Each post's reply button shows how many replies it has.

Replies (kind 1 and NIP-22 comments) are asked in their own batched #e
request beside the likes/zaps one and counted under every post of the
conversation they name; quotes ('mention') aren't replies, muted authors
aren't counted, and a sent reply counts at once.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01VP5Ljqk7EYcm5QQAbzDwog

2 files changed, 102 insertions, 2 deletions

diff --git a/src/features/messages.js b/src/features/messages.js
index 73d4c03..89e9425 100644
--- a/src/features/messages.js
+++ b/src/features/messages.js
@@ -3131,6 +3131,11 @@ export function messagesFeature(ctx) {
   // ...and, in the same REQ, what else happened to a note: likes (kind 7)
   // and boosts (kind 6). One round trip for all three.
   const NOTE_KINDS = [9735, 9737, 7, 6];
+  // Replies (kind 1, and NIP-22 comments) so the reply button can say how
+  // many — asked separately: relays cap a REQ's answer, and a busy post's
+  // replies must not crowd its likes and zaps out of it.
+  const REPLY_KINDS = [1, 1111];
+  const replyIds = new Map(); // note id -> Map(reply id -> author pubkey)
   const reacts = new Map();  // note id -> Map([emoji, url] -> { emoji, url, who: Set<pubkey> })
   // Resolve from this reaction's own tag: packs can reuse the same shortcode
   // for different pictures, and an unrelated event must not change its face.
@@ -3196,6 +3201,7 @@ export function messagesFeature(ctx) {
   // Where an event about a note goes. A zap receipt is money and has its own
   // bookkeeping (see below); a like and a boost are just tallies of who.
   function noteEvent(ev) {
+    if (ev.kind === 1 || ev.kind === 1111) { noteReply(ev); return; }
     if (ev.kind === 7 || ev.kind === 6) {
       if (seenNoteEv.has(ev.id)) return;
       seenNoteEv.add(ev.id);
@@ -3227,6 +3233,28 @@ export function messagesFeature(ctx) {
     noteReceipt(ev);
   }
 
+  // A reply counts under every post of the conversation it names: NIP-10's
+  // root and reply (or the bare positional e tags of older clients), NIP-22's
+  // E and e. A 'mention' e tag is a quote, not a reply.
+  function noteReply(ev) {
+    let changed = false;
+    for (const x of ev.tags || []) {
+      if (!x[1] || x[1] === ev.id) continue;
+      if (!(x[0] === 'e' || (ev.kind === 1111 && x[0] === 'E')) || x[3] === 'mention') continue;
+      let m = replyIds.get(x[1]);
+      if (!m) replyIds.set(x[1], m = new Map());
+      if (!m.has(ev.id)) { m.set(ev.id, ev.pubkey); changed = true; }
+    }
+    if (changed) scheduleRepaint();
+  }
+  function replyCount(id) {
+    const m = replyIds.get(id);
+    if (!m) return 0;
+    let n = 0;
+    for (const pk of m.values()) if (!hiddenPk(pk)) n++;
+    return n;
+  }
+
   function noteReceipt(ev) {
     const sats = receiptSats(ev);
     if (!sats) return;
@@ -3264,6 +3292,7 @@ export function messagesFeature(ctx) {
       const relays = zapRelays();
       for (let i = 0; i < batch.length; i += 150) {
         const slice = batch.slice(i, i + 150);
+        queryOn(relays, { kinds: REPLY_KINDS, '#e': slice }, 4000).then((evs) => evs.forEach(noteReply)).catch(() => {});
         queryOn(relays, { kinds: NOTE_KINDS, '#e': slice }, 4000)
           .then((evs) => {
             evs.forEach(noteEvent);
@@ -3283,7 +3312,7 @@ export function messagesFeature(ctx) {
       }
       zapRecent = [...batch.reverse(), ...zapRecent.filter((x) => !batch.includes(x))].slice(0, 200);
       if (zapLiveUnsub) { try { zapLiveUnsub(); } catch {} }
-      zapLiveUnsub = subscribeOn(relays, { kinds: NOTE_KINDS, '#e': zapRecent, since: Math.floor(Date.now() / 1000) - 60 }, noteEvent);
+      zapLiveUnsub = subscribeOn(relays, { kinds: [...NOTE_KINDS, ...REPLY_KINDS], '#e': zapRecent, since: Math.floor(Date.now() / 1000) - 60 }, noteEvent);
     }, 250);
   }
   // Tallies are asked of the relays again on every boot, and that takes
@@ -6817,7 +6846,7 @@ export function messagesFeature(ctx) {
     const zapMine = !!((z && z.mine) || optimistic);
     const zapLabel = zapFlying ? t('zapSending') : zapSats ? t('zapTallyTitle', { n: zapSats.toLocaleString() }) : t('zapTitle');
     return h('div', { class: 'row note-acts' },
-      btn(I_REPLY, t('msgReply'), 0, false, () => { if (!signinAsk()) replyToNote(ev); }),
+      btn(I_REPLY, t('msgReply'), replyCount(ev.id), false, () => { if (!signinAsk()) replyToNote(ev); }),
       btn(I_BOOST, t('postBoost'), boostN, iBoosted(ev.id), () => boostNote(ev).catch(() => {})),
       btn(I_QUOTE, t('postQuote'), 0, false, () => { if (!signinAsk()) quoteNote(ev); }),
       // tap to choose how you feel about it; tap again to take it back
@@ -7269,6 +7298,7 @@ export function messagesFeature(ctx) {
     const ok = await publishOn(relays, evt);
     if (!ok) throw new Error(t('msgSendFailed'));
     c.replies = [...c.replies, evt];
+    noteReply(evt); // the count under the post goes up at once
     persistThread(c);
     return evt;
   }
@@ -7276,6 +7306,8 @@ export function messagesFeature(ctx) {
   function threadScreen() {
     const s = ui.noteThread;
     const c = threadFor(s.seed);
+    // the conversation on screen is the best count of its own replies
+    for (const e of c.replies) noteReply(e);
     const boxUnder = (ev) => !!(s.replying || (s.draft || '').trim()) && (ev.id === s.focusId || (!s.focusId && c.root && ev.id === c.root.id));
     const row = (ev) => {
       const focus = ev.id === s.focusId && ev.id !== c.rootId;
diff --git a/tools/reply-count-test.js b/tools/reply-count-test.js
new file mode 100644
index 0000000..659d629
--- /dev/null
+++ b/tools/reply-count-test.js
@@ -0,0 +1,68 @@
+// Each post's reply button carries the number of replies the relays know.
+// Run: bun tools/reply-count-test.js
+import assert from 'node:assert/strict';
+import puppeteer from 'puppeteer-core';
+import { generateSecretKey, finalizeEvent } from 'nostr-tools/pure';
+import { buildHtml } from '../build.js';
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+const sk = generateSecretKey(), now = Math.floor(Date.now() / 1000);
+const notes = Array.from({ length: 40 }, (_, i) => finalizeEvent({ kind: 1, created_at: now - 60 - i * 60, tags: [],
+  content: `Post number ${i}. I walked down to the harbour this morning and watched the boats come in while the coffee went cold in my hands.` }, sk));
+const replier = generateSecretKey();
+const reply = (target, n, tags) => finalizeEvent({ kind: 1, created_at: now - 30 + n, content: 'Reply ' + n, tags }, replier);
+// post 0: two NIP-10 replies and a nested one (its root counts all three);
+// post 1: one positional reply and a quote that is not a reply
+const r1 = reply(notes[0], 1, [['e', notes[0].id, '', 'root']]);
+const replies = [r1, reply(notes[0], 2, [['e', notes[0].id, '', 'root']]),
+  reply(notes[0], 3, [['e', notes[0].id, '', 'root'], ['e', r1.id, '', 'reply']]),
+  reply(notes[1], 4, [['e', notes[1].id]]),
+  reply(notes[1], 5, [['e', notes[1].id, '', 'mention']])];
+const profile = finalizeEvent({ kind: 0, created_at: now, tags: [], content: JSON.stringify({ name: 'Poster' }) }, sk);
+const html = await buildHtml({ minify: true, pwa: false });
+// the public feed's shared snapshot (Popular): the posts arrive over HTTP
+const snapshot = JSON.stringify({ version: 1, generatedAt: Date.now(), notes, profiles: [profile], popUntil: now - 3600 });
+const server = Bun.serve({ port: 0, fetch: (req) => new URL(req.url).pathname === '/api/feed'
+  ? new Response(snapshot, { headers: { 'content-type': 'application/json' } })
+  : new Response(html, { headers: { 'content-type': 'text/html; charset=utf-8' } }) });
+const browser = await puppeteer.launch({ executablePath: '/usr/bin/google-chrome', headless: true, args: ['--no-sandbox'] });
+try {
+  const page = await browser.newPage();
+  const errors = [];
+  page.on('pageerror', (e) => errors.push(String(e)));
+  await page.setViewport({ width: 390, height: 844, isMobile: true, hasTouch: true });
+  await page.setRequestInterception(true);
+  page.on('request', (r) => r.url().startsWith(server.url.origin) ? r.continue() : r.abort());
+  await page.evaluateOnNewDocument(([notes, profile, replies]) => {
+    class FakeSocket extends EventTarget {
+      constructor(url) { super(); this.url = url; this.readyState = 0; this.subs = new Set();
+        setTimeout(() => { this.readyState = 1; this.emit('open', new Event('open')); }, 0); }
+      emit(type, ev) { this.dispatchEvent(ev); this['on' + type]?.(ev); }
+      message(d) { this.emit('message', new MessageEvent('message', { data: JSON.stringify(d) })); }
+      send(raw) {
+        let m; try { m = JSON.parse(raw); } catch { return; }
+        if (m[0] === 'CLOSE') { this.subs.delete(m[1]); return; }
+        if (m[0] !== 'REQ') return;
+        const [, id, f] = m; this.subs.add(id);
+        let evs = [];
+        if (f.kinds?.includes(1) && !f.since) evs = notes.filter((e) => (!f.until || e.created_at <= f.until)
+          && (!f.authors || f.authors.includes(e.pubkey)) && (!f.ids || f.ids.includes(e.id))).slice(0, f.limit || 100);
+        if (f.kinds?.includes(0) && f.authors?.includes(profile.pubkey)) evs = [profile];
+        if (f['#e']) evs = f.kinds?.includes(1) ? replies.filter((r) => r.tags.some((t) => t[0] === 'e' && f['#e'].includes(t[1]))) : [];
+        if (f.ids) evs = notes.filter((e) => f.ids.includes(e.id));
+        setTimeout(() => { if (!this.subs.has(id)) return; for (const e of evs) this.message(['EVENT', id, e]); this.message(['EOSE', id]); }, 30);
+      }
+      close() { this.readyState = 3; this.emit('close', new Event('close')); }
+    }
+    Object.assign(FakeSocket, { CONNECTING: 0, OPEN: 1, CLOSING: 2, CLOSED: 3 });
+    window.WebSocket = FakeSocket;
+  }, [notes, profile, replies]);
+  await page.goto(server.url.origin + '/feed', { waitUntil: 'domcontentloaded' });
+  await page.waitForFunction(() => document.querySelectorAll('.notes-feed > [data-zap-post]').length >= 10, { timeout: 20000 }).catch(async (e) => { console.log(await page.evaluate(() => ({ t: document.body.innerText.slice(0, 600), path: location.pathname, cls: [...document.querySelectorAll("[class*=feed]")].map(e=>e.className).slice(0,10) })), errors); throw e; });
+  const count = (id) => page.evaluate((id) => document.querySelector(`.notes-feed > [data-key="${id}"] .note-acts > .note-act:first-child .note-act-n`)?.textContent || '', id);
+  await page.waitForFunction((id) => document.querySelector(`.notes-feed > [data-key="${id}"] .note-acts > .note-act:first-child .note-act-n`), { timeout: 10000 }, notes[0].id);
+  assert.equal(await count(notes[0].id), '3', 'root post counts its whole conversation');
+  assert.equal(await count(notes[1].id), '1', 'a quote is not a reply');
+  assert.equal(await count(notes[2].id), '', 'no replies, no number');
+  assert.deepEqual(errors, []);
+  console.log('✓ reply buttons show 3 / 1 / nothing');
+} finally { await browser.close(); server.stop(true); }