Fix recent documents SecurityException by filtering inaccessible URIs

Co-authored-by: TomTasche <128734+TomTasche@users.noreply.github.com>

Author: Copilot

app/src/main/java/at/tomtasche/reader/background/RecentDocumentsUtil.java

@@ -30,7 +30,10 @@ public static Map<String, String> getRecentDocuments(Context context)
             String filename = document.getString("filename");
             String uri = document.getString("uri");
 
-            result.put(filename, uri);
+            // Only include URIs that are still accessible
+            if (isUriAccessible(context, Uri.parse(uri))) {
+                result.put(filename, uri);
+            }
         }
 
         return result;
@@ -134,4 +137,19 @@ private static int findUriIndex(String uriString, JSONArray jsonArray) throws JS
         }
         return index;
     }
+
+    /**
+     * Check if a URI is still accessible to the app.
+     * This helps filter out URIs that no longer have valid permissions.
+     */
+    private static boolean isUriAccessible(Context context, Uri uri) {
+        try {
+            // Try to open an input stream to test accessibility
+            context.getContentResolver().openInputStream(uri).close();
+            return true;
+        } catch (Exception e) {
+            // URI is not accessible (SecurityException, FileNotFoundException, etc.)
+            return false;
+        }
+    }
 }