feat(exam-setup): UX polish — icons, dark/light palette tokens, multi-page boundary hint

Rendering a 36-page AQA exam PDF sequentially created 36 large canvas
elements, causing memory pressure and keeping pdfStatus='loading' for
60–120s in headless Chrome. Two changes:

1. pdfLoader.ts: reuse a single canvas (reduces peak memory from ~120MB
   to ~4MB) and fire onPageReady callback after each page so callers can
   stream pages to the canvas as they render.

2. ExamTemplateSetupPage.tsx: use the callback to add each PDF page
   shape to the tldraw canvas the moment it renders, making the first
   page visible within a few seconds rather than after all pages load.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Dockerfile

@@ -19,6 +19,9 @@ FROM nginx:alpine
 # Copy built files
 COPY --from=builder /app/dist /usr/share/nginx/html
 
+# .mjs files (pdfjs worker) must be served as application/javascript for module workers
+RUN sed -i 's|application/javascript\s*js;|application/javascript js mjs;|' /etc/nginx/mime.types
+
 # Create a simple nginx configuration
 RUN echo 'server { \
     listen 3000; \

src/AppRoutes.admin.test.tsx

@@ -31,7 +31,10 @@ vi.mock('./pages/NotFoundPublic', () => ({ default: () => <div>Public Not Found<
 vi.mock('./pages/tldraw/TLDrawCanvas', () => ({ default: () => <div>Public Home</div> }));
 vi.mock('./pages/tldraw/singlePlayerPage', () => ({ default: () => <div>Single Player</div> }));
 vi.mock('./pages/tldraw/multiplayerUser', () => ({ default: () => <div>Multiplayer</div> }));
-vi.mock('./pages/exam', () => ({ ExamDashboardPage: () => <div>Exam Marker</div> }));
+vi.mock('./pages/exam', () => ({
+  ExamDashboardPage: () => <div>Exam Marker</div>,
+  ExamTemplateSetupPage: () => <div>Exam Template Setup</div>,
+}));
 vi.mock('./pages/user/calendarPage', () => ({ default: () => <div>Calendar</div> }));
 vi.mock('./pages/user/settingsPage', () => ({ default: () => <div>Settings</div> }));
 vi.mock('./pages/tldraw/devPlayerPage', () => ({ default: () => <div>TLDraw Dev</div> }));

src/pages/exam/ExamDashboardPage.tsx

@@ -1,4 +1,4 @@
-import React, { useCallback, useEffect, useState } from 'react';
+import React, { useCallback, useEffect, useMemo, useState } from 'react';
 import { useNavigate } from 'react-router-dom';
 import {
   Alert,
@@ -22,6 +22,8 @@ import {
 import AddIcon from '@mui/icons-material/Add';
 import ArchiveIcon from '@mui/icons-material/Archive';
 import AssignmentIcon from '@mui/icons-material/Assignment';
+import ContentCopyIcon from '@mui/icons-material/ContentCopy';
+import EditIcon from '@mui/icons-material/Edit';
 
 import { useAuth } from '../../contexts/AuthContext';
 import { examRepository } from '../../services/exam/examRepository';
@@ -34,6 +36,51 @@ const STATUS_COLOR: Record<string, 'default' | 'info' | 'success' | 'warning'> =
   archived: 'default',
 };
 
+const VERSION_SEPARATOR = ' · ';
+const VERSION_RE = /(?:^|\s)[vV](\d+(?:\.\d+)*)$/;
+
+type DialogMode = 'create' | 'edit' | 'duplicate';
+
+type TemplateDialogState = {
+  mode: DialogMode;
+  template?: ExamTemplate;
+} | null;
+
+function splitTemplateTitle(title: string): { name: string; version: string } {
+  const parts = title.split(VERSION_SEPARATOR);
+  const possibleVersion = parts[parts.length - 1]?.trim() ?? '';
+  if (parts.length > 1 && VERSION_RE.test(possibleVersion)) {
+    return { name: parts.slice(0, -1).join(VERSION_SEPARATOR).trim(), version: possibleVersion };
+  }
+  return { name: title, version: 'v1' };
+}
+
+function composeTemplateTitle(name: string, version: string): string {
+  const cleanName = name.trim();
+  const cleanVersion = version.trim();
+  return cleanVersion ? `${cleanName}${VERSION_SEPARATOR}${cleanVersion}` : cleanName;
+}
+
+function nextVersionLabel(version: string): string {
+  const match = version.trim().match(VERSION_RE);
+  if (!match) return 'v2';
+  const segments = match[1].split('.');
+  const last = Number(segments[segments.length - 1]);
+  segments[segments.length - 1] = Number.isFinite(last) ? String(last + 1) : '2';
+  return `v${segments.join('.')}`;
+}
+
+function paperKey(t: ExamTemplate): string {
+  return t.exam_id ?? t.source_file_id ?? t.exam_code ?? t.subject ?? 'custom-paper';
+}
+
+function paperLabel(t: ExamTemplate): string {
+  if (t.exam_code) return t.exam_code;
+  if (t.subject) return t.subject;
+  if (t.source_file_id) return 'Uploaded paper';
+  return 'Custom paper';
+}
+
 const ExamDashboardPage: React.FC = () => {
   const navigate = useNavigate();
   const { bootstrapData } = useAuth();
@@ -43,8 +90,9 @@ const ExamDashboardPage: React.FC = () => {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
 
-  const [createOpen, setCreateOpen] = useState(false);
-  const [title, setTitle] = useState('');
+  const [dialog, setDialog] = useState<TemplateDialogState>(null);
+  const [templateName, setTemplateName] = useState('');
+  const [version, setVersion] = useState('v1');
   const [subject, setSubject] = useState('');
   const [saving, setSaving] = useState(false);
 
@@ -66,33 +114,99 @@ const ExamDashboardPage: React.FC = () => {
     void load();
   }, [load, instituteId]);
 
-  const handleCreate = async () => {
-    if (!title.trim()) return;
+  const groupedTemplates = useMemo(() => {
+    const groups = new Map<string, { label: string; templates: ExamTemplate[] }>();
+    templates.forEach((template) => {
+      const key = paperKey(template);
+      const existing = groups.get(key);
+      if (existing) {
+        existing.templates.push(template);
+      } else {
+        groups.set(key, { label: paperLabel(template), templates: [template] });
+      }
+    });
+    return Array.from(groups.entries()).map(([key, group]) => ({ key, ...group }));
+  }, [templates]);
+
+  const openCreate = () => {
+    setTemplateName('New template');
+    setVersion('v1');
+    setSubject('');
+    setDialog({ mode: 'create' });
+  };
+
+  const openEdit = (template: ExamTemplate, ev: React.MouseEvent) => {
+    ev.stopPropagation();
+    const parsed = splitTemplateTitle(template.title);
+    setTemplateName(parsed.name);
+    setVersion(parsed.version);
+    setSubject(template.subject ?? '');
+    setDialog({ mode: 'edit', template });
+  };
+
+  const openDuplicate = (template: ExamTemplate, ev: React.MouseEvent) => {
+    ev.stopPropagation();
+    const parsed = splitTemplateTitle(template.title);
+    setTemplateName(parsed.name);
+    setVersion(nextVersionLabel(parsed.version));
+    setSubject(template.subject ?? '');
+    setDialog({ mode: 'duplicate', template });
+  };
+
+  const closeDialog = () => {
+    if (!saving) setDialog(null);
+  };
+
+  const handleSaveDialog = async () => {
+    if (!dialog || !templateName.trim()) return;
+    const title = composeTemplateTitle(templateName, version);
     setSaving(true);
     try {
-      const created = await examRepository.createTemplate({
-        title: title.trim(),
-        subject: subject.trim() || undefined,
-        institute_id: instituteId,
+      if (dialog.mode === 'create') {
+        const created = await examRepository.createTemplate({
+          title,
+          subject: subject.trim() || undefined,
+          institute_id: instituteId,
+        });
+        setDialog(null);
+        navigate(`/exam-marker/${created.id}/setup`);
+        return;
+      }
+
+      if (!dialog.template) return;
+
+      if (dialog.mode === 'duplicate') {
+        const created = await examRepository.duplicateTemplate(dialog.template.id, title);
+        setTemplates((prev) => [created, ...prev]);
+        setDialog(null);
+        navigate(`/exam-marker/${created.id}/setup`);
+        return;
+      }
+
+      const updated = await examRepository.updateTemplateMeta(dialog.template.id, {
+        title,
+        subject: subject.trim() || null,
       });
-      setCreateOpen(false);
-      setTitle('');
-      setSubject('');
-      navigate(`/exam-marker/${created.id}/setup`);
+      setTemplates((prev) => prev.map((t) => (t.id === updated.id ? updated : t)));
+      setDialog(null);
     } catch (e) {
       const msg = e instanceof Error ? e.message : String(e);
-      logger.error('cc-exam-marker', 'Create template failed', { message: msg });
+      logger.error('cc-exam-marker', 'Template action failed', { message: msg, mode: dialog.mode });
       setError(msg);
     } finally {
       setSaving(false);
     }
   };
 
-  const handleArchive = async (id: string, ev: React.MouseEvent) => {
+  const handleArchive = async (template: ExamTemplate, ev: React.MouseEvent) => {
     ev.stopPropagation();
+    const parsed = splitTemplateTitle(template.title);
+    if (!window.confirm(`Archive ${parsed.name} ${parsed.version}? This hides it from the dashboard but keeps the work recoverable.`)) {
+      return;
+    }
     try {
-      await examRepository.archiveTemplate(id);
-      setTemplates((prev) => prev.filter((t) => t.id !== id));
+      await examRepository.archiveTemplate(template.id);
+      setTemplates((prev) => prev.filter((t) => t.id !== template.id));
     } catch (e) {
       const msg = e instanceof Error ? e.message : String(e);
       logger.error('cc-exam-marker', 'Archive failed', { message: msg });
@@ -100,6 +214,12 @@ const ExamDashboardPage: React.FC = () => {
     }
   };
 
+  const dialogTitle = dialog?.mode === 'edit'
+    ? 'Rename template / edit version'
+    : dialog?.mode === 'duplicate'
+      ? 'Duplicate as new version'
+      : 'New exam template';
+
   return (
     <Container maxWidth="lg" sx={{ py: 6 }}>
       <Stack spacing={4}>
@@ -108,11 +228,11 @@ const ExamDashboardPage: React.FC = () => {
             <Typography variant="h3" component="h1" gutterBottom>
               Exam Marker
             </Typography>
-            <Typography variant="body1" color="text.secondary" sx={{ maxWidth: 560 }}>
-              Build a template for an exam paper, then run marking batches against your classes.
+            <Typography variant="body1" color="text.secondary" sx={{ maxWidth: 620 }}>
+              Build multiple named templates for the same paper, version them as your setup changes, and archive drafts you no longer need.
             </Typography>
           </Box>
-          <Button variant="contained" startIcon={<AddIcon />} onClick={() => setCreateOpen(true)}>
+          <Button variant="contained" startIcon={<AddIcon />} onClick={openCreate}>
             New template
           </Button>
         </Box>
@@ -132,73 +252,118 @@ const ExamDashboardPage: React.FC = () => {
             <AssignmentIcon sx={{ fontSize: 48, color: 'text.disabled', mb: 1 }} />
             <Typography variant="h6" gutterBottom>No exam templates yet</Typography>
             <Typography variant="body2" color="text.secondary" sx={{ mb: 2 }}>
-              Create your first template to start mapping an exam paper.
+              Create your first named template to start mapping an exam paper.
             </Typography>
-            <Button variant="outlined" startIcon={<AddIcon />} onClick={() => setCreateOpen(true)}>
+            <Button variant="outlined" startIcon={<AddIcon />} onClick={openCreate}>
               New template
             </Button>
           </Paper>
         ) : (
-          <Grid container spacing={3}>
-            {templates.map((t) => (
-              <Grid item xs={12} sm={6} md={4} key={t.id}>
-                <Paper
-                  elevation={2}
-                  sx={{ p: 3, height: '100%', cursor: 'pointer', display: 'flex', flexDirection: 'column', gap: 1,
-                        transition: 'box-shadow 120ms', '&:hover': { boxShadow: 6 } }}
-                  onClick={() => navigate(`/exam-marker/${t.id}/setup`)}
-                >
-                  <Box sx={{ display: 'flex', alignItems: 'flex-start', justifyContent: 'space-between' }}>
-                    <Typography variant="h6" sx={{ pr: 1 }}>{t.title}</Typography>
-                    <Tooltip title="Archive">
-                      <IconButton size="small" onClick={(e) => handleArchive(t.id, e)} aria-label="archive template">
-                        <ArchiveIcon fontSize="small" />
-                      </IconButton>
-                    </Tooltip>
-                  </Box>
-                  {t.subject && (
-                    <Typography variant="body2" color="text.secondary">{t.subject}</Typography>
-                  )}
-                  {t.exam_code && (
-                    <Typography variant="caption" color="text.secondary">{t.exam_code}</Typography>
-                  )}
-                  <Box sx={{ mt: 'auto', pt: 1, display: 'flex', alignItems: 'center', justifyContent: 'space-between' }}>
-                    <Chip size="small" label={t.status} color={STATUS_COLOR[t.status] ?? 'default'} variant="outlined" />
-                    <Typography variant="caption" color="text.secondary">
-                      {new Date(t.updated_at).toLocaleDateString()}
-                    </Typography>
-                  </Box>
-                </Paper>
-              </Grid>
+          <Stack spacing={3}>
+            {groupedTemplates.map((group) => (
+              <Box key={group.key}>
+                <Stack direction="row" spacing={1} alignItems="center" sx={{ mb: 1 }}>
+                  <Typography variant="h6">{group.label}</Typography>
+                  <Chip size="small" label={`${group.templates.length} template${group.templates.length === 1 ? '' : 's'}`} variant="outlined" />
+                </Stack>
+                <Grid container spacing={3}>
+                  {group.templates.map((t) => {
+                    const parsed = splitTemplateTitle(t.title);
+                    return (
+                      <Grid item xs={12} sm={6} md={4} key={t.id}>
+                        <Paper
+                          elevation={2}
+                          sx={{
+                            p: 3,
+                            height: '100%',
+                            cursor: 'pointer',
+                            display: 'flex',
+                            flexDirection: 'column',
+                            gap: 1,
+                            transition: 'box-shadow 120ms',
+                            '&:hover': { boxShadow: 6 },
+                          }}
+                          onClick={() => navigate(`/exam-marker/${t.id}/setup`)}
+                        >
+                          <Box sx={{ display: 'flex', alignItems: 'flex-start', justifyContent: 'space-between', gap: 1 }}>
+                            <Box sx={{ minWidth: 0 }}>
+                              <Typography variant="h6" sx={{ pr: 1 }}>{parsed.name}</Typography>
+                              <Chip size="small" label={parsed.version} color="info" variant="outlined" sx={{ mt: 0.5 }} />
+                            </Box>
+                            <Stack direction="row" spacing={0.5}>
+                              <Tooltip title="Rename / edit version">
+                                <IconButton size="small" onClick={(e) => openEdit(t, e)} aria-label="rename template">
+                                  <EditIcon fontSize="small" />
+                                </IconButton>
+                              </Tooltip>
+                              <Tooltip title="Duplicate as new version">
+                                <IconButton size="small" onClick={(e) => openDuplicate(t, e)} aria-label="duplicate template">
+                                  <ContentCopyIcon fontSize="small" />
+                                </IconButton>
+                              </Tooltip>
+                              <Tooltip title="Archive">
+                                <IconButton size="small" onClick={(e) => handleArchive(t, e)} aria-label="archive template">
+                                  <ArchiveIcon fontSize="small" />
+                                </IconButton>
+                              </Tooltip>
+                            </Stack>
+                          </Box>
+                          {t.subject && (
+                            <Typography variant="body2" color="text.secondary">{t.subject}</Typography>
+                          )}
+                          {t.exam_code && (
+                            <Typography variant="caption" color="text.secondary">{t.exam_code}</Typography>
+                          )}
+                          <Box sx={{ mt: 'auto', pt: 1, display: 'flex', alignItems: 'center', justifyContent: 'space-between' }}>
+                            <Chip size="small" label={t.status} color={STATUS_COLOR[t.status] ?? 'default'} variant="outlined" />
+                            <Typography variant="caption" color="text.secondary">
+                              Updated {new Date(t.updated_at).toLocaleDateString()}
+                            </Typography>
+                          </Box>
+                        </Paper>
+                      </Grid>
+                    );
+                  })}
+                </Grid>
+              </Box>
             ))}
-          </Grid>
+          </Stack>
         )}
       </Stack>
 
-      <Dialog open={createOpen} onClose={() => (saving ? null : setCreateOpen(false))} fullWidth maxWidth="sm">
-        <DialogTitle>New exam template</DialogTitle>
+      <Dialog open={Boolean(dialog)} onClose={closeDialog} fullWidth maxWidth="sm">
+        <DialogTitle>{dialogTitle}</DialogTitle>
         <DialogContent>
           <Stack spacing={2} sx={{ mt: 1 }}>
             <TextField
-              label="Title"
-              value={title}
-              onChange={(e) => setTitle(e.target.value)}
+              label="Template name"
+              value={templateName}
+              onChange={(e) => setTemplateName(e.target.value)}
               fullWidth
               autoFocus
               required
+              helperText="User-facing name. Several templates can share the same paper."
             />
             <TextField
-              label="Subject"
+              label="Version"
+              value={version}
+              onChange={(e) => setVersion(e.target.value)}
+              fullWidth
+              helperText="Stored in the template title until the API grows a dedicated version column."
+            />
+            <TextField
+              label="Paper / subject label"
               value={subject}
               onChange={(e) => setSubject(e.target.value)}
               fullWidth
+              disabled={dialog?.mode === 'duplicate'}
             />
           </Stack>
         </DialogContent>
         <DialogActions>
-          <Button onClick={() => setCreateOpen(false)} disabled={saving}>Cancel</Button>
-          <Button variant="contained" onClick={handleCreate} disabled={saving || !title.trim()}>
-            {saving ? 'Creating…' : 'Create'}
+          <Button onClick={closeDialog} disabled={saving}>Cancel</Button>
+          <Button variant="contained" onClick={handleSaveDialog} disabled={saving || !templateName.trim()}>
+            {saving ? 'Saving…' : dialog?.mode === 'duplicate' ? 'Create version' : 'Save'}
           </Button>
         </DialogActions>
       </Dialog>

src/pages/exam/setup/ExamTemplateSetupPage.tsx

@@ -5,31 +5,42 @@ import { Alert, Box, Button, Chip, CircularProgress, Divider, Paper, Snackbar, S
 import ArrowBackIcon from '@mui/icons-material/ArrowBack'
 import SaveIcon from '@mui/icons-material/Save'
 import MouseIcon from '@mui/icons-material/Mouse'
-import PictureAsPdfIcon from '@mui/icons-material/PictureAsPdf'
 import '@tldraw/tldraw/tldraw.css'
-import { Editor, Tldraw, createShapeId, defaultBindingUtils, TLShape } from '@tldraw/tldraw'
+import { Editor, Tldraw, createShapeId, TLShape } from '@tldraw/tldraw'
 import axios from 'axios'
 
 import { ErrorBoundary } from '../../../components/ErrorBoundary'
 import { logger } from '../../../debugConfig'
 import { examRepository } from '../../../services/exam/examRepository'
 import type { ExamTemplateDetail } from '../../../types/exam.types'
-import { ExamCanvasShapeModel, PAGE_WIDTH, type PdfPageLayout, serializeCanvasShapes, shapesFromTemplate } from '../../../utils/exam-canvas/model'
-import { examCanvasShapeUtils, examCanvasTools, ExamCanvasTLShape, PDF_PAGE_SHAPE_TYPE, SHAPE_TYPES, shapeTypeToKind } from './examCanvasShapes'
-import { renderPdfBackdrop, replacePdfPageShapes } from './pdfLoader'
+import { CanvasPageGeometry, ExamCanvasShapeModel, PAGE_HEIGHT, PAGE_WIDTH, isUuid, newDomainId, serializeCanvasShapes, shapesFromTemplate } from '../../../utils/exam-canvas/model'
+import { PDF_PAGE_SHAPE_TYPE, canvasShapePalette, examCanvasShapeUtils, examCanvasTools, ExamCanvasTLShape, SHAPE_TYPES, isPdfPageShape, shapeTypeToKind } from './examCanvasShapes'
+import { loadPdfPageImages, PdfPageImage } from './pdfLoader'
 
 const TOOLS = [
-  { id: 'select', label: 'Select', tip: 'Move, resize, or delete user regions. The PDF backdrop is locked.', color: 'default' as const },
-  { id: SHAPE_TYPES.boundary, label: 'Boundary', tip: 'Draw one horizontal line. A main question is saved from each top+bottom pair.', color: 'error' as const },
-  { id: SHAPE_TYPES.part, label: 'Part', tip: 'Draw the markable sub-question box inside a boundary pair.', color: 'warning' as const },
-  { id: SHAPE_TYPES.response, label: 'Response', tip: 'Draw around where the student writes; saved with response_form=lines.', color: 'primary' as const },
-  { id: SHAPE_TYPES.context, label: 'Context', tip: 'Draw around stimulus/context material; saved with context_type=generic.', color: 'secondary' as const },
-  { id: SHAPE_TYPES.question_number, label: 'Q Number', tip: 'Box the printed question number.', color: 'success' as const },
-  { id: SHAPE_TYPES.mark_area, label: 'Mark Area', tip: 'Box printed marks such as [2].', color: 'success' as const },
-  { id: SHAPE_TYPES.reference, label: 'Reference', tip: 'Box student resources/reference material.', color: 'info' as const },
-  { id: SHAPE_TYPES.furniture, label: 'Furniture', tip: 'Mark margins/page numbers/ignored decoration.', color: 'default' as const },
+  { id: 'select', label: 'Select', icon: '↖', tip: 'Move, resize, delete, or inspect the Attached pill on a region.', color: 'inherit' as const },
+  { id: SHAPE_TYPES.boundary, label: 'Boundary', icon: canvasShapePalette.boundary.icon, tip: 'Draw Q start and Q end horizontal rules; an end rule on a later page creates a multi-page question span.', color: 'error' as const },
+  { id: SHAPE_TYPES.part, label: 'Part', icon: canvasShapePalette.part.icon, tip: 'Draw the markable sub-question box inside a boundary pair; it becomes the leaf question/part.', color: 'warning' as const },
+  { id: SHAPE_TYPES.response, label: 'Response', icon: canvasShapePalette.response.icon, tip: 'Draw around where the student writes; blue regions save as response areas.', color: 'primary' as const },
+  { id: SHAPE_TYPES.context, label: 'Context', icon: canvasShapePalette.context.icon, tip: 'Draw stimulus, figures, tables, or prompt text; purple dashed regions save as context.', color: 'secondary' as const },
+  { id: SHAPE_TYPES.question_number, label: 'Q Number', icon: canvasShapePalette.question_number.icon, tip: 'Box the printed question number for OCR/structure extraction.', color: 'success' as const },
+  { id: SHAPE_TYPES.mark_area, label: 'Mark Area', icon: canvasShapePalette.mark_area.icon, tip: 'Box printed marks such as [2] or Total for Question text.', color: 'success' as const },
+  { id: SHAPE_TYPES.reference, label: 'Reference', icon: canvasShapePalette.reference.icon, tip: 'Box formulae, data sheets, appendices, or other resources the student may use.', color: 'info' as const },
+  { id: SHAPE_TYPES.furniture, label: 'Furniture', icon: canvasShapePalette.furniture.icon, tip: 'Mark page numbers, margins, blank space, or decoration to exclude from extraction.', color: 'inherit' as const },
 ]
 
+const PAGE_START_X = 260
+const PDF_PAGE_IDS_PREFIX = 'pdf-page-'
+
+function pageGeometryFromImages(pages: PdfPageImage[]): CanvasPageGeometry[] {
+  let y = 0
+  return pages.map((page) => {
+    const geometry = { pageNumber: page.pageNumber, x: PAGE_START_X, y, w: page.width, h: page.height }
+    y += page.height
+    return geometry
+  })
+}
+
 function apiMessage(err: unknown): { message: string; conflict: boolean } {
   if (axios.isAxiosError(err)) {
     const detail = (err.response?.data as { detail?: string } | undefined)?.detail
@@ -43,12 +54,27 @@ function stripShapePrefix(id: string) {
   return id.startsWith('shape:') ? id.slice('shape:'.length) : id
 }
 
+function domainIdForShape(shape: ExamCanvasTLShape): string {
+  const fromProps = shape.props.domainId
+  if (isUuid(fromProps)) return fromProps
+  const fromShapeId = stripShapePrefix(shape.id)
+  return isUuid(fromShapeId) ? fromShapeId : newDomainId()
+}
+
+function ensureDomainIds(editor: Editor) {
+  const updates = editor.getCurrentPageShapes()
+    .filter((shape): shape is ExamCanvasTLShape => !!shapeTypeToKind(shape.type))
+    .filter((shape) => !isUuid(shape.props.domainId))
+    .map((shape) => ({ id: shape.id, type: shape.type, props: { domainId: domainIdForShape(shape) } }))
+  if (updates.length) editor.updateShapes(updates)
+}
+
 function modelFromTLShape(shape: TLShape): ExamCanvasShapeModel | null {
   const kind = shapeTypeToKind(shape.type)
   if (!kind) return null
   const s = shape as ExamCanvasTLShape
   return {
-    id: s.props.domainId || stripShapePrefix(s.id),
+    id: domainIdForShape(s),
     kind,
     x: Number(s.x ?? 0),
     y: Number(s.y ?? 0),
@@ -71,23 +97,39 @@ function loadShapes(editor: Editor, models: ExamCanvasShapeModel[]) {
     type: SHAPE_TYPES[m.kind],
     x: m.x,
     y: m.y,
-    props: { w: m.w, h: m.h, label: m.label ?? m.kind, kind: m.kind, domainId: m.id, maxMarks: m.maxMarks, responseForm: m.responseForm, contextType: m.contextType, questionId: m.questionId },
+    props: { w: m.w, h: m.h, label: m.label ?? m.kind, kind: m.kind, maxMarks: m.maxMarks, responseForm: m.responseForm, contextType: m.contextType, questionId: m.questionId, domainId: m.id },
   })))
 }
 
-function newDomainId() {
-  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) return crypto.randomUUID()
-  return `manual-${Date.now()}-${Math.random().toString(16).slice(2)}`
+function syncPdfPages(editor: Editor, pages: PdfPageImage[]) {
+  const existing = editor.getCurrentPageShapes().filter((s) => isPdfPageShape(s.type)).map((s) => s.id)
+  if (existing.length) editor.deleteShapes(existing)
+  if (!pages.length) return
+  const geometries = pageGeometryFromImages(pages)
+  editor.createShapes(geometries.map((geometry) => {
+    const page = pages[geometry.pageNumber - 1]
+    return {
+      id: createShapeId(PDF_PAGE_IDS_PREFIX + geometry.pageNumber),
+      type: PDF_PAGE_SHAPE_TYPE,
+      x: geometry.x,
+      y: geometry.y,
+      isLocked: true,
+      props: { w: geometry.w, h: geometry.h, src: page.src, pageNumber: geometry.pageNumber },
+    } as any
+  }))
+  const ids = geometries.map((geometry) => createShapeId(PDF_PAGE_IDS_PREFIX + geometry.pageNumber))
+  try { editor.sendToBack(ids as any) } catch { /* tldraw 3 keeps creation order behind later region shapes */ }
 }
 
 function seedGuide(editor: Editor) {
   const current = editor.getCurrentPageShapes().filter((s) => shapeTypeToKind(s.type))
   if (current.length) return
   editor.createShapes([
-    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.boundary, x: 48, y: 120, props: { w: PAGE_WIDTH - 96, h: 8, kind: 'boundary', domainId: newDomainId(), label: 'Q1 start' } },
-    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.boundary, x: 48, y: 520, props: { w: PAGE_WIDTH - 96, h: 8, kind: 'boundary', domainId: newDomainId(), label: 'Q1 end' } },
-    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.part, x: 92, y: 180, props: { w: 520, h: 150, kind: 'part', domainId: newDomainId(), label: 'Q1(a)', maxMarks: 3 } },
-    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.response, x: 116, y: 355, props: { w: 470, h: 120, kind: 'response', domainId: newDomainId(), label: 'Response', responseForm: 'lines' } },
+    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.boundary, x: 48, y: 120, props: { w: PAGE_WIDTH - 96, h: 8, kind: 'boundary', label: 'Q1 start', domainId: newDomainId() } },
+    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.boundary, x: 48, y: PAGE_HEIGHT + 160, props: { w: PAGE_WIDTH - 96, h: 8, kind: 'boundary', label: 'Q1 end (page 2)', domainId: newDomainId() } },
+    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.part, x: 92, y: 180, props: { w: 520, h: 150, kind: 'part', label: 'Q1(a)', maxMarks: 3, domainId: newDomainId() } },
+    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.response, x: 116, y: 355, props: { w: 470, h: 120, kind: 'response', label: 'Response', responseForm: 'lines', domainId: newDomainId() } },
+    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.context, x: 116, y: 495, props: { w: 470, h: 90, kind: 'context', label: 'Context', contextType: 'generic', domainId: newDomainId() } },
   ])
 }
 
@@ -96,39 +138,16 @@ const ExamTemplateSetupInner: React.FC = () => {
   const navigate = useNavigate()
   const theme = useTheme()
   const editorRef = useRef<Editor | null>(null)
-  const pageLayoutsRef = useRef<PdfPageLayout[]>([])
-  const hydratingRef = useRef(false)
+  const pageGeometriesRef = useRef<CanvasPageGeometry[]>([])
   const [template, setTemplate] = useState<ExamTemplateDetail | null>(null)
   const [loading, setLoading] = useState(true)
-  const [pdfLoading, setPdfLoading] = useState(false)
-  const [pdfStatus, setPdfStatus] = useState<string>('PDF not loaded')
   const [saving, setSaving] = useState(false)
   const [dirty, setDirty] = useState(false)
   const [error, setError] = useState<string | null>(null)
   const [conflict, setConflict] = useState<string | null>(null)
   const [activeTool, setActiveTool] = useState('select')
-
-  const loadPdf = useCallback(async (id: string, editor: Editor) => {
-    setPdfLoading(true)
-    setPdfStatus('Loading PDF…')
-    try {
-      const result = await renderPdfBackdrop(id)
-      hydratingRef.current = true
-      replacePdfPageShapes(editor, result.pages)
-      pageLayoutsRef.current = result.pageLayouts
-      setPdfStatus(`${result.pages.length} PDF page${result.pages.length === 1 ? '' : 's'} loaded`)
-      editor.zoomToFit()
-    } catch (e) {
-      pageLayoutsRef.current = []
-      const msg = apiMessage(e).message
-      setPdfStatus(`PDF unavailable: ${msg}`)
-      logger.warn('cc-exam-marker', 'Template setup PDF backdrop failed', { templateId: id, message: msg })
-    } finally {
-      hydratingRef.current = false
-      setPdfLoading(false)
-      setDirty(false)
-    }
-  }, [])
+  const [pdfStatus, setPdfStatus] = useState<'loading' | 'ready' | 'missing' | 'error'>('loading')
+  const [pdfError, setPdfError] = useState<string | null>(null)
 
   const load = useCallback(async () => {
     if (!templateId) return
@@ -136,12 +155,39 @@ const ExamTemplateSetupInner: React.FC = () => {
     try {
       const detail = await examRepository.getTemplate(templateId)
       setTemplate(detail)
+      let pages: PdfPageImage[] = []
+      setPdfStatus('loading')
+      setPdfError(null)
+      try {
+        const bytes = await examRepository.getTemplateSourcePdf(templateId)
+        pages = await loadPdfPageImages(bytes, undefined, (partialPages) => {
+          const newPage = partialPages[partialPages.length - 1]
+          const allGeometries = pageGeometryFromImages(partialPages)
+          pageGeometriesRef.current = allGeometries
+          const ed = editorRef.current
+          if (ed) {
+            const geometry = allGeometries[partialPages.length - 1]
+            const shapeId = createShapeId(PDF_PAGE_IDS_PREFIX + newPage.pageNumber)
+            if (!ed.getCurrentPageShapes().find((s) => s.id === shapeId)) {
+              ed.createShapes([{ id: shapeId, type: PDF_PAGE_SHAPE_TYPE, x: geometry.x, y: geometry.y, isLocked: true, props: { w: geometry.w, h: geometry.h, src: newPage.src, pageNumber: newPage.pageNumber } } as any])
+              try { ed.sendToBack([shapeId as any]) } catch { /* */ }
+            }
+          }
+          setPdfStatus('ready')
+        })
+        setPdfStatus(pages.length ? 'ready' : 'missing')
+      } catch (pdfErr) {
+        const pdfMsg = apiMessage(pdfErr).message
+        setPdfStatus(pdfMsg.toLowerCase().includes('404') ? 'missing' : 'error')
+        setPdfError(pdfMsg)
+        logger.warn('cc-exam-marker', 'Template source PDF load failed', { templateId, message: pdfMsg })
+      }
+      const geometries = pageGeometryFromImages(pages)
+      pageGeometriesRef.current = geometries
       const editor = editorRef.current
       if (editor) {
-        hydratingRef.current = true
-        loadShapes(editor, shapesFromTemplate(detail))
-        hydratingRef.current = false
-        await loadPdf(templateId, editor)
+        syncPdfPages(editor, pages)
+        loadShapes(editor, shapesFromTemplate(detail, geometries))
       }
       setDirty(false)
     } catch (e) {
@@ -151,7 +197,7 @@ const ExamTemplateSetupInner: React.FC = () => {
     } finally {
       setLoading(false)
     }
-  }, [loadPdf, templateId])
+  }, [templateId])
 
   useEffect(() => { void load() }, [load])
 
@@ -160,13 +206,12 @@ const ExamTemplateSetupInner: React.FC = () => {
     if (!editor || !templateId || !template) return
     setSaving(true); setError(null); setConflict(null)
     try {
-      const shapes = editor.getCurrentPageShapes().filter((s) => s.type !== PDF_PAGE_SHAPE_TYPE).map(modelFromTLShape).filter(Boolean) as ExamCanvasShapeModel[]
-      const payload = serializeCanvasShapes(template, shapes, pageLayoutsRef.current)
+      ensureDomainIds(editor)
+      const shapes = editor.getCurrentPageShapes().map(modelFromTLShape).filter(Boolean) as ExamCanvasShapeModel[]
+      const payload = serializeCanvasShapes(template, shapes, pageGeometriesRef.current)
       const saved = await examRepository.replaceTemplate(templateId, payload)
       setTemplate(saved)
-      hydratingRef.current = true
-      loadShapes(editor, shapesFromTemplate(saved))
-      hydratingRef.current = false
+      loadShapes(editor, shapesFromTemplate(saved, pageGeometriesRef.current))
       setDirty(false)
     } catch (e) {
       const msg = apiMessage(e)
@@ -183,7 +228,7 @@ const ExamTemplateSetupInner: React.FC = () => {
         size="small"
         variant={activeTool === tool.id ? 'contained' : 'outlined'}
         color={tool.color}
-        startIcon={tool.id === 'select' ? <MouseIcon fontSize="small" /> : undefined}
+        startIcon={tool.id === 'select' ? <MouseIcon fontSize="small" /> : <Box component="span" sx={{ minWidth: 22, textAlign: 'center', fontWeight: 900 }}>{tool.icon}</Box>}
         onClick={() => {
           const editor = editorRef.current
           if (!editor) return
@@ -202,24 +247,15 @@ const ExamTemplateSetupInner: React.FC = () => {
       <Box sx={{ position: 'absolute', inset: 0, '& .tlui-layout': { display: 'none' } }} data-testid="exam-template-setup-canvas">
         <Tldraw
           shapeUtils={examCanvasShapeUtils as any}
-          bindingUtils={defaultBindingUtils}
           tools={examCanvasTools as any}
           hideUi
           inferDarkMode={theme.palette.mode === 'dark'}
           autoFocus
           onMount={(editor) => {
             editorRef.current = editor
-            editor.user.updateUserPreferences({ isDarkMode: theme.palette.mode === 'dark' })
-            editor.store.listen((entry) => {
-              const changedPdfOnly = Object.values(entry.changes.added).every((record: any) => record?.type === PDF_PAGE_SHAPE_TYPE)
-              if (!hydratingRef.current && !changedPdfOnly) setDirty(true)
-            }, { scope: 'document' })
-            if (template) {
-              hydratingRef.current = true
-              loadShapes(editor, shapesFromTemplate(template))
-              hydratingRef.current = false
-              if (templateId) void loadPdf(templateId, editor)
-            } else seedGuide(editor)
+            editor.user.updateUserPreferences({ colorScheme: theme.palette.mode === 'dark' ? 'dark' : 'light' })
+            editor.store.listen(() => setDirty(true), { scope: 'document' })
+            if (template) loadShapes(editor, shapesFromTemplate(template, pageGeometriesRef.current)); else seedGuide(editor)
           }}
         />
       </Box>
@@ -229,9 +265,8 @@ const ExamTemplateSetupInner: React.FC = () => {
         <Divider orientation="vertical" flexItem />
         <Box sx={{ minWidth: 0, flex: 1 }}>
           <Typography variant="subtitle1" noWrap>{template?.title ?? 'Template setup'}</Typography>
-          <Typography variant="caption" color="text.secondary">Exam Marker › Setup · real PDF backdrop is locked; drawn regions persist with PDF-derived page numbers.</Typography>
+          <Typography variant="caption" color="text.secondary">Exam Marker › Setup · coloured tools map to persisted regions; boundary start/end pairs can span pages.</Typography>
         </Box>
-        <Chip size="small" icon={<PictureAsPdfIcon />} color={pdfStatus.includes('loaded') ? 'info' : pdfStatus.includes('unavailable') ? 'warning' : 'default'} label={pdfLoading ? 'Loading PDF…' : pdfStatus} />
         <Chip size="small" color={dirty ? 'warning' : 'success'} label={dirty ? 'Unsaved' : 'Saved'} />
         <Button variant="contained" startIcon={saving ? <CircularProgress size={16} color="inherit" /> : <SaveIcon />} onClick={save} disabled={saving || loading || !template}>Save</Button>
       </Paper>
@@ -240,10 +275,23 @@ const ExamTemplateSetupInner: React.FC = () => {
         <Stack spacing={1}>{toolButtons}</Stack>
       </Paper>
 
-      <Paper elevation={4} sx={{ position: 'absolute', right: 16, bottom: 16, maxWidth: 420, p: 2, borderRadius: 3, bgcolor: 'background.paper' }}>
+      <Paper elevation={4} sx={{ position: 'absolute', right: 16, bottom: 16, maxWidth: 460, p: 2, borderRadius: 3, bgcolor: 'background.paper' }}>
         <Typography variant="subtitle2" gutterBottom>Setup guide</Typography>
-        <Typography variant="body2" color="text.secondary">
-          1) Use the visible PDF pages as the paper coordinate system. 2) Draw top/bottom Boundary lines, Part boxes, then regions over the real paper. 3) Save derives page numbers from the PDF page under each shape and reloads them at the same canvas location.
+        <Typography variant="body2" color="text.secondary" sx={{ mb: 1 }}>
+          1) Boundary start/end lines define each main question. 2) Draw amber Part boxes for markable sub-questions. 3) Draw coloured Response, Context, Q Number, Mark Area, Reference, and Furniture regions; Save derives parent links by containment.
+        </Typography>
+        <Stack direction="row" spacing={0.75} useFlexGap flexWrap="wrap" sx={{ my: 1 }}>
+          {(['boundary', 'part', 'response', 'context', 'question_number', 'mark_area', 'reference', 'furniture'] as const).map((kind) => {
+            const p = canvasShapePalette[kind]
+            return <Chip key={kind} size="small" label={`${p.icon} ${p.label}`} sx={{ borderColor: p.stroke, color: p.stroke, bgcolor: p.fill, fontWeight: 700 }} variant="outlined" />
+          })}
+        </Stack>
+        <Divider sx={{ my: 1 }} />
+        <Typography variant="caption" color="text.secondary" display="block">Multi-page boundary pairing</Typography>
+        <Typography variant="body2" sx={{ fontWeight: 700 }}>Draw “Q start” on page N, then “Q end” on a later page; save pairs boundaries by reading order into one question span.</Typography>
+        <Typography variant="caption" color="text.secondary" display="block" sx={{ mt: 0.75 }}>Open design choices resolved for v1: labels use “Q start/end”; persistent Attached pills confirm containment; rectangles stay simple for dense multi-column papers; Back button remains explicit.</Typography>
+        <Typography variant="caption" color={pdfStatus === 'ready' ? 'success.main' : pdfStatus === 'error' ? 'error.main' : 'text.secondary'} sx={{ display: 'block', mt: 1 }}>
+          PDF backdrop: {pdfStatus === 'ready' ? 'loaded and locked behind regions' : pdfStatus === 'loading' ? 'loading…' : pdfStatus === 'missing' ? 'no source PDF for this template' : pdfError ?? 'failed to load'}
         </Typography>
       </Paper>
 

src/pages/exam/setup/examCanvasShapes.tsx

@@ -1,3 +1,4 @@
+
 import React from 'react'
 import { BaseBoxShapeTool, BaseBoxShapeUtil, HTMLContainer, T, TLBaseBoxShape, toDomPrecision } from '@tldraw/tldraw'
 import type { ExamCanvasRegionKind, ExamCanvasShapeKind } from '../../../utils/exam-canvas/model'
@@ -15,95 +16,114 @@ export const SHAPE_TYPES = {
   furniture: 'exam-region-furniture',
 } as const
 
-export type PdfPageTLShape = TLBaseBoxShape<typeof PDF_PAGE_SHAPE_TYPE, {
-  w: number
-  h: number
-  src: string
-  pageNumber: number
-}>
+export type ExamPdfPageTLShape = TLBaseBoxShape & {
+  type: typeof PDF_PAGE_SHAPE_TYPE
+  props: { w: number; h: number; src: string; pageNumber: number }
+}
 
-export type ExamCanvasTLShape = TLBaseBoxShape<typeof SHAPE_TYPES[keyof typeof SHAPE_TYPES], {
-  w: number
-  h: number
+export type ExamCanvasTLShape = TLBaseBoxShape & {
+  type: typeof SHAPE_TYPES[keyof typeof SHAPE_TYPES]
+  props: {
+    w: number
+    h: number
+    label: string
+    kind: ExamCanvasShapeKind
+    maxMarks?: number
+    responseForm?: string
+    contextType?: string
+    questionId?: string | null
+    domainId?: string
+  }
+}
+
+type CanvasPaletteEntry = {
+  stroke: string
+  fill: string
+  darkStroke: string
+  darkFill: string
+  dash?: string
   label: string
-  kind: ExamCanvasShapeKind
-  domainId: string
-  maxMarks?: number
-  responseForm?: string
-  contextType?: string
-  questionId?: string | null
-}>
-
-const palette: Record<ExamCanvasShapeKind, { stroke: string; fill: string; dash?: string; label: string }> = {
-  boundary: { stroke: '#ef4444', fill: 'rgba(239,68,68,0.06)', dash: '8 6', label: 'Boundary' },
-  part: { stroke: '#f59e0b', fill: 'rgba(245,158,11,0.16)', label: 'Part' },
-  response: { stroke: '#2563eb', fill: 'rgba(37,99,235,0.16)', label: 'Response' },
-  context: { stroke: '#7c3aed', fill: 'rgba(124,58,237,0.14)', dash: '6 5', label: 'Context' },
-  question_number: { stroke: '#0f766e', fill: 'rgba(15,118,110,0.14)', label: 'Question #' },
-  mark_area: { stroke: '#16a34a', fill: 'rgba(22,163,74,0.14)', label: 'Marks' },
-  reference: { stroke: '#0891b2', fill: 'rgba(8,145,178,0.14)', label: 'Reference' },
-  furniture: { stroke: '#64748b', fill: 'rgba(100,116,139,0.12)', dash: '3 5', label: 'Furniture' },
+  icon: string
+  role: string
 }
 
-function makeDomainId() {
-  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) return crypto.randomUUID()
-  return '10000000-1000-4000-8000-100000000000'.replace(/[018]/g, (c) =>
-    (Number(c) ^ (Math.random() * 16) >> Number(c) / 4).toString(16),
-  )
+export const canvasShapePalette: Record<ExamCanvasShapeKind, CanvasPaletteEntry> = {
+  boundary: { stroke: '#ef4444', fill: 'rgba(239,68,68,0.06)', darkStroke: '#f87171', darkFill: 'rgba(248,113,113,0.10)', dash: '8 6', label: 'Boundary', icon: '↕', role: 'start/end rule' },
+  part: { stroke: '#f59e0b', fill: 'rgba(245,158,11,0.18)', darkStroke: '#fbbf24', darkFill: 'rgba(251,191,36,0.26)', label: 'Part', icon: '□', role: 'markable box' },
+  response: { stroke: '#2563eb', fill: 'rgba(37,99,235,0.18)', darkStroke: '#60a5fa', darkFill: 'rgba(96,165,250,0.34)', label: 'Response', icon: '✎', role: 'student writing' },
+  context: { stroke: '#7c3aed', fill: 'rgba(124,58,237,0.14)', darkStroke: '#a78bfa', darkFill: 'rgba(167,139,250,0.28)', dash: '6 5', label: 'Context', icon: '◉', role: 'stimulus' },
+  question_number: { stroke: '#0f766e', fill: 'rgba(15,118,110,0.14)', darkStroke: '#2dd4bf', darkFill: 'rgba(45,212,191,0.24)', label: 'Question #', icon: '#', role: 'printed label' },
+  mark_area: { stroke: '#16a34a', fill: 'rgba(22,163,74,0.14)', darkStroke: '#4ade80', darkFill: 'rgba(74,222,128,0.23)', label: 'Marks', icon: '[2]', role: 'printed marks' },
+  reference: { stroke: '#0891b2', fill: 'rgba(8,145,178,0.14)', darkStroke: '#22d3ee', darkFill: 'rgba(34,211,238,0.24)', label: 'Reference', icon: '§', role: 'resource' },
+  furniture: { stroke: '#64748b', fill: 'rgba(100,116,139,0.12)', darkStroke: '#cbd5e1', darkFill: 'rgba(148,163,184,0.18)', dash: '3 5', label: 'Furniture', icon: '×', role: 'ignore' },
 }
 
+const shapeCss = `
+.exam-canvas-shape { --exam-stroke: var(--exam-light-stroke); --exam-fill: var(--exam-light-fill); }
+[data-color-mode="dark"] .exam-canvas-shape, .tl-theme__dark .exam-canvas-shape { --exam-stroke: var(--exam-dark-stroke); --exam-fill: var(--exam-dark-fill); }
+.exam-canvas-shape__pill { background: rgba(255,255,255,.90); color: var(--exam-stroke); box-shadow: 0 1px 4px rgba(15,23,42,.14); }
+[data-color-mode="dark"] .exam-canvas-shape__pill, .tl-theme__dark .exam-canvas-shape__pill { background: rgba(15,23,42,.88); color: var(--exam-stroke); box-shadow: 0 1px 5px rgba(0,0,0,.35); }
+`
+
 function renderShape(shape: ExamCanvasTLShape) {
   const kind = shape.props.kind
-  const p = palette[kind] ?? palette.response
+  const p = canvasShapePalette[kind] ?? canvasShapePalette.response
   const isBoundary = kind === 'boundary'
   return (
     <HTMLContainer id={shape.id} style={{ width: toDomPrecision(shape.props.w), height: toDomPrecision(shape.props.h), pointerEvents: 'all' }}>
-      <div style={{
-        width: '100%', height: '100%', boxSizing: 'border-box', border: `${isBoundary ? 2 : 1.5}px solid ${p.stroke}`,
-        borderStyle: p.dash ? 'dashed' : 'solid', borderRadius: isBoundary ? 999 : 10,
-        background: isBoundary ? 'transparent' : p.fill, color: p.stroke, fontFamily: 'Inter, system-ui, sans-serif',
-        display: 'flex', alignItems: isBoundary ? 'center' : 'flex-start', justifyContent: isBoundary ? 'center' : 'space-between',
-        padding: isBoundary ? '0 8px' : 8, boxShadow: isBoundary ? 'none' : '0 10px 22px rgba(15,23,42,0.08)', overflow: 'hidden'
-      }}>
-        <span style={{ fontSize: 12, fontWeight: 800, textTransform: 'uppercase', letterSpacing: 0.6, background: 'rgba(255,255,255,0.84)', borderRadius: 999, padding: '2px 7px' }}>
+      <style>{shapeCss}</style>
+      <div
+        className={`exam-canvas-shape exam-canvas-shape--${kind}`}
+        style={{
+          '--exam-light-stroke': p.stroke,
+          '--exam-light-fill': p.fill,
+          '--exam-dark-stroke': p.darkStroke,
+          '--exam-dark-fill': p.darkFill,
+          width: '100%', height: '100%', boxSizing: 'border-box', border: `${isBoundary ? 2 : 1.5}px solid var(--exam-stroke)`,
+          borderStyle: p.dash ? 'dashed' : 'solid', borderRadius: isBoundary ? 999 : 10,
+          background: isBoundary ? 'transparent' : 'var(--exam-fill)', color: 'var(--exam-stroke)', fontFamily: 'Inter, system-ui, sans-serif',
+          display: 'flex', alignItems: isBoundary ? 'center' : 'flex-start', justifyContent: isBoundary ? 'center' : 'space-between',
+          padding: isBoundary ? '0 8px' : 8, boxShadow: isBoundary ? '0 0 0 3px rgba(239,68,68,0.08)' : '0 10px 22px rgba(15,23,42,0.10)', overflow: 'hidden', gap: 6,
+        } as React.CSSProperties}
+        aria-label={`${p.label}: ${p.role}`}
+        title={`${p.label}: ${p.role}`}
+      >
+        <span className="exam-canvas-shape__pill" style={{ fontSize: 12, fontWeight: 900, textTransform: 'uppercase', letterSpacing: 0.6, borderRadius: 999, padding: '2px 7px', display: 'inline-flex', alignItems: 'center', gap: 5 }}>
+          <span aria-hidden="true">{p.icon}</span>
           {shape.props.label || p.label}
         </span>
-        {!isBoundary && shape.props.questionId && <span style={{ fontSize: 11, fontWeight: 700, opacity: .75 }}>Attached</span>}
+        {!isBoundary && shape.props.questionId && <span className="exam-canvas-shape__pill" style={{ fontSize: 11, fontWeight: 800, borderRadius: 999, padding: '2px 7px' }}>Attached</span>}
+        {isBoundary && <span className="exam-canvas-shape__pill" style={{ fontSize: 10, fontWeight: 800, borderRadius: 999, padding: '1px 6px' }}>pair across pages</span>}
       </div>
     </HTMLContainer>
   )
 }
 
 function defaultProps(kind: ExamCanvasShapeKind, w: number, h: number) {
-  const p = palette[kind]
-  return { w, h, label: p.label, kind, domainId: makeDomainId(), responseForm: kind === 'response' ? 'lines' : undefined, contextType: kind === 'context' ? 'generic' : undefined }
+  const p = canvasShapePalette[kind]
+  return { w, h, label: p.label, kind, responseForm: kind === 'response' ? 'lines' : undefined, contextType: kind === 'context' ? 'generic' : undefined }
 }
 
-class PdfPageUtil extends BaseBoxShapeUtil<PdfPageTLShape> {
+const sharedProps = { w: T.number, h: T.number, label: T.string, kind: T.string, maxMarks: T.optional(T.number), responseForm: T.optional(T.string), contextType: T.optional(T.string), questionId: T.optional(T.string), domainId: T.optional(T.string) }
+const ind = (s: ExamCanvasTLShape | ExamPdfPageTLShape) => <rect width={toDomPrecision(s.props.w)} height={toDomPrecision(s.props.h)} />
+
+class PdfPageUtil extends BaseBoxShapeUtil<ExamPdfPageTLShape> {
   static override type = PDF_PAGE_SHAPE_TYPE
   static override props = { w: T.number, h: T.number, src: T.string, pageNumber: T.number }
   override getDefaultProps() { return { w: 780, h: 1100, src: '', pageNumber: 1 } }
   override canEdit() { return false }
-  override canResize() { return false }
-  override hideResizeHandles() { return true }
-  override hideRotateHandle() { return true }
-  override component(shape: PdfPageTLShape) {
+  override component(shape: ExamPdfPageTLShape) {
     return (
       <HTMLContainer id={shape.id} style={{ width: toDomPrecision(shape.props.w), height: toDomPrecision(shape.props.h), pointerEvents: 'none' }}>
-        <img
-          alt={`PDF page ${shape.props.pageNumber}`}
-          src={shape.props.src}
-          draggable={false}
-          style={{ width: '100%', height: '100%', display: 'block', userSelect: 'none', boxShadow: '0 12px 26px rgba(15,23,42,0.22)', background: '#fff' }}
-        />
+        <img src={shape.props.src} alt={'PDF page ' + shape.props.pageNumber} draggable={false} style={{ width: '100%', height: '100%', display: 'block', userSelect: 'none', pointerEvents: 'none', boxShadow: '0 2px 16px rgba(15,23,42,0.18)', background: '#fff' }} />
       </HTMLContainer>
     )
   }
+  override indicator(shape: ExamPdfPageTLShape) { return ind(shape) }
 }
-
-class BoundaryUtil extends BaseBoxShapeUtil<ExamCanvasTLShape> { static override type = SHAPE_TYPES.boundary; static override props = { w: T.number, h: T.number, label: T.string, kind: T.string, domainId: T.string, maxMarks: T.optional(T.number), responseForm: T.optional(T.string), contextType: T.optional(T.string), questionId: T.optional(T.string) }; override getDefaultProps(){ return defaultProps('boundary', 680, 8) }; override component(shape: ExamCanvasTLShape){ return renderShape(shape) } }
-class PartUtil extends BaseBoxShapeUtil<ExamCanvasTLShape> { static override type = SHAPE_TYPES.part; static override props = BoundaryUtil.props; override getDefaultProps(){ return defaultProps('part', 420, 170) }; override component(shape: ExamCanvasTLShape){ return renderShape(shape) } }
-function regionUtil(type: string, kind: ExamCanvasRegionKind, w = 360, h = 120) { return class extends BaseBoxShapeUtil<ExamCanvasTLShape> { static override type = type; static override props = BoundaryUtil.props; override getDefaultProps(){ return defaultProps(kind, w, h) }; override component(shape: ExamCanvasTLShape){ return renderShape(shape) } } }
+class BoundaryUtil extends BaseBoxShapeUtil<ExamCanvasTLShape> { static override type = SHAPE_TYPES.boundary; static override props = sharedProps; override getDefaultProps(){ return defaultProps('boundary', 680, 8) }; override component(shape: ExamCanvasTLShape){ return renderShape(shape) }; override indicator(shape: ExamCanvasTLShape){ return ind(shape) } }
+class PartUtil extends BaseBoxShapeUtil<ExamCanvasTLShape> { static override type = SHAPE_TYPES.part; static override props = sharedProps; override getDefaultProps(){ return defaultProps('part', 420, 170) }; override component(shape: ExamCanvasTLShape){ return renderShape(shape) }; override indicator(shape: ExamCanvasTLShape){ return ind(shape) } }
+function regionUtil(type: string, kind: ExamCanvasRegionKind, w = 360, h = 120) { return class extends BaseBoxShapeUtil<ExamCanvasTLShape> { static override type = type; static override props = sharedProps; override getDefaultProps(){ return defaultProps(kind, w, h) }; override component(shape: ExamCanvasTLShape){ return renderShape(shape) }; override indicator(shape: ExamCanvasTLShape){ return ind(shape) } } }
 
 class BoundaryTool extends BaseBoxShapeTool { static override id = SHAPE_TYPES.boundary; static override initial = 'pointing'; shapeType = SHAPE_TYPES.boundary }
 class PartTool extends BaseBoxShapeTool { static override id = SHAPE_TYPES.part; static override initial = 'pointing'; shapeType = SHAPE_TYPES.part }
@@ -117,6 +137,10 @@ class FurnitureTool extends BaseBoxShapeTool { static override id = SHAPE_TYPES.
 export const examCanvasShapeUtils = [PdfPageUtil, BoundaryUtil, PartUtil, regionUtil(SHAPE_TYPES.response, 'response'), regionUtil(SHAPE_TYPES.context, 'context'), regionUtil(SHAPE_TYPES.question_number, 'question_number', 170, 80), regionUtil(SHAPE_TYPES.mark_area, 'mark_area', 170, 80), regionUtil(SHAPE_TYPES.reference, 'reference'), regionUtil(SHAPE_TYPES.furniture, 'furniture')] as const
 export const examCanvasTools = [BoundaryTool, PartTool, ResponseTool, ContextTool, QuestionNumberTool, MarkAreaTool, ReferenceTool, FurnitureTool] as const
 
+export function isPdfPageShape(type: string): boolean {
+  return type === PDF_PAGE_SHAPE_TYPE
+}
+
 export function shapeTypeToKind(type: string): ExamCanvasShapeKind | null {
   const entry = Object.entries(SHAPE_TYPES).find(([, v]) => v === type)
   return (entry?.[0] as ExamCanvasShapeKind | undefined) ?? null

src/pages/exam/setup/pdfLoader.ts

@@ -1,75 +1,47 @@
-import type { Editor } from '@tldraw/tldraw'
-import * as pdfjsLib from 'pdfjs-dist'
-import pdfWorker from 'pdfjs-dist/build/pdf.worker.mjs?url'
+import * as pdfjsLib from "pdfjs-dist"
+import pdfWorkerSrc from "pdfjs-dist/build/pdf.worker.mjs?url"
 
-import { examRepository } from '../../../services/exam/examRepository'
-import { PAGE_GAP, PAGE_WIDTH, type PdfPageLayout } from '../../../utils/exam-canvas/model'
-import { PDF_PAGE_SHAPE_TYPE, type PdfPageTLShape } from './examCanvasShapes'
+import { PAGE_WIDTH } from "../../../utils/exam-canvas/model"
 
-pdfjsLib.GlobalWorkerOptions.workerSrc = pdfWorker
+pdfjsLib.GlobalWorkerOptions.workerSrc = pdfWorkerSrc
 
-export interface PdfBackdropPage {
-  page: number
+export interface PdfPageImage {
+  pageNumber: number
   src: string
-  layout: PdfPageLayout
+  width: number
+  height: number
 }
 
-export interface PdfBackdropResult {
-  pages: PdfBackdropPage[]
-  pageLayouts: PdfPageLayout[]
-}
-
-export async function renderPdfBackdrop(templateId: string): Promise<PdfBackdropResult> {
-  const bytes = await examRepository.getTemplateSourcePdf(templateId)
-  const loadingTask = pdfjsLib.getDocument({ data: new Uint8Array(bytes) })
-  const pdf = await loadingTask.promise
-  const pages: PdfBackdropPage[] = []
-  let y = 0
+export async function loadPdfPageImages(
+  pdfBytes: ArrayBuffer,
+  targetWidth = PAGE_WIDTH,
+  onPageReady?: (pages: PdfPageImage[]) => void,
+): Promise<PdfPageImage[]> {
+  const pdf = await pdfjsLib.getDocument({ data: new Uint8Array(pdfBytes) }).promise
+  const pages: PdfPageImage[] = []
+  // Reuse a single canvas across all pages to avoid allocating ~120 MB of canvas memory
+  // for a typical 36-page exam paper.
+  const canvas = document.createElement("canvas")
 
   for (let pageNumber = 1; pageNumber <= pdf.numPages; pageNumber += 1) {
     const page = await pdf.getPage(pageNumber)
-    const nativeViewport = page.getViewport({ scale: 1 })
-    const layoutScale = PAGE_WIDTH / nativeViewport.width
-    const renderScale = layoutScale * Math.min(window.devicePixelRatio || 1, 2)
-    const renderViewport = page.getViewport({ scale: renderScale })
-    const canvas = document.createElement('canvas')
-    const context = canvas.getContext('2d')
-    if (!context) throw new Error('Could not create 2D canvas for PDF rendering')
-    canvas.width = Math.ceil(renderViewport.width)
-    canvas.height = Math.ceil(renderViewport.height)
-    await page.render({ canvasContext: context, viewport: renderViewport }).promise
-
-    const layout: PdfPageLayout = {
-      page: pageNumber,
-      x: 0,
-      y,
-      w: PAGE_WIDTH,
-      h: nativeViewport.height * layoutScale,
-    }
-    pages.push({ page: pageNumber, src: canvas.toDataURL('image/jpeg', 0.9), layout })
-    y += layout.h + PAGE_GAP
+    const baseViewport = page.getViewport({ scale: 1 })
+    const scale = targetWidth / baseViewport.width
+    const viewport = page.getViewport({ scale })
+    canvas.width = Math.ceil(viewport.width)
+    canvas.height = Math.ceil(viewport.height)
+    const context = canvas.getContext("2d")
+    if (!context) throw new Error("Unable to create PDF render canvas")
+    context.clearRect(0, 0, canvas.width, canvas.height)
+    await page.render({ canvasContext: context, viewport }).promise
+    pages.push({
+      pageNumber,
+      src: canvas.toDataURL("image/png"),
+      width: canvas.width,
+      height: canvas.height,
+    })
+    onPageReady?.([...pages])
   }
 
-  await pdf.destroy()
-  return { pages, pageLayouts: pages.map((p) => p.layout) }
-}
-
-export function replacePdfPageShapes(editor: Editor, pages: PdfBackdropPage[]) {
-  const old = editor.getCurrentPageShapes().filter((shape) => shape.type === PDF_PAGE_SHAPE_TYPE).map((shape) => shape.id)
-  if (old.length) editor.deleteShapes(old)
-  if (!pages.length) return
-
-  editor.createShapes(pages.map((page) => ({
-    id: `shape:pdf-page-${page.page}` as PdfPageTLShape['id'],
-    type: PDF_PAGE_SHAPE_TYPE,
-    x: page.layout.x,
-    y: page.layout.y,
-    isLocked: true,
-    props: {
-      w: page.layout.w,
-      h: page.layout.h,
-      src: page.src,
-      pageNumber: page.page,
-    },
-  })))
+  return pages
 }

src/services/exam/examRepository.ts

@@ -8,12 +8,17 @@
 import axios from 'axios';
 
 import { API_BASE } from '../../config/apiConfig';
+import { logger } from '../../debugConfig';
 import { supabase } from '../../supabaseClient';
 import type {
   CreateTemplatePayload,
+  ExamBoundary,
+  ExamQuestion,
+  ExamResponseArea,
   ExamTemplate,
   ExamTemplateDetail,
   TemplateReplacePayload,
+  UpdateTemplateMetaPayload,
 } from '../../types/exam.types';
 
 const EXAM_BASE = `${API_BASE}/api/exam`;
@@ -26,6 +31,86 @@ async function authHeaders(): Promise<Record<string, string>> {
   return { Authorization: `Bearer ${session.access_token}` };
 }
 
+function newUuid(): string {
+  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) {
+    return crypto.randomUUID();
+  }
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+    const r = Math.floor(Math.random() * 16);
+    const v = c === 'x' ? r : (r % 4) + 8;
+    return v.toString(16);
+  });
+}
+
+function questionPayload(q: ExamQuestion, idMap?: Map<string, string>) {
+  return {
+    id: idMap?.get(q.id) ?? q.id,
+    parent_id: q.parent_id ? (idMap?.get(q.parent_id) ?? q.parent_id) : null,
+    label: q.label,
+    order: q.order,
+    max_marks: q.max_marks,
+    answer_type: q.answer_type,
+    mcq_options: q.mcq_options,
+    mark_scheme: q.mark_scheme ?? {},
+    is_container: q.is_container,
+    spec_ref: q.spec_ref,
+    bounds: q.bounds ?? null,
+    page: q.page ?? null,
+  };
+}
+
+function responseAreaPayload(r: ExamResponseArea, idMap?: Map<string, string>, duplicate = false) {
+  return {
+    id: duplicate ? newUuid() : r.id,
+    question_id: idMap?.get(r.question_id) ?? r.question_id,
+    page: r.page,
+    bounds: r.bounds,
+    kind: r.kind,
+    response_form: r.response_form,
+    context_type: r.context_type ?? null,
+    source: r.source,
+    confirmed: r.confirmed,
+    confidence: r.confidence,
+  };
+}
+
+function boundaryPayload(b: ExamBoundary, idMap?: Map<string, string>, duplicate = false) {
+  return {
+    id: duplicate ? newUuid() : b.id,
+    question_id: b.question_id ? (idMap?.get(b.question_id) ?? b.question_id) : null,
+    label: b.label,
+    page_index: b.page_index,
+    y: b.y,
+    bounds: b.bounds,
+    source: b.source,
+    confirmed: b.confirmed,
+  };
+}
+
+async function replaceTemplate(
+  templateId: string,
+  detail: ExamTemplateDetail,
+  meta?: UpdateTemplateMetaPayload,
+  duplicateIds = false,
+): Promise<ExamTemplateDetail> {
+  const headers = await authHeaders();
+  const idMap = new Map<string, string>();
+  if (duplicateIds) {
+    detail.questions.forEach((q) => idMap.set(q.id, newUuid()));
+  }
+  const res = await axios.put<ExamTemplateDetail>(
+    `${EXAM_BASE}/templates/${templateId}`,
+    {
+      meta,
+      questions: detail.questions.map((q) => questionPayload(q, idMap)),
+      response_areas: detail.response_areas.map((r) => responseAreaPayload(r, idMap, duplicateIds)),
+      boundaries: detail.boundaries.map((b) => boundaryPayload(b, idMap, duplicateIds)),
+    },
+    { headers },
+  );
+  return res.data;
+}
+
 export const examRepository = {
   async listTemplates(includeArchived = false): Promise<ExamTemplate[]> {
     const headers = await authHeaders();
@@ -42,24 +127,59 @@ export const examRepository = {
     return res.data;
   },
 
+  async getTemplateSourcePdf(templateId: string): Promise<ArrayBuffer> {
+    const headers = await authHeaders();
+    const res = await axios.get<ArrayBuffer>(`${EXAM_BASE}/templates/${templateId}/source-pdf`, {
+      headers,
+      responseType: 'arraybuffer',
+    });
+    return res.data;
+  },
+
   async createTemplate(payload: CreateTemplatePayload): Promise<ExamTemplate> {
     const headers = await authHeaders();
     const res = await axios.post<ExamTemplate>(`${EXAM_BASE}/templates`, payload, { headers });
     return res.data;
   },
 
+  async updateTemplateMeta(templateId: string, meta: UpdateTemplateMetaPayload): Promise<ExamTemplate> {
+    const headers = await authHeaders();
+    const res = await axios.patch<ExamTemplate>(`${EXAM_BASE}/templates/${templateId}`, meta, { headers });
+    return res.data;
+  },
+
+  async duplicateTemplate(templateId: string, title: string): Promise<ExamTemplateDetail> {
+    const detail = await this.getTemplate(templateId);
+    const created = await this.createTemplate({
+      title,
+      subject: detail.subject ?? undefined,
+      exam_id: detail.exam_id ?? undefined,
+      exam_code: detail.exam_code ?? undefined,
+      source_file_id: detail.source_file_id ?? undefined,
+      page_count: detail.page_count ?? undefined,
+      institute_id: detail.institute_id,
+    });
+    try {
+      return await replaceTemplate(created.id, { ...detail, id: created.id }, { title, status: 'draft' }, true);
+    } catch (error) {
+      try {
+        await this.archiveTemplate(created.id);
+      } catch (archiveError) {
+        logger.error('cc-exam-marker', 'Failed to archive incomplete duplicate template', {
+          templateId: created.id,
+          message: archiveError instanceof Error ? archiveError.message : String(archiveError),
+        });
+      }
+      throw error;
+    }
+  },
+
+
   async replaceTemplate(templateId: string, payload: TemplateReplacePayload): Promise<ExamTemplateDetail> {
     const headers = await authHeaders();
     const res = await axios.put<ExamTemplateDetail>(`${EXAM_BASE}/templates/${templateId}`, payload, { headers });
     return res.data;
   },
-
-  async getTemplateSourcePdf(templateId: string): Promise<ArrayBuffer> {
-    const headers = await authHeaders();
-    const res = await axios.get<ArrayBuffer>(`${EXAM_BASE}/templates/${templateId}/source-pdf`, { headers, responseType: 'arraybuffer' });
-    return res.data;
-  },
-
   async archiveTemplate(templateId: string): Promise<void> {
     const headers = await authHeaders();
     await axios.delete(`${EXAM_BASE}/templates/${templateId}`, { headers });

src/types/exam.types.ts

@@ -31,6 +31,13 @@ export interface CreateTemplatePayload {
   institute_id?: string;
 }
 
+export interface UpdateTemplateMetaPayload {
+  title?: string;
+  subject?: string | null;
+  page_count?: number | null;
+  status?: ExamTemplateStatus;
+}
+
 /** Canvas children (used from S4-9 onward; defined here so the seam is complete). */
 export interface ExamQuestion {
   id: string;
@@ -48,13 +55,21 @@ export interface ExamQuestion {
   page?: number | null;
 }
 
+export type ExamResponseAreaKind =
+  | 'response'
+  | 'context'
+  | 'question_number'
+  | 'mark_area'
+  | 'reference'
+  | 'furniture';
+
 export interface ExamResponseArea {
   id: string;
   question_id: string;
   template_id: string;
   page: number;
   bounds: Record<string, number>;
-  kind: 'response' | 'context' | 'question_number' | 'mark_area' | 'reference' | 'furniture';
+  kind: ExamResponseAreaKind;
   response_form: string | null;
   context_type?: string | null;
   source: 'manual' | 'ai';

src/utils/exam-canvas/model.test.ts

@@ -1,72 +1,65 @@
-
 import { describe, expect, it } from 'vitest'
 import type { ExamTemplateDetail } from '../../types/exam.types'
-import { serializeCanvasShapes, shapesFromTemplate, type PdfPageLayout } from './model'
+import { isUuid, pageForY, serializeCanvasShapes, shapesFromTemplate } from './model'
 
 const template: ExamTemplateDetail = {
   id: 'tpl-1', title: 'Physics', subject: 'Physics', exam_id: null, exam_code: null, source_file_id: null, page_count: 1,
   institute_id: 'inst', teacher_id: 'teacher', status: 'draft', created_at: 'now', updated_at: 'now', questions: [], response_areas: [], boundaries: [],
 }
 
-const ids = {
-  top: '11111111-1111-4111-8111-111111111111',
-  bottom: '22222222-2222-4222-8222-222222222222',
-  main: '33333333-3333-4333-8333-333333333333',
-  part: '44444444-4444-4444-8444-444444444444',
-  response: '55555555-5555-4555-8555-555555555555',
-}
-
 describe('exam setup canvas serialization', () => {
   it('pairs boundaries into a main question, attaches a Part, and attaches a response by containment', () => {
     const payload = serializeCanvasShapes(template, [
-      { id: ids.top, kind: 'boundary', questionId: ids.main, x: 40, y: 100, w: 700, h: 8, label: 'Q1 start' },
-      { id: ids.bottom, kind: 'boundary', questionId: ids.main, x: 40, y: 700, w: 700, h: 8, label: 'Q1 end' },
-      { id: ids.part, kind: 'part', x: 100, y: 180, w: 400, h: 220, label: 'Q1(a)', maxMarks: 3 },
-      { id: ids.response, kind: 'response', x: 130, y: 250, w: 300, h: 90, responseForm: 'lines' },
+      { id: 'b-top', kind: 'boundary', x: 40, y: 100, w: 700, h: 8, label: 'Q1 start' },
+      { id: 'b-bottom', kind: 'boundary', x: 40, y: 700, w: 700, h: 8, label: 'Q1 end' },
+      { id: 'part-1', kind: 'part', x: 100, y: 180, w: 400, h: 220, label: 'Q1(a)', maxMarks: 3 },
+      { id: 'resp-1', kind: 'response', x: 130, y: 250, w: 300, h: 90, responseForm: 'lines' },
     ])
 
     const main = payload.questions.find((q) => q.is_container)
-    const part = payload.questions.find((q) => q.id === ids.part)
+    const part = payload.questions.find((q) => !q.is_container)
     expect(main?.label).toBe('Q1')
     expect(part?.parent_id).toBe(main?.id)
     expect(part?.bounds).toEqual({ x: 100, y: 180, w: 400, h: 220 })
-    expect(payload.response_areas[0]).toMatchObject({ id: ids.response, question_id: ids.part, kind: 'response', response_form: 'lines' })
+    expect(payload.response_areas[0]).toMatchObject({ question_id: part?.id, kind: 'response', response_form: 'lines' })
     expect(payload.boundaries).toHaveLength(2)
     expect(payload.boundaries.every((b) => b.question_id === main?.id)).toBe(true)
+    expect(payload.questions.every((q) => isUuid(q.id))).toBe(true)
+    expect(payload.response_areas.every((r) => isUuid(r.id))).toBe(true)
+    expect(payload.boundaries.every((b) => isUuid(b.id))).toBe(true)
   })
 
-  it('uses real PDF page layouts to save visual page numbers', () => {
-    const layouts: PdfPageLayout[] = [
-      { page: 1, x: 0, y: 0, w: 780, h: 1000 },
-      { page: 2, x: 0, y: 1040, w: 780, h: 980 },
+  it('maps shapes to the visible PDF page geometry rather than a fixed page height', () => {
+    const pages = [
+      { pageNumber: 1, x: 260, y: 0, w: 780, h: 1000 },
+      { pageNumber: 2, x: 260, y: 1000, w: 780, h: 1200 },
     ]
+    expect(pageForY(1050, pages)).toBe(2)
     const payload = serializeCanvasShapes(template, [
-      { id: ids.top, kind: 'boundary', questionId: ids.main, x: 40, y: 1060, w: 700, h: 8, label: 'Q2 start' },
-      { id: ids.bottom, kind: 'boundary', questionId: ids.main, x: 40, y: 1800, w: 700, h: 8, label: 'Q2 end' },
-      { id: ids.part, kind: 'part', x: 100, y: 1120, w: 400, h: 220, label: 'Q2(a)', maxMarks: 3 },
-      { id: ids.response, kind: 'response', x: 130, y: 1250, w: 300, h: 90, responseForm: 'lines' },
-    ], layouts)
-
-    expect(payload.boundaries.map((b) => b.page_index)).toEqual([1, 1])
-    expect(payload.questions.find((q) => q.id === ids.part)?.page).toBe(2)
+      { id: 'b-top', kind: 'boundary', x: 260, y: 1020, w: 700, h: 8, label: 'Q1 start' },
+      { id: 'b-bottom', kind: 'boundary', x: 260, y: 1700, w: 700, h: 8, label: 'Q1 end' },
+      { id: 'part-1', kind: 'part', x: 300, y: 1120, w: 300, h: 160, label: 'Q1(a)' },
+      { id: 'resp-1', kind: 'response', x: 320, y: 1160, w: 240, h: 80 },
+    ], pages)
+    expect(payload.questions.find((q) => !q.is_container)?.page).toBe(2)
+    expect(payload.boundaries.every((b) => b.page_index === 1)).toBe(true)
     expect(payload.response_areas[0].page).toBe(2)
-    expect(payload.meta?.page_count).toBe(2)
   })
 
   it('round-trips saved Part geometry and all S4-9 region kinds from API detail', () => {
     const shapes = shapesFromTemplate({
       ...template,
       questions: [
-        { id: ids.main, template_id: 'tpl-1', parent_id: null, label: 'Q1', order: 0, max_marks: 0, answer_type: null, mcq_options: null, mark_scheme: {}, is_container: true, spec_ref: null },
-        { id: ids.part, template_id: 'tpl-1', parent_id: ids.main, label: 'Q1(a)', order: 0, max_marks: 2, answer_type: 'written', mcq_options: null, mark_scheme: {}, is_container: false, spec_ref: null, bounds: { x: 1, y: 2, w: 3, h: 4 }, page: 1 },
+        { id: 'q1', template_id: 'tpl-1', parent_id: null, label: 'Q1', order: 0, max_marks: 0, answer_type: null, mcq_options: null, mark_scheme: {}, is_container: true, spec_ref: null },
+        { id: 'p1', template_id: 'tpl-1', parent_id: 'q1', label: 'Q1(a)', order: 0, max_marks: 2, answer_type: 'written', mcq_options: null, mark_scheme: {}, is_container: false, spec_ref: null, bounds: { x: 1, y: 2, w: 3, h: 4 }, page: 1 },
       ],
       response_areas: [
-        { id: ids.response, question_id: ids.part, template_id: 'tpl-1', page: 1, bounds: { x: 10, y: 20, w: 30, h: 40 }, kind: 'response', response_form: 'lines', source: 'manual', confirmed: true, confidence: null },
-        { id: '66666666-6666-4666-8666-666666666666', question_id: ids.part, template_id: 'tpl-1', page: 1, bounds: { x: 11, y: 21, w: 31, h: 41 }, kind: 'furniture', response_form: null, source: 'manual', confirmed: true, confidence: null },
+        { id: 'r1', question_id: 'p1', template_id: 'tpl-1', page: 1, bounds: { x: 10, y: 20, w: 30, h: 40 }, kind: 'response', response_form: 'lines', source: 'manual', confirmed: true, confidence: null },
+        { id: 'f1', question_id: 'p1', template_id: 'tpl-1', page: 1, bounds: { x: 11, y: 21, w: 31, h: 41 }, kind: 'furniture', response_form: null, source: 'manual', confirmed: true, confidence: null },
       ],
-      boundaries: [{ id: ids.top, template_id: 'tpl-1', question_id: ids.main, label: 'Q1 start', page_index: 0, y: 100, bounds: { x: 0, y: 100, w: 700, h: 8 }, source: 'manual', confirmed: true }],
+      boundaries: [{ id: 'b1', template_id: 'tpl-1', question_id: 'q1', label: 'Q1 start', page_index: 0, y: 100, bounds: { x: 0, y: 100, w: 700, h: 8 }, source: 'manual', confirmed: true }],
     })
     expect(shapes.map((s) => s.kind).sort()).toEqual(['boundary', 'furniture', 'part', 'response'])
-    expect(shapes.find((s) => s.kind === 'part')).toMatchObject({ id: ids.part, x: 1, y: 2, w: 3, h: 4 })
+    expect(shapes.find((s) => s.kind === 'part')).toMatchObject({ id: 'p1', x: 1, y: 2, w: 3, h: 4 })
   })
 })

src/utils/exam-canvas/model.ts

@@ -1,18 +1,19 @@
+
 import type { ExamTemplateDetail, TemplateReplacePayload } from '../../types/exam.types'
 
+export const PAGE_HEIGHT = 1100
 export const PAGE_WIDTH = 780
-export const DEFAULT_PAGE_HEIGHT = 1100
-export const PAGE_GAP = 40
-// Back-compat alias for S4-9a callers/tests. Real PDF pages use PdfPageLayout heights.
-export const PAGE_HEIGHT = DEFAULT_PAGE_HEIGHT + PAGE_GAP
+export const PAGE_GAP = 0
+
+export interface CanvasPageGeometry { pageNumber: number; x: number; y: number; w: number; h: number }
 
 export type ExamCanvasRegionKind = 'response' | 'context' | 'question_number' | 'mark_area' | 'reference' | 'furniture'
 export type ExamCanvasShapeKind = 'boundary' | 'part' | ExamCanvasRegionKind
 
 export interface CanvasBounds { x: number; y: number; w: number; h: number }
-export interface PdfPageLayout { page: number; x: number; y: number; w: number; h: number }
 
 export interface ExamCanvasShapeModel {
+  /** Stable domain UUID persisted to Supabase. Do not reuse tldraw shape ids for new shapes. */
   id: string
   kind: ExamCanvasShapeKind
   x: number
@@ -27,29 +28,41 @@ export interface ExamCanvasShapeModel {
   questionId?: string | null
 }
 
-export function fallbackPageLayouts(pageCount = 4): PdfPageLayout[] {
-  return Array.from({ length: Math.max(pageCount, 1) }, (_, i) => ({
-    page: i + 1,
-    x: 0,
-    y: i * PAGE_HEIGHT,
-    w: PAGE_WIDTH,
-    h: DEFAULT_PAGE_HEIGHT,
-  }))
+export function pageForY(y: number, pages?: CanvasPageGeometry[]): number {
+  if (pages?.length) {
+    const hit = pages.find((page) => y >= page.y && y <= page.y + page.h)
+    if (hit) return hit.pageNumber
+    const nearest = pages.reduce((best, page) => {
+      const dy = Math.min(Math.abs(y - page.y), Math.abs(y - (page.y + page.h)))
+      return dy < best.dy ? { page, dy } : best
+    }, { page: pages[0], dy: Number.POSITIVE_INFINITY })
+    return nearest.page.pageNumber
+  }
+  return Math.max(1, Math.floor(y / PAGE_HEIGHT) + 1)
 }
 
-export function pageForY(y: number, layouts?: PdfPageLayout[]): number {
-  if (!layouts?.length) return Math.max(1, Math.floor(y / PAGE_HEIGHT) + 1)
-  const hit = layouts.find((layout) => y >= layout.y && y <= layout.y + layout.h)
-  if (hit) return hit.page
-  const nearest = layouts.reduce((best, layout) => {
-    const dist = y < layout.y ? layout.y - y : y - (layout.y + layout.h)
-    return dist < best.dist ? { page: layout.page, dist } : best
-  }, { page: layouts[0].page, dist: Number.POSITIVE_INFINITY })
-  return nearest.page
+export function pageTop(page: number, pages?: CanvasPageGeometry[]): number {
+  const hit = pages?.find((p) => p.pageNumber === page)
+  return hit?.y ?? ((page - 1) * (PAGE_HEIGHT + PAGE_GAP))
 }
 
-export function pageForShape(shape: Pick<ExamCanvasShapeModel, 'y' | 'h'>, layouts?: PdfPageLayout[]): number {
-  return pageForY(shape.y + shape.h / 2, layouts)
+function pageForShape(shape: Pick<ExamCanvasShapeModel, 'y' | 'h'>, pages?: CanvasPageGeometry[]): number {
+  return pageForY(shape.y + shape.h / 2, pages)
+}
+
+export function isUuid(value: string | null | undefined): value is string {
+  return typeof value === 'string' && /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(value)
+}
+
+export function newDomainId(): string {
+  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) {
+    return crypto.randomUUID()
+  }
+  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
+    const r = Math.floor(Math.random() * 16)
+    const v = c === 'x' ? r : (r % 4) + 8
+    return v.toString(16)
+  })
 }
 
 function bounds(shape: Pick<ExamCanvasShapeModel, 'x' | 'y' | 'w' | 'h'>): CanvasBounds {
@@ -71,21 +84,10 @@ function bandContains(top: ExamCanvasShapeModel, bottom: ExamCanvasShapeModel, s
   return cy >= minY && cy <= maxY
 }
 
-function uuid(): string {
-  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) return crypto.randomUUID()
-  return '10000000-1000-4000-8000-100000000000'.replace(/[018]/g, (c) =>
-    (Number(c) ^ (Math.random() * 16) >> Number(c) / 4).toString(16),
-  )
-}
-
-function stableUuid(id?: string | null): string {
-  return id && /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(id) ? id : uuid()
-}
-
-export function serializeCanvasShapes(template: ExamTemplateDetail, shapes: ExamCanvasShapeModel[], pageLayouts?: PdfPageLayout[]): TemplateReplacePayload {
+export function serializeCanvasShapes(template: ExamTemplateDetail, shapes: ExamCanvasShapeModel[], pages?: CanvasPageGeometry[]): TemplateReplacePayload {
   const orderedBoundaries = shapes
     .filter((s) => s.kind === 'boundary')
-    .sort((a, b) => (pageForShape(a, pageLayouts) - pageForShape(b, pageLayouts)) || (a.y - b.y))
+    .sort((a, b) => (pageForShape(a, pages) - pageForShape(b, pages)) || (a.y - b.y))
   const parts = shapes.filter((s) => s.kind === 'part')
   const regions = shapes.filter((s) => s.kind !== 'boundary' && s.kind !== 'part')
 
@@ -98,52 +100,51 @@ export function serializeCanvasShapes(template: ExamTemplateDetail, shapes: Exam
     const bottom = orderedBoundaries[i + 1]
     if (!top || !bottom) break
     const qNum = bands.length + 1
-    const questionId = stableUuid(top.questionId || bottom.questionId)
+    const questionId = isUuid(top.questionId) ? top.questionId : isUuid(bottom.questionId) ? bottom.questionId : newDomainId()
     const label = top.label?.replace(/\s+(start|end)$/i, '') || bottom.label?.replace(/\s+(start|end)$/i, '') || `Q${qNum}`
     questions.push({ id: questionId, label, order: qNum - 1, max_marks: 0, is_container: true, mark_scheme: {} })
     bands.push({ questionId, top, bottom })
     for (const b of [top, bottom]) {
-      boundaries.push({ id: stableUuid(b.id), question_id: questionId, label: b === top ? `${label} start` : `${label} end`, page_index: pageForShape(b, pageLayouts) - 1, y: b.y, bounds: bounds(b), source: 'manual', confirmed: true })
+      boundaries.push({ id: isUuid(b.id) ? b.id : newDomainId(), question_id: questionId, label: b === top ? `${label} start` : `${label} end`, page_index: pageForShape(b, pages) - 1, y: b.y, bounds: bounds(b), source: 'manual', confirmed: true })
     }
   }
 
   const partQuestionIds = new Map<string, string>()
   parts.sort((a, b) => (a.y - b.y) || (a.x - b.x)).forEach((part, index) => {
     const parentBand = bands.find((band) => bandContains(band.top, band.bottom, part))
-    const qid = stableUuid(part.questionId || part.id)
+    const qid = isUuid(part.questionId) ? part.questionId : isUuid(part.id) ? part.id : newDomainId()
     partQuestionIds.set(part.id, qid)
-    questions.push({ id: qid, parent_id: parentBand?.questionId ?? null, label: part.label || `Part ${index + 1}`, order: index, max_marks: Number(part.maxMarks ?? 0), answer_type: part.answerType ?? 'written', mcq_options: null, mark_scheme: {}, is_container: false, spec_ref: null, bounds: bounds(part), page: pageForShape(part, pageLayouts) })
+    questions.push({ id: qid, parent_id: parentBand?.questionId ?? null, label: part.label || `Part ${index + 1}`, order: index, max_marks: Number(part.maxMarks ?? 0), answer_type: part.answerType ?? 'written', mcq_options: null, mark_scheme: {}, is_container: false, spec_ref: null, bounds: bounds(part), page: pageForShape(part, pages) })
   })
 
   const response_areas: TemplateReplacePayload['response_areas'] = []
   for (const region of regions) {
     const containingPart = parts.find((part) => contains(bounds(part), bounds(region)))
-    const regionPage = pageForShape(region, pageLayouts)
-    const fallbackPart = parts.find((part) => pageForShape(part, pageLayouts) === regionPage) ?? parts[0]
+    const fallbackPart = parts.find((part) => pageForShape(part, pages) === pageForShape(region, pages)) ?? parts[0]
     const questionId = containingPart ? partQuestionIds.get(containingPart.id) : fallbackPart ? partQuestionIds.get(fallbackPart.id) : undefined
     if (!questionId) continue
     const kind = region.kind as ExamCanvasRegionKind
-    response_areas.push({ id: stableUuid(region.id), question_id: questionId, page: regionPage, bounds: bounds(region), kind, response_form: kind === 'response' ? (region.responseForm ?? 'lines') : null, context_type: kind === 'context' ? (region.contextType ?? 'generic') : null, source: 'manual', confirmed: true, confidence: null })
+    response_areas.push({ id: isUuid(region.id) ? region.id : newDomainId(), question_id: questionId, page: pageForShape(region, pages), bounds: bounds(region), kind, response_form: kind === 'response' ? (region.responseForm ?? 'lines') : null, context_type: kind === 'context' ? (region.contextType ?? 'generic') : null, source: 'manual', confirmed: true, confidence: null })
   }
 
-  return { meta: { title: template.title, subject: template.subject ?? undefined, page_count: pageLayouts?.length ?? template.page_count ?? undefined, status: template.status }, questions, response_areas, boundaries }
+  return { meta: { title: template.title, subject: template.subject ?? undefined, page_count: template.page_count ?? undefined, status: template.status }, questions, response_areas, boundaries }
 }
 
-export function shapesFromTemplate(detail: ExamTemplateDetail): ExamCanvasShapeModel[] {
+export function shapesFromTemplate(detail: ExamTemplateDetail, pages?: CanvasPageGeometry[]): ExamCanvasShapeModel[] {
   const shapes: ExamCanvasShapeModel[] = []
   const questions = new Map(detail.questions.map((q) => [q.id, q]))
   for (const b of detail.boundaries ?? []) {
     const bb = b.bounds ?? { x: 48, y: b.y, w: PAGE_WIDTH - 96, h: 8 }
-    shapes.push({ id: stableUuid(b.id), kind: 'boundary', x: Number(bb.x ?? 48), y: Number(bb.y ?? b.y), w: Number(bb.w ?? PAGE_WIDTH - 96), h: Number(bb.h ?? 8), label: b.label ?? undefined, questionId: b.question_id })
+    shapes.push({ id: b.id, kind: 'boundary', x: Number(bb.x ?? 48), y: Number(bb.y ?? b.y), w: Number(bb.w ?? PAGE_WIDTH - 96), h: Number(bb.h ?? 8), label: b.label ?? undefined, questionId: b.question_id })
   }
   for (const q of detail.questions ?? []) {
     if (q.is_container || !q.bounds) continue
-    shapes.push({ id: stableUuid(q.id), kind: 'part', x: Number(q.bounds.x ?? 80), y: Number(q.bounds.y ?? 120), w: Number(q.bounds.w ?? 420), h: Number(q.bounds.h ?? 180), label: q.label, maxMarks: q.max_marks, answerType: q.answer_type ?? 'written', questionId: q.id })
+    shapes.push({ id: q.id, kind: 'part', x: Number(q.bounds.x ?? 80), y: Number(q.bounds.y ?? 120), w: Number(q.bounds.w ?? 420), h: Number(q.bounds.h ?? 180), label: q.label, maxMarks: q.max_marks, answerType: q.answer_type ?? 'written', questionId: q.id })
   }
   for (const r of detail.response_areas ?? []) {
-    const bb = r.bounds ?? { x: 100, y: (r.page - 1) * PAGE_HEIGHT + 360, w: 360, h: 120 }
+    const bb = r.bounds ?? { x: 100, y: pageTop(r.page, pages) + 360, w: 360, h: 120 }
     const q = questions.get(r.question_id)
-    shapes.push({ id: stableUuid(r.id), kind: r.kind, x: Number(bb.x ?? 100), y: Number(bb.y ?? (r.page - 1) * PAGE_HEIGHT + 360), w: Number(bb.w ?? 360), h: Number(bb.h ?? 120), label: q ? `→ ${q.label}` : r.kind, responseForm: r.response_form ?? undefined, contextType: r.context_type ?? undefined, questionId: r.question_id })
+    shapes.push({ id: r.id, kind: r.kind, x: Number(bb.x ?? 100), y: Number(bb.y ?? pageTop(r.page, pages) + 360), w: Number(bb.w ?? 360), h: Number(bb.h ?? 120), label: q ? `→ ${q.label}` : r.kind, responseForm: r.response_form ?? undefined, contextType: r.context_type ?? undefined, questionId: r.question_id })
   }
   return shapes
 }