LearnSpace: full-stack educational whiteboard platform

Node.js/Express backend + vanilla JS frontend.
Features: real-time collaborative whiteboard (SSE), multi-page support,
LaTeX formulas, shapes/connectors, coordinate systems, number lines,
compass, zoom/pan, Catmull-Rom pencil smoothing, ruler/protractor with
rotation & resize controls, minimap navigation overlay, auto-measurements,
multi-page thumbnails sidebar, PNG export, page templates.
Student/teacher workflows: classes, assignments, library, dashboard.
Mobile responsive. SQLite (better-sqlite3).

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

backend/src/routes/classes.js

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+const router = require('express').Router();
+const { authMiddleware, requireRole, requirePermission } = require('../middleware/auth');
+const rateLimit = require('../middleware/rateLimit');
+const validate  = require('../middleware/validate');
+const ctrl = require('../controllers/classController');
+const assignCtrl = require('../controllers/assignmentController');
+
+const joinLimiter   = rateLimit({ windowMs: 60_000, max: 10, message: 'Слишком много попыток, подождите минуту' });
+const createLimiter = rateLimit({ windowMs: 60_000, max: 5,  message: 'Слишком много запросов, подождите минуту' });
+const joinSchema    = { body: { invite_code: { type: 'string', required: true, minLen: 1, maxLen: 20 } } };
+const createSchema  = { body: { name: { type: 'string', required: true, minLen: 1, maxLen: 200 } } };
+const updateSchema  = { body: {
+  name:        { type: 'string', minLen: 1, maxLen: 200 },
+  description: { type: 'string', maxLen: 1000 },
+}};
+const assignmentSchema = { body: {
+  title:        { type: 'string', required: true, minLen: 1, maxLen: 200 },
+  subject_slug: { type: 'string', maxLen: 100 },
+  mode:         { type: 'string', oneOf: ['exam', 'practice', 'repeat', 'ct'] },
+  count:        { type: 'number', min: 1, max: 200 },
+  deadline:     { type: 'string', maxLen: 30 },
+}};
+
+router.use(authMiddleware);
+
+/* ── Student (must be before /:id to avoid route conflicts) ── */
+router.post('/join', requireRole('student','free_student'), joinLimiter, validate(joinSchema), ctrl.joinClass);
+router.get('/student/my',   ctrl.myClasses);
+router.get('/students',     requireRole('teacher','admin'), ctrl.listStudents);
+
+/* ── Teacher / Admin ── */
+router.get('/',              requireRole('teacher','admin'), ctrl.listClasses);
+router.post('/',             requireRole('teacher','admin'), requirePermission('classes.manage'), createLimiter, validate(createSchema), ctrl.createClass);
+router.get('/:id',           requireRole('teacher','admin'), ctrl.getClass);
+router.patch('/:id',         requireRole('teacher','admin'), requirePermission('classes.manage'), validate(updateSchema), ctrl.updateClass);
+router.delete('/:id',        requireRole('teacher','admin'), requirePermission('classes.manage'), ctrl.deleteClass);
+router.post('/:id/new-code', requireRole('teacher','admin'), requirePermission('classes.manage'), ctrl.regenerateCode);
+router.get('/:id/journal',     requireRole('teacher','admin'), ctrl.classJournal);
+router.get('/:id/journal/csv', requireRole('teacher','admin'), ctrl.classJournalCsv);
+router.post('/:id/members',  requireRole('teacher','admin'), ctrl.addMember);
+router.delete('/:id/members/:uid',       requireRole('teacher','admin'), ctrl.kickMember);
+router.post('/:id/assignments',          requireRole('teacher','admin'), validate(assignmentSchema), assignCtrl.createAssignment);
+router.get('/:id/announcements',         requireRole('teacher','admin'), ctrl.getAnnouncements);
+router.post('/:id/announcements',        requireRole('teacher','admin'), requirePermission('announcements.send'), ctrl.createAnnouncement);
+router.delete('/:id/announcements/:aid', requireRole('teacher','admin'), requirePermission('announcements.send'), ctrl.deleteAnnouncement);
+router.get('/:id/feed',                            ctrl.classFeed);
+
+module.exports = router;