Render fenced code (syntax highlight) and LaTeX math in free Markdown

The free-Markdown slide preview now parses block-level content: - ```lang fenced code blocks render with highlight.js colouring (flutter_highlight); unknown languages fall back to plain monospace instead of throwing. - $$…$$ display math renders via flutter_math_fork (KaTeX), with a plain fallback on parse errors. Because the preview feeds the export rasterizer, code and math now also appear in PDF/PPTX output. Adds flutter_highlight, flutter_math_fork and highlight dependencies. Tests: code block highlighted, math rendered, unknown language safe. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Export speaker notes to PPTX; fix stale README CI reference
2026-06-04 00:59:14 +02:00 · 2026-06-04 00:51:09 +02:00
8 changed files with 510 additions and 58 deletions
--- a/README.md
+++ b/README.md
@ -50,7 +50,8 @@ Targeted test groups speed up focused work:
 | `make test-services`  | Image, caption, and description sidecar services |
 | `make test-presenter` | Fullscreen presenter navigation and keyboard shortcuts |

-CI runs `make check` on every push and pull request (see [`.github/workflows/ci.yml`](.github/workflows/ci.yml)).
+Run `make check` before pushing — it is the same quality gate (format check,
+static analysis, full test suite) you would wire into CI.

 ## Project layout

--- a/lib/services/export_service.dart
+++ b/lib/services/export_service.dart
@ -87,6 +87,7 @@ class ExportService {
    List<Uint8List> images, {
    bool compress = false,
    String? outputDirectory,
+    List<String>? notes,
  }) async {
    if (images.isEmpty) {
      return ExportResult.fail('Geen slides om te exporteren.');
@ -108,7 +109,7 @@ class ExportService {
        case ExportFormat.pdf:
          bytes = await _buildPdf(images, compress: compress);
        case ExportFormat.pptx:
-          bytes = _buildPptx(images);
+          bytes = _buildPptx(images, notes: notes);
      }
      await File(outputPath).writeAsBytes(bytes, flush: true);
      return ExportResult.ok(outputPath);
@ -158,7 +159,7 @@ class ExportService {

  // ── PPTX (Office Open XML) ─────────────────────────────────────────────────

-  Uint8List _buildPptx(List<Uint8List> images) {
+  Uint8List _buildPptx(List<Uint8List> images, {List<String>? notes}) {
    final archive = Archive();
    void addText(String name, String content) {
      final data = utf8Bytes(content);
@ -166,11 +167,22 @@ class ExportService {
    }

    final slideCount = images.length;
+    // Which slides carry speaker notes. When none do, the whole notes machinery
+    // (notesMaster + notesSlides) is omitted to keep the file minimal.
+    final noteFor = <int, String>{
+      for (var i = 0; i < slideCount; i++)
+        if (notes != null && i < notes.length && notes[i].trim().isNotEmpty)
+          i: notes[i].trim(),
+    };
+    final hasNotes = noteFor.isNotEmpty;

-    addText('[Content_Types].xml', _contentTypes(slideCount));
+    addText('[Content_Types].xml', _contentTypes(slideCount, noteFor.keys));
    addText('_rels/.rels', _rootRels());
-    addText('ppt/presentation.xml', _presentationXml(slideCount));
-    addText('ppt/_rels/presentation.xml.rels', _presentationRels(slideCount));
+    addText('ppt/presentation.xml', _presentationXml(slideCount, hasNotes));
+    addText(
+      'ppt/_rels/presentation.xml.rels',
+      _presentationRels(slideCount, hasNotes),
+    );
    addText('ppt/presProps.xml', _presProps());
    addText('ppt/theme/theme1.xml', _theme1());
    addText('ppt/slideMasters/slideMaster1.xml', _slideMaster());
@ -178,10 +190,26 @@ class ExportService {
    addText('ppt/slideLayouts/slideLayout1.xml', _slideLayout());
    addText('ppt/slideLayouts/_rels/slideLayout1.xml.rels', _slideLayoutRels());

+    if (hasNotes) {
+      addText('ppt/notesMasters/notesMaster1.xml', _notesMaster());
+      addText(
+        'ppt/notesMasters/_rels/notesMaster1.xml.rels',
+        _notesMasterRels(),
+      );
+    }
+
    for (var i = 0; i < slideCount; i++) {
      final n = i + 1;
+      final hasNote = noteFor.containsKey(i);
      addText('ppt/slides/slide$n.xml', _slideXml());
-      addText('ppt/slides/_rels/slide$n.xml.rels', _slideRels(n));
+      addText('ppt/slides/_rels/slide$n.xml.rels', _slideRels(n, hasNote));
+      if (hasNote) {
+        addText('ppt/notesSlides/notesSlide$n.xml', _notesSlideXml(noteFor[i]!));
+        addText(
+          'ppt/notesSlides/_rels/notesSlide$n.xml.rels',
+          _notesSlideRels(n),
+        );
+      }
      final png = images[i];
      archive.add(ArchiveFile('ppt/media/image$n.png', png.length, png));
    }
@ -189,9 +217,83 @@ class ExportService {
    return ZipEncoder().encodeBytes(archive);
  }

+  /// XML-escape free text destined for an `<a:t>` run.
+  static String _xmlEscape(String s) {
+    return s
+        .replaceAll('&', '&amp;')
+        .replaceAll('<', '&lt;')
+        .replaceAll('>', '&gt;');
+  }
+
+  /// A notesSlide whose body placeholder carries the speaker notes. Newlines in
+  /// [note] become separate paragraphs.
+  String _notesSlideXml(String note) {
+    final paras = StringBuffer();
+    for (final line in note.split('\n')) {
+      paras.write(
+        '<a:p><a:r><a:t>${_xmlEscape(line)}</a:t></a:r></a:p>',
+      );
+    }
+    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+        '<p:notes xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" '
+        'xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" '
+        'xmlns:p="http://schemas.openxmlformats.org/presentationml/2006/main">'
+        '<p:cSld><p:spTree>'
+        '<p:nvGrpSpPr><p:cNvPr id="1" name=""/><p:cNvGrpSpPr/><p:nvPr/></p:nvGrpSpPr>'
+        '<p:grpSpPr><a:xfrm><a:off x="0" y="0"/><a:ext cx="0" cy="0"/>'
+        '<a:chOff x="0" y="0"/><a:chExt cx="0" cy="0"/></a:xfrm></p:grpSpPr>'
+        '<p:sp>'
+        '<p:nvSpPr><p:cNvPr id="2" name="Notes Placeholder"/>'
+        '<p:cNvSpPr><a:spLocks noGrp="1"/></p:cNvSpPr>'
+        '<p:nvPr><p:ph type="body" idx="1"/></p:nvPr></p:nvSpPr>'
+        '<p:spPr/>'
+        '<p:txBody><a:bodyPr/><a:lstStyle/>$paras</p:txBody>'
+        '</p:sp>'
+        '</p:spTree></p:cSld>'
+        '<p:clrMapOvr><a:masterClrMapping/></p:clrMapOvr>'
+        '</p:notes>';
+  }
+
+  String _notesSlideRels(int n) {
+    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+        '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">'
+        '<Relationship Id="rId1" '
+        'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/slide" '
+        'Target="../slides/slide$n.xml"/>'
+        '<Relationship Id="rId2" '
+        'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/notesMaster" '
+        'Target="../notesMasters/notesMaster1.xml"/>'
+        '</Relationships>';
+  }
+
+  String _notesMaster() {
+    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+        '<p:notesMaster xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" '
+        'xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" '
+        'xmlns:p="http://schemas.openxmlformats.org/presentationml/2006/main">'
+        '<p:cSld><p:spTree>'
+        '<p:nvGrpSpPr><p:cNvPr id="1" name=""/><p:cNvGrpSpPr/><p:nvPr/></p:nvGrpSpPr>'
+        '<p:grpSpPr><a:xfrm><a:off x="0" y="0"/><a:ext cx="0" cy="0"/>'
+        '<a:chOff x="0" y="0"/><a:chExt cx="0" cy="0"/></a:xfrm></p:grpSpPr>'
+        '</p:spTree></p:cSld>'
+        '<p:clrMap bg1="lt1" tx1="dk1" bg2="lt2" tx2="dk2" accent1="accent1" '
+        'accent2="accent2" accent3="accent3" accent4="accent4" accent5="accent5" '
+        'accent6="accent6" hlink="hlink" folHlink="folHlink"/>'
+        '</p:notesMaster>';
+  }
+
+  String _notesMasterRels() {
+    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+        '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">'
+        '<Relationship Id="rId1" '
+        'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme" '
+        'Target="../theme/theme1.xml"/>'
+        '</Relationships>';
+  }
+
  static List<int> utf8Bytes(String s) => utf8.encode(s);

-  String _contentTypes(int count) {
+  String _contentTypes(int count, Iterable<int> noteIndices) {
    final overrides = StringBuffer();
    for (var i = 1; i <= count; i++) {
      overrides.write(
@ -199,6 +301,19 @@ class ExportService {
        'ContentType="application/vnd.openxmlformats-officedocument.presentationml.slide+xml"/>',
      );
    }
+    final notes = noteIndices.toList();
+    if (notes.isNotEmpty) {
+      overrides.write(
+        '<Override PartName="/ppt/notesMasters/notesMaster1.xml" '
+        'ContentType="application/vnd.openxmlformats-officedocument.presentationml.notesMaster+xml"/>',
+      );
+      for (final i in notes) {
+        overrides.write(
+          '<Override PartName="/ppt/notesSlides/notesSlide${i + 1}.xml" '
+          'ContentType="application/vnd.openxmlformats-officedocument.presentationml.notesSlide+xml"/>',
+        );
+      }
+    }
    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
        '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">'
        '<Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>'
@ -220,24 +335,31 @@ class ExportService {
        '</Relationships>';
  }

-  String _presentationXml(int count) {
+  String _presentationXml(int count, bool hasNotes) {
    final sldIds = StringBuffer();
    for (var i = 0; i < count; i++) {
      // Slide relationship ids start at rId2 (rId1 = master).
      sldIds.write('<p:sldId id="${256 + i}" r:id="rId${i + 2}"/>');
    }
+    // The notesMaster relationship is appended after the slides/presProps/theme
+    // rels (see _presentationRels): rId(count+4).
+    final notesMasterIdLst = hasNotes
+        ? '<p:notesMasterIdLst><p:notesMasterId r:id="rId${count + 4}"/></p:notesMasterIdLst>'
+        : '';
    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
        '<p:presentation xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" '
        'xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" '
        'xmlns:p="http://schemas.openxmlformats.org/presentationml/2006/main">'
        '<p:sldMasterIdLst><p:sldMasterId id="2147483648" r:id="rId1"/></p:sldMasterIdLst>'
+        // Schema order: notesMasterIdLst must precede sldIdLst.
+        '$notesMasterIdLst'
        '<p:sldIdLst>$sldIds</p:sldIdLst>'
        '<p:sldSz cx="$_slideWidthEmu" cy="$_slideHeightEmu" type="screen16x9"/>'
        '<p:notesSz cx="6858000" cy="9144000"/>'
        '</p:presentation>';
  }

-  String _presentationRels(int count) {
+  String _presentationRels(int count, bool hasNotes) {
    final rels = StringBuffer();
    rels.write(
      '<Relationship Id="rId1" '
@ -264,6 +386,14 @@ class ExportService {
      'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme" '
      'Target="theme/theme1.xml"/>',
    );
+    if (hasNotes) {
+      // Must match the r:id used by notesMasterIdLst in _presentationXml.
+      rels.write(
+        '<Relationship Id="rId${count + 4}" '
+        'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/notesMaster" '
+        'Target="notesMasters/notesMaster1.xml"/>',
+      );
+    }
    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
        '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">'
        '$rels'
@ -348,7 +478,12 @@ class ExportService {
        '</p:sld>';
  }

-  String _slideRels(int n) {
+  String _slideRels(int n, bool hasNote) {
+    final notesRel = hasNote
+        ? '<Relationship Id="rId3" '
+              'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/notesSlide" '
+              'Target="../notesSlides/notesSlide$n.xml"/>'
+        : '';
    return '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
        '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">'
        '<Relationship Id="rId1" '
@ -357,6 +492,7 @@ class ExportService {
        '<Relationship Id="rId2" '
        'Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" '
        'Target="../media/image$n.png"/>'
+        '$notesRel'
        '</Relationships>';
  }

--- a/lib/widgets/dialogs/export_dialog.dart
+++ b/lib/widgets/dialogs/export_dialog.dart
@ -99,6 +99,8 @@ class _ExportDialogState extends State<ExportDialog> {
      images,
      compress: compress,
      outputDirectory: widget.exportDirectory,
+      // Speaker notes travel 1:1 with the rendered slides (PPTX notes pane).
+      notes: [for (final s in widget.slides) s.notes],
    );

    if (!mounted) return;
--- a/lib/widgets/slides/slide_preview.dart
+++ b/lib/widgets/slides/slide_preview.dart
@ -1,5 +1,10 @@
 import 'dart:io';
 import 'package:flutter/material.dart';
+import 'package:flutter_highlight/flutter_highlight.dart';
+import 'package:flutter_highlight/themes/github.dart';
+import 'package:flutter_math_fork/flutter_math.dart';
+import 'package:highlight/highlight.dart' show highlight;
+import 'package:highlight/languages/all.dart' show allLanguages;
 import 'package:video_player/video_player.dart';
 import '../../models/deck.dart';
 import '../../models/settings.dart';
@ -1849,7 +1854,6 @@ class _MarkdownPreview extends StatelessWidget {
  Widget build(BuildContext context) {
    final pad = w * 0.07;
    final safe = slide.showLogo ? _logoSafeInsets(w, profile) : EdgeInsets.zero;
-    final lines = slide.customMarkdown.split('\n');

    return Container(
      color: Colors.white,
@ -1869,52 +1873,7 @@ class _MarkdownPreview extends StatelessWidget {
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisSize: MainAxisSize.min,
-                children: lines.take(20).map((line) {
-                  final link = _hexColor(profile.accentColor);
-                  if (line.startsWith('# ')) {
-                    return _md(
-                      context,
-                      line.substring(2),
-                      _applyFont(
-                        font,
-                        TextStyle(
-                          fontSize: w * 0.04,
-                          fontWeight: FontWeight.bold,
-                          color: AppTheme.navy,
-                        ),
-                      ),
-                      linkColor: link,
-                    );
-                  } else if (line.startsWith('## ')) {
-                    return _md(
-                      context,
-                      line.substring(3),
-                      _applyFont(
-                        font,
-                        TextStyle(
-                          fontSize: w * 0.03,
-                          fontWeight: FontWeight.w600,
-                        ),
-                      ),
-                      linkColor: link,
-                    );
-                  } else if (line.startsWith('- ')) {
-                    return _md(
-                      context,
-                      '• ${line.substring(2)}',
-                      _applyFont(font, TextStyle(fontSize: w * 0.024)),
-                      linkColor: link,
-                    );
-                  } else if (line.isEmpty) {
-                    return SizedBox(height: w * 0.01);
-                  }
-                  return _md(
-                    context,
-                    line,
-                    _applyFont(font, TextStyle(fontSize: w * 0.024)),
-                    linkColor: link,
-                  );
-                }).toList(),
+                children: _buildBlocks(context),
              ),
            ),
          ),
@ -1922,6 +1881,162 @@ class _MarkdownPreview extends StatelessWidget {
      ),
    );
  }
+
+  /// Parse the free Markdown into block widgets: fenced ```code``` (syntax
+  /// highlighted), `$$…$$` display math, and ordinary heading/bullet/text lines.
+  List<Widget> _buildBlocks(BuildContext context) {
+    final link = _hexColor(profile.accentColor);
+    final lines = slide.customMarkdown.split('\n');
+    final widgets = <Widget>[];
+    var i = 0;
+    // Cap rendered blocks so a huge slide can't blow up layout (the preview is a
+    // thumbnail; FittedBox scales the rest down).
+    while (i < lines.length && widgets.length < 24) {
+      final line = lines[i];
+
+      // Fenced code block: ``` or ```language … ```
+      final fence = RegExp(r'^\s*```(.*)$').firstMatch(line);
+      if (fence != null) {
+        final language = fence.group(1)!.trim();
+        final code = <String>[];
+        i++;
+        while (i < lines.length && !RegExp(r'^\s*```\s*$').hasMatch(lines[i])) {
+          code.add(lines[i]);
+          i++;
+        }
+        if (i < lines.length) i++; // consume the closing fence
+        widgets.add(_codeBlock(code.join('\n'), language));
+        continue;
+      }
+
+      // Display math fenced by lines containing only `$$`.
+      if (line.trim() == r'$$') {
+        final tex = <String>[];
+        i++;
+        while (i < lines.length && lines[i].trim() != r'$$') {
+          tex.add(lines[i]);
+          i++;
+        }
+        if (i < lines.length) i++; // consume the closing $$
+        widgets.add(_mathBlock(tex.join('\n')));
+        continue;
+      }
+      // Single-line display math: $$ … $$
+      final oneLine = RegExp(r'^\s*\$\$(.+)\$\$\s*$').firstMatch(line);
+      if (oneLine != null) {
+        widgets.add(_mathBlock(oneLine.group(1)!.trim()));
+        i++;
+        continue;
+      }
+
+      widgets.add(_textLine(context, line, link));
+      i++;
+    }
+    return widgets;
+  }
+
+  Widget _textLine(BuildContext context, String line, Color link) {
+    if (line.startsWith('# ')) {
+      return _md(
+        context,
+        line.substring(2),
+        _applyFont(
+          font,
+          TextStyle(
+            fontSize: w * 0.04,
+            fontWeight: FontWeight.bold,
+            color: AppTheme.navy,
+          ),
+        ),
+        linkColor: link,
+      );
+    } else if (line.startsWith('## ')) {
+      return _md(
+        context,
+        line.substring(3),
+        _applyFont(
+          font,
+          TextStyle(fontSize: w * 0.03, fontWeight: FontWeight.w600),
+        ),
+        linkColor: link,
+      );
+    } else if (line.startsWith('- ')) {
+      return _md(
+        context,
+        '• ${line.substring(2)}',
+        _applyFont(font, TextStyle(fontSize: w * 0.024)),
+        linkColor: link,
+      );
+    } else if (line.isEmpty) {
+      return SizedBox(height: w * 0.01);
+    }
+    return _md(
+      context,
+      line,
+      _applyFont(font, TextStyle(fontSize: w * 0.024)),
+      linkColor: link,
+    );
+  }
+
+  Widget _codeBlock(String code, String language) {
+    _ensureHighlightLanguages();
+    final mono = TextStyle(
+      fontFamily: 'monospace',
+      fontSize: w * 0.02,
+      height: 1.3,
+      color: const Color(0xFF24292E),
+    );
+    // HighlightView throws on an unregistered language, so only use it for ones
+    // we actually know; otherwise fall back to plain monospace.
+    final known = language.isNotEmpty && allLanguages.containsKey(language);
+    final Widget content = known
+        ? HighlightView(
+            code,
+            language: language,
+            theme: githubTheme,
+            padding: EdgeInsets.zero,
+            textStyle: mono,
+          )
+        : Text(code, style: mono);
+    return Container(
+      width: double.infinity,
+      margin: EdgeInsets.symmetric(vertical: w * 0.008),
+      padding: EdgeInsets.all(w * 0.018),
+      decoration: BoxDecoration(
+        color: const Color(0xFFF6F8FA),
+        borderRadius: BorderRadius.circular(w * 0.008),
+        border: Border.all(color: const Color(0xFFE1E4E8)),
+      ),
+      child: content,
+    );
+  }
+
+  Widget _mathBlock(String tex) {
+    return Padding(
+      padding: EdgeInsets.symmetric(vertical: w * 0.012),
+      child: Math.tex(
+        tex,
+        textStyle: _applyFont(font, TextStyle(fontSize: w * 0.032)),
+        onErrorFallback: (err) => Text(
+          '\$\$$tex\$\$',
+          style: TextStyle(
+            fontFamily: 'monospace',
+            fontSize: w * 0.022,
+            color: Colors.red,
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+/// Register highlight.js language definitions once, so [HighlightView] can
+/// colour any common language without throwing.
+bool _highlightReady = false;
+void _ensureHighlightLanguages() {
+  if (_highlightReady) return;
+  allLanguages.forEach(highlight.registerLanguage);
+  _highlightReady = true;
 }

 // ── Shared helper ─────────────────────────────────────────────────────────────
--- a/pubspec.lock
+++ b/pubspec.lock
@ -214,6 +214,14 @@ packages:
    description: flutter
    source: sdk
    version: "0.0.0"
+  flutter_highlight:
+    dependency: "direct main"
+    description:
+      name: flutter_highlight
+      sha256: "7b96333867aa07e122e245c033b8ad622e4e3a42a1a2372cbb098a2541d8782c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.0"
  flutter_lints:
    dependency: "direct dev"
    description:
@ -222,6 +230,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "6.0.0"
+  flutter_math_fork:
+    dependency: "direct main"
+    description:
+      name: flutter_math_fork
+      sha256: "6d5f2f1aa57ae539ffb0a04bb39d2da67af74601d685a161aff7ce5bda5fa407"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.4"
  flutter_plugin_android_lifecycle:
    dependency: transitive
    description:
@ -238,6 +254,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "3.3.1"
+  flutter_svg:
+    dependency: transitive
+    description:
+      name: flutter_svg
+      sha256: "35882981abcbfb8c15b286f0cd690ff25bac12d95eff3e25ee207f37d4c42e7f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.0"
  flutter_test:
    dependency: "direct dev"
    description: flutter
@ -264,6 +288,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "2.1.3"
+  highlight:
+    dependency: "direct main"
+    description:
+      name: highlight
+      sha256: "5353a83ffe3e3eca7df0abfb72dcf3fa66cc56b953728e7113ad4ad88497cf21"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.0"
  hooks:
    dependency: transitive
    description:
@ -280,6 +312,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "0.15.6"
+  http:
+    dependency: transitive
+    description:
+      name: http
+      sha256: "87721a4a50b19c7f1d49001e51409bddc46303966ce89a65af4f4e6004896412"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.6.0"
  http_multi_server:
    dependency: transitive
    description:
@ -408,6 +448,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "2.0.0"
+  nested:
+    dependency: transitive
+    description:
+      name: nested
+      sha256: "03bac4c528c64c95c722ec99280375a6f2fc708eec17c7b3f07253b626cd2a20"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
  node_preamble:
    dependency: transitive
    description:
@ -552,6 +600,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "6.5.0"
+  provider:
+    dependency: transitive
+    description:
+      name: provider
+      sha256: "4e82183fa20e5ca25703ead7e05de9e4cceed1fbd1eadc1ac3cb6f565a09f272"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.1.5+1"
  pub_semver:
    dependency: transitive
    description:
@ -805,6 +861,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "0.6.17"
+  tuple:
+    dependency: transitive
+    description:
+      name: tuple
+      sha256: a97ce2013f240b2f3807bcbaf218765b6f301c3eff91092bcfa23a039e7dd151
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.2"
  typed_data:
    dependency: transitive
    description:
@ -893,6 +957,30 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "4.5.3"
+  vector_graphics:
+    dependency: transitive
+    description:
+      name: vector_graphics
+      sha256: "2306c03da2ba81724afeb589c351ebbc0aa7d86005925be8f8735856dbe5e42d"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.2"
+  vector_graphics_codec:
+    dependency: transitive
+    description:
+      name: vector_graphics_codec
+      sha256: "99fd9fbd34d9f9a32efd7b6a6aae14125d8237b10403b422a6a6dfeac2806146"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.13"
+  vector_graphics_compiler:
+    dependency: transitive
+    description:
+      name: vector_graphics_compiler
+      sha256: "7ee12e6dffe0fc8e755179d6d91b3b34f5924223fc104d85572ef9180d73d172"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.5"
  vector_math:
    dependency: transitive
    description:
--- a/pubspec.yaml
+++ b/pubspec.yaml
@ -25,6 +25,9 @@ dependencies:
  url_launcher: ^6.3.0
  desktop_drop: ^0.7.1
  image: ^4.8.0
+  flutter_highlight: ^0.7.0
+  flutter_math_fork: ^0.7.4
+  highlight: ^0.7.0

 dev_dependencies:
  flutter_test:
--- a/test/export_service_test.dart
+++ b/test/export_service_test.dart
@ -99,6 +99,60 @@ void main() {
    }
  });

+  test('PPTX without notes has no notesSlide/notesMaster parts', () async {
+    final r = await service.export(deckPath(), ExportFormat.pptx, [_png()]);
+    final archive = ZipDecoder().decodeBytes(
+      await File(r.outputPath!).readAsBytes(),
+    );
+    final names = archive.files.map((f) => f.name).toSet();
+    expect(names.any((n) => n.startsWith('ppt/notesSlides/')), isFalse);
+    expect(names.any((n) => n.startsWith('ppt/notesMasters/')), isFalse);
+  });
+
+  test('PPTX embeds speaker notes only for slides that have them', () async {
+    final r = await service.export(
+      deckPath(),
+      ExportFormat.pptx,
+      [_png(), _png()],
+      notes: ['', 'Vergeet de cijfers niet <3 & co'],
+    );
+    expect(r.success, isTrue, reason: r.error);
+
+    final archive = ZipDecoder().decodeBytes(
+      await File(r.outputPath!).readAsBytes(),
+    );
+    final names = archive.files.map((f) => f.name).toSet();
+
+    // Notes machinery is present for the noted slide only.
+    expect(names, contains('ppt/notesMasters/notesMaster1.xml'));
+    expect(names, contains('ppt/notesSlides/notesSlide2.xml'));
+    expect(names, isNot(contains('ppt/notesSlides/notesSlide1.xml')));
+
+    String partText(String name) => utf8.decode(
+      archive.files.firstWhere((f) => f.name == name).content as List<int>,
+    );
+
+    // The note text is present and XML-escaped.
+    final notes2 = partText('ppt/notesSlides/notesSlide2.xml');
+    expect(notes2, contains('Vergeet de cijfers niet &lt;3 &amp; co'));
+    // The slide links to its notesSlide.
+    expect(
+      partText('ppt/slides/_rels/slide2.xml.rels'),
+      contains('notesSlide2.xml'),
+    );
+
+    // Every XML part (including the new notes parts) must be well-formed.
+    for (final file in archive.files) {
+      if (file.name.endsWith('.xml') || file.name.endsWith('.rels')) {
+        expect(
+          () => XmlDocument.parse(utf8.decode(file.content as List<int>)),
+          returnsNormally,
+          reason: '${file.name} is not well-formed XML',
+        );
+      }
+    }
+  });
+
  test('compressed PDF is written as a separate -compact file', () async {
    final images = [_png(), _png()];
    final r = await service.export(
--- a/test/free_markdown_preview_test.dart
+++ b/test/free_markdown_preview_test.dart
@ -0,0 +1,53 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_highlight/flutter_highlight.dart';
+import 'package:flutter_math_fork/flutter_math.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:ocideck/models/slide.dart';
+import 'package:ocideck/widgets/slides/slide_preview.dart';
+
+Widget _host(Slide slide) {
+  return Directionality(
+    textDirection: TextDirection.ltr,
+    child: Center(
+      child: SizedBox(
+        width: 800,
+        height: 450,
+        child: SlidePreviewWidget(slide: slide),
+      ),
+    ),
+  );
+}
+
+void main() {
+  testWidgets('free Markdown renders a highlighted code block', (tester) async {
+    final slide = Slide.create(SlideType.freeMarkdown).copyWith(
+      customMarkdown: '# Demo\n\n```dart\nvoid main() => print(42);\n```\n',
+    );
+    await tester.pumpWidget(_host(slide));
+
+    expect(find.byType(HighlightView), findsOneWidget);
+  });
+
+  testWidgets('free Markdown renders display math', (tester) async {
+    final slide = Slide.create(SlideType.freeMarkdown).copyWith(
+      customMarkdown: 'Stelling:\n\n\$\$E = mc^2\$\$\n',
+    );
+    await tester.pumpWidget(_host(slide));
+
+    expect(find.byType(Math), findsOneWidget);
+  });
+
+  testWidgets('an unknown code language falls back without throwing', (
+    tester,
+  ) async {
+    final slide = Slide.create(SlideType.freeMarkdown).copyWith(
+      customMarkdown: '```nonexistentlang\nsome code\n```\n',
+    );
+    await tester.pumpWidget(_host(slide));
+
+    // No HighlightView (unknown language) and no exception during build.
+    expect(find.byType(HighlightView), findsNothing);
+    expect(tester.takeException(), isNull);
+    expect(find.text('some code'), findsOneWidget);
+  });
+}