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/constants.js

@@ -0,0 +1,40 @@
+/* ── LearnSpace shared constants ───────────────────────────────────────── */
+
+exports.SESSION_MODES = new Set(['exam', 'practice', 'repeat', 'ct', 'topic', 'random']);
+
+exports.SESSION_STATUS = {
+  IN_PROGRESS: 'in_progress',
+  COMPLETED:   'completed',
+  ABANDONED:   'abandoned',
+};
+
+exports.ROLES = {
+  ADMIN:   'admin',
+  TEACHER: 'teacher',
+  STUDENT: 'student',
+};
+
+exports.NOTIFICATION_TYPES = {
+  ASSIGNMENT:  'assignment',
+  SESSION:     'session',
+  ACHIEVEMENT: 'achievement',
+  SYSTEM:      'system',
+  JOIN:        'join',
+  SUBMISSION:  'submission',
+  CHALLENGE:   'challenge',
+  DAILY_GOAL:  'daily_goal',
+};
+
+exports.SUBJECTS = {
+  BIO:  'bio',
+  CHEM: 'chem',
+  MATH: 'math',
+  PHYS: 'phys',
+};
+
+// Combo bonus XP thresholds: [minCombo, bonusXP]
+exports.COMBO_BONUSES = [
+  [10, 75],
+  [5,  30],
+  [3,  15],
+];