v3: follows, notifications, invite-only registration, unread markers

src/utils/visited.ts

@@ -0,0 +1,43 @@
+const DUMP_KEY = "visited_dumps";
+const PLAYLIST_KEY = "visited_playlists";
+const MAX_AGE_MS = 7 * 24 * 60 * 60 * 1000; // 7 days
+
+function loadSet(key: string): Set<string> {
+  try {
+    const raw = localStorage.getItem(key);
+    return raw ? new Set(JSON.parse(raw) as string[]) : new Set();
+  } catch {
+    return new Set();
+  }
+}
+
+function saveSet(key: string, set: Set<string>): void {
+  try {
+    localStorage.setItem(key, JSON.stringify([...set]));
+  } catch { /* quota exceeded — ignore */ }
+}
+
+export function isDumpVisited(id: string): boolean {
+  return loadSet(DUMP_KEY).has(id);
+}
+
+export function isPlaylistVisited(id: string): boolean {
+  return loadSet(PLAYLIST_KEY).has(id);
+}
+
+export function markDumpVisited(id: string): void {
+  const set = loadSet(DUMP_KEY);
+  set.add(id);
+  saveSet(DUMP_KEY, set);
+}
+
+export function markPlaylistVisited(id: string): void {
+  const set = loadSet(PLAYLIST_KEY);
+  set.add(id);
+  saveSet(PLAYLIST_KEY, set);
+}
+
+/** Only items newer than MAX_AGE_MS are eligible to show the unread dot. */
+export function isRecent(createdAt: Date): boolean {
+  return Date.now() - createdAt.getTime() < MAX_AGE_MS;
+}