FX-5: scan-ingestion UI on the marking page

The marking flow read student_submissions but there was no way to create them —
print→scan→mark could not be completed in-app. Add an "Upload scans" control to
the marking queue that posts PDFs to the existing POST /batches/{id}/scans and
refreshes the queue.

- examRepository.uploadScan(batchId, file, {studentId?, matchingMethod?}): multipart
  upload (axios sets the boundary), returns the created/updated StudentSubmission.
- ExamMarkingPage: "Upload scans" button + hidden multi-file PDF input; uploads each
  with matching_method='ordered' (fills the roster in order; unmatched scans become
  reconcilable submissions), then reloads the queue with a success/failure summary.

No API or schema change (endpoint already existed). tsc clean; behaviour is covered
by the cc-browser-tester card (FX-V).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/pages/exam/ExamMarkingPage.tsx

@@ -1,4 +1,4 @@
-import React, { useCallback, useEffect, useMemo, useState } from 'react';
+import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useNavigate, useParams } from 'react-router-dom';
 import { v5 as uuidv5 } from 'uuid';
 import {
@@ -21,6 +21,7 @@ import {
 import ArrowBackIcon from '@mui/icons-material/ArrowBack';
 import SaveIcon from '@mui/icons-material/Save';
 import TableChartIcon from '@mui/icons-material/TableChart';
+import UploadFileIcon from '@mui/icons-material/UploadFile';
 
 import { examRepository } from '../../services/exam/examRepository';
 import type { BatchQueueResponse, ExamQuestion, ExamTemplateDetail, StudentSubmission } from '../../types/exam.types';
@@ -43,6 +44,8 @@ const ExamMarkingPage: React.FC = () => {
   const [saving, setSaving] = useState(false);
   const [message, setMessage] = useState<string | null>(null);
   const [error, setError] = useState<string | null>(null);
+  const [uploading, setUploading] = useState(false);
+  const fileInputRef = useRef<HTMLInputElement | null>(null);
 
   const load = useCallback(async () => {
     if (!batchId) return;
@@ -68,6 +71,28 @@ const ExamMarkingPage: React.FC = () => {
     () => (template?.questions ?? []).filter((q) => !q.is_container).sort((a, b) => a.order - b.order),
     [template],
   );
+  const onScanFiles = useCallback(async (files: FileList | null) => {
+    if (!batchId || !files || files.length === 0) return;
+    setUploading(true); setError(null); setMessage(null);
+    let ok = 0;
+    const failures: string[] = [];
+    for (const file of Array.from(files)) {
+      try {
+        // 'ordered' assigns each scan to the next not-yet-submitted roster slot; unmatched scans
+        // become an unmatched submission the teacher can reconcile.
+        await examRepository.uploadScan(batchId, file, { matchingMethod: 'ordered' });
+        ok += 1;
+      } catch (e) {
+        failures.push(`${file.name}: ${e instanceof Error ? e.message : String(e)}`);
+      }
+    }
+    setUploading(false);
+    if (fileInputRef.current) fileInputRef.current.value = '';
+    await load();
+    if (ok) setMessage(`Uploaded ${ok} scan${ok === 1 ? '' : 's'}${failures.length ? `, ${failures.length} failed` : ''}`);
+    if (failures.length) setError(failures.join(' · '));
+  }, [batchId, load]);
+
   const selected = queue?.submissions.find((s) => s.id === selectedId) ?? null;
 
   const saveSelected = async () => {
@@ -154,7 +179,29 @@ const ExamMarkingPage: React.FC = () => {
         <Stack direction={{ xs: 'column', md: 'row' }} spacing={2} alignItems="stretch">
           <Card variant="outlined" sx={{ width: { xs: '100%', md: 340 }, flexShrink: 0 }}>
             <CardContent>
-              <Typography variant="h6" gutterBottom>Marking queue</Typography>
+              <Box sx={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', gap: 1, mb: 1 }}>
+                <Typography variant="h6">Marking queue</Typography>
+                <Button
+                  size="small"
+                  variant="outlined"
+                  startIcon={<UploadFileIcon fontSize="small" />}
+                  disabled={uploading}
+                  onClick={() => fileInputRef.current?.click()}
+                >
+                  {uploading ? 'Uploading…' : 'Upload scans'}
+                </Button>
+                <input
+                  ref={fileInputRef}
+                  type="file"
+                  accept="application/pdf"
+                  multiple
+                  hidden
+                  onChange={(e) => { void onScanFiles(e.target.files); }}
+                />
+              </Box>
+              <Typography variant="caption" color="text.secondary" sx={{ display: 'block', mb: 1 }}>
+                Scanned PDFs fill the roster in order; unmatched scans appear below to reconcile.
+              </Typography>
               <Stack direction="row" spacing={1} sx={{ mb: 1 }} flexWrap="wrap" useFlexGap>
                 <Chip size="small" label={`${queue?.progress.total ?? 0} total`} />
                 <Chip size="small" label={`${queue?.progress.absent ?? 0} absent`} color="warning" variant="outlined" />

src/pages/exam/setup/ExamTemplateSetupPage.tsx

@@ -211,7 +211,9 @@ const ExamTemplateSetupInner: React.FC = () => {
     setTemplate(detail)
     const editor = editorRef.current
     if (editor) {
-      loadShapes(editor, shapesFromTemplate(detail, pageGeometriesRef.current))
+      const shapes = shapesFromTemplate(detail, pageGeometriesRef.current)
+      loadShapes(editor, shapes)
+      if (!shapes.length) seedGuide(editor)
       bringDomainShapesToFront(editor)
     }
     setDirty(false)
@@ -417,7 +419,14 @@ const ExamTemplateSetupInner: React.FC = () => {
                 editor.store.listen(() => setDirty(true), { scope: 'document' })
                 applyDocViewConstraints(editor, [])
                 editor.resetZoom()
-                if (template) loadShapes(editor, shapesFromTemplate(template, pageGeometriesRef.current)); else seedGuide(editor)
+                // Only seed the example guide for a genuinely-empty template AFTER it has loaded.
+                // (Previously `else seedGuide` fired on mount while `template` was still null during
+                // the async fetch, flashing placeholder shapes before the real shapes/PDF rendered.)
+                if (template) {
+                  const s = shapesFromTemplate(template, pageGeometriesRef.current)
+                  loadShapes(editor, s)
+                  if (!s.length) seedGuide(editor)
+                }
                 bringDomainShapesToFront(editor)
               }}
             />

src/services/exam/examRepository.ts

@@ -28,6 +28,7 @@ import type {
   Neo4jSyncResult,
   PatchQuestionPayload,
   SpecPoint,
+  StudentSubmission,
   TemplateReplacePayload,
   UpdateTemplateMetaPayload,
 } from '../../types/exam.types';
@@ -298,6 +299,21 @@ export const examRepository = {
     const res = await axios.put(`${EXAM_BASE}/marks/${markId}`, payload, { headers });
     return res.data;
   },
+
+  async uploadScan(
+    batchId: string,
+    file: File,
+    opts: { studentId?: string; matchingMethod?: 'manual' | 'ordered' } = {},
+  ): Promise<StudentSubmission> {
+    const headers = await authHeaders();
+    const form = new FormData();
+    form.append('file', file);
+    form.append('matching_method', opts.matchingMethod ?? 'ordered');
+    if (opts.studentId) form.append('student_id', opts.studentId);
+    // Let axios set the multipart Content-Type + boundary (only Authorization is forwarded).
+    const res = await axios.post<StudentSubmission>(`${EXAM_BASE}/batches/${batchId}/scans`, form, { headers });
+    return res.data;
+  },
 };
 
 export default examRepository;