open-standards/wai/quantum-studio/test/studio.test.mjs

// The Studio in the installed browser, as a reader uses it:
//
//   node build.mjs --pkg PATH/TO/ENGINE/PKG && node test/studio.test.mjs
//
// Serves dist/ (with the engine package in dist/pkg/); the page's index.html names the
// live job service, https://wai.transaction.science/quantum-jobs, which the service checks use.
//   - the first example loads; the program is linted, drawn and planned as it is typed;
//   - it runs in this browser: the stabilizer tableau, only 00 and 11, ⟨Z0 Z1⟩ = 1, the
//     receipt checked here and signed by this browser's key;
//   - an error in the program is marked on its line;
//   - a rotation runs on the state vector, ⟨Z0⟩ = cos 0.3;
//   - the same Bell job on the service gives the counts run here, shot for shot, and its
//     receipt checks here as the service's (left out with STUDIO_SKIP_SERVICE=1);
//   - Ctrl+Enter in the editor runs; the program and the history survive a reload;
//   - the critique: its measures as the program changes and their change since the last
//     run; a smell named with its lines, flagged on the diagram, shown, and fixed by the
//     engine's rewrite, checked the same circuit;
//   - Alternatives: Improve offers the engine's rewrite checked equivalent, plotted and
//     applied; Explore without a model says it needs one;
//   - the classical-shortcut lens: a Clifford ring with a closing rotation layer priced by
//     the cut-rank sum, a Clifford circuit easy at any width, a contraction searched only
//     when thorough, and a check marked stale once the program changes;
//   - predict first: the form stops a run until the reader predicts, refuses an outcome of
//     the wrong width, and sets the prediction against the counts;
//   - the assistant, against a scripted model server: a tool call run on the engine, a
//     proposal the engine cannot read sent back with its reason, the corrected one checked
//     and run before it is offered, and Apply; it asks questions first by default and speaks
//     only when asked; offering a hint after refused runs only when the reader allows it,
//     and never asking the model itself; Improve and Explore with the model, each candidate
//     read, measured and compared by the engine, a rewrite that is not the same circuit
//     left out with its reason;
//   - no console error and no failed request; at a phone's width nothing scrolls sideways.
// Exit 0 iff every check passes.
import { createServer } from 'node:http';
import { existsSync, mkdirSync, readFileSync, statSync } from 'node:fs';
import { dirname, extname, join, normalize, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

const { chromium } = (await import(process.env.WAI_E2E_DRIVER ?? 'playwright')).default;
const DIST = resolve(dirname(fileURLToPath(import.meta.url)), '..', 'dist');
const SHOTS = resolve(dirname(fileURLToPath(import.meta.url)), 'screenshots');
const TYPES = { '.html': 'text/html; charset=utf-8', '.js': 'text/javascript', '.css': 'text/css', '.wasm': 'application/wasm', '.json': 'application/json' };
const server = createServer((req, res) => {
  let file = normalize(join(DIST, decodeURIComponent(new URL(req.url, 'http://x').pathname)));
  if (!file.startsWith(DIST)) { res.writeHead(403).end(); return; }
  if (existsSync(file) && statSync(file).isDirectory()) file = join(file, 'index.html');
  if (!existsSync(file)) { res.writeHead(404).end('not found'); return; }
  res.writeHead(200, { 'content-type': TYPES[extname(file)] ?? 'application/octet-stream' });
  res.end(readFileSync(file));
});
await new Promise((r) => server.listen(0, '127.0.0.1', r));
const ORIGIN = `http://127.0.0.1:${server.address().port}`;
let fails = 0;
const check = (ok, what) => { console.log(`${ok ? 'PASS' : 'FAIL'}  ${what}`); if (!ok) fails += 1; };
const LONG = 120_000;
const browser = await chromium.launch({ channel: process.env.WAI_E2E_CHANNEL ?? 'chrome', headless: true });

async function open(viewport = { width: 1400, height: 950 }) {
  const ctx = await browser.newContext({ viewport, colorScheme: 'dark' });
  const page = await ctx.newPage();
  const seen = { errors: [], failed: [] };
  page.on('console', (m) => { if (m.type() === 'error') seen.errors.push(m.text()); });
  page.on('pageerror', (e) => seen.errors.push(String(e)));
  page.on('requestfailed', (r) => seen.failed.push(`${r.url()} (${r.failure()?.errorText})`));
  page.on('response', (r) => { if (r.status() >= 400) seen.failed.push(`${r.url()} (${r.status()})`); });
  await page.goto(ORIGIN + '/', { waitUntil: 'domcontentloaded' });
  return { ctx, page, seen };
}
const done = (page) => page.waitForFunction(() => !/^Running|^On the service/.test(document.querySelector('.qs-status')?.textContent ?? '') && document.querySelector('#qs-run') && !document.querySelector('#qs-run').disabled, null, { timeout: LONG });
const verified = (page) => page.waitForFunction(() => /verifies|does not verify|not checked/.test(document.querySelector('#qs-verified')?.textContent ?? ''), null, { timeout: LONG });
const counts = (page) => page.$$eval('.qs-bar', (bs) => bs.map((b) => [b.querySelector('.qs-key').textContent, b.querySelector('.qs-n').textContent]));

const { ctx, page, seen } = await open();
await page.waitForFunction(() => /qubits/.test(document.querySelector('#qs-lint')?.textContent ?? ''), null, { timeout: LONG });
check((await page.textContent('#qs-lint')) === '2 qubits · 2 gates', `the first example is linted as the engine reads it (${await page.textContent('#qs-lint')})`);
await page.waitForFunction(() => document.querySelector('#qs-circuit')?.textContent.includes('⊕'), null, { timeout: LONG });
const drawing = await page.textContent('#qs-circuit');
check(/q0: .*H.*●/.test(drawing) && /q1: .*⊕/.test(drawing), 'the circuit is drawn as the program is typed');
const svg = await page.$eval('#qs-diagram svg', (g) => ({ label: g.getAttribute('aria-label'), rings: g.querySelectorAll('.qc-ring').length, dots: g.querySelectorAll('.qc-dot').length, joins: g.querySelectorAll('.qc-join').length, meters: g.querySelectorAll('.qc-measure').length }));
check(svg.rings === 1 && svg.dots === 1 && svg.joins === 1 && svg.meters === 2 && /2 qubits/.test(svg.label), `the circuit is drawn as a diagram with a text alternative (${JSON.stringify(svg)})`);
await page.click('#qs-astext');
check(await page.isVisible('#qs-circuit') && await page.isHidden('#qs-diagram'), '“Text” shows the circuit as text to copy');
await page.click('#qs-astext');
await page.waitForFunction(() => /Stabilizer tableau/.test(document.querySelector('#qs-plan')?.textContent ?? ''), null, { timeout: LONG });
check(true, `the plan is shown before running (${await page.textContent('#qs-plan')})`);

await page.click('#qs-run');
await done(page);
await verified(page);
check((await page.textContent('.qs-method')) === 'Stabilizer tableau', 'run in this browser: the stabilizer tableau');
const here = await counts(page);
check(here.length === 2 && here.every(([k]) => k === '00' || k === '11'), `only 00 and 11 (${JSON.stringify(here)})`);
const zz = await page.$$eval('.qs-table tbody tr', (rs) => rs.map((r) => r.textContent));
check(zz.some((t) => t.startsWith('⟨Z0 Z1⟩') && t.includes('1.000000')), `⟨Z0 Z1⟩ = 1 (${zz.slice(0, 2).join(' | ')})`);
check((await page.textContent('#qs-verified')).startsWith('✓ verifies'), `the receipt verifies, checked here (${await page.textContent('#qs-verified')})`);
check((await page.textContent('#qs-signed-by')).startsWith('this browser’s key did:key:z6Mk'), `signed by this browser's key (${await page.textContent('#qs-signed-by')})`);
check((await page.$$('.qs-hitem')).length === 1, 'the run is in the history');
// What it looks like, for a reader of the change: the dark scheme and the light.
mkdirSync(SHOTS, { recursive: true });
await page.screenshot({ path: join(SHOTS, 'studio-dark.png'), fullPage: true });
await page.emulateMedia({ colorScheme: 'light' });
await page.screenshot({ path: join(SHOTS, 'studio-light.png'), fullPage: true });
await page.emulateMedia({ colorScheme: 'dark' });

// An error is marked on its line.
await page.click('.qs-editor .cm-content');
await page.keyboard.press('ControlOrMeta+End');
await page.keyboard.type('\nfoo q[0];');
await page.waitForFunction(() => document.querySelector('#qs-lint')?.textContent === 'problem', null, { timeout: LONG });
await page.waitForSelector('.cm-lintRange-error', { timeout: LONG });
check(true, 'an unknown gate is marked in the editor');
for (let i = 0; i < 10; i++) await page.keyboard.press('Backspace');
await page.waitForFunction(() => /qubits/.test(document.querySelector('#qs-lint')?.textContent ?? ''), null, { timeout: LONG });

// A rotation: any angle, on the state vector.
await page.selectOption('#qs-example', 'rotation');
await page.waitForFunction(() => /State vector/.test(document.querySelector('#qs-plan')?.textContent ?? ''), null, { timeout: LONG });
await page.click('#qs-run');
await done(page);
const z = await page.$$eval('.qs-table tbody tr', (rs) => rs.map((r) => r.textContent));
check((await page.textContent('.qs-method')) === 'State vector, double precision' && z.some((t) => t.startsWith('⟨Z0⟩') && t.includes(Math.cos(0.3).toFixed(6))), `rx(0.3) on the state vector, ⟨Z0⟩ = cos 0.3 (${z[0]})`);

// The same Bell job on the service, and here: the same counts.
// (STUDIO_SKIP_SERVICE=1 leaves it out, where a build may not reach the service.)
if (process.env.STUDIO_SKIP_SERVICE) {
  console.log('SKIP  the service checks (STUDIO_SKIP_SERVICE)');
} else {
  await page.selectOption('#qs-example', 'bell');
  await page.click('#qs-run'); await done(page); await verified(page);
  const local = await counts(page);
  await page.click('.qs-seg[data-where=service]');
  await page.click('#qs-run'); await done(page); await verified(page);
  const remote = await counts(page);
  check(JSON.stringify(remote) === JSON.stringify(local), `the service gives the counts run here, shot for shot (${JSON.stringify(remote)})`);
  check((await page.textContent('#qs-signed-by')).startsWith('the service’s key') && (await page.textContent('#qs-verified')).startsWith('✓ verifies'), `the service's receipt checks here, as the service's (${await page.textContent('#qs-signed-by')})`);
  await page.click('.qs-seg[data-where=local]');

}

// Ctrl+Enter runs; the program and the history survive a reload. (A job run again
// unchanged gives the same signed result, which the history keeps once; so this one
// asks for other shots.)
const before = (await page.$$('.qs-hitem')).length;
await page.fill('#qs-shots', '321');
await page.click('.qs-editor .cm-content');
await page.keyboard.press('ControlOrMeta+Enter');
await done(page);
check((await page.$$('.qs-hitem')).length === before + 1, 'Ctrl+Enter in the editor runs the program');
const program = await page.evaluate(() => window.quantumStudio.view.state.doc.toString());
await page.reload({ waitUntil: 'domcontentloaded' });
await page.waitForFunction(() => /qubits/.test(document.querySelector('#qs-lint')?.textContent ?? ''), null, { timeout: LONG });
check((await page.evaluate(() => window.quantumStudio.view.state.doc.toString())) === program, 'the program survives a reload');
await page.waitForFunction((n) => document.querySelectorAll('.qs-hitem').length >= n, before + 1, { timeout: LONG });
check(true, 'the history survives a reload');

// The critique, as the program changes.
const doc = () => page.evaluate(() => window.quantumStudio.view.state.doc.toString());
const setProgram = async (q) => { await page.evaluate((q) => window.quantumStudio.fill({ qasm: q }), q); await page.waitForFunction((q) => window.quantumStudio.view.state.doc.toString() === q, q); };
const chip = (k) => page.$eval(`#qs-measures [data-k=${k}]`, (c) => c.textContent).catch(() => '');
{
  await page.selectOption('#qs-example', 'bell');
  await page.waitForFunction(() => /2 gates/.test(document.querySelector('#qs-measures')?.textContent ?? ''), null, { timeout: LONG });
  const m = await page.textContent('#qs-measures');
  check(/2 qubits/.test(m) && /1 two-qubit/.test(m) && await page.isVisible('#qs-clifford') && /fidelity, modelled/.test(m) && (await page.$$('#qs-smells li')).length === 0,
    `the critique gives the Bell pair's measures, that it is Clifford, a modelled fidelity, and no smells (${m})`);
  const SMELLY = 'OPENQASM 3.0;\nqubit[2] q;\nbit[2] c;\nh q[0];\nx q[1];\nx q[1];\ncx q[0], q[1];\nc = measure q;\n';
  await setProgram(SMELLY);
  await page.waitForSelector('.qs-smell[data-kind=cancels]', { timeout: LONG });
  const smell = await page.textContent('.qs-smell[data-kind=cancels] .qs-smell-text');
  check(smell === 'x on qubit 1 twice in a row (lines 5 and 6): together they do nothing', `a smell is named with its lines (${smell})`);
  check((await page.$$('#qs-diagram .qc-item.qc-flag')).length === 2, 'its two gates are flagged on the diagram');
  await page.hover('.qs-smell[data-kind=cancels]');
  check((await page.$$('#qs-diagram .qc-item.qc-smell')).length === 2 && (await page.$$('#qs-diagram .qc-wire.qc-smell')).length === 0, 'pointing at the smell marks its gates, and not their wires');
  await page.click('.qs-smell[data-kind=cancels] button >> text=Show');
  const sel = await page.evaluate(() => { const v = window.quantumStudio.view, d = v.state.doc, r = v.state.selection.main; return [r.from === d.line(5).from, r.to === d.line(6).to]; });
  check(sel[0] && sel[1], 'Show selects its lines in the editor');
  await page.click('#qs-run'); await done(page);
  await page.click('.qs-smell[data-kind=cancels] .qs-fix');
  await page.waitForFunction(() => !/x q\[1\];/.test(window.quantumStudio.view.state.doc.toString()), null, { timeout: LONG });
  const shows = await page.textContent('#qs-shows');
  check(/^Fixed: x on qubit 1/.test(shows) && /same tableau/.test(shows), `Fix applies the engine's rewrite, checked the same circuit (${shows})`);
  await page.waitForFunction(() => /−2/.test(document.querySelector('#qs-measures [data-k=gates]')?.textContent ?? ''), null, { timeout: LONG });
  check(true, `the measures show their change since the last run (${await chip('gates')})`);
  await page.click('.qs-editor .cm-content');
  await page.keyboard.press('ControlOrMeta+z');
  await page.waitForFunction((q) => window.quantumStudio.view.state.doc.toString() === q, SMELLY, { timeout: LONG });
  check(true, 'Undo brings the fixed lines back');
  await setProgram('OPENQASM 3.0;\nqubit[3] q;\nbit[1] c;\nh q[0];\nc[0] = measure q[0];\n');
  await page.waitForSelector('.qs-smell[data-kind=idle]', { timeout: LONG });
  check((await page.$$('#qs-diagram .qc-wire.qc-flag')).length === 2 && !(await page.$('.qs-smell[data-kind=idle] .qs-fix')), 'qubits nothing uses are flagged on their wires, with no Fix');
}

// Alternatives: Improve, without a model; Explore says it needs one.
{
  const MERGE = 'OPENQASM 3.0;\nqubit[1] q;\nbit[1] c;\nh q[0];\nrz(0.25) q[0];\nrz(0.5) q[0];\nc[0] = measure q[0];\n';
  await setProgram(MERGE);
  await page.click('#qs-improve');
  await page.waitForSelector('.qs-cand', { timeout: LONG });
  const card = await page.textContent('.qs-cand');
  check(/the engine/.test(card) && /same circuit · on every basis state/.test(card) && /2 gates/.test(card), `Improve offers the engine's rewrite, checked on every basis state (${card.slice(0, 160)})`);
  check(await page.isVisible('#qs-atlas') && (await page.$$('#qs-atlas .qs-dot')).length === (await page.$$('.qs-cand')).length && (await page.$$('#qs-atlas .qs-ring')).length === 1, 'the atlas plots the draft and each alternative');
  check(/Connect a model/.test(await page.textContent('#qs-alt-body')), 'without a model, Improve says the engine’s are the only ones');
  check((await doc()) === MERGE, 'nothing changes the program until an alternative is applied');
  await page.click('.qs-cand .qs-apply');
  check(/rz\(0\.25 \+ 0\.5\) q\[0\];/.test(await doc()), 'Apply puts the alternative in the editor');
  await page.click('#qs-explore');
  await page.waitForSelector('#qs-alt-nomodel', { timeout: LONG });
  check(true, 'Explore without a model says it needs one');
}

// The classical-shortcut lens.
{
  let RING = 'OPENQASM 3.0;\nqubit[16] q;\nbit[16] c;\nh q;\n';
  for (let i = 0; i < 16; i++) RING += `cz q[${i}], q[${(i + 1) % 16}];\n`;
  RING += 'rz(0.3) q;\nc = measure q;\n';
  await setProgram(RING);
  await page.click('#qs-shortcuts');
  await page.waitForSelector('#qs-shortcuts-summary', { timeout: LONG });
  const summary = await page.textContent('#qs-shortcuts-summary');
  const cut = await page.textContent('#qs-routes tr[data-route=cutrank]');
  check(/cut-rank sum/.test(summary) && /widest cut 2 bits/.test(cut) && await page.$('#qs-routes tr.best[data-route=cutrank]') && /does not apply/.test(await page.textContent('#qs-routes tr[data-route=stabilizer]')),
    `the lens prices a Clifford ring with a closing layer by the cut-rank sum (${summary})`);
  check(/not searched/.test(await page.textContent('#qs-routes tr[data-route=tensor_network]')), 'the quick check leaves the contraction search for a thorough one');
  await page.click('#qs-shortcuts-thorough');
  await page.waitForFunction(() => /2\^/.test(document.querySelector('#qs-routes tr[data-route=tensor_network]')?.textContent ?? ''), null, { timeout: LONG });
  check(true, `a thorough check searches a contraction tree (${(await page.textContent('#qs-routes tr[data-route=tensor_network]')).trim()})`);
  await page.click('.qs-editor .cm-content');
  await page.keyboard.press('ControlOrMeta+End');
  await page.keyboard.type('\nh q[0];');
  await page.waitForSelector('#qs-shortcuts-panel.stale .qs-stale-note', { timeout: LONG });
  check(true, 'a check is marked stale once the program changes');
  await page.selectOption('#qs-example', 'bell');
  await page.waitForFunction(() => /2 gates/.test(document.querySelector('#qs-measures')?.textContent ?? ''), null, { timeout: LONG });
  await page.click('#qs-shortcuts');
  await page.waitForFunction(() => /^Classically easy at any width/.test(document.querySelector('#qs-shortcuts-summary')?.textContent ?? '') && !document.querySelector('#qs-shortcuts-panel.stale'), null, { timeout: LONG });
  check(true, 'a Clifford circuit is classically easy at any width');
}

// Predict first.
{
  await page.selectOption('#qs-example', 'bell');
  await page.check('#qs-predict-first');
  const ran = (await page.$$('.qs-hitem')).length;
  await page.click('#qs-run');
  await page.waitForSelector('#qs-predict', { timeout: LONG });
  check((await page.$$('.qs-hitem')).length === ran && !(await page.$('.qs-method')), 'with Predict first, the run waits for a prediction');
  await page.fill('#qs-predict-bits', '000');
  await page.fill('#qs-predict-share', '50');
  await page.click('#qs-predict-run');
  check(/2 classical bits; the outcome has 3/.test(await page.textContent('#qs-predict-note')), 'an outcome of the wrong width is refused, with the width');
  await page.fill('#qs-predict-bits', '00');
  await page.click('#qs-predict-run');
  await done(page);
  await page.waitForSelector('#qs-predicted', { timeout: LONG });
  const pred = await page.textContent('#qs-predicted');
  check(/you said00 in 50%/.test(pred) && /the run00 in \d/.test(pred) && /(came out on top|Another outcome)/.test(pred) && /first prediction/.test(pred), `the prediction is set against the counts (${pred})`);
  await page.uncheck('#qs-predict-first');
}
// The assistant, against a scripted model server: it calls a tool, proposes a program
// the engine cannot read, gets the engine's reason back, and proposes a corrected one,
// which the Studio checks and runs before offering it.
{
  const asked = [];
  const GOOD = 'OPENQASM 3.0;\nqubit[2] q;\nbit[2] c;\nh q[0];\ncx q[0], q[1];\nc = measure q;\n';
  const model = createServer((req, res) => {
    const cors = { 'access-control-allow-origin': '*', 'access-control-allow-headers': 'content-type', 'access-control-allow-methods': 'GET, POST, OPTIONS' };
    if (req.method === 'OPTIONS') { res.writeHead(204, cors).end(); return; }
    if (req.url.endsWith('/models')) { res.writeHead(200, { ...cors, 'content-type': 'application/json' }).end(JSON.stringify({ data: [{ id: 'scripted' }] })); return; }
    let body = '';
    req.on('data', (c) => (body += c));
    req.on('end', () => {
      const r = JSON.parse(body);
      asked.push(r);
      const msgs = r.messages;
      // Alternatives' calls carry no tools: candidates, one of them wrong on purpose.
      if (!r.tools) {
        const want = msgs[1].content;
        const content = /^Write \d+ programs that are the same circuit/.test(want)
          ? 'Idea: the two Hadamards cancel, and the X moves past the CNOT.\n```qasm\nOPENQASM 3.0;\nqubit[2] q;\nbit[2] c;\ncx q[0], q[1];\nx q[1];\nc = measure q;\n```\nIdea: drop the X.\n```qasm\nOPENQASM 3.0;\nqubit[2] q;\nbit[2] c;\ncx q[0], q[1];\nc = measure q;\n```'
          : 'Idea: a GHZ state on three qubits.\n```qasm\nOPENQASM 3.0;\nqubit[3] q;\nbit[3] c;\nh q[0];\ncx q[0], q[1];\ncx q[1], q[2];\nc = measure q;\n```\n**Idea:** entangle with CZ instead.\n```qasm\nOPENQASM 3.0;\nqubit[2] q;\nbit[2] c;\nh q[0];\nh q[1];\ncz q[0], q[1];\nh q[1];\nc = measure q;\n```';
        res.writeHead(200, { ...cors, 'content-type': 'application/json' }).end(JSON.stringify({ choices: [{ message: { role: 'assistant', content }, finish_reason: 'stop' }] }));
        return;
      }
      const told = msgs.some((m) => m.role === 'user' && /could not read the program you proposed/.test(m.content));
      const toolDone = msgs.some((m) => m.role === 'tool');
      let message;
      if (!toolDone) message = { role: 'assistant', content: '', tool_calls: [{ id: 'c1', type: 'function', function: { name: 'lint_qasm', arguments: JSON.stringify({ qasm: GOOD }) } }] };
      else if (!told) message = { role: 'assistant', content: 'It entangles two qubits. A variant:\n```qasm\nOPENQASM 3.0;\nqubit[2] q;\nfoo q[0];\n```' };
      else message = { role: 'assistant', content: 'Corrected:\n```qasm\n' + GOOD + '```' };
      res.writeHead(200, { ...cors, 'content-type': 'application/json' }).end(JSON.stringify({ choices: [{ message, finish_reason: message.tool_calls ? 'tool_calls' : 'stop' }], usage: { prompt_tokens: 100, completion_tokens: 20, total_tokens: 120 } }));
    });
  });
  await new Promise((r) => model.listen(0, '127.0.0.1', r));
  await page.click('#qs-ai-gear');
  await page.fill('#qs-ai-endpoint', `http://127.0.0.1:${model.address().port}/v1`);
  await page.click('#qs-ai-connect');
  await page.waitForFunction(() => /connected · scripted/.test(document.querySelector('#qs-ai-state')?.textContent ?? ''), null, { timeout: LONG });
  check(true, 'the assistant connects to a model server and reads its models');
  await page.click('.qs-ai-quick button >> text=Explain this circuit');
  await page.waitForSelector('.qs-ai-apply', { timeout: LONG });
  const log = await page.$$eval('#qs-ai-log > li', (ls) => ls.map((l) => l.textContent));
  check(log.some((t) => t.includes('used lint_qasm')), 'the model\'s tool call ran on the engine, and the log shows it');
  check(log.some((t) => /could not read the proposed program \(line 3: unknown gate foo\)/.test(t)), `a proposal the engine cannot read goes back with the engine's reason (${log.find((t) => /could not read/.test(t)) ?? 'none'})`);
  const proposal = await page.textContent('.qs-ai-proposal');
  check(/checked: 2 qubits, 2 gates/.test(proposal) && /ran here on Stabilizer tableau/.test(proposal), `the corrected proposal is checked and run before it is offered (${proposal})`);
  check(asked.length === 3 && asked.every((r) => r.tools?.some((t) => t.function.name === 'run_job') && r.messages[0].role === 'system' && /Never state a probability/.test(r.messages[0].content)), 'every call to the model carries the engine\'s tools and the rule that numbers come from them');
  const toolMsg = asked[1].messages.find((m) => m.role === 'tool');
  check(toolMsg && JSON.parse(toolMsg.content).qubits === 2, 'the tool\'s answer went back to the model');
  await page.click('.qs-ai-apply');
  check((await page.evaluate(() => window.quantumStudio.view.state.doc.toString())) === GOOD, 'Apply puts the checked program in the editor');
  check((await page.inputValue('#qs-ai-stance')) === 'questions' && (await page.inputValue('#qs-ai-initiative')) === 'asked' && /ask one short question/.test(asked[0].messages[0].content),
    'by default the assistant asks questions first and speaks only when asked');
  const quick = await page.$$eval('.qs-ai-quick button', (bs) => bs.map((b) => b.textContent));
  check(quick.includes('Ask me a question') && quick.includes('Hint'), `it can be asked for a question or a hint (${quick.join(', ')})`);
  check(asked.every((r) => !r.tools || r.tools.some((t) => t.function.name === 'critique_qasm') && r.tools.some((t) => t.function.name === 'check_equivalent')), 'its tools include the critique and the equivalence check');
  // Runs refused twice: no hint offered while it speaks only when asked; offered, not sent, when allowed.
  const calls = asked.length;
  await setProgram('OPENQASM 3.0;\nqubit[1] q;\nfoo q[0];\n');
  for (let i = 0; i < 2; i++) { await page.click('#qs-run'); await done(page); }
  check(await page.isHidden('#qs-ai-stuck'), 'while it speaks only when asked, refused runs offer no hint');
  await page.selectOption('#qs-ai-initiative', 'hint');
  for (let i = 0; i < 2; i++) { await page.click('#qs-run'); await done(page); }
  check(await page.isVisible('#qs-ai-stuck') && asked.length === calls, 'allowed to, it offers a hint after refused runs, and asks the model nothing');
  await page.selectOption('#qs-ai-initiative', 'asked');
  // Improve and Explore with the model: the engine reads, measures and compares each.
  const DRAFT = 'OPENQASM 3.0;\nqubit[2] q;\nbit[2] c;\nh q[0];\nh q[0];\nx q[1];\ncx q[0], q[1];\nc = measure q;\n';
  await setProgram(DRAFT);
  await page.click('#qs-improve');
  await page.waitForFunction(() => document.querySelectorAll('.qs-cand').length && !/looking/.test(document.querySelector('#qs-alt-body')?.textContent ?? ''), null, { timeout: LONG });
  const cards = await page.$$eval('.qs-cand', (cs) => cs.map((c) => c.textContent));
  const refused = await page.textContent('#qs-alt-refused').catch(() => '');
  check(cards.some((t) => /the model/.test(t) && /the two Hadamards cancel/.test(t) && /same circuit · equal tableaus/.test(t)) && /drop the X: not the same circuit/.test(refused),
    `Improve with the model: its rewrite checked the same circuit, its wrong one left out with the reason (${refused})`);
  await page.fill('#qs-explore-aim', 'another entangler');
  await page.click('#qs-explore');
  await page.waitForFunction(() => /a GHZ state/.test(document.querySelector('#qs-alt-body')?.textContent ?? ''), null, { timeout: LONG });
  const ideas = await page.$$eval('.qs-cand', (cs) => cs.map((c) => c.textContent));
  const muse = asked.filter((r) => !r.tools).map((r) => r.messages[1].content);
  check(ideas.length === 2 && ideas.some((t) => /3 qubits/.test(t) && /a different circuit/.test(t)) && ideas.some((t) => /entangle with CZ instead/.test(t)) && muse.some((m) => /toward this aim: another entangler/.test(m)),
    `Explore: the model's ideas, each read and measured by the engine (${ideas.map((t) => t.slice(0, 60)).join(' | ')})`);
  check((await doc()) === DRAFT, 'neither changes the program until one is applied');
  // The candidates come back within the editor's redraw delay: wait for the draft's diagram.
  await page.waitForFunction(() => /4 gates/.test(document.querySelector('#qs-lint')?.textContent ?? '') && document.querySelectorAll('#qs-diagram .qc-flag').length === 2, null, { timeout: LONG });
  check(!/null/.test(await page.textContent('#qs-alt-body')) && !/null/.test(await page.textContent('#qs-measures')), 'no empty part is written out as “null”');
  await page.screenshot({ path: join(SHOTS, 'studio-alternatives.png'), fullPage: true });
  model.close();
}
check(seen.errors.length === 0, `no console error${seen.errors.length ? ': ' + seen.errors.join(' | ') : ''}`);
check(seen.failed.length === 0, `no failed request${seen.failed.length ? ': ' + seen.failed.join(' | ') : ''}`);
await ctx.close();

{
  const { ctx, page } = await open({ width: 390, height: 844 });
  await page.waitForFunction(() => /qubits/.test(document.querySelector('#qs-lint')?.textContent ?? ''), null, { timeout: LONG });
  const over = await page.evaluate(() => document.documentElement.scrollWidth - window.innerWidth);
  check(over <= 0, `at 390 px nothing scrolls sideways (overflow ${over} px)`);
  await ctx.close();
}

await browser.close();
server.close();
console.log(`\n${fails === 0 ? 'every check passed' : `${fails} check(s) failed`}`);
process.exit(fails === 0 ? 0 : 1);