Initial OSS scaffold from Songs2VID (pre-strip)

lib/titles.ts

@@ -0,0 +1,45 @@
+import { Plan } from "@prisma/client";
+import { hasProFeatures } from "./edition";
+
+export type TitleFields = {
+  /** YouTube video title */
+  title?: string | null;
+  /** On-video song / track title (art-track layouts) */
+  songTitle?: string | null;
+  artist?: string | null;
+};
+
+/** Resolve the title sent to YouTube. Pro may omit video title → `${artist} - ${songTitle}`. */
+export function resolveYouTubeTitle(meta: TitleFields, plan: Plan): string {
+  const videoTitle = meta.title?.trim();
+  if (videoTitle) return videoTitle;
+
+  if (hasProFeatures(plan)) {
+    const artist = meta.artist?.trim();
+    const song = meta.songTitle?.trim();
+    if (artist && song) return `${artist} - ${song}`;
+    if (song) return song;
+    if (artist) return artist;
+  }
+
+  return "";
+}
+
+/** Title burned into art-track layout (never the YouTube-only field alone when songTitle set). */
+export function resolveBurnedSongTitle(
+  meta: TitleFields,
+  fallback = "Untitled",
+): string {
+  return meta.songTitle?.trim() || fallback;
+}
+
+export function validateYouTubeTitle(meta: TitleFields, plan: Plan): string | null {
+  const resolved = resolveYouTubeTitle(meta, plan);
+  if (!resolved) {
+    if (hasProFeatures(plan)) {
+      return "Enter a video title, or both artist and song title for the YouTube fallback";
+    }
+    return "Each video must have a video title";
+  }
+  return null;
+}