Add retakes, quiz templates, score history, due dates, CSV export, and prerequisites

- allow_retakes flag on items: quizzes, spelling tests, and assignments can all be retaken
- Quiz templates: save any quiz as a reusable template and load it into new items
- Score history: every quiz/test attempt logged to submission_history; click a gradebook score to see all attempts
- Due dates: optional due date per item, shown in course view and gradebook (overdue flagged with ⚠️)
- Gradebook CSV export: one-click download of any course gradebook
- Prerequisites: lock an item until a prior one is completed; locked items show 🔒 in course view

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

db.js

@@ -181,8 +181,40 @@ db.exec(`
     sort INTEGER NOT NULL DEFAULT 0
   );
   CREATE INDEX IF NOT EXISTS idx_schedule_day ON schedule(student_id, date);
+
+  CREATE TABLE IF NOT EXISTS quiz_templates (
+    id INTEGER PRIMARY KEY,
+    name TEXT NOT NULL,
+    created_at TEXT NOT NULL DEFAULT (datetime('now'))
+  );
+  CREATE TABLE IF NOT EXISTS quiz_template_questions (
+    id INTEGER PRIMARY KEY,
+    template_id INTEGER NOT NULL REFERENCES quiz_templates(id) ON DELETE CASCADE,
+    type TEXT NOT NULL,
+    prompt TEXT NOT NULL,
+    choices TEXT NOT NULL DEFAULT '[]',
+    correct_answer TEXT NOT NULL,
+    points INTEGER NOT NULL DEFAULT 1,
+    sort INTEGER NOT NULL DEFAULT 0
+  );
+  CREATE TABLE IF NOT EXISTS submission_history (
+    id INTEGER PRIMARY KEY,
+    student_id INTEGER NOT NULL REFERENCES students(id) ON DELETE CASCADE,
+    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
+    score REAL,
+    points_possible REAL,
+    answers TEXT,
+    completed_at TEXT NOT NULL DEFAULT (datetime('now'))
+  );
 `);
 
+function tryAlter(sql) {
+  try { db.exec(sql); } catch { /* column already exists */ }
+}
+tryAlter(`ALTER TABLE items ADD COLUMN due_date TEXT`);
+tryAlter(`ALTER TABLE items ADD COLUMN allow_retakes INTEGER NOT NULL DEFAULT 0`);
+tryAlter(`ALTER TABLE items ADD COLUMN prereq_item_id INTEGER`);
+
 export const sha256 = (s) => createHash('sha256').update(String(s)).digest('hex');
 
 // Default parent PIN on first run

public/admin.html

@@ -113,6 +113,13 @@
             </select>
           </label>
           <label>Title <input id="ie-title" placeholder="Item title"></label>
+          <div class="inline-form">
+            <label>Due date <input type="date" id="ie-due-date"></label>
+            <label class="checkbox-label"><input type="checkbox" id="ie-allow-retakes"> Allow retakes</label>
+          </div>
+          <label>Prerequisite item (must be done first)
+            <select id="ie-prereq"><option value="">None</option></select>
+          </label>
 
           <!-- Scan a page: visible for lesson + quiz types -->
           <div id="ie-scan-section" class="scan-card" hidden>
@@ -138,6 +145,11 @@
           </div>
 
           <div id="ie-field-quiz" class="ie-field">
+            <div class="inline-form" style="margin-bottom:.5rem">
+              <select id="ie-template-select"><option value="">— load from template —</option></select>
+              <button type="button" id="ie-load-template" class="secondary">Load</button>
+              <button type="button" id="ie-save-template" class="secondary">Save as template</button>
+            </div>
             <div id="ie-questions"></div>
             <button type="button" id="ie-add-question" class="secondary">+ Add question</button>
           </div>
@@ -182,8 +194,18 @@
       <!-- Gradebook -->
       <section id="panel-gradebook" class="panel">
         <h1>Gradebook</h1>
-        <label>Course <select id="gradebook-course"></select></label>
+        <div class="inline-form">
+          <label>Course <select id="gradebook-course"></select></label>
+          <button id="gradebook-csv-btn" class="secondary">⬇ Export CSV</button>
+        </div>
         <div id="gradebook-table"></div>
+        <div id="history-modal" class="modal" hidden>
+          <div class="modal-box">
+            <h3 id="history-modal-title">Attempt History</h3>
+            <div id="history-modal-body"></div>
+            <button id="history-modal-close" class="secondary">Close</button>
+          </div>
+        </div>
       </section>
 
       <!-- Spelling (legacy word lists + weekly assignment) -->

public/admin.js

@@ -263,12 +263,31 @@ $('#add-unit-form').addEventListener('submit', async (e) => {
 // ============================================================
 
 let questionCount = 0;
+let cachedQuizTemplates = [];
 
 async function openItemEditor(unitId, itemId) {
-  [cachedLists, cachedDecks] = await Promise.all([api('/api/lists'), api('/api/decks')]);
+  let courseDetail;
+  [cachedLists, cachedDecks, cachedQuizTemplates, courseDetail] = await Promise.all([
+    api('/api/lists'),
+    api('/api/decks'),
+    api('/api/quiz-templates'),
+    api(`/api/admin/courses/${currentCourseId}`),
+  ]);
   $('#ie-list').innerHTML = cachedLists.map((l) => `<option value="${l.id}">${esc(l.name)}</option>`).join('');
   $('#ie-deck').innerHTML = cachedDecks.map((d) => `<option value="${d.id}">${esc(d.name)}</option>`).join('');
 
+  // Populate template select
+  $('#ie-template-select').innerHTML = `<option value="">— load from template —</option>` +
+    cachedQuizTemplates.map((t) => `<option value="${t.id}">${esc(t.name)} (${t.questionCount}q)</option>`).join('');
+
+  // Populate prereq select (all items in course except this one)
+  const allCourseItems = courseDetail.units.flatMap((u) => u.items);
+  $('#ie-prereq').innerHTML = `<option value="">None</option>` +
+    allCourseItems
+      .filter((it) => it.id !== Number(itemId))
+      .map((it) => `<option value="${it.id}">${esc(it.title)}</option>`)
+      .join('');
+
   $('#ie-id').value = itemId || '';
   $('#ie-unit-id').value = unitId;
   $('#ie-error').hidden = true;
@@ -283,6 +302,9 @@ async function openItemEditor(unitId, itemId) {
     $('#ie-body-lesson').value = item.body;
     $('#ie-body-assignment').value = item.body;
     $('#ie-points').value = item.points || 10;
+    $('#ie-due-date').value = item.due_date || '';
+    $('#ie-allow-retakes').checked = !!item.allow_retakes;
+    $('#ie-prereq').value = item.prereq_item_id || '';
     if (item.type === 'spelling_practice' || item.type === 'spelling_test') $('#ie-list').value = item.ref_id;
     if (item.type === 'flashcards') $('#ie-deck').value = item.ref_id;
     if (item.type === 'quiz') (item.questions || []).forEach(addQuestionRow);
@@ -299,6 +321,9 @@ async function openItemEditor(unitId, itemId) {
     $('#ie-body-lesson').value = '';
     $('#ie-body-assignment').value = '';
     $('#ie-points').value = 10;
+    $('#ie-due-date').value = '';
+    $('#ie-allow-retakes').checked = false;
+    $('#ie-prereq').value = '';
     $('#ie-delete').hidden = true;
   }
   updateItemFieldVisibility();
@@ -423,10 +448,35 @@ function addQuestionRow(q = {}) {
 }
 $('#ie-add-question').addEventListener('click', () => addQuestionRow());
 
+$('#ie-load-template').addEventListener('click', async () => {
+  const tid = $('#ie-template-select').value;
+  if (!tid) return msg('Pick a template first.');
+  const t = await api(`/api/quiz-templates/${tid}`);
+  $('#ie-questions').innerHTML = '';
+  questionCount = 0;
+  t.questions.forEach((q) => addQuestionRow({ ...q, correct_answer: q.correct_answer }));
+  msg(`Loaded "${t.name}" — ${t.questions.length} question(s).`);
+});
+
+$('#ie-save-template').addEventListener('click', async () => {
+  const itemId = $('#ie-id').value;
+  if (!itemId) return msg('Save the item first, then save as template.');
+  const name = prompt('Template name:');
+  if (!name) return;
+  try {
+    await api('/api/quiz-templates', { method: 'POST', body: { name, itemId: Number(itemId) } });
+    msg(`Template "${name}" saved.`);
+    cachedQuizTemplates = await api('/api/quiz-templates');
+    $('#ie-template-select').innerHTML = `<option value="">— load from template —</option>` +
+      cachedQuizTemplates.map((t) => `<option value="${t.id}">${esc(t.name)} (${t.questionCount}q)</option>`).join('');
+  } catch (err) { msg(err.message); }
+});
+
 $('#item-form').addEventListener('submit', async (e) => {
   e.preventDefault();
   const type = $('#ie-type').value;
   const title = $('#ie-title').value.trim();
+  const prereqVal = $('#ie-prereq').value;
   const body = {
     unitId: Number($('#ie-unit-id').value),
     type,
@@ -435,6 +485,9 @@ $('#item-form').addEventListener('submit', async (e) => {
     points: type === 'assignment' ? Number($('#ie-points').value) || 0 : 0,
     refId: type === 'spelling_practice' || type === 'spelling_test' ? Number($('#ie-list').value)
          : type === 'flashcards' ? Number($('#ie-deck').value) : null,
+    dueDate: $('#ie-due-date').value || null,
+    allowRetakes: $('#ie-allow-retakes').checked,
+    prereqItemId: prereqVal ? Number(prereqVal) : null,
   };
   if (type === 'quiz') {
     body.questions = Array.from(document.querySelectorAll('.quiz-q-row')).map((row) => ({
@@ -660,29 +713,58 @@ async function loadGrading() {
 // Gradebook
 // ============================================================
 
+let gradebookCourseId = null;
+
 async function loadGradebookPanel() {
   const courses = await api('/api/admin/courses');
   $('#gradebook-course').innerHTML = courses.map((c) => `<option value="${c.id}">${esc(c.name)}</option>`).join('');
   if (courses.length) renderGradebook(courses[0].id);
 }
 $('#gradebook-course').addEventListener('change', () => renderGradebook($('#gradebook-course').value));
+$('#gradebook-csv-btn').addEventListener('click', () => {
+  if (!gradebookCourseId) return;
+  window.location.href = `/api/gradebook/${gradebookCourseId}/csv`;
+});
+$('#history-modal-close').addEventListener('click', () => { $('#history-modal').hidden = true; });
+
+async function showHistory(studentId, itemId, label) {
+  const { history } = await api(`/api/items/${itemId}/history?studentId=${studentId}`);
+  $('#history-modal-title').textContent = `Attempts: ${label}`;
+  if (!history.length) {
+    $('#history-modal-body').innerHTML = `<p class="hint">No recorded attempts yet.</p>`;
+  } else {
+    const rows = history.map((h) => {
+      const pct = h.points_possible ? Math.round((h.score / h.points_possible) * 100) : null;
+      const cls = pct !== null ? (pct >= 80 ? 'score-good' : 'score-bad') : '';
+      return `<tr><td>${new Date(h.completed_at + 'Z').toLocaleString()}</td><td class="${cls}">${h.score}/${h.points_possible}${pct !== null ? ` (${pct}%)` : ''}</td></tr>`;
+    }).join('');
+    $('#history-modal-body').innerHTML = `<table class="results"><tr><th>Date</th><th>Score</th></tr>${rows}</table>`;
+  }
+  $('#history-modal').hidden = false;
+}
 
 async function renderGradebook(courseId) {
+  gradebookCourseId = courseId || null;
   if (!courseId) return ($('#gradebook-table').innerHTML = '');
   const gb = await api(`/api/gradebook/${courseId}`);
   if (gb.gradableItems.length === 0 || gb.students.length === 0) {
     $('#gradebook-table').innerHTML = `<p class="hint">Need at least one enrolled kid and one graded item (assignment, quiz, or spelling test) to show a gradebook.</p>`;
     return;
   }
-  const header = gb.gradableItems.map((it) => `<th>${esc(it.title)}<br><small>${it.points} pts</small></th>`).join('');
+  const header = gb.gradableItems.map((it) => {
+    const due = it.due_date ? `<br><small class="hint">due ${it.due_date}</small>` : '';
+    return `<th>${esc(it.title)}<br><small>${it.points} pts</small>${due}</th>`;
+  }).join('');
   const rows = gb.students
     .map((s) => {
       const cells = gb.gradableItems
         .map((it) => {
           const sc = s.scores[it.id];
-          if (!sc) return `<td class="hint">—</td>`;
-          if (sc.status !== 'graded') return `<td class="hint">⏳</td>`;
-          return `<td>${sc.score}/${sc.points_possible}</td>`;
+          const overdueClass = sc?.overdue ? ' overdue' : '';
+          if (!sc || (!sc.status && !sc.overdue)) return `<td class="hint">—</td>`;
+          if (sc.overdue && !sc.status) return `<td class="hint overdue" title="Overdue">⚠️</td>`;
+          if (sc.status !== 'graded') return `<td class="hint${overdueClass}">${sc.overdue ? '⚠️ ' : ''}⏳</td>`;
+          return `<td class="${sc.score / sc.points_possible >= 0.8 ? 'score-good' : 'score-bad'}${overdueClass}" style="cursor:pointer" data-history-student="${s.id}" data-history-item="${it.id}" data-history-label="${esc(it.title)} — ${esc(s.name)}">${sc.score}/${sc.points_possible}</td>`;
         })
         .join('');
       const pctClass = s.percent === null ? '' : s.percent >= 80 ? 'score-good' : 'score-bad';
@@ -690,6 +772,10 @@ async function renderGradebook(courseId) {
     })
     .join('');
   $('#gradebook-table').innerHTML = `<table class="results"><tr><th>Kid</th>${header}<th>Overall</th></tr>${rows}</table>`;
+
+  document.querySelectorAll('[data-history-student]').forEach((td) =>
+    td.addEventListener('click', () => showHistory(td.dataset.historyStudent, td.dataset.historyItem, td.dataset.historyLabel))
+  );
 }
 
 // ============================================================

public/app.js

@@ -233,10 +233,18 @@ async function openCourse(courseId) {
         <h2>${esc(u.name)}</h2>
         ${u.items
           .map((it) => {
+            if (it.locked) {
+              return `<div class="today-row locked">
+                <span class="row-check">🔒</span>
+                <span class="row-title">${esc(it.title)}<small>${TYPE_LABEL[it.type]}</small></span>
+                <span class="row-badge hint">Complete previous item first</span>
+              </div>`;
+            }
             const badge = statusBadge(it.type, it.status, it.score, it.points_possible, it.status !== 'not_started');
+            const due = it.due_date ? `<small class="due-date">Due ${it.due_date}</small>` : '';
             return `<button class="today-row" data-item-id="${it.id}" data-item-type="${it.type}">
               <span class="row-check">${it.status === 'not_started' ? TYPE_ICON[it.type] : '✅'}</span>
-              <span class="row-title">${esc(it.title)}<small>${TYPE_LABEL[it.type]}</small></span>
+              <span class="row-title">${esc(it.title)}${due}<small>${TYPE_LABEL[it.type]}</small></span>
               <span class="row-badge">${badge}</span>
             </button>`;
           })
@@ -244,7 +252,7 @@ async function openCourse(courseId) {
       </div>`
     )
     .join('');
-  document.querySelectorAll('#course-units .today-row').forEach((row) =>
+  document.querySelectorAll('#course-units .today-row:not(.locked)').forEach((row) =>
     row.addEventListener('click', () => {
       backTarget = () => openCourse(courseId);
       openItem(Number(row.dataset.itemId), row.dataset.itemType);
@@ -258,10 +266,10 @@ async function openCourse(courseId) {
 async function openItem(itemId, type) {
   if (type === 'lesson') return openLesson(itemId);
   if (type === 'assignment') return openAssignment(itemId);
-  if (type === 'quiz') return openQuiz(itemId);
+  if (type === 'quiz') return openQuiz(itemId, false);
   const item = await api(`/api/items/${itemId}?studentId=${currentStudent.id}`);
   if (type === 'spelling_practice') return startPractice({ listId: item.list.id, itemId });
-  if (type === 'spelling_test') return startTest({ listId: item.list.id, itemId });
+  if (type === 'spelling_test') return startTest({ listId: item.list.id, itemId, allowRetakes: item.allow_retakes });
   if (type === 'flashcards') return startFlashcards({ deckId: item.deck.id, deckName: item.deck.name, itemId });
 }
 
@@ -294,10 +302,19 @@ async function openAssignment(itemId) {
   const btn = $('#assignment-done-btn');
   const status = $('#assignment-status');
   if (item.submission && item.submission.status === 'graded') {
-    btn.hidden = true;
     status.hidden = false;
     status.className = 'status-banner good';
     status.textContent = `🌟 Graded: ${item.submission.score} / ${item.submission.points_possible}`;
+    if (item.allow_retakes) {
+      btn.hidden = false;
+      btn.textContent = '🔁 Retake';
+      btn.onclick = async () => {
+        await api(`/api/items/${itemId}/complete`, { method: 'POST', body: { studentId: currentStudent.id, date: todayStr() } });
+        openAssignment(itemId);
+      };
+    } else {
+      btn.hidden = true;
+    }
   } else if (item.submission && item.submission.status === 'done') {
     btn.hidden = true;
     status.hidden = false;
@@ -305,6 +322,7 @@ async function openAssignment(itemId) {
     status.textContent = `⏳ Turned in — waiting for a parent to grade it.`;
   } else {
     btn.hidden = false;
+    btn.textContent = 'Mark as done ✓';
     status.hidden = true;
     btn.onclick = async () => {
       await api(`/api/items/${itemId}/complete`, { method: 'POST', body: { studentId: currentStudent.id, date: todayStr() } });
@@ -316,18 +334,34 @@ async function openAssignment(itemId) {
 
 // ---------- quiz ----------
 
-async function openQuiz(itemId) {
+async function openQuiz(itemId, forceRetake = false) {
   const item = await api(`/api/items/${itemId}?studentId=${currentStudent.id}`);
   $('#quiz-kicker').textContent = `${item.course_name} · ${item.unit_name}`;
   $('#quiz-title').textContent = item.title;
-  const graded = item.submission && item.submission.status === 'graded';
+  const graded = !forceRetake && item.submission && item.submission.status === 'graded';
   const result = $('#quiz-result');
 
   if (graded) {
     result.hidden = false;
     result.className = 'status-banner good';
-    result.textContent = `🌟 Score: ${item.submission.score} / ${item.submission.points_possible}`;
-    $('#quiz-form').innerHTML = item.questions
+    const pct = item.submission.points_possible ? Math.round((item.submission.score / item.submission.points_possible) * 100) : 0;
+    result.innerHTML = `🌟 Score: ${item.submission.score} / ${item.submission.points_possible} (${pct}%)`;
+
+    // Attempt history
+    const { history } = await api(`/api/items/${itemId}/history?studentId=${currentStudent.id}`);
+    let historyHtml = '';
+    if (history.length > 1) {
+      const histRows = history.map((h) => {
+        const hp = h.points_possible ? Math.round((h.score / h.points_possible) * 100) : 0;
+        return `<tr><td>${new Date(h.completed_at + 'Z').toLocaleString()}</td><td>${h.score}/${h.points_possible} (${hp}%)</td></tr>`;
+      }).join('');
+      historyHtml = `<details class="attempt-history"><summary>All attempts (${history.length})</summary><table>${histRows}</table></details>`;
+    }
+
+    let retakeBtn = '';
+    if (item.allow_retakes) retakeBtn = `<button id="quiz-retake-btn" class="check-btn secondary">🔁 Retake Quiz</button>`;
+
+    $('#quiz-form').innerHTML = historyHtml + retakeBtn + item.questions
       .map((q) => {
         const correct = normalizeAnswer(q.given) === normalizeAnswer(q.correct_answer);
         return `<div class="quiz-question review">
@@ -337,6 +371,10 @@ async function openQuiz(itemId) {
         </div>`;
       })
       .join('');
+
+    if (item.allow_retakes) {
+      $('#quiz-retake-btn').addEventListener('click', () => openQuiz(itemId, true));
+    }
   } else {
     result.hidden = true;
     $('#quiz-form').innerHTML =
@@ -380,7 +418,7 @@ async function openQuiz(itemId) {
         method: 'POST',
         body: { studentId: currentStudent.id, answers, date: todayStr() },
       });
-      openQuiz(itemId);
+      openQuiz(itemId, false);
     };
   }
   show('quiz');
@@ -567,12 +605,12 @@ async function nextPracticeWord() {
 
 // ---------- spelling: test ----------
 
-const test = { list: null, words: [], i: 0, answers: [], itemId: null };
+const test = { list: null, words: [], i: 0, answers: [], itemId: null, allowRetakes: false };
 
-async function startTest({ listId, itemId } = {}) {
+async function startTest({ listId, itemId, allowRetakes = false } = {}) {
   const url = listId ? `/api/test/${currentStudent.id}?listId=${listId}` : `/api/test/${currentStudent.id}`;
   const data = await api(url);
-  Object.assign(test, { list: data.list, words: data.words, i: 0, answers: [], itemId: itemId || null });
+  Object.assign(test, { list: data.list, words: data.words, i: 0, answers: [], itemId: itemId || null, allowRetakes: !!allowRetakes });
   $('#test-card').hidden = false;
   $('#test-done').hidden = true;
   show('test');
@@ -617,13 +655,23 @@ async function finishTest() {
         : `<li>❌ ${esc(g.word)} <small>(you wrote "${esc(g.typed)}")</small></li>`
     )
     .join('');
+
+  let retakeBtn = '';
+  if (test.itemId && test.allowRetakes) retakeBtn = `<button id="test-retake-btn" class="check-btn secondary">🔁 Retake Test</button>`;
+
   $('#test-done').innerHTML = `
     <div>⭐ Test complete!</div>
     <div class="big-score">${result.score} / ${result.total}</div>
     <ul>${rows}</ul>
+    ${retakeBtn}
     <button id="test-home">Back</button>`;
   $('#test-done').hidden = false;
   $('#test-home').addEventListener('click', () => backTarget());
+  if (test.itemId && test.allowRetakes) {
+    $('#test-retake-btn').addEventListener('click', () => {
+      openItem(test.itemId, 'spelling_test');
+    });
+  }
 }
 
 $('#btn-practice').addEventListener('click', () => {

public/styles.css

@@ -392,3 +392,27 @@ button.tiny { font-size: 0.75rem; padding: 0.15rem 0.5rem; }
 .scan-provider-box legend { font-weight: 600; padding: 0 0.3rem; }
 .radio-label { display: block; margin: 0.3rem 0; cursor: pointer; }
 .radio-label input { margin-right: 0.4rem; }
+
+/* ---------- new features: locked items, due dates, overdue, history, modal ---------- */
+.today-row.locked {
+  opacity: 0.55;
+  cursor: not-allowed;
+  background: var(--bg);
+  border-color: var(--muted);
+}
+.due-date { color: var(--muted); font-size: 0.78rem; display: block; }
+td.overdue, .overdue { background: var(--bad-bg) !important; }
+.attempt-history { margin: 0.75rem 0; font-size: 0.9rem; }
+.attempt-history summary { cursor: pointer; color: var(--accent); }
+.attempt-history table { width: 100%; border-collapse: collapse; margin-top: 0.5rem; }
+.attempt-history td { border: 1px solid #ddd; padding: 0.3rem 0.5rem; }
+.modal {
+  position: fixed; inset: 0; background: rgba(0,0,0,0.45);
+  display: flex; align-items: center; justify-content: center; z-index: 100;
+}
+.modal-box {
+  background: var(--card); border-radius: var(--radius);
+  padding: 1.5rem; max-width: 520px; width: 90%; max-height: 80vh; overflow-y: auto;
+}
+.modal-box h3 { margin-bottom: 1rem; }
+.modal-box .secondary { margin-top: 1rem; }

server.js

@@ -204,6 +204,8 @@ app.post('/api/test/:studentId', (req, res) => {
         status = 'graded', score = excluded.score, points_possible = excluded.points_possible,
         completed_at = datetime('now'), graded_at = datetime('now')
     `).run(studentId, itemId, score, graded.length);
+    db.prepare(`INSERT INTO submission_history (student_id, item_id, score, points_possible) VALUES (?, ?, ?, ?)`)
+      .run(studentId, itemId, score, graded.length);
     markScheduleDone.run(studentId, itemId, isDateStr(date) ? date : today());
   }
 
@@ -453,14 +455,14 @@ app.get('/api/admin/courses/:id', requirePin, (req, res) => {
   const course = db.prepare(`SELECT id, name, subject, color, archived FROM courses WHERE id = ?`).get(req.params.id);
   if (!course) return res.status(404).json({ error: 'No such course' });
   const units = db.prepare(`SELECT id, name, sort FROM units WHERE course_id = ? ORDER BY sort, id`).all(req.params.id);
-  const itemStmt = db.prepare(`SELECT id, type, title, points, ref_id, sort FROM items WHERE unit_id = ? ORDER BY sort, id`);
+  const itemStmt = db.prepare(`SELECT id, type, title, points, ref_id, sort, due_date, allow_retakes, prereq_item_id FROM items WHERE unit_id = ? ORDER BY sort, id`);
   for (const u of units) u.items = itemStmt.all(u.id);
   res.json({ ...course, units });
 });
 
 // Full item detail for the admin item editor (quiz correct answers always included)
 app.get('/api/admin/items/:id', requirePin, (req, res) => {
-  const item = db.prepare(`SELECT id, unit_id, type, title, body, points, ref_id FROM items WHERE id = ?`).get(req.params.id);
+  const item = db.prepare(`SELECT id, unit_id, type, title, body, points, ref_id, due_date, allow_retakes, prereq_item_id FROM items WHERE id = ?`).get(req.params.id);
   if (!item) return res.status(404).json({ error: 'No such item' });
   if (item.type === 'quiz') {
     item.questions = db.prepare(`
@@ -541,13 +543,14 @@ function saveQuizQuestions(itemId, questions) {
 app.post('/api/items', requirePin, (req, res) => {
   const err = validateItemBody(req.body);
   if (err) return res.status(400).json({ error: err });
-  const { unitId, type, title, body, points, refId } = req.body;
+  const { unitId, type, title, body, points, refId, dueDate, allowRetakes, prereqItemId } = req.body;
   const sort = db.prepare(`SELECT COALESCE(MAX(sort), -1) + 1 AS n FROM items WHERE unit_id = ?`).get(unitId).n;
   const id = db.prepare(`
-    INSERT INTO items (unit_id, type, title, body, points, ref_id, sort) VALUES (?, ?, ?, ?, ?, ?, ?)
+    INSERT INTO items (unit_id, type, title, body, points, ref_id, sort, due_date, allow_retakes, prereq_item_id)
+    VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
   `).run(unitId, type, String(title).trim(), String(body || ''), Number(points) || 0,
          (type === 'flashcards' || type === 'spelling_practice' || type === 'spelling_test') ? refId : null,
-         sort).lastInsertRowid;
+         sort, dueDate || null, allowRetakes ? 1 : 0, prereqItemId || null).lastInsertRowid;
   if (type === 'quiz') {
     saveQuizQuestions(id, req.body.questions);
     const totalPoints = req.body.questions.reduce((sum, q) => sum + (Number(q.points) || 1), 0);
@@ -562,14 +565,14 @@ app.put('/api/items/:id', requirePin, (req, res) => {
   if (!db.prepare(`SELECT id FROM items WHERE id = ?`).get(req.params.id)) {
     return res.status(404).json({ error: 'No such item' });
   }
-  const { type, title, body, points, refId } = req.body;
+  const { type, title, body, points, refId, dueDate, allowRetakes, prereqItemId } = req.body;
   const finalPoints = type === 'quiz'
     ? req.body.questions.reduce((sum, q) => sum + (Number(q.points) || 1), 0)
     : (Number(points) || 0);
-  db.prepare(`UPDATE items SET type = ?, title = ?, body = ?, points = ?, ref_id = ? WHERE id = ?`)
+  db.prepare(`UPDATE items SET type = ?, title = ?, body = ?, points = ?, ref_id = ?, due_date = ?, allow_retakes = ?, prereq_item_id = ? WHERE id = ?`)
     .run(type, String(title).trim(), String(body || ''), finalPoints,
          (type === 'flashcards' || type === 'spelling_practice' || type === 'spelling_test') ? refId : null,
-         req.params.id);
+         dueDate || null, allowRetakes ? 1 : 0, prereqItemId || null, req.params.id);
   if (type === 'quiz') saveQuizQuestions(req.params.id, req.body.questions);
   res.json({ ok: true });
 });
@@ -613,7 +616,7 @@ app.get('/api/courses/:id/detail', (req, res) => {
 
   const units = db.prepare(`SELECT id, name, sort FROM units WHERE course_id = ? ORDER BY sort, id`).all(req.params.id);
   const itemStmt = db.prepare(`
-    SELECT i.id, i.type, i.title, i.points, i.sort,
+    SELECT i.id, i.type, i.title, i.points, i.sort, i.due_date, i.allow_retakes, i.prereq_item_id,
            s.status, s.score, s.points_possible
     FROM items i
     LEFT JOIN submissions s ON s.item_id = i.id AND s.student_id = ?
@@ -622,6 +625,14 @@ app.get('/api/courses/:id/detail', (req, res) => {
   for (const u of units) {
     u.items = itemStmt.all(studentId, u.id).map((it) => ({ ...it, status: it.status || 'not_started' }));
   }
+  // Build submission map for prereq locking
+  const subMap = {};
+  for (const u of units) for (const it of u.items) subMap[it.id] = it.status;
+  for (const u of units) {
+    for (const it of u.items) {
+      it.locked = it.prereq_item_id ? (subMap[it.prereq_item_id] === 'not_started' || !subMap[it.prereq_item_id]) : false;
+    }
+  }
   res.json({ ...course, units });
 });
 
@@ -629,12 +640,20 @@ app.get('/api/courses/:id/detail', (req, res) => {
 app.get('/api/items/:id', (req, res) => {
   const studentId = req.query.studentId;
   const item = db.prepare(`
-    SELECT i.id, i.type, i.title, i.body, i.points, i.ref_id, u.name AS unit_name, u.course_id, c.name AS course_name
+    SELECT i.id, i.type, i.title, i.body, i.points, i.ref_id, i.due_date, i.allow_retakes, i.prereq_item_id,
+           u.name AS unit_name, u.course_id, c.name AS course_name
     FROM items i JOIN units u ON u.id = i.unit_id JOIN courses c ON c.id = u.course_id
     WHERE i.id = ?
   `).get(req.params.id);
   if (!item) return res.status(404).json({ error: 'No such item' });
 
+  if (item.prereq_item_id && studentId) {
+    const prereqSub = db.prepare(`SELECT status FROM submissions WHERE student_id = ? AND item_id = ?`).get(studentId, item.prereq_item_id);
+    item.locked = !prereqSub;
+  } else {
+    item.locked = false;
+  }
+
   item.submission = db.prepare(`
     SELECT status, score, points_possible, answers, completed_at, graded_at
     FROM submissions WHERE student_id = ? AND item_id = ?
@@ -660,18 +679,28 @@ app.get('/api/items/:id', (req, res) => {
 });
 
 // Mark a lesson viewed, an assignment done, or a practice/flashcards session finished.
-// Never downgrades an already-graded submission (quizzes, spelling tests).
+// Never downgrades an already-graded submission unless allow_retakes is set.
 app.post('/api/items/:id/complete', (req, res) => {
   const { studentId, date } = req.body;
-  const item = db.prepare(`SELECT id, points FROM items WHERE id = ?`).get(req.params.id);
+  const item = db.prepare(`SELECT id, points, allow_retakes FROM items WHERE id = ?`).get(req.params.id);
   if (!item) return res.status(404).json({ error: 'No such item' });
 
-  db.prepare(`
-    INSERT INTO submissions (student_id, item_id, status, points_possible, completed_at)
-    VALUES (?, ?, 'done', ?, datetime('now'))
-    ON CONFLICT (student_id, item_id) DO UPDATE SET completed_at = datetime('now')
-    WHERE submissions.status != 'graded'
-  `).run(studentId, req.params.id, item.points || null);
+  if (item.allow_retakes) {
+    db.prepare(`
+      INSERT INTO submissions (student_id, item_id, status, points_possible, completed_at)
+      VALUES (?, ?, 'done', ?, datetime('now'))
+      ON CONFLICT (student_id, item_id) DO UPDATE SET
+        status = 'done', points_possible = excluded.points_possible,
+        completed_at = datetime('now'), score = NULL, graded_at = NULL
+    `).run(studentId, req.params.id, item.points || null);
+  } else {
+    db.prepare(`
+      INSERT INTO submissions (student_id, item_id, status, points_possible, completed_at)
+      VALUES (?, ?, 'done', ?, datetime('now'))
+      ON CONFLICT (student_id, item_id) DO UPDATE SET completed_at = datetime('now')
+      WHERE submissions.status != 'graded'
+    `).run(studentId, req.params.id, item.points || null);
+  }
 
   markScheduleDone.run(studentId, req.params.id, isDateStr(date) ? date : today());
   res.json({ ok: true });
@@ -701,6 +730,9 @@ app.post('/api/items/:id/quiz-submit', (req, res) => {
       answers = excluded.answers, completed_at = datetime('now'), graded_at = datetime('now')
   `).run(studentId, req.params.id, earned, possible, JSON.stringify(record));
 
+  db.prepare(`INSERT INTO submission_history (student_id, item_id, score, points_possible, answers) VALUES (?, ?, ?, ?, ?)`)
+    .run(studentId, req.params.id, earned, possible, JSON.stringify(record));
+
   markScheduleDone.run(studentId, req.params.id, isDateStr(date) ? date : today());
   res.json({ score: earned, total: possible });
 });
@@ -738,7 +770,7 @@ app.get('/api/gradebook/:courseId', requirePin, (req, res) => {
   if (!course) return res.status(404).json({ error: 'No such course' });
 
   const gradableItems = db.prepare(`
-    SELECT i.id, i.title, i.type, i.points
+    SELECT i.id, i.title, i.type, i.points, i.due_date
     FROM items i JOIN units u ON u.id = i.unit_id
     WHERE u.course_id = ? AND i.type IN (${GRADABLE_TYPES.map(() => '?').join(',')})
     ORDER BY u.sort, i.sort, i.id
@@ -750,12 +782,14 @@ app.get('/api/gradebook/:courseId', requirePin, (req, res) => {
   `).all(req.params.courseId);
 
   const scoreStmt = db.prepare(`SELECT score, points_possible, status FROM submissions WHERE student_id = ? AND item_id = ?`);
+  const now = today();
   for (const s of students) {
     s.scores = {};
     let earned = 0, possible = 0;
     for (const item of gradableItems) {
       const row = scoreStmt.get(s.id, item.id);
-      s.scores[item.id] = row || null;
+      const overdue = !!(item.due_date && item.due_date < now && (!row || row.status !== 'graded'));
+      s.scores[item.id] = row ? { ...row, overdue } : (overdue ? { overdue: true } : null);
       if (row && row.status === 'graded' && row.points_possible) {
         earned += row.score;
         possible += row.points_possible;
@@ -767,6 +801,96 @@ app.get('/api/gradebook/:courseId', requirePin, (req, res) => {
   res.json({ course, gradableItems, students });
 });
 
+// CSV export for the gradebook
+app.get('/api/gradebook/:courseId/csv', requirePin, (req, res) => {
+  const course = db.prepare(`SELECT id, name FROM courses WHERE id = ?`).get(req.params.courseId);
+  if (!course) return res.status(404).json({ error: 'No such course' });
+
+  const gradableItems = db.prepare(`
+    SELECT i.id, i.title, i.type, i.points
+    FROM items i JOIN units u ON u.id = i.unit_id
+    WHERE u.course_id = ? AND i.type IN (${GRADABLE_TYPES.map(() => '?').join(',')})
+    ORDER BY u.sort, i.sort, i.id
+  `).all(req.params.courseId, ...GRADABLE_TYPES);
+
+  const students = db.prepare(`
+    SELECT s.id, s.name FROM students s
+    JOIN enrollments e ON e.student_id = s.id WHERE e.course_id = ? ORDER BY s.name
+  `).all(req.params.courseId);
+
+  const scoreStmt = db.prepare(`SELECT score, points_possible, status FROM submissions WHERE student_id = ? AND item_id = ?`);
+  const csvEsc = (s) => `"${String(s ?? '').replace(/"/g, '""')}"`;
+  const header = ['Student', ...gradableItems.map((i) => csvEsc(`${i.title} (${i.points}pts)`)), 'Overall %'];
+  const rows = students.map((s) => {
+    let earned = 0, possible = 0;
+    const cells = gradableItems.map((item) => {
+      const row = scoreStmt.get(s.id, item.id);
+      if (!row || row.status !== 'graded') return '—';
+      if (row.points_possible) { earned += row.score; possible += row.points_possible; }
+      return `${row.score}/${row.points_possible}`;
+    });
+    const pct = possible > 0 ? Math.round((earned / possible) * 100) + '%' : '—';
+    return [csvEsc(s.name), ...cells, pct];
+  });
+
+  const filename = `gradebook-${course.name.replace(/[^a-z0-9]/gi, '-')}.csv`;
+  res.setHeader('Content-Type', 'text/csv');
+  res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
+  res.send([header, ...rows].map((r) => r.join(',')).join('\n'));
+});
+
+// Score history for a student on one item
+app.get('/api/items/:id/history', (req, res) => {
+  const { studentId } = req.query;
+  const history = db.prepare(`
+    SELECT score, points_possible, completed_at FROM submission_history
+    WHERE student_id = ? AND item_id = ? ORDER BY completed_at DESC
+  `).all(studentId, req.params.id);
+  res.json({ history });
+});
+
+// ---------- quiz templates ----------
+
+app.get('/api/quiz-templates', requirePin, (req, res) => {
+  const templates = db.prepare(`
+    SELECT t.id, t.name, COUNT(q.id) AS questionCount
+    FROM quiz_templates t LEFT JOIN quiz_template_questions q ON q.template_id = t.id
+    GROUP BY t.id ORDER BY t.name
+  `).all();
+  res.json(templates);
+});
+
+app.get('/api/quiz-templates/:id', requirePin, (req, res) => {
+  const t = db.prepare(`SELECT id, name FROM quiz_templates WHERE id = ?`).get(req.params.id);
+  if (!t) return res.status(404).json({ error: 'No such template' });
+  t.questions = db.prepare(`
+    SELECT type, prompt, choices, correct_answer, points FROM quiz_template_questions
+    WHERE template_id = ? ORDER BY sort, id
+  `).all(req.params.id).map((q) => ({ ...q, choices: JSON.parse(q.choices) }));
+  res.json(t);
+});
+
+app.post('/api/quiz-templates', requirePin, (req, res) => {
+  const { name, itemId } = req.body;
+  if (!String(name || '').trim()) return res.status(400).json({ error: 'Name required' });
+  let qs = req.body.questions;
+  if (itemId) {
+    qs = db.prepare(`SELECT type, prompt, choices, correct_answer, points, sort FROM quiz_questions WHERE item_id = ? ORDER BY sort, id`).all(itemId);
+  }
+  if (!Array.isArray(qs) || qs.length === 0) return res.status(400).json({ error: 'No questions' });
+  const id = db.prepare(`INSERT INTO quiz_templates (name) VALUES (?)`).run(String(name).trim()).lastInsertRowid;
+  const ins = db.prepare(`INSERT INTO quiz_template_questions (template_id, type, prompt, choices, correct_answer, points, sort) VALUES (?, ?, ?, ?, ?, ?, ?)`);
+  qs.forEach((q, i) => ins.run(id, q.type, String(q.prompt).trim(),
+    typeof q.choices === 'string' ? q.choices : JSON.stringify(q.choices || []),
+    String(q.correct_answer ?? q.correctAnswer ?? '').trim(), Number(q.points) || 1, i));
+  res.json({ id });
+});
+
+app.delete('/api/quiz-templates/:id', requirePin, (req, res) => {
+  db.prepare(`DELETE FROM quiz_templates WHERE id = ?`).run(req.params.id);
+  res.json({ ok: true });
+});
+
 // ---------- daily agenda / scheduling ----------
 
 // Kid's checklist for one day