Self-review H1: give useDownloadBar an explicit return type

The extracted hook relied on inferred return typing, inconsistent with the
codebase convention (useClipboardLink: ClipboardLink, useResolvedDark: boolean).
Add a compiler-verified DownloadBarController interface and annotate the hook —
the returned object is checked against it, so the surface can't silently drift.

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

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

@@ -1,4 +1,4 @@
-import { useState, useEffect, useRef } from 'react'
+import { useState, useEffect, useRef, type Dispatch, type SetStateAction } from 'react'
 import {
   parseUrlShortcutContent,
   type MediaInfo,
@@ -12,7 +12,12 @@ import { useDownloads, type MediaKind } from '../../store/downloads'
 import { QUALITY_OPTIONS } from '../../qualityOptions'
 import { sameVideo } from '../../store/queueStats'
 import { useSettings } from '../../store/settings'
-import { useClipboardLink, looksLikeUrl, firstUrlInText } from '../../useClipboardLink'
+import {
+  useClipboardLink,
+  looksLikeUrl,
+  firstUrlInText,
+  type SuggestionSource
+} from '../../useClipboardLink'
 import { logError } from '../../reportError'
 
 /** Pull the URL= target out of a dropped Windows .url Internet Shortcut file. */
@@ -29,12 +34,78 @@ export function toLocalDatetimeValue(d: Date): string {
   return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`
 }
 
+/** Everything the DownloadBar render needs — the hook's public surface. */
+export interface DownloadBarController {
+  // form state
+  url: string
+  kind: MediaKind
+  quality: string
+  // trim / schedule
+  showTrim: boolean
+  setShowTrim: Dispatch<SetStateAction<boolean>>
+  trim: string
+  showSchedule: boolean
+  setShowSchedule: Dispatch<SetStateAction<boolean>>
+  scheduleAt: string
+  setScheduleAt: Dispatch<SetStateAction<string>>
+  // drag / dup
+  dragActive: boolean
+  setDragActive: Dispatch<SetStateAction<boolean>>
+  dup: string | null
+  setDup: Dispatch<SetStateAction<string | null>>
+  // advanced / preview
+  showAdvanced: boolean
+  setShowAdvanced: Dispatch<SetStateAction<boolean>>
+  downloadOptions: DownloadOptions
+  incognito: boolean
+  setIncognito: Dispatch<SetStateAction<boolean>>
+  commandPreview: CommandPreviewResult | null
+  previewLoading: boolean
+  // probe (single video)
+  info: MediaInfo | null
+  thumbFailed: string | null
+  setThumbFailed: Dispatch<SetStateAction<string | null>>
+  probing: boolean
+  probeError: string | null
+  usingFormats: boolean
+  selectedFormat: FormatOption | undefined
+  // playlist
+  playlist: PlaylistInfo | null
+  selected: Set<number>
+  allSelected: boolean
+  // suggestion banner
+  suggestion: string | null
+  suggestionSource: SuggestionSource
+  dismissSuggestion: () => void
+  // handlers
+  onDragOver: (e: React.DragEvent) => void
+  onDrop: (e: React.DragEvent) => void
+  onUrlChange: (next: string) => void
+  onKindChange: (next: MediaKind) => void
+  onQualityChange: (v: string) => void
+  onFormatIdChange: (v: string) => void
+  onTrimChange: (v: string) => void
+  onDownloadOptionsChange: (next: DownloadOptions) => void
+  toggleCommandPreview: () => Promise<void>
+  fetchFormats: () => Promise<void>
+  paste: () => Promise<void>
+  acceptSuggestion: () => void
+  download: () => void
+  downloadAnyway: () => void
+  addPlaylist: () => void
+  toggleEntry: (index: number, on: boolean) => void
+  toggleAll: () => void
+  effKind: (index: number) => MediaKind
+  toggleItemKind: (index: number) => void
+  setAllKinds: (k: MediaKind) => void
+}
+
 /**
  * All state and behaviour for the DownloadBar. Extracted from the component so
  * the ~17 interdependent state hooks and their handlers live in one place and
  * the component is render-only.
  */
-export function useDownloadBar() {
+export function useDownloadBar(): DownloadBarController {
   const addFromUrl = useDownloads((s) => s.addFromUrl)
   const addMany = useDownloads((s) => s.addMany)
   const settingsLoaded = useSettings((s) => s.loaded)