feat: converge trusted mints on storage events

src/lnurlcash/trustedMintsEvents.ts

@@ -0,0 +1,27 @@
+// Cross-tab storage events are hints only. Subscribers reread the live
+// registry for their active owner rather than projecting event.newValue.
+
+export const TRUSTED_MINTS_STORAGE_KEY = 'sattle_trusted_mints'
+
+const listeners = new Set<() => void>()
+
+export const notifyStoredTrustedMintsChange = (): void => {
+  for (const listener of listeners) listener()
+}
+
+// Each subscription binds its own storage listener and removes exactly it on
+// unsubscribe: no shared reference counting, so an abandoned subscriber can
+// never keep another subscriber's window listener (or runtime) alive.
+export const onStoredTrustedMintsChange = (listener: () => void): (() => void) => {
+  listeners.add(listener)
+  const target = typeof window === 'undefined' ? null : window
+  const onStorage = (event: StorageEvent): void => {
+    if (event.key !== TRUSTED_MINTS_STORAGE_KEY && event.key !== null) return
+    listener()
+  }
+  target?.addEventListener('storage', onStorage)
+  return () => {
+    listeners.delete(listener)
+    target?.removeEventListener('storage', onStorage)
+  }
+}