Add per-slide TLP classification with sharing-level filtering

Each slide can now carry its own Traffic Light Protocol level. When the
presentation is shared at a given TLP level, slides classified stricter
than that level are withheld, so the same deck can be shown safely to
audiences with different clearances.

- Slide.tlp field with markdown round-trip via a <!-- tlp: <key> --> marker
  (also on code slides).
- Editor: a per-slide "TLP van deze slide" dropdown.
- Central rule slideVisibleAtTlp() compares levels on the TLP severity
  order (none < CLEAR < GREEN < AMBER < AMBER+STRICT < RED).
- Filtering lives in _slidesForPresentationOrExport, the single source of
  slides for presenting (single-window and dual-screen) and for every
  export (PDF, PPTX, HTML), so all paths honour it.
- Translations for the new strings in all supported languages, plus tests
  for the round-trip and the visibility rule.

flutter analyze is clean and all tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/l10n/app_localizations.dart

@@ -1174,6 +1174,7 @@ const _dutchSourceStrings = {
     'Vrije Markdown': 'Markdown libero',
     'Broncode': 'Codice sorgente',
     'Programmeertaal': 'Linguaggio di programmazione',
+    'TLP van deze slide': 'TLP di questa slide',
     'Plak of typ hier je broncode...':
         'Incolla o digita qui il tuo codice sorgente...',
     'Overgeslagen': 'Saltata',
@@ -1345,6 +1346,7 @@ const _dutchSourceStrings = {
     'Vrije Markdown': 'Freies Markdown',
     'Broncode': 'Quellcode',
     'Programmeertaal': 'Programmiersprache',
+    'TLP van deze slide': 'TLP dieser Folie',
     'Plak of typ hier je broncode...':
         'Quellcode hier einfügen oder eingeben...',
     'Overgeslagen': 'Übersprungen',
@@ -1517,6 +1519,7 @@ const _dutchSourceStrings = {
     'Vrije Markdown': 'Markdown libre',
     'Broncode': 'Code source',
     'Programmeertaal': 'Langage de programmation',
+    'TLP van deze slide': 'TLP de cette diapositive',
     'Plak of typ hier je broncode...':
         'Collez ou tapez votre code source ici...',
     'Overgeslagen': 'Ignorée',
@@ -1688,6 +1691,7 @@ const _dutchSourceStrings = {
     'Vrije Markdown': 'Markdown libre',
     'Broncode': 'Código fuente',
     'Programmeertaal': 'Lenguaje de programación',
+    'TLP van deze slide': 'TLP de esta diapositiva',
     'Plak of typ hier je broncode...':
         'Pega o escribe aquí tu código fuente...',
     'Overgeslagen': 'Omitida',
@@ -1860,6 +1864,7 @@ const _dutchSourceStrings = {
     'Vrije Markdown': 'Frije Markdown',
     'Broncode': 'Boarnekoade',
     'Programmeertaal': 'Programmeartaal',
+    'TLP van deze slide': 'TLP fan dizze slide',
     'Plak of typ hier je broncode...': 'Plak of typ hjir dyn boarnekoade...',
     'Overgeslagen': 'Oerslein',
     'Kopiëren': 'Kopiearje',
@@ -2032,6 +2037,7 @@ const _dutchSourceStrings = {
     'Vrije Markdown': 'Markdown liber',
     'Broncode': 'Código fuente',
     'Programmeertaal': 'Lenguahe di programashon',
+    'TLP van deze slide': 'TLP di e slide aki',
     'Plak of typ hier je broncode...': 'Pega òf tek bo código fuente akinan...',
     'Overgeslagen': 'Saltá',
     'Kopiëren': 'Kopia',
@@ -2193,6 +2199,7 @@ const _dutchSourceStringAdditions = {
     'Bullet': 'Bullet',
     'Plak of typ hier je broncode...': 'Paste or type your source code here...',
     'Programmeertaal': 'Programming language',
+    'TLP van deze slide': 'TLP of this slide',
     'Platte tekst': 'Plain text',
     'Titel (optioneel)': 'Title (optional)',
     'HTML opent in elke browser zonder internet en rendert codeblokken, wiskunde en mermaid-diagrammen.':

lib/models/deck.dart

@@ -2,8 +2,17 @@ import 'slide.dart';
 import 'settings.dart';
 
 /// Traffic Light Protocol-classificatie (FIRST TLP 2.0) van een presentatie.
+///
+/// De volgorde loopt van minst naar meest beperkend; [TlpLevel.index] is dus
+/// bruikbaar om niveaus te vergelijken.
 enum TlpLevel { none, clear, green, amber, amberStrict, red }
 
+/// Of [slide] getoond mag worden wanneer de presentatie op [presentationTlp]
+/// wordt gedeeld. Een slide wordt achtergehouden zodra zijn eigen TLP-niveau
+/// strenger (hoger) is dan het voor de presentatie gekozen niveau.
+bool slideVisibleAtTlp(Slide slide, TlpLevel presentationTlp) =>
+    slide.tlp.index <= presentationTlp.index;
+
 extension TlpLevelX on TlpLevel {
   /// De officiële markering die op de slides verschijnt ('' bij [none]).
   String get label {

lib/models/slide.dart

@@ -1,4 +1,5 @@
 import 'package:uuid/uuid.dart';
+import 'deck.dart';
 
 const _uuid = Uuid();
 
@@ -104,6 +105,10 @@ class Slide {
   final bool showLogo; // show the profile logo on this slide (default true)
   final bool showFooter; // show the profile footer on this slide (default true)
   final bool skipped; // skip this slide when presenting and exporting
+  /// Per-slide Traffic Light Protocol classification. The slide is withheld
+  /// when the presentation is shared at a lower (less restrictive) level than
+  /// this. [TlpLevel.none] = no per-slide restriction (always shown).
+  final TlpLevel tlp;
   final List<List<String>> tableRows; // first row is the header
 
   const Slide({
@@ -132,6 +137,7 @@ class Slide {
     this.showLogo = true,
     this.showFooter = true,
     this.skipped = false,
+    this.tlp = TlpLevel.none,
     this.tableRows = const [],
   });
 
@@ -184,6 +190,7 @@ class Slide {
       showLogo: src.showLogo,
       showFooter: src.showFooter,
       skipped: src.skipped,
+      tlp: src.tlp,
       tableRows: src.tableRows.map((r) => List<String>.from(r)).toList(),
     );
   }
@@ -213,6 +220,7 @@ class Slide {
     bool? showLogo,
     bool? showFooter,
     bool? skipped,
+    TlpLevel? tlp,
     List<List<String>>? tableRows,
   }) {
     return Slide(
@@ -241,6 +249,7 @@ class Slide {
       showLogo: showLogo ?? this.showLogo,
       showFooter: showFooter ?? this.showFooter,
       skipped: skipped ?? this.skipped,
+      tlp: tlp ?? this.tlp,
       tableRows: tableRows ?? this.tableRows,
     );
   }

lib/services/markdown_service.dart

@@ -354,6 +354,13 @@ class MarkdownService {
       buf.writeln('<!-- skip -->');
     }
 
+    // Per-slide TLP classification (used to withhold the slide when sharing at
+    // a lower level). Persisted so it survives save/load round-trips.
+    if (slide.tlp != TlpLevel.none) {
+      buf.writeln();
+      buf.writeln('<!-- tlp: ${slide.tlp.key} -->');
+    }
+
     if (slide.notes.isNotEmpty) {
       buf.writeln();
       buf.writeln('<!--');
@@ -597,6 +604,7 @@ class MarkdownService {
     final notesBuffer = StringBuffer();
     double advanceDuration = 0;
     bool skipped = false;
+    TlpLevel slideTlp = TlpLevel.none;
     final bullets = <String>[];
     var bullets2 = <String>[];
     // bulletsImage slides store their panel width in `<!-- _style:
@@ -610,6 +618,8 @@ class MarkdownService {
           advanceDuration = double.tryParse(content.substring(8).trim()) ?? 0;
         } else if (content == 'skip') {
           skipped = true;
+        } else if (content.startsWith('tlp:')) {
+          slideTlp = TlpLevelX.fromKey(content.substring(4));
         } else if (content.startsWith('_style:')) {
           final w = RegExp(r'--image-width:\s*(\d+)%').firstMatch(content);
           if (w != null) styleImageWidth = int.tryParse(w.group(1)!) ?? 0;
@@ -636,6 +646,7 @@ class MarkdownService {
         notes: notes,
         advanceDuration: advanceDuration,
         skipped: skipped,
+        tlp: slideTlp,
       );
     }
 
@@ -820,6 +831,7 @@ class MarkdownService {
       showLogo: showLogo,
       showFooter: showFooter,
       skipped: skipped,
+      tlp: slideTlp,
       tableRows: type == SlideType.table ? tableRows : const [],
     );
   }
@@ -832,6 +844,7 @@ class MarkdownService {
     required String notes,
     required double advanceDuration,
     required bool skipped,
+    TlpLevel tlp = TlpLevel.none,
   }) {
     final lines = remaining.split('\n');
     String title = '';
@@ -892,6 +905,7 @@ class MarkdownService {
       showLogo: !classTokens.contains('no-logo'),
       showFooter: !classTokens.contains('no-footer'),
       skipped: skipped,
+      tlp: tlp,
     );
   }
 }

lib/widgets/app_shell.dart

@@ -139,7 +139,11 @@ List<String> _imageUsages(WidgetRef ref, String absolutePath) {
 }
 
 List<Slide> _slidesForPresentationOrExport(Deck deck) {
-  final slides = deck.slides.where((s) => !s.skipped).toList();
+  // Drop skipped slides and slides whose TLP classification is stricter than
+  // the level chosen for this presentation/export.
+  final slides = deck.slides
+      .where((s) => !s.skipped && slideVisibleAtTlp(s, deck.tlp))
+      .toList();
   final closingMarkdown = deck.themeProfile.closingSlideMarkdown.trim();
   if (deck.themeProfile.closingSlideEnabled && closingMarkdown.isNotEmpty) {
     slides.add(
@@ -947,7 +951,9 @@ class _MainLayoutState extends ConsumerState<_MainLayout> {
       // zichtbare slide vertalen.
       final visible = <int>[
         for (var i = 0; i < deck.slides.length; i++)
-          if (!deck.slides[i].skipped) i,
+          if (!deck.slides[i].skipped &&
+              slideVisibleAtTlp(deck.slides[i], deck.tlp))
+            i,
       ];
       final slides = _slidesForPresentationOrExport(deck);
       if (slides.isEmpty) {

lib/widgets/panels/editor_panel.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../../models/deck.dart';
 import '../../models/settings.dart';
 import '../../models/slide.dart';
 import '../../services/image_service.dart';
@@ -126,6 +127,8 @@ class EditorPanel extends ConsumerWidget {
                 const Divider(height: 1),
                 _SlideTimingControl(slide: slide, onUpdate: update),
                 const Divider(height: 1),
+                _SlideTlpControl(slide: slide, onUpdate: update),
+                const Divider(height: 1),
                 _NotesField(slide: slide, onUpdate: update),
               ],
             ),
@@ -174,6 +177,7 @@ class EditorPanel extends ConsumerWidget {
       imageSize: slide.imageSize,
       showLogo: slide.showLogo,
       showFooter: slide.showFooter,
+      tlp: slide.tlp,
       tableRows: newType == SlideType.table
           ? (slide.tableRows.isNotEmpty
                 ? slide.tableRows
@@ -660,6 +664,57 @@ class _SlideFooterControl extends StatelessWidget {
   }
 }
 
+// ── Per-slide TLP-classificatie ───────────────────────────────────────────────
+
+class _SlideTlpControl extends StatelessWidget {
+  final Slide slide;
+  final ValueChanged<Slide> onUpdate;
+  const _SlideTlpControl({required this.slide, required this.onUpdate});
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = context.l10n;
+    return Container(
+      color: const Color(0xFFF8FAFC),
+      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 7),
+      child: Row(
+        children: [
+          const Icon(Icons.shield_outlined, size: 14, color: Color(0xFF64748B)),
+          const SizedBox(width: 8),
+          Expanded(
+            child: Text(
+              l10n.d('TLP van deze slide'),
+              style: const TextStyle(fontSize: 12, color: Color(0xFF475569)),
+            ),
+          ),
+          DropdownButtonHideUnderline(
+            child: DropdownButton<TlpLevel>(
+              value: slide.tlp,
+              isDense: true,
+              borderRadius: BorderRadius.circular(6),
+              style: const TextStyle(fontSize: 12, color: Color(0xFF0F172A)),
+              items: [
+                for (final level in TlpLevel.values)
+                  DropdownMenuItem(
+                    value: level,
+                    child: Text(
+                      level == TlpLevel.none
+                          ? l10n.d('Geen')
+                          : level.menuLabel,
+                    ),
+                  ),
+              ],
+              onChanged: (v) {
+                if (v != null) onUpdate(slide.copyWith(tlp: v));
+              },
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
 // ── Speakernotes veld ─────────────────────────────────────────────────────────
 
 class _NotesField extends StatefulWidget {

test/markdown_round_trip_test.dart

@@ -307,6 +307,32 @@ void main() {
       expect(normal.skipped, isFalse);
     });
 
+    test('keeps the per-slide TLP classification', () {
+      final out = _roundTrip(
+        Slide.create(
+          SlideType.bullets,
+        ).copyWith(title: 'Gevoelig', bullets: ['Geheim'], tlp: TlpLevel.amber),
+      );
+      expect(out.tlp, TlpLevel.amber);
+
+      final none = _roundTrip(
+        Slide.create(SlideType.bullets).copyWith(bullets: ['Open']),
+      );
+      expect(none.tlp, TlpLevel.none);
+    });
+
+    test('keeps the per-slide TLP on a code slide', () {
+      final out = _roundTrip(
+        Slide.create(SlideType.code).copyWith(
+          customMarkdown: 'secret_key = 42',
+          codeLanguage: 'python',
+          tlp: TlpLevel.red,
+        ),
+      );
+      expect(out.type, SlideType.code);
+      expect(out.tlp, TlpLevel.red);
+    });
+
     test('keeps general presentation metadata in the front matter', () {
       final service = MarkdownService();
       final markdown = service.generateDeck(

test/tlp_test.dart

@@ -34,6 +34,42 @@ void main() {
     });
   });
 
+  group('slideVisibleAtTlp', () {
+    Slide slideAt(TlpLevel level) =>
+        Slide.create(SlideType.bullets).copyWith(tlp: level);
+
+    test('an unclassified slide is always visible', () {
+      for (final level in TlpLevel.values) {
+        expect(slideVisibleAtTlp(slideAt(TlpLevel.none), level), isTrue);
+      }
+    });
+
+    test('a slide stricter than the presentation is withheld', () {
+      // Presentation at GREEN: CLEAR/GREEN shown, AMBER/RED withheld.
+      expect(slideVisibleAtTlp(slideAt(TlpLevel.clear), TlpLevel.green), isTrue);
+      expect(slideVisibleAtTlp(slideAt(TlpLevel.green), TlpLevel.green), isTrue);
+      expect(
+        slideVisibleAtTlp(slideAt(TlpLevel.amber), TlpLevel.green),
+        isFalse,
+      );
+      expect(slideVisibleAtTlp(slideAt(TlpLevel.red), TlpLevel.green), isFalse);
+    });
+
+    test('a RED presentation shows every slide', () {
+      for (final level in TlpLevel.values) {
+        expect(slideVisibleAtTlp(slideAt(level), TlpLevel.red), isTrue);
+      }
+    });
+
+    test('an unset presentation only shows unclassified slides', () {
+      expect(slideVisibleAtTlp(slideAt(TlpLevel.none), TlpLevel.none), isTrue);
+      expect(
+        slideVisibleAtTlp(slideAt(TlpLevel.clear), TlpLevel.none),
+        isFalse,
+      );
+    });
+  });
+
   group('TLP marking on slides', () {
     Widget host(TlpLevel tlp) => MaterialApp(
       home: Scaffold(