Add network reaction counts to note cards

- fetchReactionCount (kind 7 #e filter) in nostr lib
- useReactionCount hook with module-level cache to avoid refetching
- NoteCard shows count next to like button; increments optimistically on like
- Falls back to "like"/"liked" text when count is zero or still loading

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/feed/NoteCard.tsx

@@ -1,6 +1,7 @@
 import { useState, useRef } from "react";
 import { NDKEvent } from "@nostr-dev-kit/ndk";
 import { useProfile } from "../../hooks/useProfile";
+import { useReactionCount } from "../../hooks/useReactionCount";
 import { useUserStore } from "../../stores/user";
 import { useUIStore } from "../../stores/ui";
 import { timeAgo, shortenPubkey } from "../../lib/utils";
@@ -27,6 +28,7 @@ export function NoteCard({ event }: NoteCardProps) {
   };
   const [liked, setLiked] = useState(() => getLiked().has(event.id));
   const [liking, setLiking] = useState(false);
+  const [reactionCount, adjustReactionCount] = useReactionCount(event.id);
   const [showReply, setShowReply] = useState(false);
   const [replyText, setReplyText] = useState("");
   const [replying, setReplying] = useState(false);
@@ -43,6 +45,7 @@ export function NoteCard({ event }: NoteCardProps) {
       liked.add(event.id);
       localStorage.setItem(likedKey, JSON.stringify(Array.from(liked)));
       setLiked(true);
+      adjustReactionCount(1);
     } finally {
       setLiking(false);
     }
@@ -134,7 +137,7 @@ export function NoteCard({ event }: NoteCardProps) {
                   liked ? "text-accent" : "text-text-dim hover:text-accent"
                 } disabled:cursor-default`}
               >
-                {liked ? "♥ liked" : "♡ like"}
+                {liked ? "♥" : "♡"}{reactionCount !== null && reactionCount > 0 ? ` ${reactionCount}` : liked ? " liked" : " like"}
               </button>
             </div>
           )}

src/hooks/useReactionCount.ts

@@ -0,0 +1,29 @@
+import { useEffect, useState } from "react";
+import { fetchReactionCount } from "../lib/nostr";
+
+const cache = new Map<string, number>();
+
+export function useReactionCount(eventId: string): [number | null, (delta: number) => void] {
+  const [count, setCount] = useState<number | null>(() => cache.get(eventId) ?? null);
+
+  useEffect(() => {
+    if (cache.has(eventId)) {
+      setCount(cache.get(eventId)!);
+      return;
+    }
+    fetchReactionCount(eventId).then((n) => {
+      cache.set(eventId, n);
+      setCount(n);
+    });
+  }, [eventId]);
+
+  const adjust = (delta: number) => {
+    setCount((prev) => {
+      const next = (prev ?? 0) + delta;
+      cache.set(eventId, next);
+      return next;
+    });
+  };
+
+  return [count, adjust];
+}

src/lib/nostr/client.ts

@@ -191,6 +191,18 @@ export async function fetchUserNotes(pubkey: string, limit = 30): Promise<NDKEve
   return Array.from(events).sort((a, b) => (b.created_at ?? 0) - (a.created_at ?? 0));
 }
 
+export async function fetchReactionCount(eventId: string): Promise<number> {
+  const instance = getNDK();
+  const filter: NDKFilter = {
+    kinds: [NDKKind.Reaction],
+    "#e": [eventId],
+  };
+  const events = await instance.fetchEvents(filter, {
+    cacheUsage: NDKSubscriptionCacheUsage.ONLY_RELAY,
+  });
+  return events.size;
+}
+
 export async function publishContactList(pubkeys: string[]): Promise<void> {
   const instance = getNDK();
   if (!instance.signer) throw new Error("Not logged in");

src/lib/nostr/index.ts

@@ -1 +1 @@
-export { getNDK, connectToRelays, fetchGlobalFeed, fetchFollowFeed, fetchReplies, publishNote, publishArticle, publishProfile, publishReaction, publishReply, publishContactList, fetchUserNotes, fetchProfile } from "./client";
+export { getNDK, connectToRelays, fetchGlobalFeed, fetchFollowFeed, fetchReplies, publishNote, publishArticle, publishProfile, publishReaction, publishReply, publishContactList, fetchReactionCount, fetchUserNotes, fetchProfile } from "./client";