The Back button under a post returns to the feed where the reader left it, not its top.

It now walks history like the system Back (whose popstate restores the
scroll place); the profile page's Back does the same.

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

2 files changed, 76 insertions, 2 deletions

diff --git a/src/features/messages.js b/src/features/messages.js
index b696267..73d4c03 100644
--- a/src/features/messages.js
+++ b/src/features/messages.js
@@ -7445,7 +7445,10 @@ export function messagesFeature(ctx) {
       // the public no-wallet surface drops the action row)
       ctx.brandHeader(!ui.pubProf && wallet.loaded),
       h('div', { class: 'card col thread-card', style: 'gap:0;padding:2px 14px' }, ...kids),
-      h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.noteThread = null; render(); } }, t('back')),
+      // a real Back: the history entry under the thread restores the feed
+      // (or profile) and its scroll place; ui-only only when the thread was
+      // opened straight from a link and there is nothing under it
+      h('button', { class: 'btn-ghost btn-block', onClick: () => ctx.goBack(() => { ui.noteThread = null; }) }, t('back')),
       ...noteOverlays());
   }
 
@@ -7911,7 +7914,7 @@ export function messagesFeature(ctx) {
                 h('span', { class: 'spinner sm' }))
             : null);
       })(),
-      h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.profilePk = null; ui.profOverThread = false; ui.pubProf = null; ui.profEdit = null; ui.profEditFilled = false; ui.profCompose = null; render(); } }, t('back')),
+      h('button', { class: 'btn-ghost btn-block', onClick: () => { ui.profCompose = null; ctx.goBack(() => { ui.profilePk = null; ui.profOverThread = false; ui.pubProf = null; ui.profEdit = null; ui.profEditFilled = false; }); } }, t('back')),
       mine ? logoutPop() : null,
       mine ? switchPop() : null,
       ...noteOverlays());
diff --git a/tools/thread-back-scroll-test.js b/tools/thread-back-scroll-test.js
new file mode 100644
index 0000000..b1f63b3
--- /dev/null
+++ b/tools/thread-back-scroll-test.js
@@ -0,0 +1,71 @@
+// The thread page's on-screen Back returns to the feed at the row the reader
+// left, not the top. Run: bun tools/thread-back-scroll-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 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]) => {
+    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.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]);
+  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; });
+  await sleep(1000);
+  await page.evaluate(() => window.scrollTo(0, 2500));
+  await sleep(800);
+  const before = await page.evaluate(() => {
+    const row = [...document.querySelectorAll('.notes-feed > [data-zap-post]')].find((n) => n.getBoundingClientRect().top > 150);
+    return { y: scrollY, key: row.dataset.key, top: row.getBoundingClientRect().top };
+  });
+  assert(before.y > 1500, 'scrolled down the feed: ' + before.y);
+  // open the post: tap its text
+  await page.evaluate((k) => document.querySelector(`.notes-feed > [data-key="${k}"] .note-text, .notes-feed > [data-key="${k}"]`).click(), before.key);
+  await page.waitForSelector('.thread-page', { timeout: 5000 });
+  await sleep(500);
+  await page.evaluate(() => [...document.querySelectorAll('.thread-page > button')].find((b) => /back/i.test(b.textContent)).click());
+  await page.waitForSelector('.notes-feed', { timeout: 5000 });
+  await sleep(800);
+  const after = await page.evaluate((k) => ({ y: scrollY, top: document.querySelector(`.notes-feed > [data-key="${k}"]`)?.getBoundingClientRect().top }), before.key);
+  assert(!(await page.$('.thread-page')), 'the thread closed');
+  assert(after.top != null && Math.abs(after.top - before.top) < 40, `the tapped row is where it was: ${JSON.stringify({ before, after })}`);
+  assert.deepEqual(errors, []);
+  console.log('✓ on-screen Back from a thread returns to the feed at the same place', JSON.stringify({ before, after }));
+} finally { await browser.close(); server.stop(true); }