refactor: deduplicate mpv plugin config, fix CSS font fallbacks

- Extract shared getMpvPluginRuntimeConfig() helper to eliminate duplicate inline objects
- Call ensureImmersionTrackerStarted() before markActiveVideoWatched action
- Quote multi-word font names and add sans-serif generic fallback in subtitle sidebar CSS
- Add main-wiring tests asserting deduplication and tracker start ordering

src/main.ts

@@ -1233,17 +1233,7 @@ const youtubePlaybackRuntime = createYoutubePlaybackRuntime({
         resolveInstalledPluginBeforeLaunch: (detection, mpvPath) =>
           promptForLegacyMpvPluginRemovalBeforeWindowsLaunch(mpvPath, detection),
       },
-      {
-        socketPath: appState.mpvSocketPath,
-        binaryPath: getResolvedConfig().mpv.subminerBinaryPath,
-        backend: getResolvedConfig().mpv.backend,
-        autoStart: getResolvedConfig().mpv.autoStartSubMiner,
-        autoStartVisibleOverlay: getResolvedConfig().auto_start_overlay,
-        autoStartPauseUntilReady: getResolvedConfig().mpv.pauseUntilOverlayReady,
-        texthookerEnabled: getResolvedConfig().texthooker.launchAtStartup,
-        aniskipEnabled: getResolvedConfig().mpv.aniskipEnabled,
-        aniskipButtonKey: getResolvedConfig().mpv.aniskipButtonKey,
-      },
+      getMpvPluginRuntimeConfig(),
     ),
   waitForYoutubeMpvConnected: (timeoutMs) => waitForYoutubeMpvConnected(timeoutMs),
   prepareYoutubePlaybackInMpv: (request) => prepareYoutubePlaybackInMpv(request),
@@ -1254,6 +1244,21 @@ const youtubePlaybackRuntime = createYoutubePlaybackRuntime({
   clearScheduled: (timer) => clearTimeout(timer),
 });
 
+function getMpvPluginRuntimeConfig() {
+  const config = getResolvedConfig();
+  return {
+    socketPath: appState.mpvSocketPath,
+    binaryPath: config.mpv.subminerBinaryPath,
+    backend: config.mpv.backend,
+    autoStart: config.mpv.autoStartSubMiner,
+    autoStartVisibleOverlay: config.auto_start_overlay,
+    autoStartPauseUntilReady: config.mpv.pauseUntilOverlayReady,
+    texthookerEnabled: config.texthooker.launchAtStartup,
+    aniskipEnabled: config.mpv.aniskipEnabled,
+    aniskipButtonKey: config.mpv.aniskipButtonKey,
+  };
+}
+
 let firstRunSetupMessage: string | null = null;
 const resolveWindowsMpvShortcutRuntimePaths = () =>
   resolveWindowsMpvShortcutPaths({
@@ -2661,17 +2666,7 @@ const {
     getLaunchMode: () => getResolvedConfig().mpv.launchMode,
     platform: process.platform,
     execPath: process.execPath,
-    getPluginRuntimeConfig: () => ({
-      socketPath: appState.mpvSocketPath,
-      binaryPath: getResolvedConfig().mpv.subminerBinaryPath,
-      backend: getResolvedConfig().mpv.backend,
-      autoStart: getResolvedConfig().mpv.autoStartSubMiner,
-      autoStartVisibleOverlay: getResolvedConfig().auto_start_overlay,
-      autoStartPauseUntilReady: getResolvedConfig().mpv.pauseUntilOverlayReady,
-      texthookerEnabled: getResolvedConfig().texthooker.launchAtStartup,
-      aniskipEnabled: getResolvedConfig().mpv.aniskipEnabled,
-      aniskipButtonKey: getResolvedConfig().mpv.aniskipButtonKey,
-    }),
+    getPluginRuntimeConfig: () => getMpvPluginRuntimeConfig(),
     defaultMpvLogPath: DEFAULT_MPV_LOG_PATH,
     defaultMpvArgs: MPV_JELLYFIN_DEFAULT_ARGS,
     removeSocketPath: (socketPath) => {
@@ -5203,6 +5198,7 @@ async function dispatchSessionAction(request: SessionActionDispatchRequest): Pro
     toggleSubtitleSidebar: () => toggleSubtitleSidebar(),
     markLastCardAsAudioCard: () => markLastCardAsAudioCard(),
     markActiveVideoWatched: async () => {
+      ensureImmersionTrackerStarted();
       const marked = (await appState.immersionTracker?.markActiveVideoWatched()) ?? false;
       if (marked) {
         try {

src/main/main-wiring.test.ts

@@ -0,0 +1,32 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+
+function readMainSource(): string {
+  return fs.readFileSync(path.join(process.cwd(), 'src/main.ts'), 'utf8');
+}
+
+test('manual watched session action starts immersion tracker before marking watched', () => {
+  const source = readMainSource();
+  const actionBlock = source.match(
+    /markActiveVideoWatched: async \(\) => \{(?<body>[\s\S]*?)\n    \},/,
+  )?.groups?.body;
+
+  assert.ok(actionBlock);
+  assert.match(actionBlock, /ensureImmersionTrackerStarted\(\);/);
+  assert.ok(
+    actionBlock.indexOf('ensureImmersionTrackerStarted();') <
+      actionBlock.indexOf('markActiveVideoWatched()'),
+  );
+});
+
+test('main process uses one shared mpv plugin runtime config helper', () => {
+  const source = readMainSource();
+  assert.match(source, /function getMpvPluginRuntimeConfig\(\)/);
+  assert.equal((source.match(/socketPath: appState\.mpvSocketPath/g) ?? []).length, 1);
+  assert.equal(
+    (source.match(/binaryPath: getResolvedConfig\(\)\.mpv\.subminerBinaryPath/g) ?? []).length,
+    0,
+  );
+});

src/renderer/overlay-legacy-cleanup.test.ts

@@ -40,6 +40,20 @@ test('renderer stylesheet only hides visible focus chrome on top-level overlay f
   );
 });
 
+test('subtitle sidebar stylesheet keeps quoted font fallbacks and generic family', () => {
+  const cssSource = readWorkspaceFile('src/renderer/style.css');
+  const sidebarContentBlock = cssSource.match(
+    /\.subtitle-sidebar-content\s*\{(?<body>[\s\S]*?)\n\}/,
+  )?.groups?.body;
+
+  assert.ok(sidebarContentBlock);
+  assert.match(sidebarContentBlock, /'Hiragino Sans'/);
+  assert.match(sidebarContentBlock, /'M PLUS 1'/);
+  assert.match(sidebarContentBlock, /'Source Han Sans JP'/);
+  assert.match(sidebarContentBlock, /'Noto Sans CJK JP'/);
+  assert.match(sidebarContentBlock, /sans-serif/);
+});
+
 test('top-level readme avoids stale overlay-layers wording', () => {
   const readmeSource = readWorkspaceFile('README.md');
   assert.doesNotMatch(readmeSource, /overlay layers/i);

src/renderer/style.css

@@ -1912,10 +1912,11 @@ body.subtitle-sidebar-embedded-open .subtitle-sidebar-modal {
   margin-left: auto;
   font-family: var(
     --subtitle-sidebar-font-family,
-    Hiragino Sans,
-    M PLUS 1,
-    Source Han Sans JP,
-    Noto Sans CJK JP
+    'Hiragino Sans',
+    'M PLUS 1',
+    'Source Han Sans JP',
+    'Noto Sans CJK JP',
+    sans-serif
   );
   font-size: var(--subtitle-sidebar-font-size, 16px);
   background: var(--subtitle-sidebar-background-color, rgba(73, 77, 100, 0.9));