See the post before you post it.

A draft is written as plain text but doesn't arrive as plain text: a URL
ending in .jpg becomes a picture, a youtu.be link becomes a player, a
nostr: reference becomes the note it points at, an npub becomes a name.
The only way to find out how yours would land was to send it.

The eye beside the paperclip — on the composer and on a reply — opens a
preview. It runs the draft through noteBody, the very renderer the feed
uses, so this isn't a lookalike of the real thing: it IS the real thing,
in a dashed frame with a PREVIEW label so it can never be mistaken for
the post itself. It follows the draft live while it's open (and only
while it's open — a render per keystroke is not free).

Attaching a picture opens it by itself. Showing you what you attached is
the answer to the question attaching it raises, and it costs no tap.

tools/compose-preview-test.js covers both the composer and a reply: the
picture renders rather than sitting there as a URL, the YouTube link
becomes a player, the preview tracks typing, and it puts itself away.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_019mrt228Upn9nNCwGixzSLx

1 files changed, 143 insertions, 0 deletions

diff --git a/tools/compose-preview-test.js b/tools/compose-preview-test.js
new file mode 100644
index 0000000..aac7941
--- /dev/null
+++ b/tools/compose-preview-test.js
@@ -0,0 +1,143 @@
+// A post is written as plain text but doesn't arrive as plain text: a .jpg
+// URL becomes a picture, a youtu.be link becomes a player, a nostr: ref
+// becomes the note it points at. Until now the only way to find out how
+// yours would land was to post it.
+//
+// The preview runs the draft through noteBody — the renderer the feed uses —
+// so it isn't a lookalike, it's the same thing. This checks that what the
+// preview shows is what a real post shows, for the same text.
+//
+// Run: bun tools/compose-preview-test.js
+import puppeteer from 'puppeteer-core';
+import { generateMnemonic } from '@scure/bip39';
+import { wordlist } from '@scure/bip39/wordlists/english';
+import { cacheKeyFor } from '../src/wallet.js';
+import { buildHtml } from '../build.js';
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+let ok = true;
+const check = (n, c, d = '') => { console.log(` ${c ? '✓' : '✗'} ${n}${d ? ' — ' + d : ''}`); if (!c) ok = false; };
+
+const html = await buildHtml({ minify: true, pwa: false });
+const server = Bun.serve({ port: 5294, fetch: () => new Response(html, { headers: { 'content-type': 'text/html' } }) });
+const browser = await puppeteer.launch({ executablePath: '/usr/bin/google-chrome', headless: 'new', args: ['--no-sandbox'] });
+const page = await browser.newPage();
+const errs = [];
+page.on('pageerror', (e) => errs.push(String(e)));
+const click = (t) => page.evaluate((x) => { const e = [...document.querySelectorAll('button')].find((n) => n.textContent.trim().toLowerCase().includes(x)); if (e) { e.click(); return true; } return false; }, t);
+const waitText = async (x, ms = 25000) => { for (let i = 0; i < ms / 250; i++) { if ((await page.evaluate(() => document.body.innerText)).toLowerCase().includes(x)) return true; await sleep(250); } return false; };
+const type = (sel, v) => page.evaluate((s, val) => {
+  const e = document.querySelector(s);
+  if (!e) return false;
+  e.focus(); e.value = val;
+  e.dispatchEvent(new Event('input', { bubbles: true }));
+  return true;
+}, sel, v);
+
+const DRAFT = 'look at this https://coinos.io/punks/7.webp and this https://youtu.be/dQw4w9WgXcQ';
+
+try {
+  await page.setViewport({ width: 390, height: 844 });
+  await page.goto('http://localhost:5294/', { waitUntil: 'domcontentloaded' });
+  await page.evaluate(() => localStorage.setItem('btc-wallet-network', 'regtest'));
+  await page.reload({ waitUntil: 'domcontentloaded' });
+  await sleep(400);
+  await click('create a new wallet'); await sleep(500);
+  await click('import existing'); await sleep(400);
+  await page.waitForSelector('textarea');
+  const mn = generateMnemonic(wordlist);
+  await page.type('textarea', mn);
+  await click('open wallet');
+  await waitText('receive', 20000);
+  // a post in the feed, so there is something to reply to
+  const base = cacheKeyFor(mn + '\n');
+  await page.evaluate(([k, n]) => {
+    localStorage.setItem(k + ':follows', JSON.stringify({ tags: [['p', n.pubkey]], c: '', at: Math.floor(Date.now() / 1000) }));
+    localStorage.setItem(k + ':feedNotes', JSON.stringify([n]));
+  }, [base, {
+    id: 'f'.repeat(63) + '1', pubkey: '3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d',
+    kind: 1, created_at: Math.floor(Date.now() / 1000) - 60, content: 'a post to answer', tags: [],
+  }]);
+  await page.reload({ waitUntil: 'domcontentloaded' });
+  await waitText('receive', 20000);
+
+  // into the feed, where posts are written
+  await page.evaluate(() => { const b = [...document.querySelectorAll('button')].find((e) => /message/i.test(e.getAttribute('aria-label') || '')); if (b) b.click(); });
+  await sleep(1000);
+  await page.evaluate(() => { const e = [...document.querySelectorAll('.item')].find((n) => /feed/i.test(n.textContent)); if (e) e.click(); });
+  await sleep(2500);
+  const opened = await click('new post');
+  check('the composer opens', opened && !!(await page.$('textarea')));
+
+  await type('textarea', DRAFT);
+  await sleep(400);
+  check('no preview until it is asked for', !(await page.$('.draft-preview')));
+
+  await page.evaluate(() => [...document.querySelectorAll('button')]
+    .find((b) => /preview/i.test(b.getAttribute('aria-label') || ''))?.click());
+  await sleep(2500);
+  const shown = await page.evaluate(() => {
+    const p = document.querySelector('.draft-preview');
+    if (!p) return null;
+    return {
+      imgs: [...p.querySelectorAll('img')].map((i) => i.getAttribute('src') || i.src).filter(Boolean),
+      yt: !!p.querySelector('.yt-embed'),
+      text: p.innerText,
+    };
+  });
+  check('the preview appears', !!shown);
+  check('...with the picture rendered, not its URL', !!shown && shown.imgs.some((u) => /punks\/7\.webp/.test(u)),
+    shown ? shown.imgs.length + ' image(s)' : '');
+  check('...and the YouTube link as a player', !!shown && shown.yt);
+  check('...and the raw URLs are not left lying in the text', !!shown && !shown.text.includes('https://youtu.be/'),
+    shown ? JSON.stringify(shown.text.slice(0, 60)) : '');
+
+  // live: keep typing and the preview follows
+  await type('textarea', DRAFT + ' plus a word');
+  await sleep(900);
+  check('it follows the draft as you type',
+    /plus a word/.test(await page.evaluate(() => (document.querySelector('.draft-preview') || {}).innerText || '')));
+
+  // and it puts itself away
+  await page.evaluate(() => [...document.querySelectorAll('button')]
+    .find((b) => /hide preview/i.test(b.getAttribute('aria-label') || ''))?.click());
+  await sleep(500);
+  check('and it closes again', !(await page.$('.draft-preview')));
+
+  // ---- and the same thing on a reply -------------------------------------
+  await click('cancel');
+  await sleep(400);
+  // open a thread: any post in the feed does
+  const intoThread = await page.evaluate(() => {
+    const r = document.querySelector('.notes-feed > .row');
+    if (!r) return false;
+    r.click();
+    return true;
+  });
+  if (!intoThread) {
+    console.log(' — no post in the feed to reply to, skipping the reply half');
+  } else {
+    await sleep(2500);
+    const box = await page.$('.thread-reply-input');
+    check('a thread has a reply box', !!box);
+    if (box) {
+      await type('.thread-reply-input', 'my answer https://coinos.io/punks/3.webp');
+      await sleep(300);
+      check('a reply has no preview until asked either', !(await page.$('.draft-preview')));
+      await page.evaluate(() => [...document.querySelectorAll('button')]
+        .find((b) => /^preview$/i.test(b.getAttribute('aria-label') || ''))?.click());
+      await sleep(1500);
+      const rp = await page.evaluate(() => {
+        const p = document.querySelector('.draft-preview');
+        return p ? { imgs: p.querySelectorAll('img').length, text: p.innerText } : null;
+      });
+      check('the reply previews the same way', !!rp && rp.imgs > 0,
+        rp ? rp.imgs + ' image(s)' : 'no preview');
+      check('...showing the picture instead of its URL', !!rp && !rp.text.includes('punks/3.webp'),
+        rp ? JSON.stringify(rp.text.slice(0, 50)) : '');
+    }
+  }
+
+  check('no page errors', errs.length === 0, errs.slice(0, 2).join(' | '));
+} finally { await browser.close(); server.stop(true); }
+console.log(ok ? '\n✅ what you see is what they get' : '\n❌ failed');
+process.exit(ok ? 0 : 1);