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/pages/exam/setup/ExamTemplateSetupPage.tsx

@@ -14,19 +14,19 @@ import { logger } from '../../../debugConfig'
 import { examRepository } from '../../../services/exam/examRepository'
 import type { ExamTemplateDetail } from '../../../types/exam.types'
 import { CanvasPageGeometry, ExamCanvasShapeModel, PAGE_HEIGHT, PAGE_WIDTH, isUuid, newDomainId, serializeCanvasShapes, shapesFromTemplate } from '../../../utils/exam-canvas/model'
-import { PDF_PAGE_SHAPE_TYPE, examCanvasShapeUtils, examCanvasTools, ExamCanvasTLShape, SHAPE_TYPES, isPdfPageShape, shapeTypeToKind } from './examCanvasShapes'
+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 shapes.', color: 'inherit' 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: 'inherit' 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
@@ -126,9 +126,10 @@ function seedGuide(editor: Editor) {
   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', label: 'Q1 start', domainId: newDomainId() } },
-    { id: createShapeId(newDomainId()), type: SHAPE_TYPES.boundary, x: 48, y: 520, props: { w: PAGE_WIDTH - 96, h: 8, kind: 'boundary', label: 'Q1 end', 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() } },
   ])
 }
 
@@ -159,7 +160,21 @@ const ExamTemplateSetupInner: React.FC = () => {
       setPdfError(null)
       try {
         const bytes = await examRepository.getTemplateSourcePdf(templateId)
-        pages = await loadPdfPageImages(bytes)
+        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
@@ -213,7 +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
@@ -250,7 +265,7 @@ 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 · draw boundaries, part boxes, and regions; Save persists a full replace.</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" 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>
@@ -260,11 +275,21 @@ 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) Draw top and bottom Boundary lines for each main question. 2) Draw Part boxes inside the pair. 3) Draw Response/Context/metadata regions inside a Part. Save derives parent links by spatial containment and reloads from the API.
+        <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>

src/pages/exam/setup/examCanvasShapes.tsx

@@ -36,41 +36,71 @@ export type ExamCanvasTLShape = TLBaseBoxShape & {
   }
 }
 
-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' },
+type CanvasPaletteEntry = {
+  stroke: string
+  fill: string
+  darkStroke: string
+  darkFill: string
+  dash?: string
+  label: string
+  icon: string
+  role: string
 }
 
+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 ${p.stroke}`,
+      <style>{shapeCss}</style>
+      <div
+        className={`exam-canvas-shape exam-canvas-shape--${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: `${isBoundary ? 2 : 1.5}px solid var(--exam-stroke)`,
           borderStyle: p.dash ? 'dashed' : 'solid', borderRadius: isBoundary ? 999 : 10,
-        background: isBoundary ? 'transparent' : p.fill, color: p.stroke, fontFamily: 'Inter, system-ui, sans-serif',
+          background: isBoundary ? 'transparent' : 'var(--exam-fill)', color: 'var(--exam-stroke)', fontFamily: 'Inter, system-ui, sans-serif',
           display: 'flex', alignItems: isBoundary ? 'center' : 'flex-start', justifyContent: isBoundary ? 'center' : 'space-between',
-        padding: isBoundary ? '0 8px' : 8, boxShadow: isBoundary ? 'none' : '0 10px 22px rgba(15,23,42,0.08)', overflow: 'hidden'
-      }}>
-        <span style={{ fontSize: 12, fontWeight: 800, textTransform: 'uppercase', letterSpacing: 0.6, background: 'rgba(255,255,255,0.84)', borderRadius: 999, padding: '2px 7px' }}>
+          padding: isBoundary ? '0 8px' : 8, boxShadow: isBoundary ? '0 0 0 3px rgba(239,68,68,0.08)' : '0 10px 22px rgba(15,23,42,0.10)', overflow: 'hidden', gap: 6,
+        } as React.CSSProperties}
+        aria-label={`${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]
+  const p = canvasShapePalette[kind]
   return { w, h, label: p.label, kind, responseForm: kind === 'response' ? 'lines' : undefined, contextType: kind === 'context' ? 'generic' : undefined }
 }
 

src/pages/exam/setup/pdfLoader.ts

@@ -12,20 +12,27 @@ export interface PdfPageImage {
   height: number
 }
 
-export async function loadPdfPageImages(pdfBytes: ArrayBuffer, targetWidth = PAGE_WIDTH): Promise<PdfPageImage[]> {
+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 baseViewport = page.getViewport({ scale: 1 })
     const scale = targetWidth / baseViewport.width
     const viewport = page.getViewport({ scale })
-    const canvas = document.createElement("canvas")
     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,
@@ -33,6 +40,7 @@ export async function loadPdfPageImages(pdfBytes: ArrayBuffer, targetWidth = PAG
       width: canvas.width,
       height: canvas.height,
     })
+    onPageReady?.([...pages])
   }
 
   return pages