added a swipeable media gallery for chat and folder images and videos with server previews, on-demand originals and zoom, and marked document previews in chat so they no longer pass for photos

lib/widget/file_viewer/file_kind.dart

@@ -58,6 +58,29 @@ const Set<String> _textExtensions = {
   'srt', 'vtt',
 };
 
+/// Further raster formats the gallery shows. They decode via the platform
+/// codecs (HEIC/AVIF) or are JPEG/ICO under another name. SVG and TIFF stay
+/// out: without a server preview only the file viewer can render them.
+const Set<String> _galleryOnlyImageExtensions = {
+  'heic',
+  'heif',
+  'avif',
+  'jfif',
+  'jpe',
+  'ico',
+};
+
+/// Extension-only check (no content sniff) for files the media gallery can
+/// page through — the fallback when no MIME type is known.
+bool isGalleryImageName(String name) {
+  final ext = name.split('.').last.toLowerCase();
+  return _imageExtensions.contains(ext) ||
+      _galleryOnlyImageExtensions.contains(ext);
+}
+
+bool isGalleryVideoName(String name) =>
+    _videoExtensions.contains(name.split('.').last.toLowerCase());
+
 /// Detects the [FileKind] of the file at [path] from its extension, falling
 /// back to an 8 KB content sniff ([_looksLikeText]) for unknown extensions.
 Future<FileKind> detectFileKind(String path) async {

lib/widget/file_viewer/local_file_actions.dart

@@ -0,0 +1,59 @@
+import 'dart:io';
+
+import 'package:file_picker/file_picker.dart';
+import 'package:flutter/material.dart';
+import 'package:share_plus/share_plus.dart';
+
+import '../async_action_button.dart';
+import '../info_dialog.dart';
+import '../share_position_origin.dart';
+
+/// "Teilen"/"Speichern" for a file that is on disk, shared by the file viewer
+/// and the media gallery.
+Future<void> shareLocalFile(BuildContext context, String path) =>
+    runWithErrorDialog(
+      context,
+      () => SharePlus.instance.share(
+        ShareParams(
+          files: [XFile(path)],
+          sharePositionOrigin: SharePositionOrigin.get(context),
+        ),
+      ),
+    );
+
+Future<void> saveLocalFile(BuildContext context, String path) async {
+  try {
+    final source = File(path);
+    final size = await source.length();
+    // file_picker has no path/stream save API, so the whole file
+    // gets loaded into RAM. Cap big media; user falls back to share.
+    const maxBytes = 200 * 1024 * 1024;
+    if (size > maxBytes) {
+      if (!context.mounted) return;
+      InfoDialog.show(
+        context,
+        'Diese Datei ist zu groß (${(size / (1024 * 1024)).toStringAsFixed(0)} MB), '
+        'um direkt gespeichert zu werden. Nutze stattdessen die Teilen-Funktion.',
+        title: 'Speichern nicht möglich',
+      );
+      return;
+    }
+    final bytes = await source.readAsBytes();
+    final saved = await FilePicker.saveFile(
+      fileName: path.split('/').last,
+      bytes: bytes,
+    );
+    if (!context.mounted) return;
+    if (saved != null) {
+      InfoDialog.show(context, 'Datei gespeichert.');
+    }
+  } on Object catch (e) {
+    if (!context.mounted) return;
+    InfoDialog.show(
+      context,
+      'Speichern fehlgeschlagen: $e',
+      copyable: true,
+      title: 'Fehler',
+    );
+  }
+}

lib/widget/file_viewer/media_player.dart

@@ -13,11 +13,13 @@ class MediaPlayer extends StatefulWidget {
   final String path;
   final bool isAudio;
   final String? filename;
+  final bool autoPlay;
   const MediaPlayer({
     super.key,
     required this.path,
     required this.isAudio,
     this.filename,
+    this.autoPlay = false,
   });
 
   @override
@@ -57,7 +59,7 @@ class _MediaPlayerState extends State<MediaPlayer> {
         _video = controller;
         _chewie = ChewieController(
           videoPlayerController: controller,
-          autoPlay: false,
+          autoPlay: widget.autoPlay,
           looping: false,
           allowFullScreen: true,
           allowPlaybackSpeedChanging: true,