feat: window title syncs with active tab / streamer

document.title was stamped once during app boot with the static
"Twitch VOD Manager vX.Y.Z" string. After that, the H1 page-title
in the header updated as the user navigated tabs and selected
streamers, but the OS-level window title — the string shown in the
taskbar, Alt+Tab switcher, and OS notifications — never changed.

Multitasking suffered: a user with three Electron windows pinned
to taskbar all read identical "Twitch VOD Manager v4.6.x", with
no clue which window had what tab or streamer loaded.

Added a setPageTitle(text) helper in renderer.ts that:
- Updates the H1 #pageTitle textContent (the visible header)
- Updates document.title with `${text} - ${appName} v${version}`
  for non-default text, or just `${appName} v${version}` for the
  default app-name fallback
- Exposed on window so the renderer-streamers.ts and
  renderer-settings.ts modules can reach it without crossing the
  module-vs-bundle boundary

Three call sites updated to use the helper:
- showTab → uses for tab-derived titles
- selectStreamer → uses for "xrohat" style streamer titles
- the renderer-settings language-switch refresh path

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

src/renderer-settings.ts

@@ -194,9 +194,14 @@ function changeLanguage(lang: string): void {
     const activeTabId = document.querySelector('.tab-content.active')?.id || 'vodsTab';
     const activeTab = activeTabId.replace('Tab', '');
     if (activeTab === 'vods' && currentStreamer) {
-        byId('pageTitle').textContent = currentStreamer;
+        const setTitle = (window as unknown as { setPageTitle?: (text: string) => void }).setPageTitle;
+        if (typeof setTitle === 'function') setTitle(currentStreamer);
+        else byId('pageTitle').textContent = currentStreamer;
     } else {
-        byId('pageTitle').textContent = (UI_TEXT.tabs as Record<string, string>)[activeTab] || UI_TEXT.appName;
+        const setTitle = (window as unknown as { setPageTitle?: (text: string) => void }).setPageTitle;
+        const text = (UI_TEXT.tabs as Record<string, string>)[activeTab] || UI_TEXT.appName;
+        if (typeof setTitle === 'function') setTitle(text);
+        else byId('pageTitle').textContent = text;
     }
 
     void refreshRuntimeMetrics();

src/renderer-streamers.ts

@@ -751,7 +751,9 @@ async function selectStreamer(name: string, forceRefresh = false): Promise<void>
     const savedY = vodScrollPositions[name];
     pendingScrollRestore = (typeof savedY === 'number' && savedY > 0) ? { streamer: name, y: savedY } : null;
     renderStreamers();
-    byId('pageTitle').textContent = name;
+    const setTitle = (window as unknown as { setPageTitle?: (text: string) => void }).setPageTitle;
+    if (typeof setTitle === 'function') setTitle(name);
+    else byId('pageTitle').textContent = name;
 
     // Kick off the profile header load in parallel with VOD fetching.
     // It's a separate request stream and not strictly needed for the VOD

src/renderer.ts

@@ -20,6 +20,7 @@ async function init(): Promise<void> {
 
     byId('versionText').textContent = `v${version}`;
     byId('versionInfo').textContent = `Version: v${version}`;
+    appVersion = version;
     document.title = `${UI_TEXT.appName} v${version}`;
 
     byId<HTMLInputElement>('clientId').value = config.client_id ?? '';
@@ -636,6 +637,24 @@ async function updateStatsBar(): Promise<void> {
 
 let toastHideTimer: number | null = null;
 let queueSyncTimer: number | null = null;
+let appVersion = '';
+
+// Single source of truth for what the user is looking at — keeps the
+// visible H1, the document title (which drives the OS task bar / Alt+Tab
+// label), and the app version pill in sync. Previously document.title was
+// stamped once at boot, so the OS task bar always read "Twitch VOD
+// Manager v4.6.76" no matter what tab or streamer was active.
+(window as unknown as { setPageTitle: (text: string) => void }).setPageTitle = setPageTitle;
+
+function setPageTitle(text: string): void {
+    const titleEl = document.getElementById('pageTitle');
+    if (titleEl) titleEl.textContent = text;
+    const appName = UI_TEXT.appName;
+    const versionSuffix = appVersion ? ` v${appVersion}` : '';
+    document.title = text && text !== appName
+        ? `${text} - ${appName}${versionSuffix}`
+        : `${appName}${versionSuffix}`;
+}
 let queueSyncInFlight = false;
 let lastQueueActivityAt = Date.now();
 
@@ -850,9 +869,10 @@ function showTab(tab: string): void {
 
     // Only show the streamer name on the VODs tab — otherwise the title would
     // mismatch the tab content (e.g. "streamer X" while on Settings)
-    byId('pageTitle').textContent = (tab === 'vods' && currentStreamer)
+    const pageTitleText = (tab === 'vods' && currentStreamer)
         ? currentStreamer
         : (titles[tab] || UI_TEXT.appName);
+    setPageTitle(pageTitleText);
 
     persistActiveTab(tab);