Wire M5/M6/UX1: command preview, incognito mode, per-download options (Recommended SHOULD-fix-for-1.0)

M5 (Command preview):
- Added 'Show command' button in DownloadBar that calls window.api.previewCommand()
- Displays the exact yt-dlp command line that will run for the current form state
- Helps users verify the exact behavior before download

M6 (Incognito mode):
- Added incognito checkbox in Advanced panel
- Passes through AddOptions to enable no-logging, no-history, no-cookies mode
- QueueItem already shows 'Private' badge when item.incognito is set

UX1 (Per-download options):
- Expanded Advanced panel now shows full DownloadOptionsForm
- Allows overriding audio format, video codec, container, embed-subtitles,
  SponsorBlock, format-sort for any single download (not just global settings)
- Options passed through AddOptions.options to startDownload
- Same form component used for both Settings defaults + per-download overrides

UI additions:
- Advanced toggle button (Settings icon) in DownloadBar
- Collapsible Advanced panel with incognito checkbox + DownloadOptionsForm
- Command preview panel shows the yt-dlp argv (monospace) or error message
- Both features only show for single videos (not playlists)

All plumbing was already in place (previewCommand IPC, StartDownloadOptions.options,
AddOptions.incognito, mockApi); only the renderer UI was missing.

typecheck + 243 tests + eslint green.

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

src/renderer/src/components/DownloadBar.tsx

@@ -25,13 +25,18 @@ import {
   AppsListRegular,
   CutRegular,
   CalendarClockRegular,
-  WarningRegular
+  WarningRegular,
+  SettingsRegular,
+  WindowConsoleRegular
 } from '@fluentui/react-icons'
 import {
   parseUrlShortcutContent,
   type MediaInfo,
   type FormatOption,
-  type PlaylistInfo
+  type PlaylistInfo,
+  type DownloadOptions,
+  DEFAULT_DOWNLOAD_OPTIONS,
+  type CommandPreviewResult
 } from '@shared/ipc'
 import { useDownloads, type MediaKind } from '../store/downloads'
 import { QUALITY_OPTIONS } from '../qualityOptions'
@@ -41,6 +46,7 @@ import { Select } from './Select'
 import { Hint } from './Hint'
 import { SegmentedControl } from './ui/SegmentedControl'
 import { IconButton } from './ui/IconButton'
+import { DownloadOptionsForm } from './DownloadOptionsForm'
 import { useClipboardLink, looksLikeUrl, firstUrlInText } from '../useClipboardLink'
 import { logError } from '../reportError'
 import { THUMB_LG } from '../thumbSizes'
@@ -246,6 +252,28 @@ const useStyles = makeStyles({
     backgroundColor: tokens.colorNeutralBackground1,
     color: tokens.colorNeutralForeground1,
     colorScheme: 'light dark'
+  },
+  // --- command preview & options panels ---
+  commandBlock: {
+    display: 'flex',
+    flexDirection: 'column',
+    gap: '8px'
+  },
+  commandPreviewPanel: {
+    padding: '12px',
+    backgroundColor: tokens.colorNeutralBackground2,
+    ...shorthands.borderRadius(tokens.borderRadiusLarge),
+    border: `1px solid ${tokens.colorNeutralStroke2}`,
+    fontFamily: 'monospace',
+    fontSize: tokens.fontSizeBase200,
+    overflowX: 'auto',
+    color: tokens.colorNeutralForeground1
+  },
+  optionsPanel: {
+    padding: '12px',
+    backgroundColor: tokens.colorNeutralBackground2,
+    ...shorthands.borderRadius(tokens.borderRadiusLarge),
+    border: `1px solid ${tokens.colorNeutralStroke2}`
   }
 })
 
@@ -285,6 +313,13 @@ export function DownloadBar(): React.JSX.Element {
   const [dup, setDup] = useState<string | null>(null)
   const confirmDup = useRef(false)
 
+  // Per-download options (M5/M6/UX1): advanced features.
+  const [showAdvanced, setShowAdvanced] = useState(false)
+  const [downloadOptions, setDownloadOptions] = useState<DownloadOptions>(DEFAULT_DOWNLOAD_OPTIONS)
+  const [incognito, setIncognito] = useState(false)
+  const [commandPreview, setCommandPreview] = useState<CommandPreviewResult | null>(null)
+  const [previewLoading, setPreviewLoading] = useState(false)
+
   function onDragOver(e: React.DragEvent): void {
     e.preventDefault()
     if (!dragActive) setDragActive(true)
@@ -368,11 +403,35 @@ export function DownloadBar(): React.JSX.Element {
     setItemKinds({})
   }
 
+  async function loadCommandPreview(): Promise<void> {
+    const trimmed = url.trim()
+    if (!trimmed) {
+      setCommandPreview(null)
+      return
+    }
+    setPreviewLoading(true)
+    try {
+      const result = await window.api.previewCommand({
+        id: 'preview',
+        url: trimmed,
+        kind,
+        quality,
+        options: downloadOptions
+      })
+      setCommandPreview(result)
+    } catch (e) {
+      setCommandPreview({ ok: false, error: (e as Error).message })
+    } finally {
+      setPreviewLoading(false)
+    }
+  }
+
   function onUrlChange(next: string): void {
     setUrl(next)
     // Any probed info -- or a duplicate warning -- is stale once the URL changes.
     if (info || probeError || playlist) clearProbe()
     if (dup) setDup(null)
+    if (commandPreview) setCommandPreview(null)
     confirmDup.current = false
   }
 
@@ -489,6 +548,8 @@ export function DownloadBar(): React.JSX.Element {
         ...meta,
         trim: trimSpec,
         scheduledFor,
+        options: downloadOptions,
+        incognito,
         format: {
           id: selectedFormat.id,
           hasAudio: selectedFormat.hasAudio,
@@ -496,7 +557,13 @@ export function DownloadBar(): React.JSX.Element {
         }
       })
     } else {
-      addFromUrl(trimmed, kind, quality, { ...meta, trim: trimSpec, scheduledFor })
+      addFromUrl(trimmed, kind, quality, {
+        ...meta,
+        trim: trimSpec,
+        scheduledFor,
+        options: downloadOptions,
+        incognito
+      })
     }
 
     setUrl('')
@@ -504,6 +571,8 @@ export function DownloadBar(): React.JSX.Element {
     setShowTrim(false)
     setScheduleAt('')
     setShowSchedule(false)
+    setShowAdvanced(false)
+    setCommandPreview(null)
     clearProbe()
   }
 
@@ -771,6 +840,59 @@ export function DownloadBar(): React.JSX.Element {
         </div>
       )}
 
+      {!playlist && (
+        <div className={styles.commandBlock}>
+          <div className={styles.optButtons}>
+            <Button
+              size="small"
+              appearance="subtle"
+              icon={<SettingsRegular />}
+              onClick={() => setShowAdvanced((v) => !v)}
+            >
+              {showAdvanced ? 'Advanced · on' : 'Advanced'}
+            </Button>
+            <Button
+              size="small"
+              appearance="subtle"
+              icon={previewLoading ? <Spinner size="tiny" /> : <WindowConsoleRegular />}
+              onClick={loadCommandPreview}
+              disabled={!url.trim() || previewLoading}
+            >
+              {commandPreview ? 'Command · shown' : 'Show command'}
+            </Button>
+          </div>
+          {commandPreview && (
+            <div className={styles.commandPreviewPanel}>
+              {commandPreview.ok ? (
+                <>
+                  <div>{commandPreview.command}</div>
+                </>
+              ) : (
+                <div style={{ color: tokens.colorStatusDangerForeground1 }}>
+                  Error: {commandPreview.error}
+                </div>
+              )}
+            </div>
+          )}
+          {showAdvanced && (
+            <div className={styles.optionsPanel}>
+              <Checkbox
+                checked={incognito}
+                onChange={(_, d) => setIncognito(!!d.checked)}
+                label="Incognito mode (no logging, no history, no cookies)"
+              />
+              <div style={{ marginTop: '12px' }}>
+                <DownloadOptionsForm
+                  value={downloadOptions}
+                  onChange={setDownloadOptions}
+                  kind={kind}
+                />
+              </div>
+            </div>
+          )}
+        </div>
+      )}
+
       <div className={styles.controls}>
         <div className={styles.control}>
           <Caption1>Format</Caption1>