Initial OSS scaffold from Songs2VID (pre-strip)

lib/entitlements.ts

@@ -0,0 +1,62 @@
+import { Plan } from "@prisma/client";
+import { getPlanLimits } from "./plans";
+import { hasProFeatures } from "./edition";
+import {
+  requiresArtTrackLayoutEntitlement,
+  type LayoutSettings,
+} from "./layout";
+import {
+  PREMIUM_REQUIRED_CODE,
+  requiresCustomWatermarkEntitlement,
+  type WatermarkSettings,
+} from "./watermark";
+
+export class PremiumRequiredError extends Error {
+  readonly code = PREMIUM_REQUIRED_CODE;
+  readonly status = 403;
+  constructor(message: string) {
+    super(message);
+    this.name = "PremiumRequiredError";
+  }
+}
+
+export function assertCustomWatermarkAllowed(plan: Plan, settings: WatermarkSettings) {
+  if (!requiresCustomWatermarkEntitlement(settings)) return;
+  if (getPlanLimits(plan).customWatermark || hasProFeatures(plan)) return;
+  throw new PremiumRequiredError(
+    "Custom watermark, typography, logo overlay, and position controls require Pro.",
+  );
+}
+
+export function assertArtTrackLayoutAllowed(plan: Plan, settings: LayoutSettings) {
+  if (!requiresArtTrackLayoutEntitlement(settings)) return;
+  if (getPlanLimits(plan).artTrackLayouts || hasProFeatures(plan)) return;
+  throw new PremiumRequiredError(
+    "Blurred backgrounds and art-track layout templates require Pro.",
+  );
+}
+
+export function assertPerItemImagesAllowed(
+  plan: Plan,
+  sharedImagePath: string,
+  itemImagePaths: Array<string | null | undefined>,
+) {
+  const unique = new Set(
+    itemImagePaths
+      .map((p) => (p && p.trim() ? p.trim() : sharedImagePath))
+      .filter(Boolean),
+  );
+  // More than one distinct cover in the batch → Pro
+  if (unique.size <= 1) return;
+  if (getPlanLimits(plan).perItemImages || hasProFeatures(plan)) return;
+  throw new PremiumRequiredError(
+    "Matching a unique image to each audio file requires Pro. Free plan uses one shared cover image.",
+  );
+}
+
+export function premiumRequiredResponse(message: string) {
+  return {
+    error: message,
+    code: PREMIUM_REQUIRED_CODE,
+  };
+}