fix: delegate multi-line digit selection to visible overlay (#78)

src/main/runtime/youtube-playback.ts

@@ -10,6 +10,39 @@ function matchesYoutubeHost(hostname: string, expectedHost: string): boolean {
   return hostname === expectedHost || hostname.endsWith(`.${expectedHost}`);
 }
 
+function extractYoutubeVideoId(mediaPath: string | null | undefined): string | null {
+  const normalized = trimToNull(mediaPath);
+  if (!normalized) {
+    return null;
+  }
+
+  let parsed: URL;
+  try {
+    parsed = new URL(normalized);
+  } catch {
+    return null;
+  }
+
+  const host = parsed.hostname.toLowerCase();
+  if (matchesYoutubeHost(host, 'youtu.be')) {
+    return parsed.pathname.replace(/^\/+/, '').split('/')[0]?.trim() || null;
+  }
+  if (
+    !matchesYoutubeHost(host, 'youtube.com') &&
+    !matchesYoutubeHost(host, 'youtube-nocookie.com')
+  ) {
+    return null;
+  }
+  if (parsed.pathname === '/watch') {
+    return parsed.searchParams.get('v')?.trim() || null;
+  }
+  const pathSegments = parsed.pathname.replace(/^\/+/, '').split('/');
+  if (pathSegments[0] === 'shorts' || pathSegments[0] === 'embed') {
+    return pathSegments[1]?.trim() || null;
+  }
+  return null;
+}
+
 export function isYoutubeMediaPath(mediaPath: string | null | undefined): boolean {
   const normalized = trimToNull(mediaPath);
   if (!normalized) {
@@ -31,6 +64,26 @@ export function isYoutubeMediaPath(mediaPath: string | null | undefined): boolea
   );
 }
 
+export function isSameYoutubeMediaPath(
+  left: string | null | undefined,
+  right: string | null | undefined,
+): boolean {
+  const leftId = extractYoutubeVideoId(left);
+  const rightId = extractYoutubeVideoId(right);
+  return Boolean(leftId && rightId && leftId === rightId);
+}
+
+export function shouldUseCachedYoutubeParsedCues(input: {
+  videoPath: string | null | undefined;
+  cachedMediaPath: string | null | undefined;
+  cachedCueCount: number;
+}): boolean {
+  return (
+    input.cachedCueCount > 0 &&
+    isSameYoutubeMediaPath(input.videoPath, input.cachedMediaPath)
+  );
+}
+
 export function isYoutubePlaybackActive(
   currentMediaPath: string | null | undefined,
   currentVideoPath: string | null | undefined,