feat(exam-prep F4): живой дашборд — streak + последние попытки + точность 7д + хитмап активности + пробники

backend/src/routes/exam-prep.js

@@ -164,6 +164,69 @@ const SQL = {
        SET status = 'finished', finished_at = ?, score = ?, total_correct = ?
      WHERE id = ?
   `),
+
+  /* ── Dashboard aggregates (F4) ──────────────────────────────── */
+
+  /* Distinct calendar dates (UTC) on which the user had ≥1 correct attempt
+     for tasks of a specific track, last 60 days. We compute streak from this in JS. */
+  streakDays: db.prepare(`
+    SELECT DISTINCT DATE(a.created_at / 1000, 'unixepoch') AS day
+      FROM exam_attempts a
+      JOIN exam_tasks t ON t.id = a.exam_task_id
+     WHERE a.user_id = ? AND t.exam_key = ?
+       AND a.is_correct = 1
+       AND a.created_at >= ?
+     ORDER BY day DESC
+  `),
+
+  /* Accuracy over a recent time window. */
+  accuracyWindow: db.prepare(`
+    SELECT
+      COUNT(*) AS attempts,
+      COALESCE(SUM(CASE WHEN a.is_correct = 1 THEN 1 ELSE 0 END), 0) AS correct
+      FROM exam_attempts a
+      JOIN exam_tasks t ON t.id = a.exam_task_id
+     WHERE a.user_id = ? AND t.exam_key = ?
+       AND a.is_correct IS NOT NULL
+       AND a.created_at >= ?
+  `),
+
+  /* Recent attempts (last N) with task metadata. */
+  recentAttempts: db.prepare(`
+    SELECT
+      a.id, a.exam_task_id, a.is_correct, a.solution_viewed, a.mode,
+      a.user_answer, a.created_at,
+      t.variant, t.task_idx, t.task_type, t.text_html
+      FROM exam_attempts a
+      JOIN exam_tasks t ON t.id = a.exam_task_id
+     WHERE a.user_id = ? AND t.exam_key = ?
+     ORDER BY a.created_at DESC
+     LIMIT ?
+  `),
+
+  /* Activity heatmap — attempts per calendar day, last 28 days. */
+  activityHeatmap: db.prepare(`
+    SELECT
+      DATE(a.created_at / 1000, 'unixepoch') AS day,
+      COUNT(*) AS attempts,
+      COALESCE(SUM(CASE WHEN a.is_correct = 1 THEN 1 ELSE 0 END), 0) AS correct
+      FROM exam_attempts a
+      JOIN exam_tasks t ON t.id = a.exam_task_id
+     WHERE a.user_id = ? AND t.exam_key = ?
+       AND a.created_at >= ?
+     GROUP BY day
+     ORDER BY day
+  `),
+
+  /* Recent mock sessions for "your last attempts" card on dashboard. */
+  recentMocks: db.prepare(`
+    SELECT id, variant, source, started_at, finished_at, status,
+           score, total_correct, total_tasks
+      FROM exam_mock_sessions
+     WHERE user_id = ? AND exam_key = ?
+     ORDER BY started_at DESC
+     LIMIT ?
+  `),
 };
 
 /* ── GET /api/exam-prep/tracks ──
@@ -344,6 +407,104 @@ router.post('/attempts', (req, res) => {
   res.json({ id: Number(result.lastInsertRowid) });
 });
 
+/* ──────────────────────────────────────────────────────────────────
+   Dashboard (F4)
+   ────────────────────────────────────────────────────────────────── */
+
+/* Compute streak: consecutive calendar days ending today (or yesterday — a
+   one-day grace prevents the streak from being lost overnight) on which the
+   user had ≥1 correct attempt. Returns an integer >= 0.
+   `days` — array of date strings 'YYYY-MM-DD' sorted descending. */
+function computeStreak(days) {
+  if (!days.length) return 0;
+  const set = new Set(days);
+  const dayMs = 86400000;
+  const today = new Date();
+  const todayStr = toIsoDate(today);
+  const yesterdayStr = toIsoDate(new Date(today.getTime() - dayMs));
+
+  // Anchor: start from today if today's correct exists, else yesterday (grace).
+  // If neither — streak is 0.
+  let cursor;
+  if (set.has(todayStr))         cursor = new Date(today);
+  else if (set.has(yesterdayStr)) cursor = new Date(today.getTime() - dayMs);
+  else return 0;
+
+  let streak = 0;
+  while (set.has(toIsoDate(cursor))) {
+    streak++;
+    cursor = new Date(cursor.getTime() - dayMs);
+  }
+  return streak;
+}
+
+function toIsoDate(d) {
+  const y = d.getUTCFullYear();
+  const m = String(d.getUTCMonth() + 1).padStart(2, '0');
+  const day = String(d.getUTCDate()).padStart(2, '0');
+  return `${y}-${m}-${day}`;
+}
+
+/* ── GET /api/exam-prep/:examKey/dashboard ──
+   Live aggregates for the dashboard view: streak, recent attempts,
+   accuracy over the last 7 days, 28-day activity heatmap, recent mocks. */
+// @public-by-design: router-level authMiddleware (line 6) covers this route
+router.get('/:examKey/dashboard', (req, res) => {
+  const { examKey } = req.params;
+  if (!SQL.getTrack.get(examKey)) return res.status(404).json({ error: 'Unknown exam track' });
+
+  const now = Date.now();
+  const dayMs = 86400000;
+  const sixtyDaysAgo  = now - 60 * dayMs;
+  const sevenDaysAgo  = now -  7 * dayMs;
+  const twentyEightDaysAgo = now - 28 * dayMs;
+
+  const dayRows = SQL.streakDays.all(req.user.id, examKey, sixtyDaysAgo);
+  const streak  = computeStreak(dayRows.map(r => r.day));
+
+  const acc7   = SQL.accuracyWindow.get(req.user.id, examKey, sevenDaysAgo);
+  const recent = SQL.recentAttempts.all(req.user.id, examKey, 8);
+  const heat   = SQL.activityHeatmap.all(req.user.id, examKey, twentyEightDaysAgo);
+  const mocks  = SQL.recentMocks.all(req.user.id, examKey, 3);
+
+  res.json({
+    streak,
+    accuracy_7d: {
+      attempts: acc7.attempts,
+      correct:  acc7.correct,
+      pct:      acc7.attempts ? Math.round((acc7.correct / acc7.attempts) * 100) : null,
+    },
+    recent_attempts: recent.map(r => ({
+      task_id:   r.exam_task_id,
+      variant:   r.variant,
+      task_idx:  r.task_idx,
+      task_type: r.task_type,
+      is_correct: r.is_correct,
+      solution_viewed: r.solution_viewed,
+      mode:      r.mode,
+      user_answer: r.user_answer,
+      preview:   stripPreview(r.text_html),
+      created_at: r.created_at,
+    })),
+    heatmap: heat.map(h => ({ day: h.day, attempts: h.attempts, correct: h.correct })),
+    recent_mocks: mocks.map(m => ({
+      id: m.id, variant: m.variant, source: m.source,
+      started_at: m.started_at, finished_at: m.finished_at, status: m.status,
+      score: m.score, total_correct: m.total_correct, total_tasks: m.total_tasks,
+    })),
+  });
+});
+
+/* Lightweight preview: strip tags, normalize whitespace, truncate. */
+function stripPreview(html) {
+  const text = String(html || '')
+    .replace(/<svg[\s\S]*?<\/svg>/gi, '')
+    .replace(/<[^>]+>/g, ' ')
+    .replace(/\s+/g, ' ')
+    .trim();
+  return text.length > 100 ? text.slice(0, 100) + '…' : text;
+}
+
 /* ──────────────────────────────────────────────────────────────────
    Mock exam (F9)
    ────────────────────────────────────────────────────────────────── */

frontend/css/exam-prep.css

@@ -708,6 +708,128 @@
   letter-spacing: -.01em;
 }
 
+/* ═══════════════════════════════════════════════════════════════
+   Dashboard widgets (`dh-*`) — used by exam-prep.html (F4)
+   ═══════════════════════════════════════════════════════════════ */
+
+.dh-row {
+  display: grid;
+  grid-template-columns: 1.4fr 1fr;
+  gap: 14px;
+}
+@media (max-width: 880px) {
+  .dh-row { grid-template-columns: 1fr; }
+}
+
+/* Recent attempts list */
+.dh-recent { display: flex; flex-direction: column; }
+.dh-recent-list { display: flex; flex-direction: column; gap: 6px; }
+.dh-recent-item {
+  display: grid;
+  grid-template-columns: 24px 70px 1fr auto;
+  align-items: center;
+  gap: 10px;
+  padding: 8px 10px;
+  border-radius: 8px;
+  font-size: .85rem;
+  transition: background .12s;
+}
+.dh-recent-item:hover { background: rgba(155,93,229,.05); }
+
+.dh-mark {
+  width: 22px; height: 22px; border-radius: 50%;
+  display: inline-flex; align-items: center; justify-content: center;
+  font-family: 'Unbounded', sans-serif; font-weight: 800; font-size: .78rem;
+  flex-shrink: 0;
+}
+.dh-mark-ok      { background: rgba(6,214,160,.18); color: #06D6A0; }
+.dh-mark-bad     { background: rgba(230,57,70,.16); color: #E63946; }
+.dh-mark-view    { background: rgba(155,93,229,.14); color: var(--violet); }
+.dh-mark-pending { background: rgba(15,23,42,.05);   color: var(--text-3); }
+
+.dh-recent-loc {
+  font-family: 'Manrope', sans-serif; font-weight: 700; color: var(--violet);
+  font-size: .78rem;
+  text-decoration: none; white-space: nowrap;
+}
+.dh-recent-loc:hover { text-decoration: underline; }
+
+.dh-recent-preview {
+  color: var(--text-2);
+  font-size: .85rem;
+  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
+}
+
+.dh-recent-meta {
+  display: flex; flex-direction: column; align-items: flex-end;
+  gap: 1px;
+  font-size: .7rem; color: var(--text-3);
+}
+.dh-mode {
+  text-transform: uppercase; letter-spacing: .04em; font-weight: 700;
+  color: var(--violet);
+}
+
+/* Activity heatmap */
+.dh-heatmap-card { display: flex; flex-direction: column; }
+.dh-heatmap {
+  display: grid;
+  grid-template-columns: repeat(7, 1fr);
+  grid-auto-rows: minmax(20px, 1fr);
+  gap: 4px;
+  margin-bottom: 10px;
+}
+.dh-cell {
+  aspect-ratio: 1;
+  border-radius: 4px;
+  background: rgba(15,23,42,.06);
+  cursor: default;
+  transition: filter .12s;
+}
+.dh-cell:hover { filter: brightness(1.05); }
+.dh-cell.dh-l0 { background: rgba(15,23,42,.06); }
+.dh-cell.dh-l1 { background: rgba(155,93,229,.20); }
+.dh-cell.dh-l2 { background: rgba(155,93,229,.40); }
+.dh-cell.dh-l3 { background: rgba(155,93,229,.65); }
+.dh-cell.dh-l4 { background: rgba(155,93,229,.90); }
+.dh-heatmap-legend {
+  display: flex; align-items: center; gap: 4px;
+  font-size: .7rem; color: var(--text-3);
+}
+.dh-heatmap-legend .dh-cell {
+  width: 12px; height: 12px; aspect-ratio: 1;
+}
+
+/* Recent mocks rows */
+.dh-mock-row {
+  display: grid;
+  grid-template-columns: 1fr auto auto;
+  align-items: center;
+  gap: 12px;
+  padding: 10px 12px;
+  border-radius: 9px;
+  text-decoration: none;
+  color: var(--text);
+  transition: background .12s;
+  margin-bottom: 4px;
+}
+.dh-mock-row:hover { background: rgba(155,93,229,.06); }
+.dh-mock-title {
+  font-family: 'Manrope', sans-serif; font-weight: 700; font-size: .9rem;
+}
+.dh-mock-score {
+  font-size: .82rem; color: var(--text-2);
+}
+.dh-mock-active {
+  font-size: .78rem; font-weight: 800; letter-spacing: .03em;
+  color: #F8961E; text-transform: uppercase;
+  padding: 3px 8px; border-radius: 6px;
+  background: rgba(248,150,30,.12);
+}
+.dh-mock-when {
+  font-size: .72rem; color: var(--text-3);
+}
+
 /* ── Mobile tweaks ─────────────────────────────────────────────── */
 @media (max-width: 640px) {
   .ep-wrap   { padding: 20px 16px 60px; }

frontend/js/exam-prep/dashboard.js

@@ -1,8 +1,8 @@
 'use strict';
 /* ──────────────────────────────────────────────────────────────────
    Dashboard view — landing screen of /exam-prep/:examKey
-   In F1: shows track meta + global counts + first-pass user progress.
-   Full live dashboard (slabnik themes, streak, plan) ships in F4 / F8 / F10.
+   F1: track info + global counts + cumulative progress
+   F4: streak, last attempts, 7d accuracy, activity heatmap, recent mocks
    ────────────────────────────────────────────────────────────────── */
 
 (async function () {
@@ -23,12 +23,15 @@
   const solvedPct = counts.total
     ? Math.round((progress.tasks_solved / counts.total) * 100)
     : 0;
-  const accuracy = progress.total_attempts
+  const accAll = progress.total_attempts
     ? Math.round((progress.correct_attempts / progress.total_attempts) * 100)
     : null;
 
+  // Fetch F4 live aggregates in parallel with rendering shell.
+  const dashPromise = EP.api.getDashboard(track.exam_key).catch(() => null);
+
   main.innerHTML = `
-    <div class="ep-stats">
+    <div class="ep-stats" id="dh-top-stats">
       <div class="ep-stat">
         <div class="ep-stat-label">Решено задач</div>
         <div class="ep-stat-value ep-violet">${progress.tasks_solved} <span style="font-size:.7em;color:var(--text-3);font-weight:600">/ ${counts.total}</span></div>
@@ -36,20 +39,12 @@
         <div class="ep-stat-sub">${solvedPct}% от банка</div>
       </div>
       <div class="ep-stat">
-        <div class="ep-stat-label">Точность</div>
-        <div class="ep-stat-value ${accuracy == null ? '' : accuracy >= 70 ? 'ep-good' : 'ep-warn'}">${accuracy == null ? '—' : accuracy + '%'}</div>
+        <div class="ep-stat-label">Точность (всё время)</div>
+        <div class="ep-stat-value ${accAll == null ? '' : accAll >= 70 ? 'ep-good' : 'ep-warn'}">${accAll == null ? '—' : accAll + '%'}</div>
         <div class="ep-stat-sub">${progress.correct_attempts} верно из ${progress.total_attempts} попыток</div>
       </div>
-      <div class="ep-stat">
-        <div class="ep-stat-label">Серия (streak)</div>
-        <div class="ep-stat-value">—</div>
-        <div class="ep-stat-sub">Будет в F4</div>
-      </div>
-      <div class="ep-stat">
-        <div class="ep-stat-label">До экзамена</div>
-        <div class="ep-stat-value">—</div>
-        <div class="ep-stat-sub">Задайте дату в F10</div>
-      </div>
+      <div class="ep-stat" id="dh-streak"><div class="ep-stat-label">Серия дней</div><div class="ep-stat-value"><span class="ep-skel" style="width:42px;height:1em">&nbsp;</span></div></div>
+      <div class="ep-stat" id="dh-acc7"><div class="ep-stat-label">Точность 7 дней</div><div class="ep-stat-value"><span class="ep-skel" style="width:42px;height:1em">&nbsp;</span></div></div>
     </div>
 
     <div class="ep-card">
@@ -57,7 +52,7 @@
       <div class="ep-card-hint">${escapeHtml(stripTags(track.intro_html || ''))}</div>
       <div class="ep-cta-row">
         <a class="ep-btn ep-btn-primary" href="/exam-prep/${track.exam_key}/practice">
-          <i data-lucide="play"></i> Начать тренировку
+          <i data-lucide="play"></i> Тренировка
         </a>
         <a class="ep-btn" href="/exam-prep/${track.exam_key}/variants">
           <i data-lucide="layout-grid"></i> Все варианты
@@ -68,6 +63,22 @@
       </div>
     </div>
 
+    <div class="dh-row">
+      <div class="ep-card dh-recent">
+        <h3>Последние попытки</h3>
+        <div id="dh-recent-list" class="dh-recent-list"><div class="ep-empty" style="padding:24px"><span class="ep-skel" style="width:200px;height:1em">&nbsp;</span></div></div>
+      </div>
+      <div class="ep-card dh-heatmap-card">
+        <h3>Активность · 28 дней</h3>
+        <div id="dh-heatmap"><div class="ep-empty" style="padding:24px"><span class="ep-skel" style="width:200px;height:1em">&nbsp;</span></div></div>
+      </div>
+    </div>
+
+    <div class="ep-card" id="dh-mocks">
+      <h3>Пробники</h3>
+      <div id="dh-mocks-list"><div class="ep-empty" style="padding:24px"><span class="ep-skel" style="width:200px;height:1em">&nbsp;</span></div></div>
+    </div>
+
     <div class="ep-card">
       <h3>Банк задач</h3>
       <div class="ep-card-hint">Всего ${counts.total} задач в ${track.variants_count} вариантах.</div>
@@ -92,13 +103,173 @@
 
     <div class="ep-card" style="opacity:.7">
       <h3>Слабые темы</h3>
-      <div class="ep-card-hint">Топ-3 темы с худшей точностью появятся после фазы F6 (тегирование) и F8.</div>
+      <div class="ep-card-hint">Топ-3 темы с худшей точностью появятся после F6 (тегирование) и F8.</div>
     </div>
   `;
 
   if (window.lucide) lucide.createIcons();
+
+  // Stitch in live aggregates once they arrive.
+  const dash = await dashPromise;
+  if (dash) {
+    renderStreak(dash.streak);
+    renderAcc7(dash.accuracy_7d);
+    renderRecent(dash.recent_attempts, track.exam_key);
+    renderHeatmap(dash.heatmap);
+    renderMocks(dash.recent_mocks, track.exam_key);
+    if (window.lucide) lucide.createIcons();
+  }
 })();
 
+/* ════════════════════════════════════════════════════════════════
+   Widgets
+   ════════════════════════════════════════════════════════════════ */
+
+function renderStreak(streak) {
+  const el = document.getElementById('dh-streak');
+  if (!el) return;
+  const label = streak === 0 ? 'Нет серии'
+              : streak === 1 ? '1 день подряд'
+              : `${streak} ${pluralRu(streak, ['день', 'дня', 'дней'])} подряд`;
+  el.innerHTML = `
+    <div class="ep-stat-label">Серия</div>
+    <div class="ep-stat-value ${streak >= 3 ? 'ep-good' : ''}">${streak}</div>
+    <div class="ep-stat-sub">${label}${streak >= 3 ? ' · так держать!' : ''}</div>`;
+}
+
+function renderAcc7(a) {
+  const el = document.getElementById('dh-acc7');
+  if (!el) return;
+  const valClass = a.pct == null ? '' : a.pct >= 70 ? 'ep-good' : 'ep-warn';
+  el.innerHTML = `
+    <div class="ep-stat-label">Точность 7 дней</div>
+    <div class="ep-stat-value ${valClass}">${a.pct == null ? '—' : a.pct + '%'}</div>
+    <div class="ep-stat-sub">${a.correct} верно из ${a.attempts} попыток</div>`;
+}
+
+function renderRecent(items, examKey) {
+  const el = document.getElementById('dh-recent-list');
+  if (!el) return;
+  if (!items.length) {
+    el.innerHTML = `<div class="ep-empty" style="padding:20px">
+      <i data-lucide="hourglass"></i>
+      <p>Ещё нет попыток. Откройте <a href="/exam-prep/${examKey}/practice" style="color:var(--violet)">тренажёр</a>.</p>
+    </div>`;
+    return;
+  }
+  el.innerHTML = items.map(it => {
+    const mark = it.is_correct === 1 ? '<span class="dh-mark dh-mark-ok">✓</span>'
+               : it.is_correct === 0 ? '<span class="dh-mark dh-mark-bad">✗</span>'
+               : it.solution_viewed   ? '<span class="dh-mark dh-mark-view">i</span>'
+               : '<span class="dh-mark dh-mark-pending">·</span>';
+    const when = relativeTime(it.created_at);
+    const modeLabel = it.mode === 'mock' ? 'Пробник'
+                    : it.mode === 'variant' ? 'Вариант'
+                    : it.mode === 'practice' ? 'Тренажёр'
+                    : it.mode === 'topic'    ? 'Тема'
+                    : '';
+    const variantBadge = it.variant != null
+      ? `<a class="dh-recent-loc" href="/exam-prep/${examKey}/variants?v=${it.variant}" title="Открыть вариант ${it.variant}">В${it.variant}·№${it.task_idx}</a>`
+      : `<span class="dh-recent-loc">№${it.task_idx}</span>`;
+    return `<div class="dh-recent-item">
+      ${mark}
+      ${variantBadge}
+      <div class="dh-recent-preview">${escapeHtml(it.preview)}</div>
+      <div class="dh-recent-meta"><span class="dh-mode">${modeLabel}</span><span class="dh-time">${when}</span></div>
+    </div>`;
+  }).join('');
+}
+
+function renderHeatmap(items) {
+  const el = document.getElementById('dh-heatmap');
+  if (!el) return;
+  // Build 28 cells ending today.
+  const byDay = new Map(items.map(d => [d.day, d]));
+  const cells = [];
+  const today = new Date();
+  for (let i = 27; i >= 0; i--) {
+    const d = new Date(today);
+    d.setUTCDate(today.getUTCDate() - i);
+    const key = toIsoDate(d);
+    const v = byDay.get(key);
+    const a = v ? v.attempts : 0;
+    let lvl = 0;
+    if (a >= 1)  lvl = 1;
+    if (a >= 5)  lvl = 2;
+    if (a >= 12) lvl = 3;
+    if (a >= 25) lvl = 4;
+    const tip = v ? `${key}: ${v.attempts} попыток, ${v.correct} верно` : `${key}: 0`;
+    cells.push(`<div class="dh-cell dh-l${lvl}" title="${tip}"></div>`);
+  }
+  el.innerHTML = `
+    <div class="dh-heatmap">${cells.join('')}</div>
+    <div class="dh-heatmap-legend">
+      <span>меньше</span>
+      <span class="dh-cell dh-l0"></span>
+      <span class="dh-cell dh-l1"></span>
+      <span class="dh-cell dh-l2"></span>
+      <span class="dh-cell dh-l3"></span>
+      <span class="dh-cell dh-l4"></span>
+      <span>больше</span>
+    </div>`;
+}
+
+function renderMocks(items, examKey) {
+  const el = document.getElementById('dh-mocks-list');
+  if (!el) return;
+  if (!items.length) {
+    el.innerHTML = `<div class="ep-empty" style="padding:20px">
+      <i data-lucide="timer-off"></i>
+      <p>Пробников пока не было. <a href="/exam-prep/${examKey}/mock" style="color:var(--violet)">Запустить первый</a>?</p>
+    </div>`;
+    return;
+  }
+  el.innerHTML = items.map(m => {
+    const isActive = m.status === 'active';
+    const title = m.source === 'variant' ? `Вариант ${m.variant}` : `Случайные ${m.total_tasks}`;
+    const when  = relativeTime(m.started_at);
+    const score = isActive
+      ? `<span class="dh-mock-active">В процессе</span>`
+      : `<span class="dh-mock-score">${m.score != null ? m.score + ' баллов' : '—'} · ${m.total_correct}/${m.total_tasks}</span>`;
+    return `<a class="dh-mock-row" href="/exam-prep/${examKey}/mock/${m.id}">
+      <span class="dh-mock-title">${title}</span>
+      ${score}
+      <span class="dh-mock-when">${when}</span>
+    </a>`;
+  }).join('');
+}
+
+/* ════════════════════════════════════════════════════════════════
+   Utils
+   ════════════════════════════════════════════════════════════════ */
+
+function pluralRu(n, forms) {
+  const mod10 = n % 10;
+  const mod100 = n % 100;
+  if (mod100 >= 11 && mod100 <= 14) return forms[2];
+  if (mod10 === 1) return forms[0];
+  if (mod10 >= 2 && mod10 <= 4) return forms[1];
+  return forms[2];
+}
+
+function relativeTime(ts) {
+  if (!ts) return '';
+  const diff = (Date.now() - Number(ts)) / 1000;
+  if (diff < 60)       return 'только что';
+  if (diff < 3600)     return `${Math.floor(diff/60)} мин назад`;
+  if (diff < 86400)    return `${Math.floor(diff/3600)} ч назад`;
+  if (diff < 7 * 86400) return `${Math.floor(diff/86400)} ${pluralRu(Math.floor(diff/86400), ['день','дня','дней'])} назад`;
+  const d = new Date(Number(ts));
+  return `${String(d.getDate()).padStart(2,'0')}.${String(d.getMonth()+1).padStart(2,'0')}`;
+}
+
+function toIsoDate(d) {
+  const y = d.getUTCFullYear();
+  const m = String(d.getUTCMonth() + 1).padStart(2, '0');
+  const day = String(d.getUTCDate()).padStart(2, '0');
+  return `${y}-${m}-${day}`;
+}
+
 function escapeHtml(s) {
   return String(s || '').replace(/[&<>"']/g, c => ({ '&':'&amp;', '<':'&lt;', '>':'&gt;', '"':'&quot;', "'":'&#39;' }[c]));
 }