feat: streamlink quality preference + per-item notifications + path validation

Three Phase-11 wins.

1. Streamlink stream quality is now configurable. config.streamlink_quality
   defaults to "best" (preserves prior behaviour) but can be set to source,
   1080p60, 720p60, 720p, 480p, or audio_only via a new dropdown in
   Settings -> Download. The chosen quality is passed as STREAMS to
   streamlink with ",best" appended as a fallback so an old VOD lacking
   the chosen rendition still completes. Used by both the queue
   downloadVODPart and the standalone download-clip IPC. The whitelist is
   enforced via normalizeStreamlinkQuality so an arbitrary string in the
   config file falls back to "best".

2. Per-item completion notifications. Default off because long queues
   would spam the OS notifications panel. When enabled (Settings ->
   Queue zwischen App-Starts checkbox area), every successful download
   pops a "{title}" notification whose click brings the window forward
   AND opens shell.showItemInFolder on the produced file (or the
   download folder if the file is gone). The end-of-queue summary
   notification still fires regardless.

3. Download-path writability check on selectFolder. The renderer now
   asks the new check-folder-writable IPC after the user picks a
   folder; if isDownloadPathWritable returns false, a warning toast
   surfaces immediately instead of the next download failing with a
   cryptic "datei zu klein" / "ENOENT" error. Save proceeds anyway —
   the user might be picking a USB-stick path that is offline at the
   moment.

Plus DE + EN locale strings for every label/option/hint, all wired
through applyLanguageToStaticUI for live language switch.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/index.html

@@ -480,6 +480,18 @@
                                 <option value="2" id="parallelDownloads2">2 (Parallel)</option>
                             </select>
                         </div>
+                        <div class="form-group">
+                            <label id="streamlinkQualityLabel">Stream-Qualitaet</label>
+                            <select id="streamlinkQuality">
+                                <option value="best" id="streamlinkQualityBest">Best (Standard)</option>
+                                <option value="source" id="streamlinkQualitySource">Source (Original)</option>
+                                <option value="1080p60" id="streamlinkQuality1080p60">1080p60</option>
+                                <option value="720p60" id="streamlinkQuality720p60">720p60</option>
+                                <option value="720p" id="streamlinkQuality720p">720p</option>
+                                <option value="480p" id="streamlinkQuality480p">480p</option>
+                                <option value="audio_only" id="streamlinkQualityAudio">Audio only</option>
+                            </select>
+                        </div>
                         <div class="form-group">
                             <label id="performanceModeLabel">Performance-Profil</label>
                             <select id="performanceMode">
@@ -505,6 +517,10 @@
                                 <input type="checkbox" id="autoResumeQueueToggle">
                                 <span id="autoResumeQueueLabel">Queue beim Start automatisch fortsetzen</span>
                             </label>
+                            <label style="display:flex; align-items:center; gap:8px; margin-top: 8px;">
+                                <input type="checkbox" id="notifyEachCompletionToggle">
+                                <span id="notifyEachCompletionLabel">Benachrichtigung bei jedem fertigen Download</span>
+                            </label>
                         </div>
                         <div class="form-group">
                             <label id="metadataCacheMinutesLabel">Metadata-Cache (Minuten)</label>

src/main.ts

@@ -205,6 +205,8 @@ interface Config {
     parallel_downloads: number;
     auto_resume_queue_on_startup: boolean;
     downloaded_vod_ids: string[];
+    streamlink_quality: string;
+    notify_on_each_completion: boolean;
 }
 
 interface RuntimeMetrics {
@@ -318,9 +320,32 @@ const defaultConfig: Config = {
     metadata_cache_minutes: DEFAULT_METADATA_CACHE_MINUTES,
     parallel_downloads: 1,
     auto_resume_queue_on_startup: false,
-    downloaded_vod_ids: []
+    downloaded_vod_ids: [],
+    streamlink_quality: 'best',
+    notify_on_each_completion: false
 };
 
+// Whitelist of streamlink stream specifiers we surface in Settings. The
+// user's choice is passed to streamlink with "best" appended as a fallback
+// (streamlink supports comma-separated stream lists, picks the first match)
+// so a missing quality on the source stream still produces a download.
+const VALID_STREAMLINK_QUALITIES = ['best', 'source', '1080p60', '720p60', '720p', '480p', 'audio_only'] as const;
+
+function normalizeStreamlinkQuality(value: unknown): string {
+    if (typeof value === 'string' && (VALID_STREAMLINK_QUALITIES as readonly string[]).includes(value)) {
+        return value;
+    }
+    return 'best';
+}
+
+function getStreamlinkStreamArg(): string {
+    const choice = normalizeStreamlinkQuality(config.streamlink_quality);
+    if (choice === 'best') return 'best';
+    // Fall back to "best" if the chosen rendition isn't offered (e.g. an
+    // older stream archived before that resolution existed).
+    return `${choice},best`;
+}
+
 function normalizeFilenameTemplate(template: string | undefined, fallback: string): string {
     const value = (template || '').trim();
     return value || fallback;
@@ -364,7 +389,9 @@ function normalizeConfigTemplates(input: Config): Config {
         persist_queue_on_restart: input.persist_queue_on_restart !== false,
         metadata_cache_minutes: normalizeMetadataCacheMinutes(input.metadata_cache_minutes),
         auto_resume_queue_on_startup: input.auto_resume_queue_on_startup === true,
-        downloaded_vod_ids: trimmedIds
+        downloaded_vod_ids: trimmedIds,
+        streamlink_quality: normalizeStreamlinkQuality(input.streamlink_quality),
+        notify_on_each_completion: input.notify_on_each_completion === true
     };
 }
 
@@ -2576,7 +2603,7 @@ function downloadVODPart(
 ): Promise<DownloadResult> {
     return new Promise((resolve) => {
         const streamlinkCmd = getStreamlinkCommand();
-        const args = [...streamlinkCmd.prefixArgs, url, 'best', '-o', filename, '--force'];
+        const args = [...streamlinkCmd.prefixArgs, url, getStreamlinkStreamArg(), '-o', filename, '--force'];
         let lastErrorLine = '';
         const expectedDurationSeconds = parseClockDurationSeconds(endTime);
         let lastStreamlinkPercent = 0;
@@ -3311,6 +3338,40 @@ async function processOneQueueItem(item: QueueItem): Promise<void> {
             item.outputFiles = [...finalResult.outputFiles];
         }
 
+        // Per-VOD completion notification (separate from the queue-end
+        // notification fired at the end of processQueue). Off by default
+        // because users with long queues would get spammed.
+        if (finalResult.success && config.notify_on_each_completion) {
+            try {
+                if (Notification.isSupported()) {
+                    const itemNotification = new Notification({
+                        title: 'Twitch VOD Manager',
+                        body: `${item.title || item.url}`
+                    });
+                    const firstFile = item.outputFiles?.[0];
+                    itemNotification.on('click', () => {
+                        try {
+                            if (mainWindow) {
+                                if (mainWindow.isMinimized()) mainWindow.restore();
+                                mainWindow.focus();
+                            }
+                            // Click on a per-item notification opens the
+                            // file directly when we know it; falls back to
+                            // the download folder otherwise.
+                            if (firstFile && fs.existsSync(firstFile)) {
+                                shell.showItemInFolder(firstFile);
+                            } else if (config.download_path && fs.existsSync(config.download_path)) {
+                                void shell.openPath(config.download_path);
+                            }
+                        } catch (e) {
+                            appendDebugLog('per-item-notification-click-failed', String(e));
+                        }
+                    });
+                    itemNotification.show();
+                }
+            } catch { /* notifications optional */ }
+        }
+
         if (finalResult.success) {
             // Record the VOD ID so the renderer can mark this VOD as
             // already-downloaded the next time the user browses the
@@ -4232,7 +4293,7 @@ ipcMain.handle('download-clip', async (_, clipUrl: string) => {
         const proc = spawn(streamlinkCmd.command, [
             ...streamlinkCmd.prefixArgs,
             `https://clips.twitch.tv/${clipId}`,
-            'best',
+            getStreamlinkStreamArg(),
             '-o', filename,
             '--force'
         ], { windowsHide: true });
@@ -4298,6 +4359,11 @@ ipcMain.handle('open-debug-log-file', (): boolean => {
     return true;
 });
 
+ipcMain.handle('check-folder-writable', (_, folderPath: string): boolean => {
+    if (typeof folderPath !== 'string' || !folderPath) return false;
+    return isDownloadPathWritable(folderPath);
+});
+
 ipcMain.handle('is-downloading', () => isDownloading);
 
 ipcMain.handle('get-runtime-metrics', () => getRuntimeMetricsSnapshot());

src/preload.ts

@@ -87,6 +87,7 @@ contextBridge.exposeInMainWorld('api', {
     openFile: (path: string) => ipcRenderer.invoke('open-file', path),
     showInFolder: (path: string) => ipcRenderer.invoke('show-in-folder', path),
     openDebugLogFile: () => ipcRenderer.invoke('open-debug-log-file'),
+    checkFolderWritable: (path: string) => ipcRenderer.invoke('check-folder-writable', path),
 
     // Video Cutter
     getVideoInfo: (filePath: string): Promise<VideoInfo | null> => ipcRenderer.invoke('get-video-info', filePath),

src/renderer-globals.d.ts

@@ -18,6 +18,8 @@ interface AppConfig {
     parallel_downloads?: number;
     auto_resume_queue_on_startup?: boolean;
     downloaded_vod_ids?: string[];
+    streamlink_quality?: string;
+    notify_on_each_completion?: boolean;
     [key: string]: unknown;
 }
 
@@ -204,6 +206,7 @@ interface ApiBridge {
     openFile(path: string): Promise<boolean>;
     showInFolder(path: string): Promise<boolean>;
     openDebugLogFile(): Promise<boolean>;
+    checkFolderWritable(path: string): Promise<boolean>;
     getVideoInfo(filePath: string): Promise<VideoInfo | null>;
     extractFrame(filePath: string, timeSeconds: number): Promise<string | null>;
     cutVideo(inputFile: string, startTime: number, endTime: number): Promise<{ success: boolean; outputFile: string | null }>;

src/renderer-locale-de.ts

@@ -69,6 +69,14 @@ const UI_TEXT_DE = {
         persistQueueLabel: 'Queue zwischen App-Starts speichern',
         autoResumeQueueLabel: 'Queue beim Start automatisch fortsetzen',
         autoResumeQueueHint: 'Wenn aktiv und die gespeicherte Queue noch ausstehende Eintraege hat, starten Downloads ~5 Sekunden nach dem Fensteroeffnen. Deaktivieren = Start-Klick noetig.',
+        notifyEachCompletionLabel: 'Benachrichtigung bei jedem fertigen Download',
+        notifyEachCompletionHint: 'Standardmaessig aus — bei langen Queues wuerde das System-Notifications-Panel sonst zugespammt. Die Queue-End-Zusammenfassung erscheint trotzdem.',
+        streamlinkQualityLabel: 'Stream-Qualitaet',
+        streamlinkQualityHint: 'Streamlink versucht erst diese Qualitaet; falls das VOD sie nicht anbietet, faellt es auf "best" zurueck.',
+        streamlinkQualityBest: 'Best (Standard)',
+        streamlinkQualitySource: 'Source (Original)',
+        streamlinkQualityAudio: 'Nur Audio',
+        downloadPathNotWritable: 'Download-Ordner ist nicht beschreibbar. Waehle einen anderen Ordner oder pruefe die Schreibrechte.',
         streamerSectionTitle: 'Streamer',
         streamerListFilterPlaceholder: 'Filtern...',
         streamerBulkRemoveTitle: 'Alle entfernen (oder gefilterte)',

src/renderer-locale-en.ts

@@ -69,6 +69,14 @@ const UI_TEXT_EN = {
         persistQueueLabel: 'Keep queue between app restarts',
         autoResumeQueueLabel: 'Auto-resume the queue on startup',
         autoResumeQueueHint: 'When enabled and the persisted queue has pending entries, downloads kick off ~5 seconds after the window opens. Disable to require an explicit Start click.',
+        notifyEachCompletionLabel: 'Notify on every completed download',
+        notifyEachCompletionHint: 'Off by default — long queues would otherwise spam the OS notifications panel. The end-of-queue summary notification fires either way.',
+        streamlinkQualityLabel: 'Stream quality',
+        streamlinkQualityHint: 'Streamlink will try this quality first; if the VOD does not offer it, falls back to "best".',
+        streamlinkQualityBest: 'Best (default)',
+        streamlinkQualitySource: 'Source (original)',
+        streamlinkQualityAudio: 'Audio only',
+        downloadPathNotWritable: 'Download folder is not writable. Pick another folder or grant write permission.',
         streamerSectionTitle: 'Streamer',
         streamerListFilterPlaceholder: 'Filter...',
         streamerBulkRemoveTitle: 'Remove all (or filtered)',

src/renderer-settings.ts

@@ -387,6 +387,8 @@ function collectDownloadSettingsPayload(): Partial<AppConfig> {
         prevent_duplicate_downloads: byId<HTMLInputElement>('duplicatePreventionToggle').checked,
         persist_queue_on_restart: byId<HTMLInputElement>('persistQueueToggle').checked,
         auto_resume_queue_on_startup: byId<HTMLInputElement>('autoResumeQueueToggle').checked,
+        notify_on_each_completion: byId<HTMLInputElement>('notifyEachCompletionToggle').checked,
+        streamlink_quality: byId<HTMLSelectElement>('streamlinkQuality').value,
         metadata_cache_minutes: parseInt(byId<HTMLInputElement>('metadataCacheMinutes').value, 10) || 10
     };
 }
@@ -430,6 +432,8 @@ function getSettingsFingerprint(payload: Partial<AppConfig>): string {
         effective.prevent_duplicate_downloads !== false,
         effective.persist_queue_on_restart !== false,
         effective.auto_resume_queue_on_startup === true,
+        effective.notify_on_each_completion === true,
+        effective.streamlink_quality ?? 'best',
         effective.metadata_cache_minutes ?? 10,
         effective.filename_template_vod ?? '{title}.mp4',
         effective.filename_template_parts ?? '{date}_Part{part_padded}.mp4',
@@ -448,6 +452,8 @@ function syncSettingsFormFromConfig(): void {
     byId<HTMLInputElement>('duplicatePreventionToggle').checked = (config.prevent_duplicate_downloads as boolean) !== false;
     byId<HTMLInputElement>('persistQueueToggle').checked = (config.persist_queue_on_restart as boolean) !== false;
     byId<HTMLInputElement>('autoResumeQueueToggle').checked = (config.auto_resume_queue_on_startup as boolean) === true;
+    byId<HTMLInputElement>('notifyEachCompletionToggle').checked = (config.notify_on_each_completion as boolean) === true;
+    byId<HTMLSelectElement>('streamlinkQuality').value = (config.streamlink_quality as string) || 'best';
     byId<HTMLInputElement>('metadataCacheMinutes').value = String((config.metadata_cache_minutes as number) || 10);
     byId<HTMLInputElement>('vodFilenameTemplate').value = (config.filename_template_vod as string) || '{title}.mp4';
     byId<HTMLInputElement>('partsFilenameTemplate').value = (config.filename_template_parts as string) || '{date}_Part{part_padded}.mp4';
@@ -559,7 +565,9 @@ function initSettingsAutoSave(): void {
         'smartSchedulerToggle',
         'duplicatePreventionToggle',
         'persistQueueToggle',
-        'autoResumeQueueToggle'
+        'autoResumeQueueToggle',
+        'notifyEachCompletionToggle',
+        'streamlinkQuality'
     ] as const;
 
     const debouncedSaveIds = [
@@ -643,6 +651,18 @@ async function selectFolder(): Promise<void> {
 
     byId<HTMLInputElement>('downloadPath').value = folder;
     config = await window.api.saveConfig({ download_path: folder });
+
+    // Warn-only validation — the user explicitly chose this folder, so don't
+    // refuse to save (they might be picking a path on a USB stick that's
+    // currently disconnected). Just surface the writability problem early
+    // instead of letting the next download fail with a cryptic error.
+    try {
+        const writable = await window.api.checkFolderWritable(folder);
+        if (!writable) {
+            const toast = (window as unknown as { showAppToast?: (msg: string, kind?: 'info' | 'warn') => void }).showAppToast;
+            if (toast) toast(UI_TEXT.static.downloadPathNotWritable, 'warn');
+        }
+    } catch { /* ignore — preflight will catch it later */ }
 }
 
 function openFolder(): void {

src/renderer-texts.ts

@@ -117,6 +117,15 @@ function applyLanguageToStaticUI(): void {
     setText('autoResumeQueueLabel', UI_TEXT.static.autoResumeQueueLabel);
     setTitle('autoResumeQueueLabel', UI_TEXT.static.autoResumeQueueHint);
     setTitle('autoResumeQueueToggle', UI_TEXT.static.autoResumeQueueHint);
+    setText('notifyEachCompletionLabel', UI_TEXT.static.notifyEachCompletionLabel);
+    setTitle('notifyEachCompletionLabel', UI_TEXT.static.notifyEachCompletionHint);
+    setTitle('notifyEachCompletionToggle', UI_TEXT.static.notifyEachCompletionHint);
+    setText('streamlinkQualityLabel', UI_TEXT.static.streamlinkQualityLabel);
+    setTitle('streamlinkQualityLabel', UI_TEXT.static.streamlinkQualityHint);
+    setTitle('streamlinkQuality', UI_TEXT.static.streamlinkQualityHint);
+    setText('streamlinkQualityBest', UI_TEXT.static.streamlinkQualityBest);
+    setText('streamlinkQualitySource', UI_TEXT.static.streamlinkQualitySource);
+    setText('streamlinkQualityAudio', UI_TEXT.static.streamlinkQualityAudio);
     setText('streamerSectionTitleText', UI_TEXT.static.streamerSectionTitle);
     setPlaceholder('streamerListFilter', UI_TEXT.static.streamerListFilterPlaceholder);
     setTitle('btnStreamerBulkRemove', UI_TEXT.static.streamerBulkRemoveTitle);