fix: skip pdfrx cache initialization folder on web platforms

lib/main.dart

@@ -2,32 +2,15 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:pdfrx/pdfrx.dart';
-import 'package:path_provider/path_provider.dart';
-import 'dart:io';
 import 'package:pdf_signature/app.dart';
+import 'package:pdf_signature/utils/pdfrx_cache_init/pdfrx_cache_init.dart';
 export 'package:pdf_signature/app.dart';
 
-Future<void> _initPdfrxCache() async {
-  try {
-    // Only set once; guard for hot reload/tests
-    if (Pdfrx.getCacheDirectory == null) {
-      final dir = await getTemporaryDirectory();
-      final cacheDir = Directory('${dir.path}/pdfrx_cache');
-      if (!await cacheDir.exists()) {
-        await cacheDir.create(recursive: true);
-      }
-      Pdfrx.getCacheDirectory = () async => cacheDir.path;
-      debugPrint('[main] Pdfrx cache directory set to ${cacheDir.path}');
-    }
-  } catch (e, st) {
-    debugPrint('[main] Failed to initialize Pdfrx cache directory: $e');
-    debugPrint(st.toString());
-  }
-}
-
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
-  await _initPdfrxCache();
+  // Initialize pdfrx core (safe to call multiple times) and set up cache directory.
+  pdfrxFlutterInitialize();
+  await initPdfrxCache();
   // Disable right-click context menu on web using Flutter API
   if (kReleaseMode) {
     debugPrint = (String? message, {int? wrapWidth}) {

lib/ui/features/pdf/view_model/pdf_view_model.dart

@@ -1,3 +1,4 @@
+// ignore_for_file: unnecessary_import
 import 'dart:typed_data';
 import 'package:cross_file/cross_file.dart';
 import 'package:flutter/material.dart';
@@ -10,6 +11,7 @@ import 'package:pdfrx/pdfrx.dart';
 import 'package:file_picker/file_picker.dart' as fp;
 import 'package:go_router/go_router.dart';
 import 'package:path_provider/path_provider.dart';
+import 'package:flutter/foundation.dart';
 
 class PdfViewModel extends ChangeNotifier {
   final Ref ref;
@@ -322,10 +324,8 @@ class PdfSessionViewModel extends ChangeNotifier {
     int pageCount = 1; // default
     try {
       // Defensive: ensure Pdfrx cache directory set (in case main init skipped in tests)
-      if (Pdfrx.getCacheDirectory == null) {
-        debugPrint(
-          '[PdfSessionViewModel] Pdfrx.getCacheDirectory was null; setting temp directory',
-        );
+      if (Pdfrx.getCacheDirectory == null && !kIsWeb) {
+        debugPrint('[PdfSessionViewModel] Setting Pdfrx cache directory (io)');
         try {
           final temp = await getTemporaryDirectory();
           Pdfrx.getCacheDirectory = () async => temp.path;
@@ -336,6 +336,8 @@ class PdfSessionViewModel extends ChangeNotifier {
           debugPrint(st.toString());
         }
       }
+      // Ensure engine initialized (safe multiple calls)
+      pdfrxFlutterInitialize();
       final doc = await PdfDocument.openData(bytes);
       pageCount = doc.pages.length;
       debugPrint(

lib/utils/pdfrx_cache_init/pdfrx_cache_init.dart

@@ -0,0 +1,3 @@
+// Conditional export: use IO implementation except when compiling for web (html).
+export 'pdfrx_cache_init_io.dart'
+    if (dart.library.html) 'pdfrx_cache_init_web.dart';

lib/utils/pdfrx_cache_init/pdfrx_cache_init_io.dart

@@ -0,0 +1,26 @@
+import 'dart:io';
+import 'package:flutter/foundation.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:pdfrx/pdfrx.dart';
+
+/// Initialize Pdfrx cache directory for IO platforms (mobile/desktop). No-op on web.
+Future<void> initPdfrxCache() async {
+  try {
+    if (kIsWeb) return; // Guard (should not be used on web, but extra safety)
+    if (Pdfrx.getCacheDirectory != null) return; // Already set
+    final dir = await getTemporaryDirectory();
+    final cacheDir = Directory('${dir.path}/pdfrx_cache');
+    if (!await cacheDir.exists()) {
+      await cacheDir.create(recursive: true);
+    }
+    Pdfrx.getCacheDirectory = () async => cacheDir.path;
+    debugPrint(
+      '[pdfrx_cache_init_io] Pdfrx cache directory set to ${cacheDir.path}',
+    );
+  } catch (e, st) {
+    debugPrint(
+      '[pdfrx_cache_init_io] Failed to initialize Pdfrx cache directory: $e',
+    );
+    debugPrint(st.toString());
+  }
+}

lib/utils/pdfrx_cache_init/pdfrx_cache_init_web.dart

@@ -0,0 +1,17 @@
+import 'package:flutter/foundation.dart';
+import 'package:pdfrx/pdfrx.dart';
+
+/// Web stub: pdfrx can operate without a filesystem cache; leave getCacheDirectory null.
+Future<void> initPdfrxCache() async {
+  // Intentionally no-op. If desired, could set an in-memory indicator.
+  debugPrint(
+    '[pdfrx_cache_init_web] Skipping Pdfrx cache directory setup on web',
+  );
+  // Ensure any previous (hot-reload) IO assignment isn't kept when switching target.
+  if (kIsWeb && Pdfrx.getCacheDirectory != null) {
+    // Leave as-is; clearing could break existing references. Merely log.
+    debugPrint(
+      '[pdfrx_cache_init_web] Existing getCacheDirectory left unchanged',
+    );
+  }
+}