feat: improve profile cache (again)

packages/app/src/Hooks/useUserProfile.ts

@@ -0,0 +1,21 @@
+import { useEffect, useSyncExternalStore } from "react";
+import { MetadataCache } from "State/Users";
+import { HexKey } from "@snort/nostr";
+import { System } from "System";
+import { UserCache } from "State/Users/UserCache";
+
+export function useUserProfile(pubKey?: HexKey): MetadataCache | undefined {
+  const user = useSyncExternalStore<MetadataCache | undefined>(
+    h => UserCache.hook(h, pubKey),
+    () => UserCache.get(pubKey)
+  );
+
+  useEffect(() => {
+    if (pubKey) {
+      System.TrackMetadata(pubKey);
+      return () => System.UntrackMetadata(pubKey);
+    }
+  }, [pubKey]);
+
+  return user;
+}