
@@ -431,6 +437,15 @@ export function useDownloadBar(): DownloadBarController {
           existing.title.endsWith(' download') ||
           existing.title === 'New download'
         setDup(isPlaceholder ? existing.url : existing.title)
+        setDupInHistory(false)
+        return
+      }
+      // Not in the queue, but maybe already downloaded earlier (L144): warn so a
+      // re-download is a deliberate choice, not an accidental duplicate.
+      const downloaded = useHistory.getState().entries.find((h) => sameVideo(h.url, trimmed))
+      if (downloaded) {
+        setDup(downloaded.title || downloaded.url)
+        setDupInHistory(true)
         return
       }
     }
@@ -513,6 +528,7 @@ export function useDownloadBar(): DownloadBarController {
     scheduleAt,
     setScheduleAt,
     // drag / dup
+    dupInHistory,
     dragActive,
     setDragActive,
     dup,

src/renderer/src/components/ui/Toaster.tsx

@@ -0,0 +1,92 @@
+import { Caption1, Button, makeStyles, tokens, shorthands } from '@fluentui/react-components'
+import {
+  DismissRegular,
+  ErrorCircleFilled,
+  CheckmarkCircleFilled,
+  InfoFilled
+} from '@fluentui/react-icons'
+import { useToasts, type ToastTone } from '../../store/toasts'
+import { Z, ELEVATION, RADIUS, ICON } from './tokens'
+
+/**
+ * Renders the transient-toast stack (UX6/UX9) bottom-center. Deliberately NOT a
+ * Fluent Toaster/portal — this app avoids portal-based overlays (they blank/flicker
+ * on the dev GPU; see Select.tsx / CommandPalette.tsx) — so it's a plain fixed
+ * stack. No enter/exit animation, matching the app's conservative motion policy on
+ * this machine.
+ */
+const useStyles = makeStyles({
+  stack: {
+    position: 'fixed',
+    left: '50%',
+    bottom: '24px',
+    transform: 'translateX(-50%)',
+    zIndex: Z.tooltip,
+    display: 'flex',
+    flexDirection: 'column',
+    alignItems: 'center',
+    gap: '8px',
+    // Let clicks fall through the gaps between toasts to the app underneath.
+    pointerEvents: 'none'
+  },
+  toast: {
+    pointerEvents: 'auto',
+    display: 'flex',
+    alignItems: 'center',
+    gap: '10px',
+    maxWidth: 'min(520px, 90vw)',
+    padding: '10px 8px 10px 12px',
+    backgroundColor: tokens.colorNeutralBackground1,
+    border: `1px solid ${tokens.colorNeutralStroke2}`,
+    ...shorthands.borderRadius(RADIUS.surface),
+    boxShadow: ELEVATION.overlay
+  },
+  icon: {
+    flexShrink: 0,
+    fontSize: `${ICON.control}px`,
+    display: 'flex'
+  },
+  info: { color: tokens.colorNeutralForeground3 },
+  error: { color: tokens.colorStatusDangerForeground1 },
+  success: { color: tokens.colorStatusSuccessForeground1 },
+  message: {
+    flexGrow: 1,
+    minWidth: 0
+  }
+})
+
+const ICONS: Record<ToastTone, React.JSX.Element> = {
+  info: <InfoFilled />,
+  error: <ErrorCircleFilled />,
+  success: <CheckmarkCircleFilled />
+}
+
+export function Toaster(): React.JSX.Element | null {
+  const styles = useStyles()
+  const toasts = useToasts((s) => s.toasts)
+  const dismiss = useToasts((s) => s.dismiss)
+  const toneClass: Record<ToastTone, string> = {
+    info: styles.info,
+    error: styles.error,
+    success: styles.success
+  }
+
+  if (toasts.length === 0) return null
+  return (
+    <div className={styles.stack} role="status" aria-live="polite">
+      {toasts.map((t) => (
+        <div key={t.id} className={styles.toast}>
+          <span className={`${styles.icon} ${toneClass[t.tone]}`}>{ICONS[t.tone]}</span>
+          <Caption1 className={styles.message}>{t.message}</Caption1>
+          <Button
+            size="small"
+            appearance="subtle"
+            icon={<DismissRegular />}
+            onClick={() => dismiss(t.id)}
+            aria-label="Dismiss notification"
+          />
+        </div>
+      ))}
+    </div>
+  )
+}

src/renderer/src/mockApi.ts

@@ -135,7 +135,7 @@ export const mockApi: Api = {
   chooseFolder: async () => null,
   openPath: async () => '',
   openUrl: async () => {},
-  showInFolder: async () => {},
+  showInFolder: async () => '',
   readClipboard: async () => '',
   logError: () => {},
   getSettings: async () => MOCK_SETTINGS,

src/renderer/src/reveal.ts

@@ -0,0 +1,19 @@
+import { toast } from './store/toasts'
+import { logError } from './reportError'
+
+/**
+ * Open a downloaded file, or reveal it in its folder, surfacing any failure as a
+ * toast (UX6) instead of silently doing nothing. Clicking "Open file" on a
+ * download that was later moved or deleted used to no-op with no message; now the
+ * main-process reason ("File not found — it may have been moved…", "Refusing to
+ * open this file type.") is shown. Both IPC calls resolve to '' on success or an
+ * error string; a rejected promise (a bridge failure) is logged.
+ */
+export function revealFile(action: 'open' | 'folder', filePath: string): void {
+  const call = action === 'open' ? window.api.openPath(filePath) : window.api.showInFolder(filePath)
+  call
+    .then((err) => {
+      if (err) toast(err, 'error')
+    })
+    .catch(logError(action === 'open' ? 'openPath' : 'showInFolder'))
+}

src/renderer/src/store/downloadTypes.ts

@@ -116,6 +116,8 @@ export interface DownloadState {
   /** internal: promote any 'saved' item whose scheduledFor time has arrived */
   promoteDueScheduled: () => void
   cancel: (id: string) => void
+  /** cancel every active (downloading + queued) item at once (UX15) */
+  cancelAll: () => void
   remove: (id: string) => void
   clearFinished: () => void
   openFile: (id: string) => void

src/renderer/src/store/downloads.ts

@@ -2,6 +2,7 @@ import { create } from 'zustand'
 import { type MediaKind } from '@shared/ipc'
 import { isPreview as PREVIEW } from '../isPreview'
 import { logError } from '../reportError'
+import { revealFile } from '../reveal'
 import { useSettings } from './settings'
 import { useHistory } from './history'
 import { emit, on } from './coordinator'
@@ -335,6 +336,25 @@ export const useDownloads = create<DownloadState>((set, get) => {
       pump()
     },
 
+    cancelAll: () => {
+      const active = get().items.filter((i) => i.status === 'downloading' || i.status === 'queued')
+      if (active.length === 0) return
+      // Kill the live processes for the running ones; queued items never started.
+      if (!PREVIEW) {
+        for (const i of active) {
+          if (i.status === 'downloading') window.api.cancelDownload(i.id).catch(() => {})
+        }
+      }
+      set((s) => ({
+        items: s.items.map((i) =>
+          i.status === 'downloading' || i.status === 'queued'
+            ? { ...i, status: 'canceled', speedBytesPerSec: undefined, etaSeconds: undefined }
+            : i
+        )
+      }))
+      pump()
+    },
+
     remove: (id) => {
       set((s) => ({ items: s.items.filter((i) => i.id !== id) }))
       pump()
@@ -353,12 +373,12 @@ export const useDownloads = create<DownloadState>((set, get) => {
 
     openFile: (id) => {
       const item = get().items.find((i) => i.id === id)
-      if (!PREVIEW && item?.filePath) window.api.openPath(item.filePath)
+      if (!PREVIEW && item?.filePath) revealFile('open', item.filePath)
     },
 
     showInFolder: (id) => {
       const item = get().items.find((i) => i.id === id)
-      if (!PREVIEW && item?.filePath) window.api.showInFolder(item.filePath)
+      if (!PREVIEW && item?.filePath) revealFile('folder', item.filePath)
     },
 
     applyEvent: (ev) => {

src/renderer/src/store/history.ts

@@ -2,6 +2,7 @@ import { create } from 'zustand'
 import { HISTORY_MAX_ENTRIES, type HistoryEntry } from '@shared/ipc'
 import { isPreview as PREVIEW } from '../isPreview'
 import { logError } from '../reportError'
+import { revealFile } from '../reveal'
 
 // Mock history so the History tab has content during UI design.
 const seed: HistoryEntry[] = PREVIEW
@@ -87,12 +88,12 @@ export const useHistory = create<HistoryState>((set, get) => ({
 
   openFile: (id) => {
     const e = get().entries.find((x) => x.id === id)
-    if (!PREVIEW && e?.filePath) window.api.openPath(e.filePath)
+    if (!PREVIEW && e?.filePath) revealFile('open', e.filePath)
   },
 
   showInFolder: (id) => {
     const e = get().entries.find((x) => x.id === id)
-    if (!PREVIEW && e?.filePath) window.api.showInFolder(e.filePath)
+    if (!PREVIEW && e?.filePath) revealFile('folder', e.filePath)
   }
 }))
 

src/renderer/src/store/toasts.ts

@@ -0,0 +1,45 @@
+import { create } from 'zustand'
+import { newId } from '../id'
+
+/**
+ * A tiny transient-notification store (audit UX6/UX9). The app had no way to tell
+ * the user about a background failure — a swallowed `openPath` error, a file that
+ * moved — so those actions silently did nothing. This backs a lightweight,
+ * non-blocking toast stack rendered by `Toaster`; any store or component can raise
+ * one via {@link toast}.
+ */
+export type ToastTone = 'info' | 'error' | 'success'
+
+export interface Toast {
+  id: string
+  message: string
+  tone: ToastTone
+}
+
+interface ToastState {
+  toasts: Toast[]
+  show: (message: string, tone?: ToastTone) => void
+  dismiss: (id: string) => void
+}
+
+/** How long a toast lingers before auto-dismissing. */
+const AUTO_DISMISS_MS = 5000
+
+export const useToasts = create<ToastState>((set, get) => ({
+  toasts: [],
+  show: (message, tone = 'info') => {
+    const id = newId('toast')
+    set((s) => ({ toasts: [...s.toasts, { id, message, tone }] }))
+    // Auto-dismiss so the stack self-clears; the user can also dismiss early.
+    setTimeout(() => get().dismiss(id), AUTO_DISMISS_MS)
+  },
+  dismiss: (id) => set((s) => ({ toasts: s.toasts.filter((t) => t.id !== id) }))
+}))
+
+/**
+ * Imperative shortcut for non-component callers (the Zustand stores), so a store
+ * action can surface an error without wiring the hook through a component.
+ */
+export function toast(message: string, tone?: ToastTone): void {
+  useToasts.getState().show(message, tone)
+}

test/toasts.test.ts

@@ -0,0 +1,40 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { useToasts, toast } from '../src/renderer/src/store/toasts'
+
+describe('toasts store', () => {
+  beforeEach(() => {
+    useToasts.setState({ toasts: [] })
+    vi.useRealTimers()
+  })
+
+  it('show() adds a toast with the given message and tone', () => {
+    toast('could not open file', 'error')
+    const ts = useToasts.getState().toasts
+    expect(ts).toHaveLength(1)
+    expect(ts[0]?.message).toBe('could not open file')
+    expect(ts[0]?.tone).toBe('error')
+  })
+
+  it('defaults the tone to info', () => {
+    toast('heads up')
+    expect(useToasts.getState().toasts[0]?.tone).toBe('info')
+  })
+
+  it('dismiss() removes only the matching toast', () => {
+    toast('a')
+    toast('b')
+    const firstId = useToasts.getState().toasts[0]?.id ?? ''
+    useToasts.getState().dismiss(firstId)
+    const ts = useToasts.getState().toasts
+    expect(ts).toHaveLength(1)
+    expect(ts[0]?.message).toBe('b')
+  })
+
+  it('auto-dismisses after the timeout elapses', () => {
+    vi.useFakeTimers()
+    toast('temporary')
+    expect(useToasts.getState().toasts).toHaveLength(1)
+    vi.advanceTimersByTime(5000)
+    expect(useToasts.getState().toasts).toHaveLength(0)
+  })
+})